Owner’s Manual Rev 1.0 Page 18 of 18
2.4 Main Features and Services
The modem performs a set of telecom services (TS) according to GSM
standard phase 2+, ETSI and ITU-T. The services and functions of the
modem are implemented by issuing AT commands over the RS232 serial
interface.
2.4.1 Types of Mobile Station
The TT4031 (SE-GM29) is a dual band serial modem with the GSM radio
characteristics shown in the table below.
TT4031 (SE-GM29) GSM 900 E-GSM900 GSM 1800
Frequency Range (MHz) TX: 890-915
RX: 935-960
TX: 880-890
RX: 925-935
TX: 1710-1785
RX: 1805-1880
Channel spacing 200 kHz 200 kHz
Number of channels 173 carriers *8 (TDMA)
GSM: channels 1 to 124
E-GSM: channels 975 to 1023
374 carriers *8 (TDMA)
DCS: channels 512 to 885
Modulation GMSK GMSK
TX Phase Accuracy < 5º RMS phase error (burst) < 5º RMS phase error (burst)
Duplex spacing 45 MHz 95 MHz
Receiver sensitivity at
antenna connector
< –102 dBm < –102 dBm
Transmitter output power
at antenna connector
Class 4
2 W (33 dBm)
Class 1
1 W (30 dBm)
Automatic hand-over between GSM 900 and GSM 1800
2.4.2 Short Message Service
The modem supports the following SMS services:
Sending; MO (mobile-originated) with both PDU (protocol data
unit) and text mode supported.
Receiving; MT (mobile-terminated) with both PDU and text
mode supported.
CBM (cell broadcast message); a service in which a message is
sent to all subscribers located in one or more specific cells in the
