text:
|Publication number
|Publication type
|Application number
|Publication date
|Jan 19, 2010
|Filing date
|Aug 16, 2006
|Priority date
|Aug 16, 2006
|Fee status
|Also published as
|Publication number
|Christopher D. Moffatt
|Original Assignee
|Harris Corporation
|Export Citation
|BiBTeX, EndNote, RefMan
|Patent Citations (44), Non-Patent Citations (3), Referenced by (18), Classifications (8), Legal Events (3)
|External Links: USPTO, USPTO Assignment, Espacenet
The present invention relates to communications systems, and more particularly, this invention relates to multiple carrier communication systems, including but not limited to, Orthogonal Frequency Division Multiplexing (OFDM) communications systems.
In OFDM communications systems the frequencies and modulation of a frequency-division multiplexing (FDM) communications signal are arranged orthogonal with each other to eliminate interference between signals on each frequency. In this system, low-rate modulations with relatively long symbols compared to the channel time characteristics are less sensitive to multipath propagation issues OFDM thus transmits a number of low symbol-rate data streams on separate narrow frequency subbands using multiple frequencies simultaneously instead of transmitting a single, high symbol-rate stream on one wide frequency band on a single frequency. These multiple subbands have the advantage that the channel propagation effects are generally more constant over a given subband than over the entire channel as a whole. A classical In-phase/Quadrature (I/Q) modulation can be transmitted over individual subbands. Also, OFDM is typically used in conjunction with a Forward Error Correction scheme, which in this instance, is sometimes termed Coded Orthogonal FDM or COFDM.
An OFDM signal can be considered the sum of a number of orthogonal subcarrier signals, with baseband data on each individual subcarrier independently modulated, for example, by Quadrature Amplitude Modulation (QAM) or Phase-Shift Keying (PSK). This baseband signal can also modulate a main RF carrier.
OFDM communications systems have high spectrum efficiency (a high number of bits per second per Hz of bandwidth), simple mitigation of multi-path interference, and an ease in filtering noise. OFDM communications systems suffer, however, from time-variations in the channel, especially those which cause carrier frequency offsets. Because the OFDM signal is the sum of a large number of subcarrier signals, it can have a high peak-to-average amplitude or power ratio. It is also necessary to minimize intermodulation between subcarrier signals, which can create self-interference in-band, and create adjacent channel interference. Carrier phase noise, Doppler frequency shifts, and clock jitter can create Inter-Carrier Interference (ICI) for closely frequency-spaced subcarriers. The subcarriers are typically transmitted at assigned frequency locations within a transmission spectrum. Over the duration of the transmission of an OFDM signal, the average power per subcarrier is significant, and can be easily detected and intercepted, which is undesirable to a system requiring Low Probability of Detection (LPD) and Low Probability of Interception (LPI) characteristics. The receiver that is to receive the OFDM signal requires a minimum signal-to-noise ratio (SNR) per subcarrier in order to demodulate and decode the signal with an acceptably low bit error rate (BER). If there is other unwanted energy within the transmission spectrum, the SNR can decrease causing an increase in BER. Said unwanted energy can be unintentional noise from other sources. In this case the noise is referred to as "interference" and the sources are referred to as "interferers." If the unwanted energy corrupting the transmission is transmitted intentionally by some third party source known as a jammer, it is referred to as a jamming signal. The conventional OFDM signal is susceptible to such interferers and jammers because of the required minimum SNR per subcarrier for an acceptably low BER. Further, frequency selective fading in the channel causes transmission nulls within the OFDM signal's transmission spectrum, which selectively reduce the SNR on certain subcarriers within those nulls, depending on their frequency location, leading to an undesirable increase in HER.
A device and system communicates data and includes a modulation and mapping circuit that modulates and maps data symbols into a plurality of multiple subcarrier frequencies that are orthogonal to each other to form an Orthogonal Frequency Division Multiplexed (OFDM) communications signal based on a fixed or variable OFDM symbol rate. A pseudo-random signal generator operative with the modulation and mapping circuit generates pseudo-random signals to the modulation and mapping circuit based on an encryption algorithm for frequency hopping each subcarrier at an OFDM symbol rate to lower any probability of interception and detection, reduce power per frequency (dB/Hz/sec), and lower any required transmission power while maintaining an instantaneous signal-to-noise ratio, A frequency domain spreader circuit is operatively connected to the modulation and mapping circuit for spreading the multiple subcarriers over the frequency domain.
The frequency domain spreader can be formed as a Walsh Transform circuit that is operative for applying a Walsh Transform and spreading the multiple subcarriers over the frequency domain. This Walsh Transform circuit is operative for multiplying an input vector of a symbol by the Walsh Transform. An Inverse Fast Fourier Transform (IFFT) circuit is positioned to receive signals from the frequency domain spreader circuit. The pseudo-random signal generator is operative for generating a pseudo-random signal based on the encryption algorithm such that consecutive OFDM symbols do not transmit subcarriers on the same frequency. The pseudo-random signal generator is operative for generating a pseudo-random signal based on the encryption algorithm such that OFDM symbols do not transmit subcarriers on adjacent frequencies for reduced Inter-Carrier Interference (ICI). The pseudo-random signal generator can also be operative for generating a pseudo-random signal based on the encryption algorithm such that a guard interval is reduced or eliminated.
In yet another aspect, the modulation and mapping circuit is operative for inserting signals for reducing peak-to-average power ratio (PAPR). A modulator can map the communications data into modulated symbols based on a specific mapping algorithm. The pseudo-random signal generator is operatively connected to the modulator for varying amplitude and phase values using an encryption algorithm. An encoder as a forward error correction circuit can add a FEC code.
In yet another aspect, the device can be part of a transmitter that transmits the communications signal that carries communications data. A receiver can receive the communications signal and include a demapping and demodulation circuit and frequency domain despreading circuit for processing the communications signal to obtain the communications data. The transmitter is operative for modulating a main carrier signal.
In yet another aspect, a method is disclosed in which communications data is distributed over multiple subcarriers that are orthogonal to each other to form an Orthogonal Frequency Division Multiplexed (OFDM) communications signal based on a fixed or variable OFDM symbol rate. Each subcarrier can be frequency hopped at an OFDM symbol rate to lower any probability of interception and detection, reduce power per frequency (dB/Hz/sec), and lower any required transmission power while maintaining an instantaneous signal-to-noise ratio. The multiple subcarriers are spread over the frequency domain and the communications data is transmitted over the signal,
Other objects, features, and advantages of the present invention will become apparent from the detailed description of the invention which follows, when considered in light of the accompanying drawings in which:
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
The system, apparatus and method in accordance with a non-limiting example of the present invention uses a Symbol Based Randomization (SBR), Orthogonal Frequency Division Multiplexing (OFDM) communications signal to enhance the Low Probability of Interception (LPI) and Low Probability of Detection (LPD). This signal also allows an increased transmit power within a Federal Communications Commission (FCC) spectral mask by reducing the average power per Hertz per second while maintaining the same instantaneous signal-to-noise ratio (SNR). A frequency-domain spreading function, such as the Walsh transform, can also be applied in the frequency domain to enhance performance.
Orthogonal Frequency Division Multiplexing (OFDM) is also termed Multicarrier Modulation (MCM) because the signal uses multiple carrier signals that are transmitted at different frequencies. Some of the bits or symbols normally transmitted on one channel or carrier are now transmitted by this system on multiple carriers in the channel. Advanced Digital Signal Processing (DSP) techniques distribute the data over multiple carriers (subcarriers) at predetermined frequencies. For example, if the lowest-frequency subcarrier uses a base frequency, the other subcarriers could be integer multiples of that base frequency. The particular relationship among the subcarriers is considered the orthogonality such that the energy from one subcarrier can appear at a frequency where all other subcarrier's energy equal zero. There can be a superposition of frequencies in the same frequency range. This results in a lower symbol rate on each subcarrier with less Inter-Symbol Interference (ISI) due to adverse effects of multipath. In many OFDM communications systems, a Guard Interval (GI) or Cyclic Prefix (CP) is prefixed or appended to the OFDM symbol to mitigate the effects of ISI.
The drawings in
In an OFDM communications system using a transmitter and receiver such as shown in
The OFDM system as shown in
An OFDM signal is typically the sum of each of the orthogonal subcarriers. Baseband data is independently modulated onto each of the orthogonal subcarriers using some type of modulation, such as Quadrature Amplitude Modulation (QAM) or Phase Shift Keying (PSK) schemes as discussed before. Because the spectrum of each subcarrier overlaps, it can be considerably wider than if no overlap were allowed. Thus, OFDM provides high spectrum efficiency. Because each subcarrier operates at a low symbol rate, the duration of each symbol in the subcarrier is long. (For clarity, "symbol rate" is equal to the inverse of "symbol duration"). By using Forward Error Correction (FEC) equalization and modulation, there can be an enhanced resistance against a) link dispersion, b) slowly changing phase distortion and fading, c) frequency response nulls, d) constant interference, and e) burst noise. Further, the use of a Guard Interval (GI) or cyclic prefix provides enhanced resistance against multipath in the transmission channel.
Typically, in OFDM communications system, a subcarrier and somewhat rectangular pulse can be employed and operative by an Inverse Discrete Fourier Transform (IDFT) using an Inverse Fast Fourier Transform (IFFT) circuit within the transmitter. At a receiver, a Fast Fourier Transform (FFT) circuit reverses this operation. The rectangular pulse shape results in a Sin(x)/x spectrum in the subcarriers.
The spacing of subcarriers can be chosen such that the received subcarriers can cause zero or acceptably low Inter-Carrier Interference (ICI) when the receiver and transmitter are synchronized. Typically, OFDM communications systems split the available bandwidth into many narrow-band subbands from as little as a few dozen to as many as eight thousand to ten thousand. Unlike the communications system providing multiple channels using classical FDM as in
Usually, in an OFDM communications system, the spectrum required for transmitting data is chosen based on the input data and a desired modulation scheme to be used with each carrier that is assigned the data to transmit. Any amplitude and phase of the carrier is calculated based on the modulation, for example, BPSK, QPSK or QAM as noted before. Any required spectrum is converted using the IFFT circuit to ensure carrier signals are orthogonal.
It should be understood that a FFT circuit transforms a cyclic time domain signal to an equivalent frequency spectrum by finding an equivalent waveform that is generated as a sum of orthogonal sinusoidal components. The frequency spectrum of the time domain signal is usually represented by the amplitude and phase sinusoidal components. The IFFT circuit performs the reverse process and transforms the spectrum of the amplitude and phase into a time domain signal. For example, an IFFT circuit can convert a set of complex data points into a time domain signal of the same number of points. Each complex input point will result in an integral number of sinusoid and cosinusoid cycles represented by the same number of points as were input to the IFFT. Each sinusoid known as the in-phase component, and cosinusoid known as the quadrature component, will be orthogonal to all other components generated by the IFFT. Thus, orthogonal carriers can be generated by setting an amplitude and phase for each frequency point representing a desired subcarrier frequency and performing the IFFT.
It should be understood that a Guard Interval (GI), also termed a cyclic prefix, often is added to an OFDM symbol. The guard interval reduces the effects of the wireless channel on Inter-Symbol Interference (ISI) and contains redundant transmission information. Referring to the IEEE 802.11a standard as a non-limiting example, if a carrier spacing is 3125 KHz, and the Fourier Transforms are performed over 3.2 microseconds, then a 0.8 microsecond guard interval can be applied for ISI rejection. The guard "interval" could be the last Tg seconds of an active symbol period that is prefixed to an OFDM symbol, making it a cyclic prefix. It is kept short for a fraction of "T," corresponding to the total length of the active symbol, yet longer than the channel impulse response. This helps reduce the ISI and Inter-Carrier Interference (ICI) and maintains subcarrier orthogonality. In this example, a time waveform appears periodic to the receiver over the duration of the FFT.
To reduce ICI, the OFDM symbol can be cyclically extended in the guard time to ensure that delayed replicas of the OFDM symbol can have an integer number of cycles within the FFT interval, as long as the delay is smaller than the guard time. As a result, multipath signals with delays smaller than the guard time would not produce ICI.
