Metrics Provided by the GSM and EDGE Analyzer Measurement

Metrics Provided by the GSM and EDGE Analyzer Measurement
This section contains descriptions of the individual GSM transmit parameters in the metrics display of the screen. The "Interpretation of GSM Tx Analyzer Measurement Results" section contains expected result values and possible causes of error if the expected results are not met.

Frequency
Frequency of the channel indicated by the vertical yellow line on the Channel Scanner display. The position of this yellow line can be adjusted by using the [Display], [Position] menu keys. For further details, see "Setting the Display Position"

Frequency Error
Frequency error is the frequency difference between your transmitter's actual center frequency and the frequency (or channel) you entered.

BSIC (Base Station Identification Code)
A two digit number that identifies the base station for the indicated channel. It consists of the PLMN color code with a range from 0 to 7, and the S color code with a range from 0 to 7. The BSIC is shown in Decimal format (8 * NCC) + BCC. For example, if the NCC is 4, BCC is 3, the BSIC will be 35 (4*8+3 = 35). BSIC is transmitted on a synchronization channel and is used to identify a cell and to indicate the timing sequence being used.
BCC = Base station Color Code
BSIC = Base Station Identity Code
NCC = Network Color Code
PLMN = Public Land Mobile Network

TSC
TSC (Training Sequence Code) is a single digit integer from 0 to 7, "n/a (Sync)" if the demodulated slot is a GMSK Sync burst. The training Sequence is in the center of every burst, and is used to determine the start and stop of the useful part of the burst.

Mod Type
Modulation Type can be either GMSK or 8PSK. GSM signals use GMSK modulation, and EDGE signals use 8PSK modulation.

TS Pwr (Timeslot Power)
The average power of the highest power timeslot in the acquired frame. This is the absolute power level and displayed in both dBm and microWatts.

OBW (Occupied Bandwidth)
This is the 99% power bandwidth of the centered 500 kHz span at the channel frequency. In other words, the total power of 500 kHz span centered at the channel frequency is computed, then the bandwidth that contains 99% of the total power is returned as the occupied bandwidth.

I/Q Offset
I/Q origin offset is a value in dB of the I and Q error (magnitude squared) offset from the origin. It indicates the magnitude of the carrier feedthrough signal. When there is no carrier feedthrough, I/Q Offset is zero.

RMS and Peak Phase Error
Phase error is the fundamental measure of modulation quality in GSM and EDGE systems. Since GSM and EDGE systems use relative phase to transmit information, the phase accuracy of the GSM or EDGE transmission is critical to the system's performance, and ultimately to its effective range.
The Phase Error metrics are only reported for GSM signals with their GMSK modulation. Phase Error is not reported for EDGE signals, with their 8PSK modulation, since this measurement of signal quality is reported as part of the Error Vector Magnitude metric. For more details on Error Vector Magnitude measurements with EDGE signals, see "RMS, Pk, and 95%tile Error Vector Magnitude" (below).
The phase error is computed by measuring the test signal and computing the difference between the phase of the transmitted signal and the phase of a theoretically perfect signal.
RMS Phase Error: This is the RMS of the phase error (in degrees) between the measured phase and the ideal phase of a TCH timeslot. The GSM standard specifies the RMS phase error not to exceed 5 degrees during the useful part of the GSM burst.
Pk Phase Error: Peak phase error is the maximum phase error (in degrees) between the measured phase and the ideal phase of a TCH timeslot, at a single instant. The GSM standard specifies the peak phase error not to exceed 20 degrees during the useful part of the GSM burst.

RMS, Pk, and 95%tile Error Vector Magnitude
Error Vector Magnitude (EVM) is used as a measure of the quality of a signal, and represents the difference, in both phase and magnitude, between a theoretically perfect signal and the actual signal received.
Another measure of quality similar to EVM is Modulation Error Ratio (MER), which is sometimes referred to as Carrier to Interference Ratio (C/I). For further details on MER and C/I, see the section at the end of "Interpretation of GSM and EDGE Analyzer Measurement Results"

NOTE: RMS EVM, Peak EVM, and 95%tile EVM measurements are only available if Option 235 - EDGE Analyzer is installed

RMS EVM: This is the RMS of the EVM (Error Vector Magnitude), and is only reported for 8PSK modulated signals, that is, for EDGE signals only and not for GSM signals. EVM is measured and calculated over the useful part of the burst, and is shown as a percentage.
The EVM metrics are only reported for EDGE signals with their 8PSK modulation. EVM is not reported for GSM signals, with their GMSK modulation, since this measurement of signal quality is reported as the Phase Error metric. For more details on Phase Error measurements with GSM signals, see "RMS and Pk Phase Error" (above)
Pk EVM: This is the Peak of the EVM (Error Vector Magnitude), and is only reported for 8PSK modulated signals, that is, for EDGE signals only and not for GSM signals. EVM is measured and calculated over the useful part of the burst, and is shown as a percentage.
95%tile EVM: This is the 95th Percentile of the EVM (Error Vector Magnitude), and is only reported for 8PSK modulated signals, that is, for EDGE signals only and not for GSM signals. In other words, it is the EVM value below which 95% of all measurements fall. EVM is measured and calculated over the useful part of the burst, and is shown as a percentage.