Raspberry Pi Used As A Beacon Transmitter

January 25, 2013 by Mike Szczys 14 Comments

[m0xpd] got his hands on an inexpensive AD9850 DDS Module from eBay but needed a way to control it. He took inspiration from the projects that used a PIC microcontroller, but decided to add his own twist by using a Raspberry Pi to build a multi-mode beacon transmitter.

At the center of this breadboarded circuit lies the green AD9850 module. To its left is a level converter he built to get the 3.3V levels from the RPi board to work with the rest of the 5V hardware. The signal then feeds into a QRP amplifier and a low pass filter.

He didn’t start from square one when it came time to write the code for the RPi. Instead he grabbed an Arduino sketch for the very same DDS and ported it over to Python. The first test signal was his call sign sent in Morse code at QRSS speeds. But he also managed to get Hellschreiber messages working, making it a multiple-mode device.

[via Solder Smoke]

Morse Code Beacon Wins The LayerOne Badge Hacking Contest

May 30, 2012 by Mike Szczys 2 Comments

Ham skills prevail in this year’s LayerOne badge hacking contest. [Jason] was the winner with this Morse Code beacon hack.He got a head start on the competition after seeing our preview feature on the badge hardware development. It got him thinking and let him gather his tools ahead of arrival.

The hardware is segregated into two parts of the board. The lower portion is a take on the Arduino, and the upper portion is a wireless transmitter meant to control some cheap RC cars. [Jason] figured this was perfect for conversion as a CW beacon (continuous wave is what Morse Code is called if you’re a ham). The first issue he encountered was getting the badge to play nicely with the Arduino IDE. It was setup to run Slowduino firmware which uses the internal oscillator. [Jason] soldered on his own crystal and reflashed the firmware. He found that the transmitter couldn’t be directly keyed because of the shifting used in the RC car protocol. He cut the power to the transmitter, and found that it could be more accurately keyed by injecting power to one of the other pins. Check out the video after the break for a better explanation of his technique.

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