Multipath interference is caused when multiple copies of the transmitted signal arrive at the receiver at different times. It should be understood that an OFDM communications system reduces the effect of multipath interference by providing the ability to add signal redundancy in both frequency and time by the use of various coding algorithms. For example, with the IEEE 802.11a standard using OFDM, 48 carriers can be transmitted simultaneously. The coding gain can be provided using a one-half (�.) convolutional encoder at the transmitter and later a Viterbi decoder. Data bits can be interleaved across multiple symbols and carriers. Lost data often is recoverable because of interleaving across the frequency and time space.
Increasing the data rate requires an increase in the symbol rate for a fixed number of carriers, fixed modulation scheme and fixed sample rate. For a single carrier system, complex equalizers and adaptive filters are required at the receiver to compensate for the magnitude and time distortions caused by the channel. The accuracy and dynamic range required of such equalizers and filters increases markedly as symbol times are decreased. However, in an OFDM system, for example, when 48 subcarriers are transmitted simultaneously, the symbol rate is effectively reduced by 48 times, significantly reducing the requirements of channel equalizers and filters. The reduced symbol rate of an OFDM system enables a robust communication link, resistant to ISI.
It should be understood that an OFDM receiver receives a sum of the different signals as subcarriers. The addition of a guard interval can further enhance performance in an OFDM system by ensuring that no symbol transitions occur during each received symbol time. For example, if an OFDM subcarrier is BPSK modulated, there would be a 180 degree phase jump at symbol boundaries. By choosing a guard interval that is longer than the largest expected time difference between the first and last multipath signals, such phase transitions can occur only during the guard time, meaning there are no phase transitions during the FFT interval. If the phase transitions of a delayed path occur within the FFT interval of the receiver, then the summation of the subcarriers of the first path with the phase modulated waves of the delayed path would no longer produce a set of orthogonal subcarriers, resulting in a certain level of interference.
As discussed above, OFDM communications systems can use FEC techniques and known interleaving and mapping techniques before IFFT processing as shown in
These interleaving, coding, e.g., convolutional codes, including puncturing, and deinterleaving and decoding and related techniques often are integral parts of OFDM communications systems. As an example, a rate �, K=7 convolutional code can be used as an industry standard code for forward error correction (FEC) during encoding. For purposes of understanding the present invention, a more detailed description of these basic system components now follows A convolutional code is an error-correcting code, and usually has three parameters (n, k, m) with n equal to the number of output bits, k equal to the number of input bits, and m equal to the number of memory registers, in one non-limiting example. The quantity k/n could be called the code rate with this definition and is a measure of the efficiency of the code. K and n parameters range typically from 1 to 8, m ranges typically from 2 to 10, and the code rate typically ranges from ⅛ to ⅞ in non-limiting examples. Sometimes convolutional code chips are specified by parameters (n, k, L) with L equal to the constraint length of the code. Thus, the constraint length can represent the number of bits in an encoder memory that would affect the generation of n output bits. Sometimes the letters may be switched depending on the definitions used.
The transformation of the encoded data is a function of the information symbols and the constraint length of the code. Single bit input codes can produce punctured codes that give different code rates. For example, when a rate � code is used, the transmission of a subset of the output bits of the encoder can convert the rate � code into a rate ⅔ code. Thus, one hardware circuit or module can produce codes of different rates. Punctured codes can be used also, which allow rates to be changed dynamically through software or hardware depending on channel conditions, such as rain or other channel impairing conditions.
An encoder for a convolutional code typically uses a Linear Feedback Shift Register (LFSR) or look-up table (LUT) for encoding, which usually includes an input bit as well as a number of previous input bits (known as the state of the encoder), the table value being the output bit or bits of the encoder. It is possible to view the encoder function as a state diagram, a tree diagram or a trellis diagram.
Decoding systems for convolutional codes can use 1) sequential decoding, or 2) maximum likelihood decoding, such as Viterbi decoding in one non-limiting example, which typically is more desirable. Sequential decoding allows both forward and backward movement through the trellis. Viterbi decoding as maximum likelihood decoding examines a receive sequence of given length, computes a metric for each path, and makes a decision based on the metric. Turbo codes are another example of a forward error correction scheme that can be used.
Puncturing convolutional codes is a common practice in some OFDM systems and can be used in accordance with non-limiting examples of the present invention. It should be understood that in some examples a punctured convolutional code is a higher rate code obtained by the periodic elimination of specific logic bits or symbols from the output of a low rate encoder. Punctured convolutional code performance can be degraded compared with original codes, but typically the data rate increases.
Some of the basic components that could be used as non-limiting examples of the present invention include the transmitter as described before that incorporates a convolutional encoder, which encodes a sequence of binary input vectors to produce the sequence of binary output vectors and can be defined using a trellis structure. An interleaver, for example, a block interleaver, can permute the bits of the output vectors. The interleaved data would also be modulated at the transmitter (by mapping to transmit symbols) and transmitted. At a receiver, a demodulator demodulates the signal.
A block deinterleaver recovers the bits that were interleaved. A Viterbi decoder could decode the deinterleaved bit soft decisions to produce binary output data.
Often a Viterbi forward error correction module or core is used that would include a convolutional encoder and Viterbi decoder as part of a radio modem or transceiver as described above. For example if the constraint length of the convolutional code is 7, the encoder and Viterbi decoder could support selectable code rates of �, ⅔, �, ⅘, ⅚, 6/7, ⅞ using industry standard puncturing algorithms.
Different design and block systems parameters could include the constraint length as a number of input bits over which the convolutional code is computed, and a convolutional code rate as the ratio of the input to output bits for the convolutional encoder. The puncturing rate could include a ratio of input to output bits for the convolutional encoder using the puncturing process, for example, derived from a rate � code.
The Viterbi decoder parameters could include the convolutional code rate as a ratio of input to output bits for the convolutional encoder. The puncture rate could be the ratio of input to output bits for the convolutional encoder using a puncturing process and can be derived from a rate � mother code. The input bits could be the number of processing bits for the decoder. The Viterbi input width could be the width of input data (i.e. soft decisions) to the Viterbi decoder A metric register length could be the width of registers storing the metrics. A trace back depth could be the length of path required by the Viterbi decoder to compute the most likely decoded bit value. The size of the memory storing the path metrics information for the decoding process could be the memory size. In some instances, a Viterbi decoder could include a First-In/First-Out (FIFO) buffer between depuncture and Viterbi function blocks or modules. The Viterbi output width could be the width of input data to the Viterbi decoder.
The encoder could include a puncturing block circuit or module as noted above. Usually a convolutional encoder may have a constraint length of 7 and take the form of a shift register with a number of elements, for example, 6. One bit can be input for each clock cycle. Thus, the output bits could be defined by a combination of shift register elements using a standard generator code and be concatenated to form an encoded output sequence. There could be a serial or parallel byte data interface at the input. The output width could be programmable depending on the punctured code rate of the application.
A Viterbi decoder in non-limiting examples could divide the input data stream into blocks, and estimate the most likely data sequence. Each decoded data sequence could be output in a burst. The input and calculations can be continuous and require four clock cycles for every two bits of data in one non-limiting example. An input FIFO can be dependent on a depuncture input data rate.
Also turbo codes could be used as high-performance error correction codes or low-density parity-check codes that approach the Shannon limit as the theoretical limit of maximum information transfer rate over a noisy channel. Thus, some available bandwidth can be increased without increasing the power of the transmission. Instead of producing binary digits from the signal, the front-end of the decoder could be designed to produce a likelihood measure for each bit.
It should be understood that OFDM coded transmissions may be easily detected and received by unintended recipients by detection of data subcarriers and pilot tones. Addition of multiple sine waves or carriers with random amplitudes and phases to the waveform will cause it to approach a Gaussian distribution due to the central limit theorem. A signal having a Gaussian random distribution inherently has an enhanced Low Probability of Interception (LPI) and Low Probability of Detection (LPD) because it appears similar to additive white Gaussian noise (AWGN) to a receiver.
In accordance with a non-limiting example of the present invention, a modified transmitter as explained in detail below uses an IFFT to create multiple subcarriers located at specific frequencies. Only a small subset of the possible carriers need to be used at any one time to enhance power, reduce ICI, and enhance LPI and LPD. Subcarrier center frequencies can be changed at OFDM symbol times according to an encryption algorithm. Such an algorithm can generate a pseudo-random frequency hopping sequence and frequency hopping subcarriers in accordance with a non-limiting example of the present invention. Thus, fast-frequency hopping can change the subcarriers frequency for each OFDM symbol, and provide a one thousand (1,000) times faster frequency hopping than the Bluetooth standard, and ten times its data rate. Additional benefits can include a reduced ICI, a reduced ISI, and reduced transmitter overhead from the guard interval. The system, apparatus and method in accordance with a non-limiting example of the present invention allows a symbol-based randomization for the OFDM signal.
A Walsh transform can be applied to spread subcarriers over the frequency domain, in contrast with spreading over the time domain as with conventional CDMA systems. Applying a Walsh transform before any IFFT circuit can reduce average power for enhanced LPI/LPD. Various aspects of the communications system can be readily varied for improved performance. With fewer subcarriers as compared to the IFFT size and the spreading sequence length, more processing gain may be realized from frequency domain spreading. Furthermore, LPI/LPD and Anti-Jamming (AJ) performance can be enhanced, and there can be higher SNR per subcarrier.
Increasing the sample rate also increases the bandwidth, data rate, and improves the LPI/LPD/AJ performance.
Referring now to
Many of the high-level components of the illustrated transmitter 100 and receiver 200 are functionally similar to the components shown in the prior art modem of
Added functional components that aid in generating the frequency hopping, OFDM signal that can be Walsh transformed in accordance with a non-limiting example of the present invention include a Pseudo-Random Amplitude and Phase Generator 102 and Pseudo-Random Subcarrier Locations circuit 104. Both the Generator 102 and circuit 104 are operative with an Encryption Algorithm 106 and a Cryptographic and Key generator circuit (Crypto-Key) 108 and Master Clock 110. These components can be generally referred to as an encrypted pseudo-random signal generator. A Frequency Domain Spreader circuit 112 is located before an IFFT circuit, as illustrated, and is operable for frequency spreading the signal, such as by applying a Walsh transform. Also, a digital/analog converter can receive a signal from a Bandwidth Adjust DAC Sample Rate circuit 114 for removing spectral lines. These components are explained in further detail below.
As illustrated in
The Encryption Algorithm 106 is operative not only with the Crypto-Key circuit 108 and the Master Clock 110, but also the Pseudo-Random Amplitude and Phase Generator 102, which generates pseudo-random signals to the QAM/PSK Modulator 134 in accordance with a non-limiting example of the present invention. The Pseudo-Random Subcarrier Location circuit 104 is also operative with the Subcarrier Mapper circuit 138 and receives signals from the Encryption Algorithm 106. The OFDM Subcarriers are frequency hopped quickly by means of such circuits.
In accordance with a non-limiting example of the present invention, the Frequency Domain Spreader circuit 112 is located before the IFFT circuit 140 and applies the Walsh transform in the frequency domain. If the Frequency Domain Spreader circuit 112 were located after the IFFT circuit 140, then the Walsh or other function would force a time-domain spreading. It should be understood that the Frequency Domain Spreader circuit 112 and IFFT circuit 140 can typically be considered with the modulation and mapping circuit 132 as an OFDM modulation circuit or OFDM modulation and mapping circuit. In accordance with a non-limiting example of the present invention, the spreading resulting from application of the Walsh transform occurs in the frequency domain. A cyclic extension as a guard interval can be added within a Cyclic Extension circuit 142. A symbol-shaping filter 144 such as a Finite Impulse Response (FIR) filter, cosine filter, or raised cosine filter can be operative as a "Time Window" for symbol shaping in conjunction with the Cyclic Extensions. A packet buffer 146 receives the signals, and after buffering, the signals are converted to analog signals in a digital/analog converter 148. The D/A converter 148 also receives from a Bandwidth Adjust DAC Sample Rate circuit 114 a signal for further processing that removes spectral lines. The D/A Converter 148 passes signals to a Radio Integrated Circuit (IC) Wideband Slow Frequency Hopping circuit 150. The RF carrier can be subjected to a pseudo-random frequency hopping algorithm for enhanced bandwidth, and is operative also as a frequency up-converter, as illustrated.
