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GSM Specifications
Specifications for different personal communication services (PCS) systems are different among the different PCS networks. Description of the specifications and characteristics for GSM is as follows.

Frequency band:
For GSM the frequency range is varying from 1,850 to 1,990 MHz (mobile station to base station).

Duplex distance:
80 MHz is the duplex distance. Distance between the uplink and downlink frequencies is called Duplex distance.

Channel separation:
The separation between adjacent carrier frequencies is 200 kHz in GSM.

Modulation:
The process of sending a signal by changing the characteristics of a carrier frequency is called Modulation. In GSM, this is done by Gaussian minimum shift keying (GMSK).

Transmission rate:
GSM is a digital system with transmission rate of 270 kbps.

Access method:
GSM implement the time division multiple access (TDMA) concept. In TDMA technique several different calls may share the same carrier. For each call a particular time slot is allotted.

Speech Coder:
GSM make use of linear predictive coding (LPC). The use of LPC is to decrease the bit rate. The LPC offers parameters for a filter which mimics the vocal tract. The signals pass through speech coder leaving behind a residual signal. The signal is encoded at 13 kbps

GSM Network
GSM offers recommendations not requirements. GSM specifications do not address the hardware but define the functions and interface requirements in detail. The reason is to bind the designers as little as possible but still make it possible for the operators to buy different equipment from different suppliers. GSM network is divided into three major systems:

1) Mobile Station
The mobile station (MS) includes mobile equipment and a smart card known as Subscriber Identity Module (SIM). The SIM offers mobility so that the user can have access to subscribed services irrespective of a specific location. The SIM card can be inserting into another GSM terminal so that the user is able to receive calls at that terminal make calls from that terminal and receive other subscribed services.

2) Base Station Subsystem
The Base Station Subsystem consists of two parts, Base Transceiver Station (BTS) and Base Station Controller (BSC). These stations communicate across the standardized interface allowing operation between components made by different suppliers.

The Base Transceiver Station addresses the radio transceivers that defines a cell and handles the radio-link protocols with the Mobile Station. The Base Station Controller handles the radio resources for one or more BTSs. It manages radio-channel setup and frequency hopping. The BSC is the connection between the mobile station and the Mobile service Switching Center (MSC).

3) Network Subsystem
Network Subsystem’s central component is the Mobile services Switching Center (MSC). It work as normal switching node of the PSTN or ISDN and additionally offers all the functionality needed to handle a mobile subscriber such as authentication, registration, location updating and call routing to a roaming subscriber. These services are offered in conjunction with several functional entities which together form the Network Subsystem.

Garmin and Magellan GPS Antennas

Click the button at right to browse new and improved remote GPS antennas with multiple mounting options and low profiles. Magnetic mounts for the outside of your vehicle or boat; and suction mounts, which holds the antenna in place against the inside of your windshield or window. Rebroadcast antennas to relay and strenghen the signal. Low voltage to minimize battery drain. Connects to your Garmin or Magellan units via a standard connectors.

 

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News & Evens
vehicle tracking system is an electronic device installed in a vehicle to enable the owner or a third party to track the vehicle's location. Most modern vehicle tracking systems use Global Positioning System (GPS) modules for accurate location of the vehicle. Many systems also combine a communications component such as cellular or satellite transmitters to communicate the vehicle’s location to a remote user. Vehicle information can be viewed on electronic maps via the Internet or specialized software.
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