e that of the information system resources on an as-needed basis-a key goal of bandwidth. Since an SDR may not have advance knowledge of the bandwidth of the signal it will be used to receive, the sample rate must be appropriately high Single carrier enough to sample all anticipated bandwidths. Not all SDR applications require more than one channel. Current ADC technology allows high dynamic range Low-capacity systems may require only one carrier. In bandwidths of up to 100 MHz to be digitized. With this these applications, a high over-sampling is still desired. If much bandwidth, it is also possible to process multiple the channel is reprogrammable, it is possible that it may channels. Figure 2.3-5 shows a typical multi-carrier re- be as narrow as a few kHz or as wide as 5 to 10 MHz. In ceiver example and Figure 2.3-6 shows a spectral display. order to accommodate this range of bandwidths, the In this example, the sample rate of the ADC is set to sample rate should be suitable for the highest potential 61.44 mega-samples-per-second (MSPS), which gives bandwidth, in this case 10 MHz. From the multi-carrier a Nyquist bandwidth of 30.72 MHz. If each RF channel is example, we would typically sample at least three times 1.25 MHz wide, then Nyquist indicates that the number the bandwidth. In this example, a sample rate of 30.72 of potential channel is about 24.5. In practice, by MSPS or higher would allow signal bandwidths from allowing for reasonable transition bands on the a few kHz up to 10 MHz to be processed. Aside from the anti-aliasing filters, the typical available bandwidth is fact that only one channel is processed, the single-carrier one-third the sample rate instead of the Nyquist one- receiver has all of the capacities of that of a multi-carrier half. Thus the available bandwidth for our example is receiver; it can be reconfigured as necessary. 20.48 MHz, which is just over 16 channels at 1.25 MHz. Since the channel characteristics can be changed, it is easy enough to change the CDMA example to a GSM SDR 