User’s Manual
GSM35
20
RTD Finland Oy
The GSM wireless modem module
The GSM35 wireless GSM modem is built around the Siemens TC35 dual
band 900/1800MHz cellular engine. It is designed both for handling
complex industrial applications such as telemetry, telematics or
communication, and for integration in stationary or mobile fields all over
the world. General information on these products is available at the
following Internet addresses: http://www.siemens.de/gsm_e and
http://www.siemens.de/gsm in german language.
The GSM35 is capable of powerful communication over a speed of 9,6
kbps or CSD up to 14,4 kbps (as of 06/2001). It is capable of FAX and
SMS text messages. The data terminal rate is 9600 baud for all host
commands (AT commands). The GSM35 modem module antenna
interface connector uses an OSX connector. The mating antenna
connectors and cables are supplied from RTD Finland Oy. Temperature
monitoring is possible using the onboard temperature sensor. Limit data
can be interrogated from the GSM35 status register bits 2-3.
GSM Antenna considerations
The antenna used must meet the following specifications: Frequency 890-
910 MHz (TX), 935-960MHz (RX); Impedance 50 Ohms; VSWR 1,7:1 (TX)
1,9:1 (RX); Gain <1,5dB references to 1/2-dipole; 1W power (cw) max 2W
peak at 55 degrees Centigrade. Typically standard GSM antennas use a
female FME connector. This connector needs an adapter unit before it
can be connected to the GSM35.
RTD Finland Oy recommends the use of high quality antennas with the
GSM35. We have tested successfully with antennas from Hirschmann
Rheinmetall Elektronik.
Visit http://www.hirschmann.de/ for information on GSM antennae.
A very useful AT command that shows quality of the signal reception is :
AT+SCQ, the signal qCSQ: value (Value should be > 11) shows
the quality of the network signal.