modulated: amplitude, phase and frequency. For received signals, by determining how much in-phase carrier and how much quadrature carrier is present in the signal it is possible represent that signal using in-phase and quadrature components, so IQ data can get generated from a signal with reference to a carrier sine wave. IQ data has extensive use in many signal processing contexts, including for radio modulation, software-defined radio , audio signal processing and electrical engineering. I/Q data is a two-dimensional stream. Some sources treat I/Q as a complex number; with the I and Q components corresponding to the real and imaginary parts. Others treat it as a distinct pairs of values, or as separate streams. When called "I/Q data" the information is likely digital. However, I/Q may be represented as analogue signals. The concepts are applicable to both the analog and digital representations of IQ. This technique of using I/Q data to represent the modulations of a signal separate to the signal's frequency is known as equivalent baseband signal, supported by the . The data rate of I/Q is largely independent to the frequency of the signal being modulated. I/Q data can be generated at a relatively slow rate (e.g. millions of bits per second), perhaps generated by software in part of the physical layer of a protocol stack. I/Q data is used to modulate a carrier frequency, which may be faster (e.g. Gigahertz, perhaps an intermediate frequency). As well as within a transmitter, I/Q data is also a common means to transfer the data from some receiver. Designs such as the Digital down converter allow the input signal to be represented as streams of IQ data, likely for further processing and symbol extraction in a DSP. Analog systems may suffer from issues, such as IQ imbalance. I/Q data may also be used as a means to capture and store data used in spectrum monitoring. Since I/Q allows the representation of the modulation separate to the actual carrier frequency, it is possible to represent a capture of all the radio traffic in some RF band or section thereof, with a reasonable amount of data, irrespective of the frequency being monitored. E.g. if there is a capture of 100 MHz of Wi-Fi channels within the 5 GHz U-NII band, that IQ capture can be sampled at 200 million samples per second (according to Nyquist) as opposed to the 10,000 million samples per