This section is applicable to both GSM and GPRS.
How is a transmit power (TXP) measurement made?
The TXP measurement performs a power measurement on a mobile station, averaged over the useful part of the burst. The signal is captured with a wide band 3 GHz fast RF power detector.
For GPRS mobiles, TXP provides a broadband measurement of the peak transmitted carrier power of a GMSK modulated signal for a specified burst in a multislot configuration which consists of adjacent timeslots. Only one burst which you specify using
RFANalyzer:MSLot:MEASurement:BURSt
is measured at a time.
In order to provide you with a very fast TXP measurement the test set measures the power without synchronizing it to the midamble. The measurement is made with RF amplitude synchronization; therefore, the signal does not need to be demodulated to determine the midamble. This technique is different than the TXP measurement defined in 3GPP 51.010 (formerly ETSI GSM 11.10). (See
Burst Synchronization of Measurements
). The power versus time measurement provides a carrier power measurement that is synchronized to the burst's midamble, and conforms to 3GPP 51.010 (formerly ETSI GSM 11.10), section 13.3 and 3GPP 51.010 (formerly ETSI GSM 11.10), section 13.16.2. (See
Power versus Time Measurement Description
for more details.)
The output RF spectrum measurement makes the TXP measurement as part of its measurement process, and makes this measurement result available along with output RF spectrum due to modulation and switching.
The TXP measurement is completely controlled by the digital signal processor (DSP) in the test set. Any power measurement requires calibration to ensure accuracy. The power meter used for this measurement is zeroed automatically by the DSP as needed, with no action required by you. No temperature dependent calibration is required because temperature compensation in the power detector circuits provide temperature stability.
Single or Multi-Measurements
The DSP analyzes the data and calculates the results. A single burst for a TXP measurement calculates the average power over the useful part of the burst. A multiple burst transmit power measurement is made when the multi-measurement state is on. This measurement calculates average, minimum, maximum, and standard deviation of the average power measured. All of these results are available to the user with the FETCh command. The test set always has an integrity indicator available regardless of whether single or multiple burst measurements are selected.
