User`s guide

5 Using E9300 E-Series Power Sensors
160 N1911A/1912A P-Series Power Meters User’s 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 440 Hz 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 (Agilent 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.
Procedure
Set the averaging as follows:
1 Press . On dual channel meters, select the required channel.
2 Use the and keys to select the Filter setting field.
3 Press and use the and keys to step through the available
settings. Select MAN.
4 Use the key to to select the Meas Avg: value field.