Frequency spectrum analyzer with high carrier:noise ratio

摘要

The analyzer has a first frequency converter (11,21,31) for generating a first intermediate frequency signal. A second frequency converter (12,22,32) receives the first intermediate frequency signal and generates a second intermediate frequency signal. A third frequency converter (13,23,33) generates a signal representing the frequency spectrum of the input signal from the second intermediate frequency signal. Each frequency converter comprises a frequency mixer (11-13), an intermediate frequency filter (21-23) and a local signal oscillator (31-33). A frequency divider (40) divides a frequency of the first local signal by a factor of N. A fourth frequency mixer (14) transmits the frequency divided signal as a fourth local signal. A frequency multiplier (45) multiplies a frequency of the third local signal. A fifth frequency mixer (15) mixes the input signal to be analyzed and the signal from the multiplier to form a fifth local signal and transmits a frequency converted input signal to the fourth frequency mixer. The fourth frequency mixer mixes the fourth local signal and the frequency converted input signal and transmits the intermediate frequency signal to the third frequency converter.