How hard is it to make a fully standalone SDR? [101 Things] shows you how to take a breadboard, a PI Pico, and two unremarkable chips to create a capable radio. You can see the whole thing in the video below.
The design uses a standard Tayloe demodulator. There’s also an encoder and an OLED display for a user interface. You might also want to include some PC speakers to get a bit more audio out of the device.
The decline of AM broadcast radio is a slow but inexorable process over much of the world, but for regions outside America there’s another parallel story happening a few hundred kilohertz further down the spectrum. The long wave band sits around the 200kHz mark and has traditionally carried national-level programming due to its increased range. Like AM it’s in decline due to competition from FM, digital, and online services, and one by one the stations that once crowded this band are going quiet. In the middle of all this it’s a surprise then to find a new long wave station in the works in the 2020s, bucking all contemporary broadcasting trends. Arctic 252 is based in Finland with programming intended to be heard across the Arctic region and aims to start testing in September.
The hack in this is that it provides an opportunity for some low-frequency DXing, and given the arctic location, it would be extremely interesting to hear how far it reaches over the top of the world into the northern part of North America. The 252KHz frequency is shared with a station in North Africa that may hinder reception for some Europeans, but those with long memories in north-west Europe will find it fairly empty as it has been vacated in that region by the Irish transmitter which used to use it.
So if you have a receiver capable of catching long wave and you think you might be in range, give it a listen. Closer to where this article is being written, long wave stations are being turned off.
Harris & Ewing, photographer, Public domain.
The QN8066 is a fun little FM transmitter chip. It covers the full FM broadcast band and has built-in DSP. You would find this sort of part in car cell phone adapters before every vehicle included Bluetooth or an AUX port. [Ricardo] has created an Arduino library to bring the QN8066 to the masses.
The chip is rather easy to use – control is handled with a common I2C interface. All the complex parts – Phase Locked Loop (PLL), RF front end, power management, and audio processing are all hidden inside. [Ricardo’s] library makes it even easier to use. One of the awesome features of the 8066 is the fact that it handles Radio Data System (RDS). RDS is the subcarrier datastream that allows FM stations to inject information like song title and artist into the signal. The data is then displayed on your radio screen.
You can find the source to [Ricardo’s] library on GitHub. Using it is as simple as picking it up from the Arduino IDE.
If you are looking for an RDS-enabled radio to test out your QN8066 design, you wouldn’t do too bad with this Gameboy cartridge receiver.
Click through the break for a video from [Ricardo] explaining his QN8066 design. Continue reading “Be Your Own DJ With QN8066 And An Arduino Library”
Anyone who has done an electronic engineering qualification will at some point have had to get to grips with transmission lines, and then if they are really lucky, waveguides. Perhaps there should be one of those immutable Laws stating that for each step in learning about these essential parts, the level of the maths you are expected to learn goes up in an exponential curve, for it’s certainly true that most of us breathe a hefty sigh of relief when that particular course ends. It’s not impossible to understand waveguides though, and [Old Hack EE] is here to slice through the formulae with some straightforward explanations.
First of all we learn about the basics of propagation in a waveguide, then we look at the effects of dimension on frequency. Again, there’s little in the way of head-hurting maths, just real-world explanations of cutt-off frequencies, and of coupling techniques. For the first time we’ve seen, here are simple and understandable explanations of the different types of splitter, followed up by the famous Magic T. It’s all in the phase, this is exactly the stuff we wish we’d had at university.
The world needs more of this type of explanation, after all it’s rare to watch a YouTube video and gain an understanding of something once badly taught. Take a look, the video is below the break.
Continue reading “The Waveguide Explanation You Wish You’d Had At School”
The classic crystal radio was an oatmeal box with some wire and a few parts. [Michael Simpson] has something very different. He found an assembled Philmore “selective” radio kit. The simple kit had a coil, a germanium diode, and a crystal earphone.
We were sad when [Michael] accidentally burned a part of the radio’s coil. But–well–in the end, it all worked out. We’ll just say that and let you watch for yourself. The radio is simplicity itself, built on a wooden substrate with a very basic coil and capacitor tuned circuit. Continue reading “Vintage Crystal Radio Draws The Waves”
It is one of Murphy’s laws, we think, that you can’t get great things when you need them. Back in the heyday of shortwave broadcasting, any of us would have given a week’s pay for even a low-end receiver today. Digital display? Memory? Digital filtering? These days, you have radios, and they aren’t terribly expensive, but there isn’t much to listen to. Making matters worse, it isn’t easy these days to string wires around in your neighborhood for a variety of reasons. Maybe you don’t have a yard, or you have deed restrictions, or your yard lacks suitable space or locations. This problem is so common that there are a crop of indoor antennas that seem attractive. Since I don’t often tune in shortwave and I don’t want to have to reset my antenna after every storm, I decided to look at the Tecsun AN-48X along with a YouLoop clone from China. Let’s start with the Tecsun. Continue reading “An Antenna To Throw You For A Loop”
There’s an old saying in the amateur radio community that when it comes to antennas all you need is a piece of wet string. This may be a little fanciful, but it’s certainly true that an effective antenna can be made with surprisingly little in the way of conductor. It’s something [Evan Pratten VZ3ZZA] demonstrates amply with a description of the antenna he took camping in a Canadian provincial park.
Most of us would try some form of dipole on our adventures, but the antenna he’s using caught our eye as it’s described as an end-fed half-wave, but it has both a half-wave and quarter-wave element. Made from speaker cable or in this case thin mains cable for lamps, it’s obviously far from a perfect match and requires an ATU, but it generates an impressive array of FT4 contacts on a pretty meagre power level. We particularly like his in-plain-sight test run in the parking lot of a supermarket.
We frequently talk about the diversity of pursuits in amateur radio aside from that of the chequebook ham, and this project shows one of those. The world of QRP, operating at extreme low power, is not expensive to enter and can be extremely rewarding.
