Trouble Shooting Guide, Advanced
4/00021-3/FEA 209 544/25 C
Ericsson Mobile Communications AB
40(78)
One method to measure the transient spectrum is to use the following settings at the spectrum
analyser:
CF – 903.2 MHz, SPAN – 0 MHz, RBW – 30 kHz, VBW – 100 kHz and SWEEP – 6 ms.
You measure the highest level of the signal.
The easiest way to do it is to use ”single sweep” to freeze the picture and ”peak search” to
find the highest level. The spectrum should look like the Fig. 12.3 below.
Fig. 12.3
For the example in the picture we have measured the transient spectrum at channel 64 + 400
kHz.
Do the same measurement at channel 64 – 400 kHz, by changing CF at the spectrum analyser
to 902,4 MHz. The power level must be inside the limits, (Table 12.1).
It is very difficult to make an exact transient spectrum measurement on a trouble-shooting site
since there are a lot of disturbances in the air. It can be a difference of a few dBm compared
to the measurement in EFRA.
You can also check the transient spectra with a Anritsu.
Start the transmitter in switched mode and go to “Tx measure/Output RF spectrum”.
“Switching Transients Lower” (-400 kHz) and “Switching Transients Upper” (+400 kHz)
must be inside the limits, Table 12.1.
GSM1800:
Same as for EGSM900, but do not forget to change to GSM1800 and Power level 0 in the test
program, also change CF at the spectrum analyser.
The Power level must be inside the limits, Table 12.1.