software-defined radio

122 Articles

Homebrew SDR Ham Radio In 9 Parts

June 6, 2018 by 31 Comments

It used to be homebrew ham gear meant something simple. A couple of active devices that could send CW. Maybe a receiver with a VFO. But only the most advanced builders could tackle a wide range SSB transceiver. Today, that goal is still not trivial, but it is way easier due to specialty ICs, ready access to high-speed digital signal processing, and advances in software-defined radio techniques. [Charlie Morris] decided to build an SSB rig that incorporated these technologies and he shared the whole process from design to operation in a series of nine videos. You can see the first one below.

The NE612 is a child of the popular NE602 chip, which contains a Gilbert-cell mixer, and an oscillator that makes building a receiver much easier than it has been in the past. The chips are set up as direct conversion receivers and feed a Teensy which does the digital signal processing on the recovered audio.

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Dual SDR Receives Two Bands At Once

May 21, 2018 by 15 Comments

There was a time when experimenting with software defined radio (SDR) was exotic. But thanks to cheap USB-based hardware, this technology is now accessible to anyone. While it is fun to play with the little $20 USB sticks, you’ll eventually want to move up to something better and there are a lot of great options. One of these is SDRPlay, and they recently released a new piece of hardware — RSPduo — that incorporates dual tuners.

We’ve talked about using the SDRPlay before as an upgrade from the cheap dongles. The new device can tune either a single 10 MHz band over the range of 1 kHz to 2 GHz, or you can select two 2 MHz bands. This opens up a lot of applications where you need to pick up signals in different areas of the spectrum (e.g., monitoring both sides of a cross-band repeater).

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Icoboard Software Defined Radio Platform

March 20, 2018 by 8 Comments

The Icoboard is a plug-in for the Raspberry Pi with a Lattice iCE FPGA onboard. Combined with a cheap A/D converter, [OpenTechLab] build a software-defined radio using all open source tools. He found some inexpensive converters that cost about $25 and were fast enough (32 MHz) for the purpose at hand. The boards also had a digital to analog converter and he was able to find the data sheets. You can see a video with the whole project covered, below.

The video, by the way, is pretty extensive (about an hour’s worth) and covers the creation of a PC board to connect from the Icoboard to the converters. There’s also a 3D printed frame, and that’s explained in detail as well.

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Image Source: Brannon Dorsey

Art Eavesdrops On Life And Pagers

December 24, 2017 by 32 Comments

Before cell phones, pagers were the way to communicate on the go. At first, they were almost a status symbol. Eventually, they became the mark of someone who couldn’t or wouldn’t carry a cell phone. However, apparently, there are still some users that clutch their pagers with a death grip, including medical professionals. In an art project called HolyPager, [Brannon Dorsey] intercepted all the pager messages in a city and printed them on a few old-style roll printers. The results were a little surprising. You can check out the video below.

Almost all the pages were medical and many of them had sensitive information. From a technical standpoint, [Brannon’s] page doesn’t shed much light, but an article about the project says that it and other art projects that show the hidden world or radio waves are using our old friend the RTL-SDR dongle.

Pagers use a protocol — POCSAG — that predates our modern (and well-founded) obsession with privacy and security. That isn’t surprising although the idea that private medical data is flying through the air like this is. Decoding POCSAG isn’t hard. GNU Radio, for example, can easily handle the task.

We’ve looked at pager hacking in the past. You can even run your own pager network, but don’t blame us if you get fined.

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Grabbing Better Images From A Newer Russian Satellite

December 5, 2017 by 46 Comments

The Soviet Union took the world by surprise when it sent its Sputnik satellite into low earth orbit way back in 1957. The event triggered a space race between the Soviets and the United States and ushered in technologies that would go on to touch the lives of every human on earth. Today, several nations have a space program. And one of the more useful things to put in orbit are weather satellites.

In 2014, the Russians launched their Meteor N M-2 weather satellite into a polar orbit. The part that were most interested in is the fact that it transmits images at 137.1 MHz using the standard LRPT protocol. However, the newer Meteor N M-2 transmits images at twelve times the resolution of US NOAA satellites. No typo there –  that’s twelve (12!) times. Have we got your attention now?

We shouldn’t have to tell you to jump on over to [phasenoise’s] blog which gives you everything you need to start grabbing some of these awesome images.

Now, before you get your jumper wires in a bunch – we are well aware that receiving satellite images is nothing new.

Thanks to [Roy Tremblay] for the tip!

Emergency Cell Tower On A Budget

September 30, 2017 by 22 Comments

Cell phone towers are something we miss when we’re out of range, but imagine how we’d miss them if they had been destroyed by disastrous weather. In such emergencies it is more important than ever to call loved ones, and tell them we’re safe. [Matthew May] and [Brendan Harlow] aimed to make their own secure and open-source cellular network antenna for those occasions. It currently supports calling between connected phones, text messaging, and if the base station has a hard-wired internet connection, users can get online.

This was a senior project for a security class, and it seems that the bulk of their work was in following the best practices set by the Center for Internet Security. They adopted a model intended for the Debian 8 operating system which wasn’t a perfect fit. According to Motherboard their work scored an A+, and we agree with the professors on this one.

Last year, the same SDR board, the bladeRF, was featured in a GSM tower hack with a more sinister edge, and of course Hackaday is rife with SDR projects.

Thank you [Alfredo Garza] for the tip.

ColibriNANO USB SDR Receiver Reviewed

August 8, 2017 by 26 Comments

At first glance, the ColibriNANO SDR looks like another cheap SDR dongle. But after watching [Mile Kokotov’s] review (see video below), you can see that it was built specifically for software defined radio service. When [Mile] takes the case off, you notice the heavy metal body which you don’t see on the typical cheap dongle. Of course, a low-end RTL-SDR is around $20. The ColibriNANO costs about $300–so you’d hope you get what you pay for.

The frequency range is nominally 10 kHz to 55 MHz, although if you use external filters and preamps you can get to 500 MHz. In addition to a 14-bit 122.88 megasample per second A/D converter, the device sports an Altera MAX10 FPGA.

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