Basic components of the frequency up-converter circuit 150 can include a transmit chain circuit 152 that receives the signal into a mixer 154. The signal passes through a Bandpass Filter 156, a series of amplifiers 158 and through a Single Pole Double Throw (SPDT) switch 160. After switching, a low pass filter 162 filters the signal. The radio frequency signal is amplified by the Power Amplifier 164 for subsequent transmission through antenna 166. Other components in the circuit 150 include a Phased-Lock Loop circuit 170, a 40. MHz signal generator 172 as a non-limiting example, a low pass filter 174, an amplifier 176, a synthesizer 170, another amplifier 180, a bandpass filter 182, a summer circuit 184, and another amplifier 186 that connects to the mixer 154. The component parts of frequency upconverter circuit 150 may be used to affect a low rate frequency hopping scheme, where the entire OFDM baseband waveform is frequency translated to different center frequencies. Such slow frequency hopping can further guard against interference and provide an additional level of encryption if the slow hopping sequence is designed as such.
The transmitter 100 as described is a non-limiting example and many other types of transmitters could be used. It should be understood that with advances in DSP and other circuit functions, processing can possibly occur directly at baseband.
It should also be understood that the subcarrier mapper circuit 138 maps carriers to the IFFT circuit 140. For example, if the IFFT circuit 140 has an input with a 64 sample signal in the frequency domain, it would give a 64 sample signal in the time domain as a matrix operation. The subcarrier mapper circuit 138 can change the order of the vectors to position symbols on arbitrary subcarriers and apply zero to other subcarriers. For example, some of the samples in a 64 sample vector would be zeros, meaning they would not show up in the frequency domain if they are OFF. Any that are ON or non-zero will change location with every IFFT cycle (once per symbol) to produce the frequency hopping OFDM signal. The nature of the frequency hopping for the OFDM signal is generated by the Encryption Algorithm 106 and the Pseudo-Random Subcarrier Locations circuit 104 and the Pseudo-Random Amplitude and Phase Generator 102. The QAM/PSK Modulator 134 aids in producing the constellation amplitude and phase.
One of the aspects of this invention involves obscuring to an unintended receiver that the data has been encrypted. To obscure the encryption, three unknowns are produced by the transmitter. For example, there is a) the unknown of the transmitted amplitude and phase; b) the unknown of the pseudo-random amplitude and phase; and c) the unknown of the channel amplitude and phase. Because there are three unknowns, it is not possible to know which signal is transmitted with an encryption algorithm, based on the Cryptographic Key and Master Clock.
The Frequency Domain Spreader circuit 112 operates as a matrix operation. For example, if a 64 IFFT circuit 140 is employed, then a 64�64. Walsh Matrix (as a non-limiting example) can be used to frequency-spread the subcarriers and provide processing gain. An input vector would be multiplied by the Walsh matrix. It should be understood that a Walsh matrix is a square matrix with dimensions that can be a power of "two." The entries are positive or negative one (+1, −1). The Walsh matrix can be obtained from a Hadamard Matrix that is defined by a recursive formula of the same dimension by arranging rows such that the number of sign changes is in increasing order, i.e., sequential ordering. Each row of a Walsh matrix corresponds to a Walsh function. The ordering of rows in a Walsh matrix can be derived from ordering a Hadamard matrix by applying a bit-reversal permutation and a Gray code permutation. The Walsh functions form an orthogonal basis of a square that is integratable on a unit interval. Thus, it can generate statistically unique sets of numbers suitable for use in encryption, also known as "pseudo-random and noise codes." The multiplication may be implemented efficiently as a series of additions and subtractions.
The Bandwidth Adjust DAC Sample Rate circuit 114 is operative with the D/A converter 148 and can adjust the sample rate and remove spectral lines. As a result, it is harder to detect the waveform with a Spectrogram. It should be understood that the transmitter 100 as described is operative to form a Frequency Hopping OFDM signal with a Walsh transform. For example, if an IFFT is used with 64 samples per symbol, the frequency location of each subcarrier can be changed every 64 samples. As an example, if an IFFT is computed every four microseconds, then frequency hopping on all 64 carriers can occur every four microseconds to impart a fast hopping rate. Because this can be accomplished symbol-by-symbol, the frequency hopping OFDM communications system as described can also be termed a Symbol-Based Randomized OFDM because the subcarrier frequency locations are randomly changed. Another receiver would not be able to determine the subcarrier locations without the Encryption Algorithm and related circuits, and a full synchronization.
Other high-level components illustrated for this receiver circuit 200 include an antenna 220, a low noise amplifier (LNA) 222, and Radio Integrated circuit down-converter 224, which can process a frequency hopping carrier signal in reverse if it had been processed for wideband by the Radio IC Wideband Slow Frequency Hopping circuit 150 shown in the transmitter 100 of
The transmitter 100 and receiver 200 shown in
For example, the receiver 200 could measure the received Signal-to-Noise ratio per subcarrier, for example, by using channel estimation symbols, a preamble, or a special channel estimation packet. Information can be passed back to the transmitter as a "channel mask", specifying the number of subcarriers to "turn-off" and the possible frequency locations of interferers as channel impairments such that the transmitter 100 could use the negotiated channel mask to avoid transmission on any undesirable frequencies. In one example, ten carriers are turned on simultaneously over a 100 MHz bandwidth, and each carrier is transmitted for 640 nanoseconds (corresponding to a 1/FFT rate), such that each carrier can hop 1,562,500 times per second. This is about a one thousand times faster hopping than the Bluetooth protocol and can provide more than ten times the data rate.
The transmitter 100 can create multiple subcarriers located at specific frequencies and can generate a pseudo-random frequency hop for each subcarrier frequency by applying the frequency hopping algorithm as explained before. The IFFT circuit 140 creates multiple subcarriers located at specific frequencies. In accordance with a non-limiting example of the present invention, only a small subset of all possible subcarriers need to be used at any one time, although all subcarriers can be used if necessary. For example, as in the example discussed above, instead of 64 subcarriers, only 10 subcarriers can be used in this non-limiting example, giving in that example the 1,562,500 hops per second.
The subcarrier center frequencies can be changed at the OFDM symbol rate using the encryption algorithm for the pseudo-random frequencies. This occurs at the modulation and mapping circuit 132 in which the carriers are mapped to the IFFT. The center frequencies of the subcarriers can appear random because of the frequency hopping algorithm. The symbol time duration can be very short as noted above, and therefore, each subcarrier would appear for a short time at any specific frequency.
The guard time can be reduced or eliminated by ensuring that consecutive symbols do not contain subcarriers at the same frequency location. For example, in prior art systems, if two symbols are back-to-back on the same frequency, multipath signals could arrive at different times at the same location. By using the system and circuits shown in
It is possible using the transmitter 100 and receiver 200 as shown in
It is also possible to dynamically add and remove subcarriers depending on the required data rate. The minimum carrier spacing can increase to reduce the Inter-Carrier Interference (ICI) and provide robustness to jamming i.e. anti-jamming (AJ) capability, because of the frequency hopping signal. As long as carriers are not transmitted next to each other in the frequency domain, the Inter-Carrier Interference will be reduced.
It is also possible for the carrier frequency to hop pseudo-randomly and cover a wide bandwidth. This can be accomplished by the Radio IC Wideband Slow Frequency Hopping circuit 150 shown in
A "dead-time" pseudo-random generator can be introduced into the system to decrease "on" time, and the output spacing between symbols can be increased. The spacing can be varied using the pseudo-random generator to prevent spectral lines and reduce cyclostationary statistics of the signal. This type of system can be implemented without an output sample control. The system can wait a random amount of time before transmitting. By removing the spectral lines, it is more difficult for other systems to detect the transmitted communications. The term cyclostationary can refer to the mean standard deviation as a second order statistic of the signal. The output sample control can refer to control at the D/A Converter 148.
The subcarrier constellation amplitude and phase values can also be varied pseudo-randomly using the generator 102 operative with the modulator 134 as shown in
It should be understood that these algorithms can be added to Software Defined Radios (SDR) and can be implemented with some changes to vary data rate and modulation. The data rates, bandwidth, transmission power and LPI/LPD performance can be improved by varying the subcarrier modulation scheme, sample rate, IFFT size, IFFT duration and the number of subcarriers used per OFDM symbol.
As shown in
It should be understood that OFDM is susceptible to Frequency Selective Fading because of multipath. The Walsh transform can provide processing gain to the system and robustness against frequency selective fading.
The system, apparatus and method as described provides a very fast frequency hopping by changing subcarrier frequency locations, for example, at the OFDM symbol rate. Thus, it can provide a reduced spectral density over time (decibel/hertz/second) in order to provide a Low Probability of Interception (LPI) and Low Probability of Detection (LPD). The system as described is much faster than Bluetooth systems, and makes the transmission within the FCC spectral mask possible at greater distances. It also eliminates or substantially reduces a guard interval by ensuring that subcarriers do not appear on the same frequency for consecutive OFDM symbols. The system also provides robustness against Inter-Symbol Interference (ISI) due to multipath. The Walsh transform can be applied in the frequency-domain to spread the frequency-hopping subcarriers over the spectrum and reduce the power spectral density (decibels over hertz) to improve LPI/LDP performance or help comply with FCC spectral mask requirements. It can also provide a processing gain against frequency selective fading and provide robustness against jamming.
Referring now to
An example of a communications system that can be modified for use with the present invention is now set forth with regard to
An example of a radio that can be used with such system and method is a Falcon™ III radio manufactured and sold by Harris Corporation of Melbourne, Fla. The Falcon™ III can include a basic transmit switch, and other functional switches and controls known to those skilled in the art. It should be understood that different radios can be used, including but not limited to software defined radios that can be typically implemented with relatively standard processor and hardware components. One particular class of software radio is the Joint Tactical Radio (JTR), which includes relatively standard radio and processing hardware along with any appropriate waveform software modules to implement desired communication waveforms. JTR radios also use operating system software that conforms to the software communications architecture (SCA) specification (see www.jtrs.saalt.mil), which is hereby incorporated by reference in its entirety. The SCA is an open architecture framework that specifies how hardware and software components are to interoperate so that different manufacturers and developers can readily integrate the respective components into a single device.
The Joint Tactical Radio System (JTRS) Software Component Architecture (SCA) defines a set of interfaces and protocols, often based on the Common Object Request Broker Architecture (CORBA), for implementing a Software Defined Radio (SDR). In part, JTRS and its SCA are used with a family of software re-programmable radios. As such, the SCA is a specific set of rules, methods, and design criteria for implementing software re-programmable digital radios.
The JTRS SCA specification is published by the JTRS Joint Program Office (JPO). The JTRS SCA has been structured to provide for portability of applications software between different JTRS SCA implementations, leverage commercial standards to reduce development cost, reduce development time of new waveforms through the ability to reuse design modules, and build on evolving commercial frameworks and architectures.
The JTRS SCA is not a system specification, as it is intended to be implementation independent, but a set of rules that constrain the design of systems to achieve desired JTRS objectives. The software framework of the JTRS SCA defines the Operating Environment (OE) and specifies the services and interfaces that applications use from that environment. The SCA OE comprises a Core Framework (CF), a CORBA middleware, and an Operating System (OS) based on the Portable Operating System Interface (POSIX) with associated board support packages. The JTRS SCA also provides a building block structure (defined in the API Supplement) for defining application programming interfaces (APIs) between application software components.
