Building an extremely small ARPS Tracker

1 Project goal

This project has the goal to assemble a lowest possibly imaginable power saving and absolute supercompact highly packed APRS traching transmitter.

2 Ingredients

At last, I got all my ingredients collected:

• EM-406A, a 20 Channel SiRF III GPS Receiver from USGlobalSat with Antenna
• Open Tracker SMT
• Radiometrix HX1-144.800-3 300 mW transmitter

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3 Data

3.1 Datasheets

• http://www.sparkfun.com/datasheets/GPS/EM-406A_User_Manual.PDF EM-406A User Manual
• http://www.datasheetarchive.com/pdf-datasheets/Datasheets-3/DSA-56110.pdf RadioMetrix Module Datasheet
• http://www.sparkfun.com/datasheets/GPS/NMEA%20Reference%20Manual1.pdf NMEA Reference

3.2 Other data

The tracker's inner values:

   * Voltage: DC 6.5 to 28V unregulated or 5V DC regulated
   * Current: 8 mA idle, 20 mA transmitting Max 200 mA @ 5 V available for GPS
   * Modes: 1200 bps AFSK (send and receive); 300 bps AFSK, PSK31 (send only)
   * Radio Connector: pin header
   * Serial Connector: pin header
   * Dimensions: 31mm x 18mm x 5mm
   * GPS interface: NMEA in/out 

Pinout:

Pin Name Funktion 1 5VIN Geregelter 5-Volt-Eingang 2 RxD RS-232 Data in der (vom GPS oder Computer) 3 1Wire Dallas 1-Draht-Bus für externe Sensoren 4 AOUT Audio-Ausgang an Radio 5 ADC5 Analog-Eingang 6 T1CH1 Timer-Kanal 7 ADC6 Analog-Eingang 8 RST Reset (active low) 9 ADC7 Analog-Eingang 10 IRQ- Transmit-now, Profil wählen, oder Zähler 11 ADC8 Analog-Eingang 12 ADC9 Analog-Eingang 13 AIN Audio-Eingang von Radio 14 ADC4 Analog-Eingang 15 ADC3 Analog-Eingang 16 TXD RS-232 Data aus 17 rot rot LED-Ausgang 18 grün grün LED-Ausgang 19 ADC2 Analog-Eingang 20 ADC1 Analog-Eingang 21 PTT Push-to-talk-Signal an Radio 22 REGOUT Regulator-Ausgang - 5 Volt 23 GND Ground 24 REGIN Regulator-Eingang - 6,5 bis 28 Volt

• http://www.jaeger-edv.de/Shop/index.php?page=shop.getfile&file_id=40&product_id=25&option=com_virtuemart&Itemid=53 Config Tool for the OpenTracker SMT

4 Project plan

• Find a cabling arrangement that works
• Program the Opentracker SMT
• Rearrange all the three components on minimal space
• Build a suitable case

5 Tests

• Since I have my APRS relay station ready to go anyway, I just need the tracker to start tracking!