The modulator receives the bits from the encryption unit@ see GSM 05.01 [1]@ and produces an RF signal. The filtering of the Radio Frequency (RF) signal necessary to obtain the spectral purity is not defined@ neither are the tolerances associated with the theoretical filter requirements specified. These are contained in GSM 05.05 [4].
ETSI EN 300 959:1998 history
2001ETSI EN 300 959:2001 Digital Cellular Telecommunications System (Phase 2+); Modulation (GSM 05.04 Version 8.1.2 Release 1999)
2000ETSI EN 300 959:2000 Digital Cellular Telecommunications System (Phase 2+); Modulation (GSM 05.04 Version 6.1.1 Release 1997)
1999ETSI EN 300 959:1999 Digital Cellular Telecommunications System (Phase 2+); Modulation (GSM 05.04 Version 6.0.1 Release 1997)
1998ETSI EN 300 959:1998 Digital Cellular Telecommunications System (Phase 2+); Modulation (GSM 05.04 Version 6.0.0 Release 1997)