HP 8901B Operation And Calibration Manual page 79

Audio Analyzer 1-15
Audio Analyzer
The HP 8901B enables you to measure your audio signal sources as well
as your RF signal sources. Use the HP 8901B to make audio frequency,
distortion, and level measurements.
Set up your HP 8901B, Sensor Module, and signal generator as shown
in Diagram
1-1.
Adjust Your Signal Generator
RF Frequency
....................
100 MHz
Depth
...........................
.50%
Amplitude
.......................
0.0 dBm
Modulation
......................
AM
Rate
.............................
1 kHz
Measuring
Audio Frequency
The HP 8901B enables you to accurately count the frequency of the
internally-demodulated audio signal or of an external audio signal
connected to the MODULATION OUTPUT/AUDIO INPUT port.
Demo&/ated Audio 1.
Press the
AM
key and then the green
AUTOMATIC OPERATION
key.
Entering the AM measurement mode first, selects the AM demodulator for
measuring the AM input signal. The HP 8901B uses the last demodulator
selected before entering an audio measurement mode to make its audio
measurements. (Notice that the yellow AM MODULATION OUTPUT LED
is lit. When you are making audio measurements, the MODULATION
OUTPUT LEDs will show you which demodulator is selected.)
2. Press
the
gold S
key
and then
AUDIO
FREQ
(AM)
key (both
keys should remain lit). The HP 8901B is now displaying
the frequency of the demodulated audio signal (approximately
1 kHz). The demodulated audio signal is also available at the
front-panel MODULATION OUTPUT/AUDIO INPUT port.
External Audio Press the
AUDIO INPUT
key (key lit) to convert the MODULATION
OUTPUT port to an AUDIO INPUT port. The HP 8901B is
now able
to make its audio measurements on an external audio signal source
connected to the AUDIO INPUT port. Press the AUDIO INPUT
key again to convert the port back to a modulation output and
continue measuring the internally demodulated audio signal.