Characterising radio frequency signal processing paths

A method of determining relative amplitude and phase correction coefficients for a plurality of parallel signal processing paths across a frequency band of interest, each of the plurality of parallel signal processing paths having an input and an output, the method comprising:

• transforming an output test signal, resulting from an input test signal provided to the respective inputs of the each of the plurality of parallel signal processing paths being processed along the respective signal processing path, from the time domain to the frequency domain to obtain an output magnitude spectrum and an output phase spectrum for the each of the plurality of parallel signal processing paths;
• comparing the output magnitude spectrum of a first of the plurality of parallel signal processing paths with the output magnitude spectrum of another of the plurality of parallel signal processing paths to determine, at one or more frequencies of the frequency band of interest, a relative amplitude correction coefficient for the another of the plurality of parallel signal processing paths;
• and/or
• comparing the output phase spectrum of the first of the plurality of parallel signal processing paths with the output phase spectrum of the another of the plurality of parallel signal processing paths to determine, at one or more frequencies of the frequency band of interest, a relative phase correction coefficient for the another of the plurality of parallel signal processing paths.