Last updated: November 10, 2006
Channel power measurements are made by analyzing a digitized version of the input signal's downconverted IF using the test set's DSP (see Block Diagram ). The measurement triggers on the test set's internal ~1.667 ms slot clock. The measurement thus always starts at the beginning of a slot. Depending upon the Measurement Speed setting, the test set either measures the power over an entire slot or just the first 1/4 of the slot, and reports the average power. Because the measurement is triggered on the slot clock rather than the frame clock, any slot within the frame can be measured, increasing measurement speed. The measurement only measures power within a 1.23 MHz measurement bandwidth. The measurement is cross-calibrated with digital average power to determine the absolute power level. The result is given in dBm/1.23 MHz.
When ON, this enables averaging of multiple channel power results. For example, when multi-measurement count is set to 3, the test set calculates the average power in a slot, then calculates the average power in the next available slot, then calculates the average power in the next available slot. The test set then averages these 3 results, and reports the maximum and minimum results as well. (See Statistical Measurement Results ).
There are two channel power measurement speeds,
Fast
and
Very Fast
, which are determined by the signal sampling time.
When measurement speed is set to
Fast
, the measurement triggers on the test set's internal ~1.667 ms slot clock and samples the input signal for 1 slot (1.667 ms).
When the measurement speed is set to
Very Fast
, the measurement samples the input signal for 1/4 slot (0.3125 milliseconds) with immediate trigger.
GPIB command: SETup:CPOWer:MSPeed .
Expected Terminal Power
(see
Expected Power
) is also displayed on the measurement screen when either of the following conditions is met:An example measurement result display (for subtype 0 physical layer) is shown below:
An example measurement result display (for subtype 2physical layer) is shown below:
Refer to Calibrating the Test Set for a description of channel power calibration.
Manual Operation: Measuring Channel Power
Programming a Channel Power Measurement
Channel Power Measurement Troubleshooting
C.S0029 Test Application Specification Description (TAP/ETAP)