The JTRS SCA Core Framework (CF) is an architectural concept defining the essential, "core" set of open software Interfaces and Profiles that provide for the deployment, management, interconnection, and intercommunication of software application components in embedded, distributed-computing communication systems. Interfaces may be defined in the JTRS SCA Specification. However, developers may implement some of them, some may be implemented by non-core applications (i.e., waveforms, etc.), and some may be implemented by hardware device providers.
For purposes of description only, a brief description of an example of a communications system that would benefit from the present invention is described relative to a non-limiting example shown in
The HF radio can include a demodulator circuit 362 a and appropriate convolutional encoder circuit 362 b, block interleaver 362 c, data randomizer circuit 362 d, data and framing circuit 362 e, modulation circuit 362 f, matched filter circuit 362 g, block or symbol equalizer circuit 362 h with an appropriate clamping device, deinterleaver and decoder circuit 362 i modem 362 j, and power adaptation circuit 362 k as non-limiting examples. A vocoder (voice encoder/decoder) circuit 362 l can incorporate the encode and decode functions and a conversion unit which can be a combination of the various circuits as described or a separate circuit. A transmit key switch 362 m is operative as explained above. These and other circuits operate to perform any functions necessary for the present invention, as well as other functions suggested by those skilled in the art. The circuits referenced here may include any combination of software and/or hardware elements, including but not limited to general purpose microprocessors and associated software, specialized microprocessors for digital signal processing and their associated software, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), logic circuits, or other kinds of devices and/or software or firmware known to those skilled in the art. Other illustrated radios, including all VHF mobile radios and transmitting and receiving stations can have similar functional circuits.
The base station segment 352 includes a landline connection to a public switched telephone network (PSTN) 380, which connects to a PABX 382. A satellite interface 384, such as a satellite ground station, connects to the PABX 382, which connects to processors forming wireless gateways 386 a, 386 b. These interconnect to the VHF radio 360 or HF radio 362, respectively. The processors are connected through a local area network to the PABX 382 and e-mail clients 390. The radios include appropriate signal generators and modulators. The packetized or non-packetized digital voice information transmitted within the network using the techniques of the present invention can originate at or be delivered to a handset connected to one of the radios, a telephone or other interface device attached to a wireless gateway device such as the RF-6010. Tactical Network Hub, or a subscriber telephone connected to the PABX or within the public switched telephone network.
An Ethernet/TCP-IP local area network can operate as a "radio" mail server. E-mail messages can be sent over radio links and local air networks using STANAG-5066 as second-generation protocols/waveforms, the disclosure which is hereby incorporated by reference in its entirety and, of course, preferably with the third-generation interoperability standard: STANAG-4538, the disclosure which is hereby incorporated by reference in its entirety. An interoperability standard FED-STD-1052, the disclosure which is hereby incorporated by reference in its entirety, can be used with legacy wireless devices. Examples of equipment that can be used in the present invention include different wireless gateway and radios manufactured by Harris Corporation of Melbourne, Fla. This equipment includes RF5800, 5022, 7210, 5710, 6010, 5285 and PRC 117 and 138 series equipment and devices as non-limiting examples.
These systems can be operable with RF-5710A high-frequency (HF) modems and with the NATO standard known as STANAG 4539, the disclosure which is hereby incorporated by reference in its entirety, which provides for transmission of long distance HF radio circuits at rates up to 9,600 bps. In addition to modem technology, those systems can use wireless email products that use a suite of data-link protocols designed and perfected for stressed tactical channels, such as the STANAG 4538r STANAG 5066, the disclosures which are hereby incorporated by reference in their entirety. It is also possible to use a fixed, non-adaptive data rate as high as 19,200 bps or higher with a radio set to ISB mode and an HF modem set to a fixed data rate. It is possible to use code combining techniques and ARQ.
This application is related to copending patent applications entitled, "SYSTEM AND METHOD FOR COMMUNICATING DATA USING SYMBOL-BASED RANDOMIZED ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING (OFDM)," and "SYSTEM AND METHOD FOR APPLYING FREQUENCY DOMAIN SPREADING TO MULTI-CARRIER COMMUNICATIONS SIGNALS," and "SYSTEM AND METHOD FOR COMMUNICATING DATA USING SYMBOL-BASED RANDOMIZED ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING (OFDM) WITH SELECTED SUBCARRIERS TURNED ON OR OFF," and "METHOD OF COMMUNICATING AND ASSOCIATED TRANSMITTER USING CODED ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING (COFDM)," which are filed on the same date and by the same assignee and inventors, the disclosures which are hereby incorporated by reference.
Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.
|Cited Patent
|Filing date
|Publication date
|Jul 31, 1997
|Mar 14, 2000
|Motorola, Inc.
|Method and apparatus for transmitting signals in a communication system
|Jul 31, 1997
|Jan 16, 2001
|Lucent Technologies, Inc.
|Transmission system and method employing peak cancellation to reduce the peak-to-average power ratio
|Apr 26, 1999
|Jul 31, 2001
|Intellon Corporation
|Windowing function for maintaining orthogonality of channels in the reception of OFDM symbols
|Mar 30, 2000
|Oct 29, 2002
|Qualcomm Incorporated
|Method and apparatus for measuring reporting channel state information in a high efficiency, high performance communications system
|Jun 2, 1999
|Apr 29, 2003
|At&T Corp.
|Method and system for reducing of peak-to-average power ratio of transmission signals comprising overlapping waveforms
|Jun 3, 1996
|Feb 24, 2004
|Broadcom Corporation
|Spread spectrum transceiver module utilizing multiple mode transmission
|Feb 22, 2002
|Apr 20, 2004
|Albert L. Garrett
|Threshold detector for detecting synchronization signals at correlator output during packet acquisition
|Dec 21, 2001
|Sep 28, 2004
|Samsung Electronics Co., Ltd.
|Transmit antenna diversity apparatus and method for a base station in a CDMA mobile communication system
|Feb 7, 2001
|Aug 9, 2005
|At & T Corp.
|OFDM communication system and method having a reduced peak-to-average power ratio
|Oct 18, 2002
|Apr 11, 2006
|Samsung Electronics Co., Ltd.
|Transceiver apparatus and method for efficient high-speed data retransmission and decoding in a CDMA mobile communication system
|Jan 10, 2003
|May 2, 2006
|Qualcomm, Incorporated
|Channel estimation for OFDM communication systems
|Mar 8, 2002
|Jan 30, 2007
|Cisco Systems Wireless Networking (Australia) Pty Limited
|Interleaver, deinterleaver, interleaving method, and deinterleaving method for OFDM data
|Sep 27, 2002
|Oct 9, 2007
|Rockwell Collins, Inc.
|Featureless synchronization in multi-user OFDM
|Aug 7, 2002
|Oct 30, 2007
|Motorola Inc.
|Radio communication system with adaptive interleaver
|Feb 26, 2001
|Sep 13, 2001
|Kabushiki Kaisha Toshiba
|Transmitter apparatus and receiver apparatus and base station making use of orthogonal frequency division multiplexing and spectrum spreading
|Feb 6, 2001
|Dec 19, 2002
|Dan-Keun Sung
|Multi-dimensional orthogonal resource hopping multiplexing communications method and apparatus
|Jun 1, 2001
|Feb 6, 2003
|Wataru Matsumoto
|Communication apparatus and communication method
|Oct 18, 2001
|May 1, 2003
|Walton Jay R.
|Multiple-access hybrid OFDM-CDMA system
|Apr 4, 2003
|Jan 1, 2004
|Jianglei Ma
|Dual-mode shared OFDM methods/transmitters, receivers and systems
|Jul 8, 2002
|Jan 8, 2004
|Ahmed Tewfik
|High bit rate ultra-wideband OFDM
|Jul 3, 2002
|Jan 15, 2004
|Kenichi Miyoshi
|Multi-carrier transmission apparatus, multi-carrier reception apparatus, and multi-carrier radio communication method
|Oct 29, 2003
|May 6, 2004
|Walton Jay R.
|Multiple-access hybrid OFDM-CDMA system
|Oct 22, 2003
|May 13, 2004
|Bbnt Solutions Llc
|Spectrum-adaptive networking
|Feb 26, 2004
|Sep 30, 2004
|Nortel Networks Limited
|Sub-carrier allocation for OFDM
|May 1, 2003
|Nov 4, 2004
|Prabodh Varshney
|Method and apparatus for increasing data rates in a wideband MC-CDMA telecommunication system
|Aug 20, 2004
|Feb 3, 2005
|Zion Hadad
|Bi-directional communication channel
|Aug 3, 2004
|Feb 10, 2005
|Lowell Rosen
|Epoch-variant holographic communications apparatus and methods
|Dec 31, 2003
|Feb 10, 2005
|Sadri Ali S.
|Apparatus and associated methods to perform intelligent transmit power control with subcarrier puncturing
|Jun 14, 2004
|Feb 24, 2005
|Lowell Rosen
|Software-defined wideband holographic communications apparatus and methods
|Sep 15, 2004
|Jun 16, 2005
|Lei Shao
|Apparatus and associated methods to implement a high throughput wireless communication system
|Jun 7, 2004
|Jul 14, 2005
|Maltsev Alexander A.
|Multicarrier communication system and methods for link adaptation using uniform bit loading and subcarrier puncturing
|Dec 31, 2003
|Jul 21, 2005
|Sumeet Sandhu
|Apparatus and associated methods to perform space-frequency interleaving in a multicarrier wireless communication channel
|Feb 2, 2004
|Aug 4, 2005
|Wei An
|Post despreading interpolation in CDMA systems
|Jul 26, 2004
|Sep 8, 2005
|Fujitsu Limited
|Radio communication device and control method of amplification circuit thereof
|Aug 7, 2003
|Oct 6, 2005
|Mills Diane G
|Multiuser detection aided multiple access differential frequency-hopped spread spectrum
|Oct 6, 2005
|Feb 9, 2006
|David Mottier
|Method of assigning a spreading sequence to a user of a telecommunications network
|Aug 23, 2004
|Feb 23, 2006
|Divaydeep Sikri
|Multi-band wideband transmission methods and apparatus having improved user capacity
|Sep 2, 2005
|Mar 9, 2006
|University Of South Florida
|Covert OFDM Transmission Using Cyclic Prefix
|Oct 11, 2005
|Apr 20, 2006
|Rajiv Laroia
|Methods and apparatus for adjusting bandwidth allocation in a wireless communications system
|Nov 23, 2004
|May 25, 2006
|Harris Corporation
|Wireless communications device providing time and frequency-domain channel estimates interpolation and related methods
|Nov 14, 2005
|Jun 15, 2006
|Tae-Joon Kim
|Apparatus of selectively performing fast hadamard transform and fast fourier transform, and CCK modulation and demodulation apparatus using the same
|Dec 22, 2004
|Jun 22, 2006
|Arak Sutivong
|MC-CDMA multiplexing in an orthogonal uplink
|Dec 14, 2005
|Jul 6, 2006
|Ryosuke Mori
|OFDM signal receiving apparatus
|Sep 13, 2005
|Mar 15, 2007
|Via Technologies Inc.
|Circuit for improving channel impulse response estimation and compensating for remnant frequency offset in the orthogonal frequency division multiplexing baseband receiver for IEEE 802.11a/g wireless LAN standard standard
|Cariou, et al., "MIMO Frequency Hopping Spread Spectrum Multi-Carrier Multiple Access: A Novel Uplink System for B3G Cellular Networks," Telecommunications Systems, vol. 30, No. 1-3, Nov. 1, 2005, pp. 193-214.
|Kim et al.,"Frequency-Hopped Multiple-Access Communications with Multicarrier On-Off Keying in Rayleigh Fading Channels," IEEE Transactions on Communications, vol. 48, No. 10, Oct. 2000, pp. 1692-1701.
|Tsumura et al., "Performance Comparison of OFDM-FH and MC-CDM in Single- and Multi-Cell Environments," Vehicular Technology Conference, May 1, 2005, pp. 1730-1734.
|Citing Patent
|Filing date
|Publication date
|Jul 20, 2007
|Dec 14, 2010
|Industrial Technology Research Institute
|Orthogonal frequency division multiplexing transmitting and receiving method and device thereof
|Oct 31, 2007
|May 17, 2011
|Lightwaves Systems, Inc.
|High bandwidth data transport system
|Jul 15, 2009
|Jun 5, 2012
|Linear Signal, Inc.
|Apparatus, system, and method for integrated phase shifting and amplitude control of phased array signals
|Oct 31, 2007
|Jan 1, 2013
|Lightwaves Systems, Inc.
|High bandwidth data transport system
|Oct 28, 2010
|Jan 8, 2013
|Industrial Technology Research Institute
|Orthogonal frequency division multiplexing transmitting and receiving device
|Oct 31, 2007
|May 28, 2013
|Lightwaves Systems, Inc.
|High bandwidth data transport system
|Dec 19, 2011
|Feb 4, 2014
|Khalifa University of Science, Technology & Research (KUSTAR)
|Chaotic cryptography for OFDM based communications systems
|Nov 9, 2010
|Oct 28, 2014
|Linear Signal, Inc.
|Apparatus, system, and method for integrated modular phased array tile configuration
|Mar 11, 2011
|Nov 24, 2015
|Sunrise Micro Devices, Inc.
|Power efficient communications
|Aug 15, 2012
|Jul 12, 2016
|Hughes Network Systems, Llc
|Method and system of providing efficient packetized voice communcations and data bearers in mobile satellite systems
|Jul 20, 2007
|Dec 4, 2008
|Industrial Technology Research Institute
|Orthogonal frequency division multiplexing transmitting and receiving method and device thereof
|Oct 31, 2007
|Apr 30, 2009
|Lightwaves Systems, Inc.
|High bandwidth data transport system
|Oct 31, 2007
|Apr 30, 2009
|Lightwaves Systems, Inc.
|High bandwidth data transport system
|Oct 31, 2007
|Apr 30, 2009
|Lightwaves Systems, Inc.
|High bandwidth data transport system
|Nov 25, 2009
|Aug 5, 2010
|Je-Hong Jong
|Method and system of providing efficient packetized voice communcations and data bearers in mobile satellite systems
|Oct 28, 2010
|Feb 17, 2011
|Industrial Technology Research Institute
|Orthogonal frequency division multiplexing transmitting and receiving device
|Mar 11, 2011
|Sep 15, 2011
|Sunrise Micro Devices, Inc.
|Power efficient communications
|Apr 30, 2015
|Nov 2, 2016
|Harris Corporation
|Wireless communications device providing peak-to-average power ratio (papr) reduction based upon walsh transformation matrix permutations and related methods
|U.S. Classification
|375/260, 375/133
|International Classification
|Cooperative Classification
|European Classification
|Sep 22, 2006
Owner name: HARRIS CORPORATION, FLORIDA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MOFFATT, CHRISTOPHER D.;REEL/FRAME:018334/0421
Effective date: 20060821
|Jul 19, 2013
|Fee payment
Year of fee payment: 4
|Jul 19, 2017
|Fee payment
Year of fee payment: 8


