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
•Video bandwidth is at least 10 times the resolution bandwidth.
•Detector mode is sample (SP). (You can use DETECTOR PK SP NG to change the detector mode.)
•Resolution bandwidth is less than or equal to 100 kHz.
•Video averaging is OFF.
•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
3.Press (AMPLITUDE_) and adjust the reference level to bring the signal near the top of the display.