2.4Main 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.

2.4.1Types 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

TX: 880-890

 

TX: 1710-1785

 

 

 

RX: 935-960

RX: 925-935

 

RX: 1805-1880

 

 

 

 

 

 

 

 

Channel spacing

200 kHz

 

 

200 kHz

 

 

 

 

 

 

Number of channels

 

173 carriers *8 (TDMA)

374 carriers *8 (TDMA)

 

 

GSM: channels 1 to 124

 

DCS: channels 512 to 885

 

 

 

E-GSM: channels 975 to 1023

 

 

 

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

 

< –102 dBm

 

 

< –102 dBm

antenna connector

 

 

 

 

 

 

 

 

 

 

 

 

 

Transmitter output power

 

Class 4

 

 

Class 1

at antenna connector

 

2 W (33 dBm)

 

 

1 W (30 dBm)

Automatic hand-over between GSM 900 and GSM 1800

2.4.2Short 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

Owner’s Manual

Rev 1.0

Page 18 of 18