Appendix A—492/492P Service Vol. 1
GLOSSARY
The following glossary is presented as an aid to better un
derstand the terms as they are used in this document and
with reference to spectrum analyzers.
GENERAL TERMS
Spectrum Analyzer. An apparatus which is generally
used to display the power distribution of an incoming signal
as a function of frequency.
Line Display. The display produced on a spectrum ana
lyzer when the resolution bandwidth is less than the spacing
of the signal amplitudes of the individual frequency
components.
Line Spectrum. A spectrum composed of signal ampli
tudes of the discrete frequency components.
Maximum Safe Input Power
NOTE
It is useful in analyzing the characteristics of repetitive
electrical waveforms in general, since repetitively
sweeping through the frequency range of interest will
display all components of the signal.
Center Frequency. That frequency which corresponds
to the center of a frequency span, expressed in hertz.
dBc. dB below carrier level.
Effective Frequency Range. That range of frequency
over which the instrument performance is specified. The
lower and upper limits are expressed in hertz.
Frequency Band. A part of effective frequency range
over which the frequency can be adjusted, expressed in
hertz.
Full Span (Maximum Span). A mode of operation in
which the spectrum analyzer scans an entire frequency
band.
Zero Span. A mode of operation in which the frequency
span is reduced to zero.
Envelope Display. The display produced on a spectrum
analyzer when the resolution bandwidth is greater than the
spacing of the individual frequency components.
WITHOUT DAMAGE. The maximum power applied at
the input which will not cause degradation of the instrument
characteristics.
WITH DAMAGE. The minimum power applied at the in
put which will damage the instrument.
Intermodulation Spurious Response (Intermodulation
Distortion). An unwanted spectrum analyzer response re
sulting from the mixing of the nth order frequencies, due to
non-linear elements of the spectrum analyzer, the resultant
unwanted response being displayed.
Baseline Clipper (Intensifier). Increasing the brightness
of the signal relative to the baseline portion of the display.
Pulse Stretcher. A pulse shaper that produces an output
pulse, whose duration is greater than that of the input pulse,
and whose amplitude is proportional to that of the peak
amplitude of the input pulse.
Signal Identifier. A means to identify the spectrum of the
input signal when spurious responses are possible.
Video Filter. A post detection lowpass filter.
Scanning Velocity. Frequency span divided by sweep
time and expressed in hertz per second.
REV AUG 1981
A-1
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