text:
A blog about genealogy and thoughts about the various roots and branches of my family tree as well as the times in which my ancestors lived.Included are the West, White,and McFarland families.WARNING:DO NOT TAKE ALL OF MY FAMILY RECORDS AS GOSPEL. ALWAYS CONFIRM YOUR OWN RESEARCH!
Saturday, May 04, 2013
Groton Ma., the second of the five children of John Ames and Lydia Phelps.
The family moved to Oxford County, Maine between 1790 and 1810, where
John made his living as a farmer and blacksmith in several towns. It was inone
of those towns, Hartford, Maine, that Jonathan met and married his first wife,
my 4x great grandmother Mary "Polly" Griffith on 6Sep 1807. They were married
twenty seven years and produced ten children, seven boys and three girls.Polly
died in 1834. Three years later Jonathan married Polly's sister Sarah Griffith and
the couple had two more daughters. Jonathan died on 16Dec 1863 at Canton,
Oxford, Maine, at age 82.
I've been lucky with many of my New England lines; they lived in towns that have
had books written about their history and those books have provided me with a lot of information and stories. But with a few like the Ames and Coburn lines the information
dries up after the families moved north to MaIne, so I piece together what I can with
whatever records and documents I can find online. Recently I found the 1860 U.S. Federal Census Non-Population Agriculture Schedule for Canton Maine and Jonathan's farm was
one of those enumerated. It gave me a little insight into what his life was like as it was
drawing to a close. Here's a transcript:
Acres of land: Developed-75 acres
Undeveloped-25 acres
Cash value of Farm- 1500 (dollars)
Value of farming Implements and Machinery- 53 (dollars)
Mules and Asses-0
Milch Cows-3
Working Oxen-2
Other cattle-3
Value of Livestock-280 (dollars)
Wheat, bushels of -0
Rye, bushels of- 5
Indian Corn, bushels of -5
Oats, bushels of-4
Rice, lbs of-0
Tobacco, lbs of-0
Ginned Cotton, bales of 400lbs ea-0
Wool,lbs of-65
Peas and Beans, bushels of-4
Irish Potatoes, bushels of-75
Sweet Potatoes, bushels of-0
Barley, bushels of-0
Buckwheat, bushels of-3
Value of Orchard Products, in dolls.-0
Butter, lbs. of-150
Cheese, lbs of-50
Hay, tons of-20
Clover Seed, bushels of-0
Grass seeds, bushels of-0
Hops, lbs. of-0
Dew Rotted, tons of-0
Water Rotted, tons of-0
Other prepared Hemp-0ItalicFlax, lbs of-0
Flaxseed, bush. of-0
Silk Cocoons, lbs, of-0
Maple Sugar, lbs of-0
Cane Sugar,hhds of 1000 lbs,-0
Molasses, gallons of and from what made-0
Beeswax, lbs. of-0
Honey, lbs.of-0
Value of Homemade Manufacture-0 (dollars)
Value of Slaughtered Animals-58 (dollars)
Looking at this, the first thought that struck me was the livestock. We tend to think
of a farmer using a horse to draw his wagon or plow, but nearly all the records I've
seen of ancestors from this period shows them owning at least two pair of oxen. I
think given the rocky New England terrain and the winter snows oxen did most of the
heavy farm work until modern machinery came along. The horse was probably more
for transportation than work. Also, the number of cows is lower than what we think of
when we think of New England farms, but remember, back then there was no milk
pasteurization yet, no refrigeration to transport large amounts of milk to city dwellers.
"Milch cows" were more valuable for the amount of cheese and butter that could be
made from their milk. So while Jonathan had a total of six cows, he had over twice that
amount, fifteen, in sheep. I checked the rest of the entries for Canton and there were
over 1200 sheep on the farms in town. In 1860 the New England textile mills were in
their heyday and wool would have been in demand to make into clothing.
Then I looked at the crops grown on Jonathan's farm and how much he harvested. For a
farm of its size the amounts are low. Jonathan's son -in-law, my 3x great grandfather
John Cutter West farmed fewer acres than Jonathan, forty acres, and had a harvest of
500 bushels of potatoes compared to the 75 on Jonathan's farm. In every crop planted
on both farms, the yield at Jonathan's farm was smaller.
I don't think it was because Jonathan was a poor farmer. I think the answer is simply that
he was old, nearly 80! All his sons were gone from the farm: Jonathan Jr. had moved to
Illinois, Ezekiel was in Massachusetts. Generous, Hezekiah and Atwood were running
their own farms, and two sons, Ephraim and Americus, had already died. The regular
1860 Census shows Jonathan and Sarah living on the farm with a Henry and Emily Potter.
I believe Emily is their daughter, although I haven't found a record of her marriage yet.
So for the moment that's all I know about Jonathan Phelp Ames, my 4x great grandfather,
but I'm still hoping to find more!
4 comments:
- Kathy said...
My Mother mentioned and linked me this blog post. I am descended from Jonathan Phelps Ames as well through his son Generous.
- Bill West said...
Hi Cousin Kathy!
- Sandra Taylor said...
hi there...I am decended also from this line. Jonathan and Mary "polly" Ames daughter( Ruhama was married to Simeon Otis Reynolds Jr. they were my 3x great grandparents...)so I believe that makes Jonathan and "polly" my 4x great grandparents.
- Bill West said...
Hi cousin Sandra! Yes they are 4x great grandparents to us both. There's also a link through the marriage between my 2x great grandfather Jonathan Phelps West and Orpha Reynolds, who was the daughter of Ruhama and Simeon. Unfortunately she died in a diphtheria epidemic and J.P.West remarried later to Louisa Richardson.
If I can be of any help email me. :)

