Amp Droop (GSM/EDGE/EDGE Evolution)

Amp Droop displays the average amplitude droop for the current Timeslot.

Amplitude droop (also called burst amplitude droop) is a measure of the change in the magnitude of the signal over the burst.

This data result is significant for pulsed signals. A high number can indicate a problem with the pulse modulation process or the transmitter amplifier.

The amplitude droop shown in the Summary table is computed only at the symbol times (the instant in time when symbols are detected). The computation does not include points between symbols.

Amplitude droop is computed by calculating an amplitude ratio between symbol i+1 and i for all symbols in the burst, excluding tail symbols. Then the amplitude ratios are averaged to compute a per-symbol average and converted to dB using 20*log10(AvgRatio).

Since bursts can use either Normal Symbol Rate or High Symbol Rate, the dB/symbol amplitude droop average is converted to dB/slot by multiplying the average value by the number of symbols that the average was calculated over in a slot.

Amplitude droop is calculated over the middle 142 symbols for NSR bursts and over the middle 169 symbols for HSR bursts. The amplitude droop average for Access bursts is multiplied by 142 symbols, even though these bursts are not actually this long.

Amplitude droop is not calculated when the current burst uses a modulation scheme other than GMSK and the Enable Droop Compensation parameter is cleared. In this case, the Amp Droop data result will show "***" instead.