Operating instructions

OPERATING MANUAL 2945A
46882-311D 3-27
The harmonic number and frequency is shown over each active bar chart, with the level, in dBc,
given as a digital read-out.
The level of a harmonic which has a frequency above the RF range of the monitor cannot be
measured and bar charts which would be given to these frequencies remain inactive.
IF passband filters
When making harmonic analysis readings, the IF passband of the Service Monitor can be set
independently to that set in the main
Tx TEST mode. Pressing the [IF Filter] key when the
harmonic analysis function is displayed, allows selection of the following IF passband filters.
300 Hz 3 kHz 30 kHz 300 kHz
The filter selection is retained within the harmonic analysis setup. The IF filter selected in the
main
Tx TEST mode will be unchanged.
For accurate results, the noise floor over the measurement range should be as low as possible, but
the passband should not clip the sidebands of the fundamental signal. Select the filter that will
best suit these requirements.
As the Spectrum Analyzer uses the same IF filters, the optimum filtering can be selected by
examining the signal using the Spectrum Analyzer.
Pressing the [Return] key will display the top level Tx TEST mode screen.
If the operating mode of the Service Monitor is changed from Tx TEST mode with the harmonic
analysis function selected, the harmonic analysis screen will be displayed again when Tx TEST
mode is next selected.
RF transient power analysis
This facility is used to capture, display and record changes to power levels of RF signals. The
TRANSIENT ANALYSIS screen, used to control and display this function, is accessed from the
Tx TEST mode by the key sequence [Tx Power], [Trans Analys]. See Fig. 3-6, Power Transient
Analysis screen.
1 Ref Level 5 Display Centre-line
2 Trigger Level 6 Marker Datum
3 Trigger Datum 7 Marker Point
4 Trigger Point 8 Time/Div Adjustment
Fig. 3-6 Power Transient Analysis screen