Power spectrum measurement of high frequency angle modulated digital signal from ouput power spectrum of a digital divider

This paper shows how to measure high frequency angle modulated digital signals using a relatively low frequency spectrum analyzer and a digital frequency divider. The mathematical proof is based on comparison of the signal spectrum before and afther the frequency divider. The spectral scaling of angle modulated digital signal by the divider is predictable mathematically implying that the spectrum at the input of the divider can be deduced from the spectrum at the digital output of the frequency divider. The proposed method was confirmed by measurement.