Hellduino: Hellschreiber radio transmissions from an Arduino board

[Mark VandeWettering] was experimenting with a simple transmitting circuit and an Arduino. The circuit in the project was designed by [Steve Weber] to broadcast temperature and telemetry data using Morse Code. But [Mark] wanted to step beyond that protocol and set out to write a sketch that broadcasts using the Hellschreiber protocol.

This protocol transmits glyph images, which are decoded as you see above. For some reason we can’t help but think this is like Captcha for radio enthusiasts. We have seen Hellschreiber used with AVR microcontrollers before, but this is the first Arduino implementation that we’ve come across. [Mark] does a great job of demonstrating his project in the video after the break. He mentions that the transmitter has no antenna, but is still being picked up by his receiving antenna mounted behind his house.

Since [Mark] doesn’t really cover the hardware he used, you will need to look back at [Steve's] original design schematics for more information.

[Read more...]

Beating the wrong amateur balloon record

Friday, we covered a little project that attempted to beat the UK altitude record for an amateur balloon launch. Things don’t always go as planned, but the APEX team did manage to beat the several other UK records, including ones for the longest distance and flight duration for a latex balloon.

The APEX team was originally trying to beat the altitude record set by [Darkside] and his Horus 15.5 payload that made it to 40,575 meters. The APEX balloon was launched and slowly climbed over the North Sea to the expected burst point. Unfortunately for the trackers, the balloon leveled off at about 36km and just kept going.

The total Great Circle distance of the APEX Alpha flight was 1347km, with a total flight time of 12 hours, 20 minutes. The balloon eventually drifted out the radio range of anyone aware of the project. Despite the valiant efforts of HAMs across Europe, APEX Alpha was lost in the “HAM wastelands of Eastern Europe,” somewhere over Poland.

Even though the APEX team lost contact with their balloon, Alpha was still transmitting at the time. The balloon surely burst at this point, so it could have landed anywhere from Poland to Ukraine to Russia. The APEX team is offering a reward for finding Alpha, so if you see a small styrofoam box in Eastern Europe, drop the APEX boys a line.

Of course this flight couldn’t have taken place without the efforts of HAMs across Europe. [Darkside], [2E0UPU], and so many others helped out with the tracking as Alpha passed over the Netherlands and continued towards Berlin. The last contact was made by the awesome [OZ1SKY], who was very gracious to stay up until the wee hours of Sunday morning.

Not a bad flight for something that was supposed to take a swim in the North Sea. If you’d like to see the raw data from the flight, the APEX team posted everything they pulled down.

A ham radio receiver, Manhattan Style


If you’ve never heard of “Manhattan Style” circuit construction, you’re not alone. Popular in ham radio circles, the process looks nicer than straight dead bug style circuit building, but not as involved as etching your own PCB – consider it a nice middle of the road solution.

This type of construction is often used to build circuits inside enclosures that are made of copper clad, which is a somewhat common practice among ham radio operators. Manhattan Style circuits are built using glued-on metal pads to which components are mounted. One might think that the large pads you see in the image above would limit you to through-hole components, but that’s definitely not the case. A wide array of SMD pads are available in common pin configurations as well, allowing you to use pretty much any type of component you prefer.

While it might not be appropriate for every project you work on, Manhattan Style circuits and copper clad boxes definitely add a nice touch to certain items, like the Wheatstone Bridge Regenerative Receiver you see above.

[via Make]

[Jeri Ellsworth] builds a software radio

[Jeri Ellsworth] has been working on a direct conversion receiver using an FPGA as an oscillator and a PC sound card DSP. Being the excellent presenter she is, she first goes through the history and theory of radio reception (fast forward to 1:30), before digging into the meat of the build (parts 2 and 3 are also available).

[Read more...]

Quick hack disables iPod dock auto-standby


[Aaron] wrote in to share with us a quick hack that has made his life a little easier. He bought a Rocketfish RF-HV3 portable iPod dock to listen to his music, but he wanted to utilize it as an alarm clock as well. He also found that the speakers worked quite well when he hooked up his Yaesu handheld transmitter to the dock.

The only problem he had with it was that the dock would automatically power down when there was no input for 5 minutes. That’s fine when the dock is running on batteries, but if [Aaron] was going to use it as an alarm clock or to listen to his HAM radio, that simply wouldn’t do.

He pulled the dock apart and started poking around with his DSO Nano scope. He found that if pin 16 stays low for 5 minutes, it turns off the dock even if there is a signal coming through. His fix for the problem was actually quite simple – all he did was solder the VDD pin to the pin in question, and the 5-minute timeout was disabled.

We’re glad that [Aaron] was able to solve his problem in such an easy manner – it just goes to show what you can do with a scope and a few minutes’ time.

PIC-based Ham radio autotuner


A few years back, [Floyd, K8AC] built a high frequency autotuner as an addition to his Ham radio setup. Based off a design he saw in QST magazine back in the early ’90s, he has been using the tuner almost daily for the last few years, on both the 3.5 MHz and 7 MHz bands.

Built into the wall in his radio room, it is a pretty impressive sight. His “L” circuit is controlled by a pair of mechanically coupled inductors which are driven in concert by a pair of two-way motors. The positioning of the C and L components are monitored by a PIC controller which stores the tuning data for up to 30 predefined frequencies. A couple of button presses on his controller’s front end sends the tuner into action, dialing in his unit’s inductors and capacitor to their proper settings. The PIC monitors the tuner’s progress, informing him when the proper frequency has been tuned in, or if the frequency can not be set, indicating issues with the equipment.

His setup has undergone several revisions over the years, with the most recent iteration being the most automated of the bunch. Check out his site for plenty more details, or keep an ear out for [K8AC] on 40 or 80 meters.

[Thanks, Rich V]

Launchpad serial Morse code transmitter


LaunchPad dev boards from Texas Instruments are cheap and easy to program, making them a great Arduino alternative if you can do without some of the bells and whistles. [ech0s] put his to good use by constructing a Morse code transmitter with dual operating modes. The transmitter can not only encode and transmit messages entered in a terminal client, it also allows the user to send messages by manually operating the key switch. Inspired by the high altitude balloon transmitter we featured last summer, this project uses similar components for signal amplification and transmission. Text can be entered in a Putty terminal window, which then is encoded into Morse by the MCU before transmission. At the moment, the speed of the radio transmission is about 15 WPM, which is reasonably quick. Even though his system performs quite well [ech0s] has some improvements planned, including having a proper PCB built as well as some software tweaks to improve buffering and bandwidth. Be sure to check out his video of the transmitter in action after the jump.

[Read more...]