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Making Measurements Using Spectrum Analyzer Mode
Using the Power Measurement Functions to make Transmitter Measurements
Adjacent
Channel
Power
Ratio
(ACP)
The leakage of a transmitter into adjacent channels can be measured quickly
and easily. Enter the channel spacing and channel bandwidth, and activate
the adjacent channel power measurement. The spectrum analyzer computes
and displays the ACP ratio of both the lower and upper adjacent channels,
marking the higher of the two. The absolute carrier power is read out and
vertical lines on the display mark the channel bandwidth edges.
Selecting ACPGRAPH ON OFF (ON) computes a graph showing the adjacent
channel power ratio for the selected channel as a function of channel spacing,
and disables the numerical adjacent channel power display.
Normally, the spectrum analyzer measurement parameters are set
automatically. Parameter setting can be changed from automatic to manual
control using
PARAM
AUTO MAN The following conditions must be
maintained to make a valid rms measurement. If these conditions are not
met, errors of up to -2.5
dB
can occur for noise-like signals.
l Video bandwidth is at least 10 times the resolution bandwidth.
l Detector mode is sample (SP). (You can use
DETECTOR
PK SP NG to
change the detector mode.)
l Resolution bandwidth is less than or equal to 100
kHz.
l Video averaging is OFF.
l Neither MAX HOLD nor MIN HOLD trace mode is selected.
A wider dynamic range is available using the
ADJ
GHAN POWER extd
function. This extended range is measured by taking two different sweeps
with different reference levels and combining the trace data. The results are
displayed in a 13
dB
per division format. The extended ACP function does
not provide a continuous measurement mode.
Example: Measure the adjacent channel power of a signal
1. Connect a signal to the spectrum analyzer’s INPUT 75
61.
2. Press (FREQUENCY] and enter the frequency of your input signal to place
the signal at the spectrum-analyzer center frequency.
3. Press (AMPLITUDE_) and adjust the reference level to bring the signal near
the top of the display.
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