KD7LMO - Pico Beacon


Payloads Payload Computer Micro Beacon Cut Down HF-APRS Video Link Pico Beacon Overview Block Diagram Hardware Mechanical Source Code Telemetry Data Logger NSRV Beacon APRS Beacon

Hardware

Shown below is the Pico Beacon controller board. The board is a custom built, 3" x 3½" double sided circuit board. The board contains the processor as well as the power converter, temperature sensor, DDS, amplifier chain, and GPS engine.

Programming Port In-circuit serial programming and debug port for PIC18F2525 processor. Software developed in C programming language. Interfaces directly to Microchip's newest MPLAB ICD-2 USB based programmer/debugger.

Flight Data Recorder 1M x 8 bit (1,048,576 bytes) serial flash memory for flight data recorder.

Temperature Sensor National Semiconductor LM92 digital temperature sensor.

Power Converter High efficiency power converter. Heat sink not required. Provides 3.2 VDC for PA and controller. Designed to operate from 2, 1½VDC AA Lithium batteries.

Output Filter Traditional, 5 pole low pass filter using LC network with surface mount capacitors and inductors.

SMA RF Output Light-weight, compact SMA connector serves as RF output port.

RF Power Amplifier RF Microdevices RF2192 1 watt power amplifier biased to 500mW for improved battery life and reliability. Thanks to our local sales representative for providing sample parts and an evaluation board.

RF Filter/Amplifier Chain A pair of band pass filters and MMIC amplifiers provide a gain of 18 and 10dB in the transmit operational band.

DDS (Direct Digital Synthesizer) Analog Devices AD9954 DDS generates modulated UHF carrier. Digital modulator is multi-standard capable. Software currently supports 1200bps A-FSK and 9600bps FSK.

19.2 MHz TCXO Temperature Compensated Crystal Oscillator services as master clock for DDS and processor. Part rated at +/- 2.5 PPM accuracy. Transmit frequency automatically adjusted using GPS 1-PPS.

Embedded Controller Microchip PIC18F2525 flash memory based processor running at 19.2MHz.

Pico Beacon board.

Schematic / PCB Layout

For best quality, print the schematic on a single 8½ x 11" sheet of paper in landscape mode using your favorite graphics application.

NOTE: There were white wire and component value changes that are not reflected in the schematics and board layout provided below. The change will be incorporated into the design information as time permits.


Schematic (Graphic - GIF)	PCB Layout Top Layer (Adobe PDF)	PCB Layout Bottom Layer (Adobe PDF)

Additional information on viewing the PCB artwork, PCB tools, and component libraries is available in the Technology section.

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