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APRS Beacon



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The APRS Beacon is an embedded controller suitable for tracking and locating a balloon based payload using Amateur Radio APRS protocol. APRS, Automatic Position Reporting System, is a scheme developed by Bob Bruninga, WB4APR, that utilizes amateur radio signals to transmit location, weather reports, and messages between users. The APRS Beacon utilizes an ARM7 based controller with a power converter, GPS engine, flash memory, and MODEM to provide a number of standard functions. The APRS Beacon is a 3” x 3” PCB (Printed Circuit Board) with 1/8” mounting holes on each corner.

The APRS Beacon utilizes an ARM7 based processor. The ARM7 is a very popular embedded controller that is used in a large number of commercial products including cell phones, PDAs, and portable MP3 players. The board includes a RS-232 serial port that is used for in-circuit programming. No additional hardware or special cables are required for software development. In addition, the development tools are all open source and based on GNU GCC. The GNU tool set provides an excellent learning platform for a college Computer Science or Computer Engineering program.

The majority of the connections to the APRS Beacon are made through Phoenix Contact terminal blocks. Phoenix Contact terminal blocks are an industry standard connection designed for rugged, industrial applications. Each wire connection is made through a screw clamp terminal. The terminals utilized on the APRS Beacon accept any wire gauge from 20-30 AWG. To keep the APRS Beacon size to a minimum, sub-miniature style terminal blocks are installed. The screw terminals require a small blade screw driver. The terminals in each block are numbered starting with 1 (one) in the left-hand connection.

Phoenix Contact Terminal Block

Phoenix Terminal Block

Feature List

The following are the major features of the APRS Beacon system.

Small 3" x 3" Printed Circuit Board.

Operational over full industrial temperature range (-40° C to +85° C).

Trimble Lassen iQ GPS Receiver. Lowest power (less than 90mW) commercial receiver. Functional above 60,000'.

ARM-7 based Embedded Controller (NXP LPC2148). Software development using no cost GNU C/C++ tool chain. Ideal platform for under-graduate computer science/engineering students.

Integral Switching Power supply for operation at 5 to 20VDC.

USB port to allow for configuration and download of Flight Data Recorder in the field. Configuration under software control as COM port, HID device, or mass storage device.

Firmware updates over the USB port. No special programming pods or hardware are required.

MODEM chip provides 1200 bps TNC MODEM (1200/2200Hz Tone) and DTMF encoder/decoder. Allows for remote commanding through DTMF equipped ground radio.

Generic Radio interface with line/microphone level input and output under software control. Transciever capability for full TNC functions (Digipeater, Mail Box, connected mode). Dry contact (open drain) control outputs for PTT (Push-To-Transmit) and channel (frequency) selection.

Flight Data Recorder with 1MB of memory.

Software to predict landing location after burst based on winds aloft data gathered during ascent

Internal and external temperature sensor. External connection is powerd and includes ESD protection.

3x dry contact (open drain) control outputs. Suitable for camera control or remote functions such as balloon cut down.

2x analog inputs with ESD/Over Voltage protection. ADC (Analog/Digital Converter) for 0 to 3.3 VDC operation.

1x analog output withs ESD protection. DAC (Digital/Analog Converter) generates 0 to 3.3 VDC control signal.

Full open source hardware and software. Developed for NASA Space Grant and ANSR, Arizona Near Space Research.


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