Table of Contents
Advertisement
Frequency Response
Tracking Generators
Subject to change without notice
then, is sensitivity. To ensure a maximum dynamic range on the
CRT display, check to see that the following requirements are
satisfied.
1.The largest input signal does not exceed the optimum input
level of the analyzer (typically -27dBm with 0dB input attenuation).
2.The peak of the largest input signal rests at the top of the CRT
display (reference level).
The frequency response of an analyzer is the amplitude linearity
of the analyzer over its frequency range. If a spectrum analyzer is
to display equal amplitudes for input signals of equal amplitude,
independent of frequency, then the conversion (power) loss of
the input mixer must not depend on frequency. If the voltage
from the LO is too large compared to the input signal voltage
then the conversion loss of the input mixer is frequency depen-
dent and the frequency response of the system is nonlinear. For
accurate amplitude measurements, a spectrum analyzer should
be as flat as possible over its frequency range. Flatness is usually
the limiting factor in amplitude accuracy since its extremely
difficult to calibrate out. And, since the primary function of the
spectrum analyzer is to compare signal levels at different
frequencies, a lack of flatness can seriously limit its usefulness.
The tracking generator (HM5011 only) is a special signal source
whose RF output frequency tracks (follows) some other signal
beyond the tracking generator itself. In conjunction with the
spectrum analyzer, the tracking generator produces a signal
whose frequency precisely tracks the spectrum analayzer tuning.
The tracking generator frequency precisely tracks the spectrum
analyzer tuning since both are effectively tuned by the same VTO.
This precision tracking exists in all analyzer scan modes. Thus, in
full scan, the tracking generator output is a start-stop sweep, in
zero scan the output is simply a CW signal.
The tracking generator signal is generated by synthesizing and
mixing two oscillators. One oscillator is part of the tracking
generator itself, the other oscillator is the spectrum analyzer's
1st LO. The spectrum analyzer/tracking generator system is used
27
Hide quick links:
Advertisement
Table of Contents
