The Keysight / Agilent / HP 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. The instrument will very accurately measure modulation and recover the modulated signal. It can determine RF frequency and measure RF power. The major additional capabilities of the 8901B are its improved power meter accuracy, its ability to use external power sensors, to make adjacent channel power measurements, and its ability to count audio frequencies and measure distortion on 400 Hz and 1 kHz signals. Fully automatic for all major measurements with the push of a key or under HPIB control.