Crowdsourcing The Study Of An Eclipse’s Effect On Radio Propagation

If you are an American, you’ll probably now find yourself in one of three camps. People who are going to see the upcoming solar eclipse that will traverse your continent, people who aren’t going to see the eclipse, and people who wish everyone would just stop going on incessantly about the damn eclipse.

Whichever of those groups you are in though, there is an interesting project that you can be a part of, an effort from the University of Massachusetts Boston to crowdsource scientific observation of the effect a solar eclipse will have on the upper atmosphere, and in particular upon the propagation of low-frequency radio waves. To do this they have been encouraging participants to build their own simple receiver and antenna, and make a series of recordings of the WWVB time signal station before, during, and after the eclipse traverse.

This is an interesting and unusual take upon participation in the eclipse, and has the potential to advance the understanding of atmospheric science. It would be fascinating to also look at the effect of the eclipse on WSPR contacts, though obviously those occur in amateur bands at higher frequencies.

If you are an EclipseMob participant, we’d love to hear from you in the comments. Does your receiver perform well?

Thanks [Douglas] for the tip.

Amateur Radio Just Isn’t Exciting

As ARRL president, [Rick Roderick, K5UR] spends a significant amount of time proselytising the hobby. He has a standard talk about amateur radio that involves tales gleaned from his many decades as a licence holder, and features QSL cards from rare DX contacts to show how radio amateurs talk all over the world.

He’s delivered this talk countless times, and is used to a good reception from audiences impressed with what can be done with radio. But when he delivered it to a group of young people, as Southgate ARC reports, he was surprised to see a lack of interest from his audience, to whom DX or contesting just don’t cut it when they have grown up with the pervasive Internet. Writing in the 2016 ARRL Annual Report, he said:

“Change generally doesn’t come easy to us. But when I looked out at that group of young faces and saw their disinterest in traditional ham pursuits, I realized that I had to change. We have to change. It won’t come easy, but it’s essential that we get to work on it now.”

If you were to profile a typical group of radio amateurs, it would not be difficult to see why [K5UR] found himself in this position. It might be an unflattering portrait for some amateurs, but it’s fair to say that amateur radio is a hobby pursued predominantly by older more well-off men with the means to spend thousands of dollars on commercial radios. It is also fair to say that this is hardly a prospect that would energize all but the most dedicated of youthful radio enthusiasts. This is not a new phenomenon, where this is being written it was definitely the case back in the days when they were issuing G7 callsigns, for instance.

Were Hackaday to find ourselves in the position of advising the ARRL on such matters, we’d probably suggest a return to the roots of amateur radio, a time in the early 20th century when it was the technology that mattered rather than the collecting of DXCC entities or grid squares, and an amateur had first to build their own equipment rather than simply order a shiny radio before they could make a contact. Give a room full of kids a kit-building session, have them make a little radio. And lobby for construction to be an integral part of the licensing process, it is very sad indeed that where this is being written at least, the lowest tier of amateur radio licence precludes home-made radio equipment. Given all that, why should it be a surprise that for kids, amateur radio just isn’t exciting?

We’ve shown you some fantastic amateur radio builds over the years. If you have a youngster with an interest in radio, show them a BitX transceiver, or the world of QRP.

Header image: enixii. [CC BY 2.0]. We hope these snoozing kids aren’t in the middle of a lecture on amateur radio.

Rapidly Prototyping RF Filters

RF filters are really just a handful of strategically placed inductors and capacitors. Yes, you can make a 1 GHz filter out of through-hole components, but the leads on the parts turn into inductors at those frequencies, completely ruining the expected results in a design.

The solution to this is microstrip antennas, or carefully arranged tracks and pads on a PCB. Anyone can build one of these with Eagle or KiCad, but that means waiting for an order from a board house to verify your design. [VK2SEB] has a better idea for prototyping PCB filters: use copper tape on blank FR4 sheets.

The first, and simplest, filter demonstrated is a simple bandstop filter. This is really just a piece of fiberglass with copper laminated to one side. Two RF connectors are soldered to the edges and a strip of copper tape strung between them. Somewhere around the middle of this copper tape, [VK2SEB] put another strip of copper tape in a ‘T’ configuration. This is the simplest bandstop filter you can make, and the beauty of this construction is that it can be tuned with a razor blade.

Of course, a filter can only be built with copper tape if you can design them, and for that [SEB] is turning to software. The Qucs project is a software tool for designing and simulating these microstrip filters, and after inputting the correct parameters, [SEB] got a nice diagram of what the filter should look like. A bit of taping, razor blading, and soldering and [SEB] had a working filter connected to a spectrum analyzer. Did it work? To a limited extent; the PCB material probably wasn’t right, and board houses are more accurate than a razor blade, but [SEB] did manage to create a 10 GHz filter out of fiberglass and copper tape.

