phase noise
Refer to noise sidebands
position units
The position unit describes the location of a point along the horizontal axis of a trace. Position unit values of a trace begin on the
positive peak
The maximum, instantaneous value of an incoming signal. On digital displays, each displayed point of the signal indicates the maximum value of the signal for that part of the frequency span or time interval represented by the point,
preamplifier
An external,
predefined trace
Trace A, B, or C of an analyzer. Refer also to trace.
preselector
A tunable bandpass lilter placed ahead of a frequency converter, or mixer, of an analyzer. It tracks the appropriate mixing mode and passes signals of a desired frequency and reduces others. Preselectors are typically used only above 2 GHz. They essentially eliminate multiple and image responses and, for certain signal conditions, improve dynamic range.
A detector circuit designed with time constants that give a weighted value to the amplitude of a detected signal. The displayed signal output is an indication of the degree to which the detected signal would impair the intelligibility of a desired signal The time constants (rise, fall, average) for EM1 purposes are based on the recommendations of CISPR that are in turn based on subjective tests. Interference limits for commercial EM1 tests are often given in
Glossary20