2 Making Measurements
36 Keysight E-Series E9300 Operating and Service Guide
Measuring TDMA Signals
Power meter and sensor operation
The voltages generated by the diode detectors in the power sensor can be very
small. Gain and signal conditioning are required to allow accurate measurement.
This is achieved using a 220 Hz (440 Hz in fast mode) square wave output from
the power meter to drive a chopper-amplifier in the power sensor. Digital Signal
Processing (DSP) of the generated square wave is used by the power meter to
recover the power sensor output and accurately calculate the power level.
The chopper-amplifier technique provides noise immunity and allows large
physical distances between power sensor and power meter (Keysight 11730
series cables available up to 61 metres). Additional averaging helps reduce noise
susceptibility.
Achieving stable results with TDMA signals
The averaging settings in the power meter are designed to reduce noise when
measuring continuous wave (CW) signals. Initial measurement of a pulsed signal
may appear unstable with jitter on the less significant displayed digits. With
pulsed signals the averaging period must be increased to allow measurement over
many cycles of the pulsed signal.
To set the averaging proceed as follows:
1 Press , , . Press the softkey to access
the filter menu.
2 The filter setting is displayed under the softkey label. To change this
setting first set manual mode by pressing the softkey to
highlight .
The example shows the key labels for a single channel power meter. Dual
channel meter are similar, adding only channel identification to the softkey
labels.
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