You can check out the video for this experiment below.

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Serious DX: The Deep Space Network

Humanity has been a spacefaring species for barely sixty years now. In that brief time, we’ve fairly mastered the business of putting objects into orbit around the Earth, and done so with such gusto that a cloud of both useful and useless objects now surrounds us. Communicating with satellites in Earth orbit is almost trivial; your phone is probably listening to at least half a dozen geosynchronous GPS birds right now, and any ham radio operator can chat with the astronauts aboard the ISS with nothing more that a $30 handy-talkie and a homemade antenna.

But once our spacecraft get much beyond geosynchronous orbit, communications get a little dicier. The inverse square law and the limited power budget available to most interplanetary craft exact a toll on how much RF energy can be sent back home. And yet the science of these missions demands a reliable connection with enough bandwidth to both control the spacecraft and to retrieve its precious cargo of data. That requires a powerful radio network with some mighty big ears, but as we’ll see, NASA isn’t the only one listening to what’s happening out in deep space. Continue reading “Serious DX: The Deep Space Network”

Hackaday Prize Entry: Open Narrowband RF Transceiver

We have so many options when we wish to add wireless control to our devices, as technology has delivered a stream of inexpensive devices and breakout boards for our experimentation. A few dollars will secure you all your wireless needs, it seems almost whatever your chosen frequency or protocol. There is a problem with this boundless availability though, they can often be rather opaque and leave their users only with what their onboard firmware chooses to present.

The Open Narrowband RF Transceiver from [Samuel Žák] promises deliver something more useful to the experimenter: an RF transceiver for the 868 or 915MHz allocations with full control over all transmission parameters. Transmission characteristics such as frequency, bandwidth, and deviation can be adjusted, and the modulation and encoding schemes can also be brought under full control. Where a conventional module might simply offer on-off keying or frequency shift keying, this module can be programmed to deliver any modulation scheme its chipset is capable of. Spread-spectrum? No problem!

Onboard, the device uses the TI CC1120 transceiver chip, paired with the CC1190 front end and range extender. Overseeing it all is an ST Microelectronics STM32F051 microcontroller, which as you might expect is fully accessible to programmers. Interfaces are either USB, through an FTDI serial chip, or directly via a serial port.

There are a host of transceiver chips on the market which just beg to be exploited, so it is very good indeed to see a board like this one. It’s worth noting though that the CC1120 has a much wider frequency band than that of the CC1190, and with a different front end and PA circuitry, this could cover other allocations including some amateur bands.

At Last, (Almost) A Cellphone With No Batteries!

If you are tired of constantly having to worry about the state of the battery in your mobile phone, then maybe help is at hand courtesy of the University of Washington. They are reporting the first-ever battery free cell phone, able to make calls by scavenging ambient power. An impressive achievement, and one about which we’d all like to know more.

On closer examination though, the story is revealed as not quite what it claims to be. It’s still a very impressive achievement, but instead of a cell phone with which you can make calls through the public cell network, it’s more of a remote handset for a custom base station through which it can place Skype calls. Sadly the paper itself is hidden behind a journal publisher’s paywall, so we’re left to poke underneath the research group’s slightly baffling decision to use the word “Cellphone” for something that plainly isn’t, and the university PR department’s dumbing-down for the masses. Aren’t peer reviewers supposed to catch misleading descriptions as well as dodgy science?

In radio terms, it’s an analog AM two-way radio that uses a backscatter transmission technique of applying the modulation as switching to an absorbing antenna tuned to the RF source whose ambient energy is being utilized. This modulates the ambient field within the range of the device, and resulting modulated field can be received and demodulated like any other radio signal. It’s a simplex device, in that you can’t listen and talk at the same time. Other ambient power used by the circuitry is harvested by rectifying received RF and through capturing ambient light on a set of photodiodes. There is a short video explaining the system, which we’ve placed below the break.

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Retro-Styled Raspberry Pi Radio

Ok, so you want a radio — but not just any radio. It has to be wireless, access a variety of music services, and must have a vintage aesthetic that belies its modern innards. Oh, and a tiny screen that displays album art, because that’s always awesome. This 1938 Emerson AX212-inspired radio delivers.

Building on the backbone of a Raspberry Pi Zero W and an Adafruit MAX 98357 mono amp chip, the crux of this single-speaker radio is the program Mopidy. Mopidy is a music player that enables streaming from multiple services, with the stipulation that you have a premium Spotify account. Once signed up, [Tinkernut] helpfully outlines how to set up Mopidy to run automatically once the Pi boots up. The addition of a screen to display album art adds flair to the design,  and Adafruit’s 1.8″ TFT LCD screen is small enough to fit the bill.

But wait — there’s more!

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