Specifications

Chapter 8 – SocketModem GPRS (MTSMC-G)
Multi-Tech Systems, Inc. Universal Socket Hardware Guide for Developers (S000342C) 119
General Guidelines for the Use of the SocketModem
Hardware and RF
• Ground plane: Multi-Tech recommends having a common ground plane for analog, digital, and
RF grounds.
• ESD protection on serial link.
• Possible spurious emission radiated by the application to the RF receiver in the receiver band
The Antenna
The antenna sub-system and integration in the application is a major issue: Choice of antenna
cable (type, length, performances, thermal resistance, etc.) These elements could affect GSM
performances such as sensitivity and emitted power.
The antenna should be isolated as much as possible from the digital circuitry including the interface
signals.
Multi-Tech recommends shielding the terminal. On terminals including the antenna, a poor
shielding could dramatically affect the sensitivity of the terminal. Subsequently, the power emitted
through the antenna could affect the application.
Soldering and Cleaning the SocketModem
The pins of the SocketModem may be hand soldered or wave soldered. If wave soldered, the
temperature on the top of the SocketModem must not exceed 100° C.
There should be no solvent or water washing of the SocketModem.
Do not use a hot air gun on the SocketModem.
Initial Configuration Using Mobile PhoneTools
For initial configuration of your wireless device, Multi-Tech offers a Windows-based mobile
PhoneTools application.
To load Mobile PhoneTools, click the Mobile PhoneTools icon on the SocketModem CD and follow
the on-screen prompts.
Sources for Peripheral Devices
GSM Antenna
The integrated modem antenna connector is a MMCX connector. The MMCX connector
incorporates a 'Snap On' latching action in order to make the connection easier with an excellent
RF performance. An additional advantage is its small physical size, which is 50% of the standard
MCX connector.
This type of connector is suitable for the standard ranges of flexible and semi-rigid cables. The
characteristic impedance of the MMCX coaxial connector is 50 ohm. The antenna manufacturer
must guarantee that the antenna will be working according to the radio characteristics presented in
the table below.
Radio Characteristics
GSM 850 EGSM 900 GSM 1800 GSM 1900
Frequency RX
869 to 894 MHz 925 to 960 MHz 1805 to 1880 MHz 1930 to 1990 MHz
Frequency TX
824 to 849 MHz 880 to 915 MHz 1710 to 1785 MHz 1850 to 1910 MHz
RF Power Stand
2W at 12.5% duty cycle 2W at 12.5% duty cycle 1W at 12.5% duty cycle 1W at 12.5% duty cycle
Impedance 50 ohms
VSWR <2
Typical Radiated Gain 0 dBi on azimuth plane