Specifications

Chapter 8 – SocketModem GPRS (MTSMC-G)
Multi-Tech Systems, Inc. Universal Socket Hardware Guide for Developers (S000342F) 119
Application Notes
Flashing LED Interface
The flashing LED signal is used to indicate the working mode of the SocketModem.
LED and SocketModem Status
Signal SocketModem Status
OFF Download mode or switched OFF>
Continuously lit Switched ON (not registered on the network) ON
Flashing Switched ON (registered on the network)
RF Interface
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
RF Performances
RF performances are compliant with the ETSI recommendation 05.05 and 11.10.
The main parameters are:
Receiver Features
• EGSM Sensitivity : < -104 dBm
• GSM 1800/GSM 1900 Sensitivity : < -102 dBm
• Selectivity @ 200 kHz : > +9 dBc
• Selectivity @ 400 kHz : > +41 dBc
• Dynamic range : 62 dB
• Intermodulation : > -43 dBm
• Co-channel rejection : + 9 dBc
Transmitter Features
• Maximum output power (EGSM) : 33 dBm ± 2 dB
• Maximum output power (DCS/PCS) : 30 dBm ± 2 dB
• Minimum output power (EGSM): 5 dBm ± 5 dB
• Minimum output power (DCS/PCS): 0 dBm ± 5 dB
• H2 level : < -30 dBm
• H3 level : < -30 dBm
• Noise in 925 - 935 MHz : < -67 dBm
• Noise in 935 - 960 MHz : < -79 dBm
• Noise in 1805 - 1880 MHz : < -71 dBm
• Phase error at peak power : < 5 ° RMS
• Frequency error : ± 0.1 ppm max
RF Connection
The RF connector on the SocketModem GPRS is an MMCX standard type. An antenna can be directly
connected through a mating MMCX to SMA adapter as shown in Peripheral Devices on the next page.
Microphone Inputs
The MIC inputs are differential ones. They already include the convenient biasing for an electret microphone
(0,5 mA and 2 Volts). This electret microphone can be directly connected on these inputs. The impedance of
the microphone has to be around 2K. These inputs are the standard ones for a handset design.
The gain of the MIC inputs is internally adjusted. The gain can be tuned from 30dB to 51dB. The connection
to the microphone is direct.
MIC2N
MIC2P
C1
C1 = 22pF to 100 pF
33 pF recommended