Terminal Node Controller In A Router

July 23, 2010 by Mike Szczys 17 Comments

[Andrew] used a DSL router to make his own Terminal Node Controller. This will become part of an APRS-IS network, an Internet-based network built by amateur radio operators. The router used here is a Dlink DSL-502T with an AVR based TNC module attached to the serial port header. The phone line connector and its accompanying hardware have been removed to make room for the TNC module, which is supplied with 12V via that red wire. When the router boots up it sends data to the serial port header so the firmware on the TNC needed some tweaking to accommodate this (yay for open source).

Want some more APRS goodness? Check out this AVR APRS tracker.

Texting With Some Walkie-talkies

July 7, 2010 by Mike Szczys 44 Comments

[Travers Buda] is giving new life to his abandoned childhood toys. He cracked open a set of Family Radio Services radios he had received for a birthday which work up to 2 kilometers apart. With just a bit of extra circuitry he was able to get them to act as wireless modems. The system functions but it looks like it would benefit from some more refinement, including error correction. In the end [Travers] manages to send and receive ASCII based messages at a whopping baud rate of 10.

Adding Motion Control To An RC Transmitter

June 25, 2010 by Mike Szczys 5 Comments

If your soldering skills are up to snuff you can add a motion control feature to your radio controlled transmitter. [Starlino] used a combination accelerometer and gyroscope module as an alternate source of analog control information. He built a filter to dial in the analog voltage range to match that of one of the sticks on the controller. A switch is used to disconnect the signal when motion input is not desired. This would be a nice addition to one of those more creative aerial hacks.

X-Band Linear Rail SAR Imaging

June 17, 2010 by Caleb Kraft 17 Comments

[Greg Charvat] really wanted high resolution X-Band linear rail SAR imaging system. He wanted it bad enough to scrounge through parts at HAM radio swap meets until he had the bits to build one himself. The unit is used to take high resolution radar imaging. For example, the image above is constructed of push pins behind a foam wall. The synthetic aperture radar system came in at roughly $250. Not bad at all. You may have to dig through the links a bit to find the build information. Be sure to check out the hardware gallery and the schematics(pdf).

[via Makezine]

Building Air Variable Capacitors

May 12, 2010 by Mike Szczys 14 Comments

In keeping with our opinion that radio operators were the original electronic hackers here’s a guide to building your own transmitting air variable capacitors. Using some roof flashing, Plexiglas, and various fasteners [David Hammack] was able to make it work. It’s not a perfect solution but he has some ideas to make the next one better. Give this a try after you’re done tweaking your crystals and building input devices.

[Thanks Rich]