subset: commoncrawl


text:
Samus Varia Suit!
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Registered User
Join Date: Nov 2012
Posts: 14
Samus Varia Suit!
Hey guys!
I'm fairly new to cosplay, I made an assassin's creed costume a couple months ago for the Edmonton Expo and also for Halloween.
It was almost 100% sewing which I have never done before haha.
But I had the help of a lot of tutorials and I love how it turned out!
Here's a pic:
The blades were made out of ball bearing slides.
I made a locking mechanism where when I pulled on a string (attached to a ring on my finger) the blades slide out.
Makes a really awesome metal-clink-slide-out noise
My next project is a much more difficult and completely opposite of the assassin's creed costume. I'm making the full Samus Varia Suit.
I've decided to go with an EVA foam build for some of it and craft foam for the rest.
For painting the pieces I am going to coat in Plasti-Dip then some kind of paint primer
followed by my paint choices (going to be metallic) then a gloss finish/sealer.
I'm going to be making it much like Pixelninja's Suit she re-made in 2010, I'm absolutely in love with it!
Here's a pic of her suit:
I plan on adding all the lights on the suit and the arm cannon.
As this is my very first project like this, I would love to hear any comments/suggestions/criticisms.
Last edited by kitnip : 01-15-2013 at
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"The Nanny Diaries" authors Emma McLaughlin and Nicola Kraus are set to write the screenplay of "Five Men Who Broke My Heart" for Paramount.
The dynamic duo is returning. Shifting from book to screenplay, "The Nanny Diaries" authors Emma McLaughlin and Nicola Kraus have been selected to pen the script of Paramount's new project, "Five Men Who Broke My Heart", Variety has revealed.
Intended to be a romantic comedy, the movie is based on Susan Shapiro's romance memoir of the same title which follows the writer as she faced her midlife crisis that later led her to seek out five boyfriends who dumped her to find out why she didn't measure up. Blumhouse's Jason Blum and Rachael Horovitz of Specialty Film are both seating as the producers.
An alumna of New York University's Gallatin School of Individualized Study, McLaughlin has been covered in virtually every major newspaper and magazine all around the country following her success with "The Nanny Diaries." Her other work, "Citizen Girl", was published in 2004 and takes a look at one woman's career odyssey in the 21st century economy.


text: If you don't want to bother with updating the html, just update the .txt. When we build the next release, we need to make sure and update the html anyway. Docutils from CVS is what Ian was using, and what I used as well. Although very likely slightly different versions... ;-( When we discussed this before, I think we settled on grabbing a snapshot of the docutils package as a good way to insure consistency. We could always dump the snapshot when they release a new version if we wanted to. It is just that nobody has jumped up and done this yet. -Stuart- Jason Hildebrand wrote: >Hi all, > >I just wanted to check in a doc fix that was mentioned on >webware-discuss. As I Stuart found (in a thread from last January), >using the current release of docutils to generate the .html file from >the .txt file resulted in a very different .html than the one Ian >generated (Ian uses docutils CVS). > >I agree that we should be moving towards removing the .html files from >CVS, but in the meantime, is it necessary for me to update the .html >file, or can I simply check in the fixed .txt file? > >Ian, how are you invoking buildhtml.py? Are there any special config >or command-line options you are using? I may just break down and grab >docutils from CVS. :) > > >


text:
Anyone know any good out of waist band holsters for the sig scorpion 1911
Are you looking for leather or kydex? I use a Blackhawk Serpa for my 1911 when I compete in IDPA. But I also have a homemade leather holster that keeps it tighter against my body. What are you going to use it for?
Just for the shooting range give me a place to put it when I'm shooting my ar15 I don't need anything fancy
Look at Fobus. They're inexpensive and they'll hold your pistol.
We will be offering custom holsters for the Sig 1911 platform in just a few days.
To zombihunter where??????
Try Garrett Industries in your search bar. Hybrid Kydex and Leather. 3 week turnaround on receiving product.
I have never liked Kydex, tried 3 different holsters over the last 2 years took them all back. I ordered one for my P 266 Scorpion from Garrett Industries and was trying my best to find fault with it. I wore it for 2 days and decided I liked it. I have always been a big fan of pure leather in high end holsters paying often more than $100 but love that quality and craftsmanship.
These hybrids are not cheap but the quality is there. They hold the weapon tight and tension adjustable and cant adjustable. Be mindful of choosing the correct one for the type of weapon you carry. Example I would not buy a IWB for a P266 as it would be to big an heavy for that type of holster. Good Luck
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Perimeter lighting
Polished stainless steel bezel
Contoured pointer
Domed glass lens
Fahrenheit and Celsius scales
Faria instruments get the job done with style and proven performance. The Chesapeake SS family of gauges provide clear, easy-to-read displays with beautiful styling that will bring your dashboard to life. Design features include perimeter lighting, polished stainless steel bezel, contoured pointer, domed glass lens, and Fahrenheit and Celsius scales with icons. Requires 2-1/16" dia. hole. Available in white with blue and black graphics and black with blue and white graphics.


