Patent ID: 7705609

Claim:
A method of measuring frequency distortions of a device under test, said device to configured convert an input signal in an input frequency range to an output signal in a different output frequency range, comprising: (a) for each test frequency f i , where i=1, . . . , N and N a positive integer, in a selected frequency range, providing a corresponding test signal with multiple frequency components comprising a measurement component with a frequency f i , a first reference component with a frequency f A, and a second reference component with a frequency f B ; (b) inputting said test signals into the device under test; (c) measuring output test signals at the output of the device under test corresponding to the input test signals; and (d) determining, for each test frequency f i , information representative of frequency distortions based on the corresponding input test signal and the corresponding output test signal; and (e) outputting the information.