Patent ID: 7701195

Claim:
A process for distinguishing image signal frequencies and actual signal frequencies generated in a frequency converting device that receives an input signal, the frequency converting device including a first mixer that mixes the input signal and a signal provided by a local frequency source, and a filter assembly that filters the mixed signals output by the first mixer, the filter assembly including a first band-pass filter and a second band-pass filter filtering respective bandwidths of frequencies, the process comprising: performing a first frequency sweep and a second frequency sweep, said first and second frequency sweeps being performed while input signals are received by the frequency converting device, wherein for each of the first frequency sweep and the second frequency sweep, the frequency of the signal provided by the local frequency source is varied through a predetermined frequency range, and wherein signal levels including actual and image signals at the output of the frequency converting device are recorded for a set of converted frequencies; and performing a third frequency sweep, said third frequency sweep being performed while an input signal is received by the frequency converting device, in which the frequency of the signal provided by the local frequency source is varied; wherein the first frequency sweep comprises filtering the mixed signals output by the first mixer by the first band-pass filter, the second frequency sweep comprises filtering the mixed signals output by the first mixer by second band-pass filter, and the third frequency sweep comprises filtering the mixed signals output by the first mixer, by one of the first band-pass filter and the second band-pass filter.