Adding More Frequencies To Your Software Defined Radio

July 8, 2012 by Brian Benchoff 32 Comments

[regveg] was looking for a way to receive signals outside the normal 64-1700MHz range his TV tuner software defined radio dongle can get. After finding a few $100+ upconverters on the Internet, he stumbled across a DIY project that greatly expands the frequencies his RTLSDR can receive.

[George]’s upconverter uses heterodyning to increase the frequencies received by a SDR dongle. The basic idea is mixing a signal from an antenna with a 100MHz frequency oscillator. The resulting output will be λ + 100MHz and λ – 100MHz, allowing for a wider range of frequencies that can be received by the SDR TV tuner dongle.

Now [regveg] has a board and schematic that makes it possible to receive just about anything with his TV tuner dongle. Interestingly, this upconverter contains less than $10 in parts and is easily etched at home thanks to a single-sided construction and through-hole parts.

As a small aside, [Andrew] sent in a tip a few days ago telling us his RTL dongle didn’t have any ESD protection. This is a very bad thing, but the good news is the fix is very cheap: just solder in a 10 cent diode and you’re good to go.

Putting A Software Defined Radio On A Mac

May 12, 2012 by Brian Benchoff 12 Comments

A few months ago [Antti Palosaari] discovered cheap USB TV tuners could be used as a software-defined radio. Since then, we’ve seen these TV tuners receive signals from GPS satellites and even the signals between air traffic control and passenger aircraft. Like everything cool, Mac support for these drivers is slightly terrible so [hpux735] wrote his own Cocoa app to support these amazing dongles.

[hpux735]’s driver is a port of the osmocom driver, repackaged as a native Cocoa app so the terribly fickle libusb and other dependencies aren’t needed. All the code is up on GitHub, ready for you to start playing around with SDR.

As far as tutorials for those wading into the deep waters of software-defined radio, a number of how-to guides have popped up over the last month to get SDR noobs up and running quickly. Here’s a few of the best ones we’ve seen:

[braingram] put up an Instructable for Ubuntu users.

For people who have a Windows box lying around [balint] put up a getting started guide.

There’s a slightly more thorough Windows guide here.

Most of the development in the TV tuner SDR community is happening on the RTLSDR subreddit, and there’s more than enough info there to do just about anything with these TV tuner dongles. If you come up with a novel use for one of these dongles, send it in on the tip line.

Playing Air Traffic Controller With Software Defined Radio

April 16, 2012 by Brian Benchoff 20 Comments

Being an air traffic controller is a very cool career path – you get to see planes flying around on computer screens and orchestrate their flight paths like a modern-day magician. [Balint] sent in a DIY aviation mapper so anyone can see the flight paths of all the planes in the air, with the added bonus of not increasing your risk of heart attack or stroke.

[Balint]’s Aviation Mapper uses software defined radio to overlay RADAR and ACARS messages from aircraft and control towers in an instance of Google Earth running in a web browser. After grabbing all the radio data from a software defined radio, [Balint]’s server parses everything and chucks it into the Google Earth framework. There’s a ton of info, pictures, and explanations of the inner machinations of the hardware on [Balint]’s official project page.

Right now, Aviation Mapper only displays planes within 500 km of Sydney airspace, but [Balint] is working on expanding the coverage with the help of other plane spotters. If you’re willing to help [Balint] expand his coverage, be sure to drop him a line.

Of course, [Balint] is the guy who gave us a software radio source block for those cheap USB TV tuner dongles. Just a few days ago we saw these dongles receiving GPS data, so we’re very impressed with what these little boxes can do in the right hands. [Balint] says his Aviation Mapper application will work with any GNU Radio receiver, so it’s entirely possible to copy his work with a handful of TV tuner dongles.

After the break, there’s two videos of [Balint] sitting at the end of the runway near the Sydney airport watching arrivials come in right above his head and on his laptop. It’s very cool, but we’d be interested in an enterprising hacker in the New York City area copy [Balint]’s work.

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Those USB TV Tuners Used For SDR Can Also Grab GPS Data

April 13, 2012 by Mike Szczys 23 Comments

Talk about versatile hardware. These inexpensive TV tuner dongles can also grab GPS data. You may remember seeing this same hardware used as a $20 option for software defined radio. But [Michele Bavaro] decided to see what other tricks they could pull off.

Would it surprise you that he can get location data accurate to about 20 centimeters? That figure doesn’t tell the whole story, as readings were taken while the dongle was stationary for three hours, then averaged to achieve that type of accuracy. But depending on what you need the data for this might not be a problem. And [Michele] does plan to implement real-time GPS data in his next iteration of the project. He plans to use an SDR acquisition algorithm to measure doppler shift in accounting for the slow clock speed of the dongles compared to standard GPS receivers. We can understand how that would work, but we’re glad he has the skills to actually make it happen because we’re at a loss on how the concept could be implemented.

[via Reddit]

Working Software-defined Radio With A TV Tuner Card.

March 30, 2012 by Brian Benchoff 77 Comments

[Balint Seeber] just sent in a small yet timely project he’s been working on: a software radio source block for the Realtek RTL2832U. Now with a cheap USB TV tuner card, you can jump right into the world of software-defined radio.

[Balint]’s code comes just a week after hackaday and other outlets posted stories about using a $20 USB TV capture dongle for software defined radio. At the time, these capture cards could only write data directly to a file. With [Balint]’s work, anyone can use a cheap tv tuner dongle with HDSDR, Winrad, or GNU Radio. If you’ve ever thought about trying out software-defined radio, now might be the time.

Elsewhere on the Internet, a surprisingly active RTL-SDR subreddit popped up dedicated to using the Realtek RTL2832U tuner for software defined radio. There’s an awesome compatibility chart listing compatible USB dongles. The cheapest (so far, and subject to change) is the Unikoo UK001T available for $11 on eBay.

With his source block, [Balint] can listen to anything on the radio between 64-1700 MHz. The sample depth is 8 bits and the sample rate can be anything up to 3.2 MHz. You can watch [Balint] testing out his $20 GNU Radio rig after the break.

Continue reading “Working Software-defined Radio With A TV Tuner Card.” →

Scratch-built Software-Defined Radio

December 21, 2011 by Mike Szczys 11 Comments

[Ben] is showing off some results from his Software-Define Radio project. The board seen above, which he designed from the ground up, is receiving a WWV radio broadcast. This is the atomic clock signal from Fort Collins, Colorado. The audio heard in the clip after the break is a bit noisy, but since he’s about 2000 miles from the origin of the signal we think he’s done really well!

The seed for this build was planted in [Ben’s] head back in July when he saw [Jeri Ellsworth’s] SDR project. He’s posted some of the build details up in a forum post. The approach is similar to [Jeri’s] but there are several key differences. He’s using a DS1085 programmable oscillator where she chose an FPGA for that purpose. Once his hardware demodulates and filters the incoming signal, a PIC32 does the rest of the work and outputs a PWM signal to an Op-Amp to generate audio.

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