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Nemacolin casino construction begins
Construction on a $50 million casino at a Fayette County resort has begun, and a mid-summer opening is projected, according to a resort spokesman.
Work on the Lady Luck Casino at Nemacolin Woodlands Resort in Farmington began in early October, shortly after the state Supreme Court upheld its gaming license, said Jeff Nobers, resort spokesman.
Isle of Capri Casinos Inc., which will run the gaming facility, has projected a July opening, Nobers said.
"It's moving along a little more quickly than they anticipated," Nobers said.
Nobers said construction is under the direction of Isle of Capri. Jill Alexander, senior director of corporate communications for the group, did not return a phone call seeking comment.
Construction on the casino was put on hold because Mason-Dixon resort near Gettysburg challenged the state Gaming Control Board's decision to grant Nemacolin the last Category 3 resort gaming license in April 2011.
In affirming the gaming board's decision, the Supreme Court rejected Mason-Dixon's contention Nemacolin was ineligible and its allegations the board was politically influenced.
Mason-Dixon was denied the license in April, as were West Shore casino near Harrisburg and Fernwood Resort & Casino in the Poconos.
Nemacolin officials have said gambling there would generate $1.3 million a year in taxes for Wharton Township, $2.1 million for Fayette County and $37.7 million for the state. The gaming board report said the license will create 400 jobs related to the casino and 200 additional jobs at the resort hotel.
The 70,000-square-foot Lady Luck Casino will be located in the resort's former 48,000-square-foot Wildside arcade. It will have 600 slot machines, 28 table games and a restaurant and lounge.
Nobers said a bowling alley, video-game arcade, climbing wall and billiard tables were among the items that had to be removed from the Wildside facility to accommodate the casino.
Several additions will be made to the Wildside building to make space for the casino's table games and an office, Nobers said.
Other than the interior climbing wall, most of the items that were taken out of the Wildside facility have been relocated to Nemacolin's new Sundial Lodge, Nobers said.
The original Sundial Ski Lodge, built in 1995, was destroyed by fire in February. The rebuilt facility, under the new name Sundial Lodge, will open on Christmas Eve.
Liz Zemba is a reporter for Trib Total Media. She can be reached at 412-601-2166 or firstname.lastname@example.com.


text: As the old adage goes, it's better to give than to receive. And, the best networking advice I've ever given (or received) is to give first and then give some more. With all that giving going on, it's also important to know how and when it's time to receive. I recently asked a group of managers, "Is it more difficult for you to give or to receive?" and "What percentage of


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All Android applications categories
India News Videos provides quick access to the most discussed news videos, trending news videos and eye witness videos generally covering major events, political events and natural disasters.
The application provides fast access to:
- The Most Discussed News Videos.
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- Top Rated News Videos.
- Trending News Videos.
- Recently Featured News Videos.
This app makes it easy to access the latest Indian news from YouTube on your android phone/tablet.
YouTube is becoming a new form of video journalism. YouTube news contains a mix of professional journalism and citizen content which can create real powerful imagery.
YouTube is emerging as a major platform for news as viewers increasingly turn for eyewitness videos in times of major events and natural disasters.
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General C++ Programming
Call out to all the C++ GAME PROGRAMMERS
Call out to all the C++ GAME PROGRAMMERS!!
Oct 5, 2012 at 8:41pm UTC
If there is any c++ game programmers (or any other game programming language programmers) I would like to ask you guys a question.
How much math and physics do you need to be able to be a decent game programmer? I'm quite ok at physics, but math is my Achilles heel. Do you need to be good at math that you can an A-Level and or a degree out of or just some detailed of knowledge of trigonometry, algebra etc.
I'd really appreciate this because I'm about to go to college (England College, not US) and if I know that need to be a wiz at math, I can go beyond my C grade and go for a B or A.
Oct 5, 2012 at 8:53pm UTC
If you're doing things like graphics, then a firm understanding of linear algebra is required to understand how to translate planes or objects to different views.
If you're doing an RPG, then I suppose you need to know how to do addition to subtract the damage from your HP.
Advanced stuff like calculus isn't really needed so much if you're not in the engineering simulation side of things.
Unless you're actually writing a physics model, you probably don't need to know that much about physics, only enough so that you can implement such a model.
As an aerospace engineer, the toughest part about coding for me is the structure of a problem, how to share data between elements, where to stick methods, and how to provide nice interfaces for classes. The content of the implementation has never really been a big problem for me. Sure I've had to do fluid-dynamics simulations and stress analysis, but a quick google search tells me all I need to know on those subjects, it's the design of the class that is the toughest and is what will make you a good programmer.
Oct 5, 2012 at 8:56pm UTC
Strong math skills are definitely something you want. The more advanced concepts in comp-sci require good foundational math skills.
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Travis is currently admitted to an unspecified physical therapy facility to help his recovery after he was released from Heart Hospital at Baylor Plano.
Country singer Randy Travis has been discharged from The Heart Hospital at Baylor Plano, Texas, after being treated for heart issue and stroke. According to his publicist, Travis is currently admitted to an unspecified physical therapy facility to help him recover.
"Thanks to all the fans and friends for your continued prayers and support as Randy continues on the road to recovery," Travis' fiancee Mary Davis said in a statement on Wednesday, July 31, as quoted by CNN.
The "Forever and Ever, Amen" singer was rushed to hospital on July 7. According to his doctors, he suffered from idiopathic cardiomyopathy, which is scarring on his heart muscle. The condition weakened his heart, so it could not pump blood normally without the help of medical devices or medication.
The 54-year-old singer, however, suffered from stroke during treatment and underwent surgery on July 10, to relieve pressure on his brain. His condition got better after the brain surgery. A few days later, Travis' doctors and his fiancee announced that the singer was awake and able to respond to people's voices.
Travis' family history of cardiomyopathy apparently contributed to his condition. "[His mother] passed away at an early age with her heart, so it is like these boys are following right in their footsteps," Travis' sister-in-law Teresa Trawick told PEOPLE.


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"Game changer" is a term you hear often when people talk about how technology has changed their industry.
Are you frustrated and concerned about everything going on in the economy right now? "Credit crisis, stock market crash, banking fiascos, housing meltdown—Who is going to buy from me now?"

 You CAN make the sale, even in this uncertain economy. While some things may have changed, companies are still in business and work is still getting done. So the real question becomes, what can sales professionals do today to position themselves for success during these turbulent times?

 Here are a few keys to making and even exceeding your quota in a down economy.

 1. Focus on the positive. Right now, it's very easy to be overwhelmed by the negative messages and bad news. It seems to be human nature, that the bad news is always more interesting than the good. To be successful during this time, attitude is very important. Tune out all the information that is not helpful to you. Turn off the 24-hour news cycle and the minute-by-minute updates from the pundits. As a sales manager or sales representative there is quite a bit going on in the market that is outside of your control. It's important to focus on those things you can control. Don't become a Pollyanna and hide your heads in the sand. Just realize that successful people find opportunity and positive news even in the most difficult times. A positive attitude and keeping that attitude positive will be critical for you to be successful in this economy.

 2. Focus on your customer with empathy. The best salespeople in any industry are the ones who know how to solve customer problems. The problems facing your customers and prospects are not going away and, right now, they may even be magnified. However, things may be changing for your customers that will impact your sales cycles. In difficult times, people become much more risk-averse. Our jobs will have to become focused on risk mitigation for our clients. This risk aversion may manifest in multiple ways including longer time to make decisions and more people involved in each of those decisions.

 3. Focus on real value. Now, more than ever, real value must be understood by your customers and prospects. Soft-dollar ROI may no longer be enough to justify the decision to purchase. In difficult times, clients expect the time-to-value to be short. In other words, in good times it may be okay to realize ROI in 18-24 months. Now, the ROI expectation may be six months in order for the project to get funded. Clients will be focused on real monetary gains as a result of their investments. Are you positioned to save them money or grow revenue?

 4. Focus on preparation. The top 20% of sales executives will not be affected by this economy. They will out-prepare and outsell their competition. Sales executives do not have the luxury of just showing up for a sales call and hoping that they stumble across an opportunity. They need to be purposeful, customer focused and ready to execute. More time needs to be spent understanding your clients, their industries and markets and building creative solutions with them.

 5. Focus on activities. Increase your activity by 35%. Yes, 35%! The trap many sales executives fall into during a down economy is to reduce activity and cling to their pipeline. You will need more prospects and more sales calls to meet your quota and objectives. Also, you will need to make more new business calls and more calls to engage current prospects and qualify them. Leverage existing relationships and referrals at every opportunity where you interact with someone. Now is not the time to stop prospecting; it's the time to increase your prospect activity and continually engage potential buyers.

 6. Focus on qualification. World-class sales organizations make the most of sales methodologies and sales processes. These top companies have customer-centric processes that leverage best practices and repeatable strategies. Mastering prospect qualification is a multidimensional process. Many sales executives only focus on who has the budget. But just because someone can, doesn't mean they will. Your prospect qualification process is reverse engineered from how your prospects will make decisions:

 a. Should I buy this?
 b. Can I buy this?
 c. Is it worth it?
 d. Am I convinced?

 These are questions that you should be able to answer with your prospects before you begin investing time and resources in a sales cycle. If your prospect is not qualified, let them go and find someone who can be qualified in this economy.

 Remember, your competitors are facing the same difficulties that you are. Stay calm, stay focused and look for their vulnerabilities in the marketplace. You should be playing both defense and offense with your current customers to defend your position. By staying focused on the customer, you will not be outsold and you can win the customer's business and loyalty.

