To Tag
Pls check the CDMA interference.
and check out ur combiner whether it is for GSM and or EGSM
1)900 MHz band Uplink (MS transmitting and BS receiving) frequency range: 890 MHz ~ 915 MHz
Downlink (BS transmitting and MS receiving) frequency range: 935 MHz ~ 960 MHz
2)Extended 900 MHz band Uplink (MS transmitting and BS receiving) frequency range: 880 MHz ~ 915 MHz Downlink (BS transmitting and MS receiving) frequency range: 925 MHz ~ 960 MHz
CDMA also operates in 820-888MHz so there is very high chance of Interference.
CDMA downlink is were close to the uplink of the GSM frequecny so this can be one possible reason for the interference. In this case I suggest you to use BAND PASS FILTERS for the BTS and reduce the interference level.
Regards
Madhu