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HP 85325A Operating and Service Manual
System Performance Verification
Detailed Test Description
Compression
This test measures the input power at which the mixer exhibits 0.1 dB
compression.Each channel is tested over the test frequency range. Data is
taken at 51 frequency points.
First, a power level is input to the test mixer that is within its normal
operating range. The input to reference mixer is set to a much lower level.
The test mixer output is ratioed to the reference mixer output and the data is
put into memory. The data is then normalized to give a 0 dB reference,
Next, the input level is increased until the normalized data changes by 0.1
dB. The test mixer power level is the 0.1 dB compression point.