 Julie Thomas is president and CEO of ValueSelling Associates, based in Rancho Santa Fe, Calif., is the creator of the ValueSelling Framework™, the sales methodology preferred by sales executives around the globe. Visit www.valueselling.com.


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Map courtesy of Marist
Welcome to Hudson Valley YarnsWe are a group of yarn shops and farms in the Hudson River Valley region of New York. The purpose of this web site is to present you with local choices for your yarn shopping that do not involve "big box" stores. Our shops and farms are all unique and diverse, with one common goal: to provide you with the opportunity to purchase quality yarns locally.
Some members of our group are full service yarn shops offering a full line of products to meet your knitting, crocheting, weaving or felting needs. Others are more limited in their offerings. Many of the yarns we have available for sale are from animals raised in this region. This web site covers Greene, Ulster, Putnam, Dutchess and Columbia counties.
Each shop or farm is unique, independently owned and operated and worth a visit!
If you are a yarn shop or a farm that offers yarn in Greene, Ulster, Putnam, Dutchess and Columbia counties of the Hudson Valley and would like to be part of this web site, please contact Steve McCarthy.
This web site was developed and maintained by Jeff Lick and Steve McCarthy of Spruce Ridge Farm. We assume no responsibility for the accuracy of the information contained therein. Please contact us with comments or questions.


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Kingwin Multi Function LCD Fan Controller - 2-Channel, LCD Display, USB 3.0, eSATA Port, Media Card Reader, Fits 5.25" Bay, - FPX-004Item#: KIW-101746760 | Model#: FPX-004
Currently Out Of Stock!
Additional Resources
Kingwin Multi Function LCD Fan Controller Product Details
Additional Resources: Product Manuals
Recommended Items
Manufactured by: Kingwin
Warranty provided by: Kingwin
UPC No: 812348012191
Mfg Part No: FPX-004
Box Size:
( Length:7, Width:6, Depth:2)
Shipping Weight: 1.3000 pound(s)
Click here for full warranty and support information
- Kingwin logos are registered trademarks of Kingwin. All others trademarks and copyrights mentioned herein are the property of their respective owners.


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2001 Liquid Force Trip 43
The 43 may be the biggest in the series, but with a fly core, batwing tail, spiral V hull at the end, and it's own fin configuration, this board will still create the best combination of thrust, speed, hold, and lift you've ever experienced. Chase Heavener and Shaun Moore, have been preaching the benefits of this Trip all summer long. It's time to join our Trip!
Add Your Review
Add Your Review
Reviewer: **DoUbLe C**
07/13/2001 12:00am
i weigh 195. i used to ride on a skinny lil hyperlite, until i tried my friends new TRIP. WOW. i have become a better rider jus cuz of that board. TAKE A TRIP...
Reviewer: Mike Matz
07/11/2001 12:00am
This is one kickass board. I had to sell mine last winter (needed the money), but I loved it every second I had it. I'm a big guy (220-235lbs) but I was able to get great air with the board. It cuts really well for a wide body board, and its extra fins help you hold on to those really hard corners. The middle fins aren't as deep as they might be on a standard 2 fin board, which makes the Trip fun for surface slides and stuff, as well. The only problem I had was that I got so much air that the landings hurt! Again, I am around 230 lbs, so this is to be expected. The landings are way better than with most other boards, though. Get your hands on a Trip 143 ASAP!
Reviewer: Michael Freedman
07/04/2001 12:00am
You cant find anything wrong with this board. Its a great all around ride. Except what is the design suppose to be?
Reviewer: Ben Baxter
06/08/2001 12:00am
Wow! This board rocks! The 6 fins makes it so easy to cut and when you can cut you can jump, so the pop was huge! Great Board!
Reviewer: John Hatley
05/21/2001 12:00am
I have Collin Wright Skeletree and knew that I would never find a board that I liked to ride more than mine - WRONG, I have never ridden a board that tracks as fast and with as much ease as the TRIP. The increase in air is noticeable from the first jump - the 3fin setup is the key.
Reviewer: Logan Suttmann
05/18/2001 12:00am
I have a 2000 Trip 43 and it has really helped my skills improve vastly. This board really throws you up in the air, and has GREAT tracking (ex fins) I will never buy another board!
Reviewer: Brandon Godsey
04/28/2001 12:00am
Reviewer: Jimmy tart
04/18/2001 12:00am
The board is great for all my needs, i just reomve teh center fins and look out its free style time, it sort of like riding the new helix but just a little better. with more control
Reviewer: David Williams
03/16/2001 12:00am
This board is pretty unique in its feel. I love the way it's loose enough to give the rider a lot of freedom, but tracks very well when it's supposed to. It is not slippery, but more of a controlled looseness. Lots of pop and rides like a much smaller board.
Reviewer: Leo Lacheki
07/22/2002 12:00am
Great board, very fast up the wake. edges hard and tracks well. great pop. I did my first tantrum on the third try with this board. I like the 3 fin style so you can ride without center fin for better spin. great pop and even better landings in the flats. This is a must buy board because you can get one for 230 on ebay. It is definately the best board on ebay for the price. It is paper light and well designed. Trips are the best boards for the price if you go on ebay. check one out
Reviewer: Kevin Burek
09/11/2001 12:00am
Like Double C I used to ride a scrawny Hyperlite piece o' spam and I also found that my riding improved just because of this board. This board is plenty fast and will turn on a dime. The tracking is unreal but the board is easy to break loose for slides or spins. The pop is huge and the landings are sweet. You can't go wrong with this board.
Reviewer: wd boarder
09/10/2001 12:00am
LF says 145-250+ I would say 230-250+ unless you only like to go straight. Although It had a good pop, it still was very slow. Totally different that the other trips.
Reviewer: Rob Ferrin
09/09/2001 12:00am
I weigh about 195 lbs. This board does give you great pop, however feels a little slow and sluggish to me. If you are my weight or less you may want to try the trip 38. That is the board I ride and it just feels so much faster and gives you great pop too. If you weigh too much for the 38 this may be the way to go.


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The General Managers of Raising Cane's Restaurants throughout Acadiana recently handed over a check for $546 to Lafayette Animal Aid. The check represented profits from sales of Raising Cane's "Plush Puppies" during this past Christmas.
John Raxsdale, manager of the West Congress location, told TV10, "Our hope is to help bring awareness to this organization and the need for animal adoptions. This organization was voted on by the local Cane's managers as our fund organization because it is local and has a no kill policy. Our hope is to increase sales of these puppies in the years to come as 100% of all puppy sales will be donated to helping animals. "
A big thank you to the management and staff of all area Raising Cane's Restaurants, on behalf of all the homeless pets that will benefit from this generous donation!


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Softer Cotton Prices Ahead
Measures of consumer spending, job creation, factory output and the housing market came in well below expectations recently, and it's prompting some to speculate whether the Federal Reserve will continue its efforts to taper stimulus. Fed Chair Janet Yellen commented that recent economic data have pointed to weaker-than-expected gains in consumer spending and job growth. She said the Fed will be watching to see whether the slowdown proves only a temporary blip caused by severe winter weather.
The better-than-expected January read on core capital goods orders and the favorable February reading on domestic manufacturing, offered by Markit Economics, suggest there is life in the economy....504 more words left in this article. To read them, just click below and try Real Money FREE for 14 days.
There's no substitute for a trading floor to get great ideas, so Jim Cramer created a better one at Real Money and blogs there exclusively. We then added legendary hedge fund manager, Doug Kass, with his exclusive Daily Diary and best investing ideas. Staffed with more than 4 dozen investing pros, money managers, journalists and analysts, Real Money Pro gives you a flood of opinions, analysis and actionable trading advice found nowhere else, and allows you to interact directly with each expert.
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Thursday, January 29, 2009
Media General Board of Directors Suspends Dividend
RICHMOND, Va. – Media General (NYSE: MEG) announced today that due to the uncertain economic outlook, the Board of Directors determined it is prudent to suspend the dividend on the company's Class A and Class B shares.
"While we regret having to take this action, this allows the company to direct additional cash flow to the reduction of our debt," said Marshall N. Morton, president and chief executive officer.
About Media General
Media General is a leading provider of local news, information and entertainment over multiple media platforms. The company serves markets primarily in the Southeastern United States. Media General publishes 24 daily newspapers, including The Tampa Tribune, Richmond Times-Dispatch, and Winston-Salem Journal; and community newspapers in Virginia, North Carolina, Florida, Alabama and South Carolina; plus approximately 275 weekly newspapers and other targeted publications. The company owns and operates 19 network-affiliated television stations that reach approximately 30 percent of the television households in the Southeast and nearly 9 percent of those in the United States. The company's interactive media operations include Web sites and portals that are associated with each of its newspapers and television stations as well as with many specialty publications, and two growing interactive advertising services companies, Blockdot, Inc. and DealTaker.com.
Investor Contact:
Lou Anne Nabhan
(804) 649-6103
Media Contact:
Ray Kozakewicz
(804) 649-6748


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The Country Christian Cougars made a valiant run in 1A volleyball playoffs last week in Redmond. On Friday, Nov. 8, they beat first-ranked Lowell 3-1, with set scores of 25-19, 23-25, 25-20 and 25-19.
Just hours later, the Cougars faced the Condon/Wheeler Knights in the semifinals. The Knights swept the game 3-0. Set scores were 25-18, 25-11 and 25-16.
Though the Cougars didnt make it to the final, they still had one more playoff game, which would either land them in third or fifth place. On Saturday, Nov. 9, they played Dufur. The teams were extremely well matched, but Dufur came away with the win 3-1, with set scores of 25-21, 19-25, 25-18 and 25-22.
Country Christian brought home the fifth place trophy. It was a strong season for the Cougars. The team is mostly made up of sophomores and juniors. Adding this years experience to the pot should put them in a good spot for next year.


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A New Year's Wish and Resolution:
This year, become a Natural Teacher, a Regional Campaign Leader, a Natural Family, a young Natural Leader, a Pediatrician Who Prescribes Nature, a Let's G.O.! (Get Outside) event organizer, an architect for change, and more. Or support C&NN through a tax deductible donation. And thanks to those who already connect kids to nature.