Measurement Considerations

Using the Power Sensor

For example, a CW tone at –30 dBm is to be measured to 0.01 dB resolution. Using the table in the sensor manual, the required number of averages is 38 averages using High Aperture Time mode (the same measurement would require more than 256 averages in Low Aperture Time mode).

Settling Time

The MA24106A samples power continuously every 70 ms in the Low Aperture Time (LAT) mode and 700 ms in the High Aperture Time (HAT) mode. The sensor’s front end and digitizer settles completely to a step change in power in this amount of time. However, there is no way to synchronize the sensor’s sampling to any other event, such as a power step or bus request for a measurement. Therefore, the first measurement requested from the sensor after a power step may not be fully settled. To ensure a fully settled measurement when operating the sensor over the bus, wait 70 ms (700 ms if in HAT) after a power step before requesting the measurement from the sensor. Alternatively, request two measurements from the sensor and discard the first.

If averaging is required as described above, settling time increases by N × sample period, where N is the number of averages and the sample period is the time is milliseconds. The measurement sample period is

70 ms for LAT and 700 ms for HAT. When operating the sensor over the bus, request N+1 measurements from the sensor, discard the first, and then average the subsequent readings. The settling time is approximately (N+1) × sample period.

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MA24106A UG

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Image 34
Anritsu 0701012, MA24106A manual Settling Time