[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).
[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.
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 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.
If you’re into ham radio and want it when you’re on the go give this antenna mount a try. [Cirictech] started with a design from the November 2009 issue of QST and added his own fabrication touches. Everything except the antenna itself is available from the hardware store for just a few bucks, and you should be able to complete this project in a flash. This makes us wonder what the antenna for the 47 GHz band radio setup would look like.
Host of the Soldersmoke podcast, [Bill Meara], contributed this guest post.
WSPR is a new communications protocol written by radio amateur and Nobel Prize winner [Joe Taylor]. Like the very slow QRSS system described in a previous post, WSPR (Weak Signal Propagation Reporter) trades speed for bandwidth and allows for the reception of signals that are far below the level of radio noise. WSPR takes “low and slow” communications several important steps ahead, featuring strong error correction, high reliability, and (and this is really fun part) the automatic uploading (via the net) of reception reports — [Taylor]’s WSPR web page constantly gathers reports and produces near real-time Google maps of showing who is hearing who. The WSPR mode is very hack-able: [Bill Meara] is running a 20 milliwatt homebrew transmitter from Rome, Italy that features an audio amplifier from a defunct computer speaker pictured below. This contraption recently crossed the Atlantic and was picked up by the Princeton, New Jersey receiving station of WSPR’s esteemed creator, [Joe Taylor]. Continue reading “WSPRing Across The Atlantic”
Today, I stumbled across this morse code keyboard. I couldn’t find any sign on the promised schematics or code, but I like the design. It’s not that hard to train yourself in Morse code, and it’s nearly impossible to send an erroneous code thanks to the unique slide=dash tap=dot physical interface.
