The 8901B modulation analyzer combines the capabilities of several RF instruments to give complete, accurate characterization of modulated signals in the 150 kHz to 1300 MHz frequency range. It very accurately measures modulation and recovers the modulation signal, determines RF frequency and meaures RF power. The major additional capabilities of the 8901B are its improved power-meter accuracy, its ability to make adjacent-channel power measurements or carrier-noise measurements (with Options 030 through 037), and its ability to count audio frequencies and measure distortion on 400 Hz and 1 kHz signals.