Digital Average Power Measurement Description

Last updated: October 28, 2004

How is a Digital Average Power Measurement Made?

Digital average power measurements are broadband power measurements made directly on the RF input (the signal is not downconverted in frequency, see Block Diagram ). The input waveform is detected by a peak detector with sufficient AM bandwidth to track the instantaneous power changes of a CDMA signal. The test set's digital signal processor (DSP) then determines the average power (true rms power level) of the signal over a 10 ms (one-half of a frame) measurement period.

This measurement uses autoranging based on the open loop power control response of the mobile station to set up the receiver signal path attenuation. Triggering is handled by internal mechanisms and no external triggering is available.

This measurement can be made on signals that are power-gated or signals that are not power-gated. It is not necessary to specify whether the input signal is power-gated. If the input signal is power-gated, only the active power control groups will be measured.

NOTE

For the lab application, the digital average power measurement result is not accurate for gated MS transmissions in radio configurations greater than 2 (see R-FCH Gating ), which the integrity indicator returns the value of 16.

The digital average power measurement has greater than 2 GHZ bandwidth. For this reason, significant signal energy outside the IS-2000 SR1 (1.25 MHz) signal bandwidth will increase the measured value.

Digital Average Power Measurement Parameters

Multi-Measurement Count - (See Statistical Measurement Results ).
Trigger Arm - (see Trigger Arm (Single or Continuous) Description ).
Timeout Time/State - (see Timeouts ).

Digital Average Power Measurement Results

Integrity Indicator - (see Integrity Indicator ).
Digital Average Power (in dBm)
Expected Mobile Power - the Expected Mobile Power (see Expected Power ) is also displayed on the measurement screen when the test set is configured as:
- receiver power control is set to auto (see Automatic Receiver Control ).
- the test set does not make the R-FCH data rate assumption (see Reverse Traffic Channel Data Rate Determination ) when calculating the expected mobile power. That is, the test set is in a loopback call (SO2, SO9, or SO55, see Service Option ) with the Traffic Data Rate set to other than Random .

A typical measurement result is shown below:

Input Signal Requirements

The digital average power measurement meets or exceeds specifications when the following requirements are met:

The frequency of the signal being measured must be in the range of 412 MHz to 483 MHz, 800 MHz to 960 MHz, or 1.7 GHz to 2.0 GHz.
The signal level into the test set's RF IN/OUT connector must be between +37 dBm and -30 dBm. The test set can autorange to a signal that is within +/- 9 dB of the expected input level (see RFANalyzer:AUTO:POWer[:SELected]? ).

Key TIA/EIA-98-E Tests Using the Digital Average Power Measurement

Testing 4.4.5 Maximum RF Output Power

Calibrating the Digital Average Power Measurement

Refer to Calibrating the Test Set for a description of digital average power calibration.