Morse Code RF Transmitter from a Micro’s Clock Output

If you’re looking for a simple way to make an RF transmitter, check out [Tomasz]’s Morse code transmitter. His design uses nothing more than a microcontroller and a 16MHz crystal to transmit CW Morse code on 96MHz. We’ve seen some similar designs that work at lower frequencies, but transmitting up at 96MHz is pretty impressive.

[Tomasz] used an STM32L microcontroller for this project, which isn’t specced to run up at the high frequencies he wanted to transmit at. To get around this, [Tomasz] wired a 16Mhz oscillator up to microcontroller’s clock input. The clock input is run into the micro’s PLL which is capable of generating high frequencies. He mentions that you can use the internal oscillator instead of a crystal, but it has a ton of phase noise and splatters all over the spectrum.

[Tomasz] chose to start transmitting at 96MHz, which can be picked up by a standard FM radio. To generate this frequency, he set the PLL to multiply the 16MHz crystal up to 192MHz followed by a clock divide of 2 which brings it down to 96MHz. The microcontroller’s CPU runs on the 16MHz crystal input before it goes into the PLL. Next [Tomasz] enabled the MCO clock output pin which routes the 96MHz signal to the outside world.

Transmitting CW is pretty simple; it just involves turning a fixed-frequency transmitter on and off. [Tomasz] wrote a function that enables and disables the MCO output pin. This has the effect of keying any Morse code string you throw at it. Check out the video after the break to see the transmitter in action.

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Transmitting Data Long-Distance with Morse Code

[Konstantinos] wrote in to tell us about his CDW project: a digital encoding scheme for ham radio that uses CW (continuous wave) Morse code for digital data transfer. CW operation with Morse code is great for narrow-bandwidth low-speed communication over long distances. To take advantage of this, [Konstantinos] developed a program that takes binary or text files, compresses them, and translates them to a series of letters and numbers that can be represented with Morse code.

The software translates the characters into sequences of Morse code pulses, and plays an audio stream of the result. His software doesn’t support decoding Morse from an audio stream, so [Konstantinos] recommends using one of many existing programs to get the job done. Alternatively those with a good ear and working knowledge of Morse can transcribe the characters by hand.

After receiving a broadcast, the user pastes received characters back in the software. The software re-assembles the binary file from the Morse characters and decompresses the result. [Konstantinos] also added a simple XOR encryption feature, but keep in mind that using encryption on ham radio bands is technically illegal.

Retrotechtacular: How to Teletypewriter

This week, you’re going to learn the ins and outs of the AN/GRC-46 thanks to this army training film from 1963. What is the AN/GRC-46, you ask? Why it’s a complete mobile-tactical sheltered radio-teletypewriter rig capable of CW, voice, and teletype transmission.

The film covers the components that make up the AN/GRC-46, their functions, the capabilities of the system, and proper operation procedures. There’s a lot going on in the tiny 1400lb. steel shelter, so each piece will be introduced from the ground up.

You’ll become familiar with the voltage distribution system and the AN/GRC-46’s included accessories. This introduction will be followed by a short course in RF signal transmission and the Frequency-Shift Keying (FSK) that is performed by the modulator. The ranges of both the transmitter and receiver are discussed, along with the capabilities mentioned before: CW operation using the keyer, voice operation, teletype operation, and reperforation of teletype tape.

Finally, you’ll observe a seasoned operator make contact and send a teletype message with movements so careful and deliberate that they border on mesmerizing. When he’s not sending messages or taking long walks on the beach, he can usually be found cleaning and/or lubricating the transmitter filter.

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THP Semifinalist: A Continuous Wave Radar

There aren’t many Hackaday Prize entries playing around in RF, save for the handful of projects using off the shelf radio modules. That’s a little surprising to us, considering radio is one of the domains where garage-based tinkerers have always been very active. [Luke] is bucking the trend with a FM continuous wave radar, to be used in experiments with autonomous aircraft, altitude finding, and synthetic aperture radar imaging.

[Luke]’s radar operates around 5.8-6 GHz, and is supposed to be an introduction to microwave electronics. It’s an extremely modular system built around a few VCOs, mixers, and amplifiers from Hittite, all connected with coax.

So far, [Luke] has all his modules put together, a great pair of cans for the antennas, everything confirmed as working on his scope, and a lot of commits to his git repo.

You can check out [Luke]’s demo video is available below.


SpaceWrencherThe project featured in this post is a quarterfinalist in The Hackaday Prize.

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Guest Post: Try Radar for Your Next Project

Sensors. The low-end stuff that we can get our hands on usually suffers from poor range, lack of sensitivity, and no way to characterize what the target is. But today we can use the good stuff that, until recently, was only available to military: radar. In this post we will discuss how radar works, commercially available small radar devices, and where to learn more to help make it easy to add radar to your next project. Reach out and sense something!
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Morse code beacon wins the LayerOne badge hacking contest

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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Fine tune your Morse Code skills with this mint tin practice keyer

mint-tin-keyer

Hackaday reader [svofski] wrote in to share a device he built, which would be useful to any ham operators out there trying to hone their CW skills. He calls his practice keyer the Morseshnik, and it is a combination of various items [svofski] found while digging through his parts drawer.

He disassembled an old hard drive, saving its read arm to serve as the keyer’s paddle. He purchased some small angle brackets to create a set of contacts for the device, between which the lever sits, automatically centered by a pair of springs.

An MSP430, which was also collecting dust in [svofski’s] junk pile, resides inside the Morseshnik’s mint tin base on a small DIY PCB. It allows him to toggle between manual and automatic keying modes with the flick of a switch as he whiles his time away practicing his dits and dahs.

Continue reading to see a short video of the Morseshnik in action, and swing by his site for code and PCB schematics should you want to build one of your own.

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