Hardware Interface Description - KORE Telematics

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XT55/56 Hardware Interface Description Confidential / Released s 4 GPS application interface The XT55/56 module integrates a GPS receiver which offers the full performance of GPS technology. The GPS receiver continuously tracks all satellites in view, thus providing accurate satellite position data. The GPS block can be used even if the XT55/56 module is deregistered from the GSM network. 4.1 Theory of operation Figure 26: Theory of operation The XT55/56 GPS part is designed to use L1 Frequency (C/A Code) GPS receiver and performs the entire GPS signal processing, from antenna input to serial position data output. The processing steps involved are: • RF section In the RF section the GPS signal detected by the antenna is amplified, filtered and converted to an intermediate frequency (IF). An A/D converter transforms the analogue intermediate frequency into a digital IF signal. • GPS channels The received digital IF signal bit stream is passed to the baseband section, where it is fed into the correlators. The function of the correlators is to acquire and track the satellite signals. There are 12 channels used in parallel, with each correlator looking for a characteristic PRN code sequence in the bit stream. Once the correlator has found a valid signal, pseudo range, carrier phase and orbit information can be extracted from the GPS signal. • Navigation The on-board processor is running an algorithm that calculates the position, velocity and time. This calculation is called navigation solution. Once the navigation solution is calculated, it can be transformed into the desired coordinate system, e.g. Latitude/ Longitude/ Altitude. For further details refer to [3]. • Interface The data of the navigation solution are available at the serial RS-232 interface. XT55/56_hd_v02.06a Page 70 of 125 17.12.2004
XT55/56 Hardware Interface Description Confidential / Released s 4.2 Technical data Industry leading GPS performance • 12 channel GPS receiver • Signal acquisition using 1920 time / frequency search channels • Multipath-mitigation hardware • Cold start < 45 sec Low power • Typ. 220mW without active antenna (continuous mode) • TricklePower mode reduces power to < 60mW • Adaptive TricklePower switches between full and TricklePower • Push-to-Fix reduces power by as much as 98% Additional software options (can be obtained separately) • AVL (for further information refer to [3]) • SiRFXtrac (high sensitivity stand alone software) • SiRFDrive (high sensitivity dead reckoning software) Protocols • SDI1 / SDO1: NMEA 9600 baud, Msg.: GLL, GGA, RMC, VTG, GSV, GSA 8 data bits, no parity, 1 stop bit • SDI2 / SDO2: RTCM, 9600 baud Specification • Position accuracy Autonomous: < 10m Beacon DGPS: < 2.5m • Receiver Tracking: L1, CA code Channels: 12 Max. update rate: 10 Hz Sensitivity: -138 ± 2 dBm 1) Max. altitude:
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Hardware Interface Description - KORE Telematics

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