9 ms·

Welcome to the World of Software Defined Radio

300 points by robputt796 10y ago

mindentropy 10y ago
I am interested in using a SDR for exploring the PHY in software. This includes having to sniff the GSM, bluetooth etc. I have a Nooelec SDR USB dongle but I am yet to experiment with it. I have used to listen to FM radio and that's it. I am thinking of starting decoding FM radio by myself to understand the basics.I do not want to use GNU radio except for better understanding. I would like to learn and have an understanding of things from scratch so that I get an intuitive feel when I am developing sniffers. Is this a good way to start? I really love wireless protocols but have worked from link layer upwards and would love to understand wireless PHY implementations.
w8rbt 10y ago
"I’ll be honest I have always thought radio related stuff is a bit of a strange and boring hobby, the electronics side fine, but sitting and chatting to people in a slow and often poor quality conversation didn’t really seem that interesting to me" --- You can send data over radio links and do other very interesting things... All without using a network! Just two nodes transmitting and receiving data via antennas at the speed of light. You don't have to talk at all. A lot of people don't get this when they think about radio. Radio is not just old, retired guys talking about health problems on VHF/UHF repeaters. Rather, it's a world-wide network, that has no infrastructure dependencies, transmitting data at the speed of light.
- qwertyuiop924 10y ago
  Yeah, it's full of cool stuff. Like old guys talking about emergency systems over VHF/UHF repeaters. And younger people, too.
- mmaunder 10y ago
  What many people don't realize is that right now, as you're reading this, you're probably using radio. Either wifi or 4G cellphone. Seems like an obvious statement, but RF engineers have done such a great job at making IP over the air reliable with 802.11X and 4G/LTE that we can forget about the fact that we're using it. The problem with this though is security. We tend to focus as security engineers too much on stuff riding on top of IP and forget about the underlying layer 1 protocols. And so that's for me what makes radio really interesting - especially dark corners that haven't been looked at for some time because they've been forgotten about.
  - cortesoft 10y ago
    Nope, good old CAT6 for me ;)
    - TickleSteve 10y ago
      ...which also broadcasts RF. ...and can be quite easily sniffed with the right equipment.
  - comboy 10y ago
    If you have proper security on a higher abstraction layer you don't care at all how the data gets transmitted, who can listen to it or modify it.
    - jonah 10y ago
      Note that on the Amateur frequencies, it's illegal to "Obfuscate" your transmissions. You can't even use coded language.
      - comboy 10y ago
        Didn't know that. Surely some people tried steganography? Or is there too much noise to try something like that? (and thanks for the antenna book recommendation)
        pjc50 10y ago
        That would count as "obfuscation".
        comboy 10y ago
        It's really hard to prove steganography if you are hiding encrypted data (which looks like noise if it's properly encrypted)
    - mmaunder 10y ago
Tempest1981 10y ago
How do Ham radio operators feel about SDR? (In general) Do they think it's interesting and cool, or do they reject it for being different and inferior vs. more expensive and sensitive equipment?
- vvanders 10y ago
  Generally favorably, most of the mid-high end HF rigs are about 50% SDR based anyway. As far as I can tell the average user doesn't tinker with them much however.
  - Johnythree 10y ago
    The other side of this coin is the reason that high-end Receivers don't use SDR techniques in their front end is because the intermodulation characteristics of current A/D converters fall a long way short of conventional Superhet technology. It will be a long time before an A/D converter chip can equal the performance of a high-level mixer. In fact it will probably never happen, as any advances will apply equally to both technologies. But yes, I agree with you that few hams are building SDRs. This was my biggest disappointment with SDR. Five years ago I thought that SDRs would usher in a new area of home-brew, but it's evolved into yet another bunch of appliance operators who have little interest in writing the software. So sad, because it's such a fascinating field..
- w8rbt 10y ago
  It depends on who you ask. The younger generation who have ECE/CS degrees love SDR. So does the military and the commercial/corporate radio industry. Some of the older generation frown upon SDR as voodoo magic with too many computer/network dependencies. There is a general distrust (among older hams) of computer/network technology and especially anything that depends on a non-human (computer program) to modulate or demodulate a message. For example, you can send Morse Code with a Carrier Wave and a simple switch (on and off) that you built from wood scraps and copper. You don't need an external thing (program, software, device, etc.) to do that for you. So there are less dependencies and in general it is much simpler to reason about and use. When the shit hits the fan, you want simple, reliable things. The problem is, most humans don't know Morse Code. So they can't decode a message anymore. Thus the reliance on computers and software. The efficiency gains are hard to argue with as well. You can do things with SDR that would be impossible or far too costly in hardware... Like resurrecting and communicating with a 36 year-old satellite http://www.rtl-sdr.com/rebooting-isee-3-usrp-software-defined-radios/ http://www.rtl-sdr.com/rebooting-isee-3-usrp-software-define...
heywire 10y ago
SDR has been an endless source of fun for me. I have a half a dozen different rtl dongles hooked up to raspberry pis and my laptop at any one time. Most recently I wrote a program to read the 900MHz broadcasts from my electric and water meters [1]. I'm also using an existing program to monitor our gas meter [2]. rtl_433 is another fun one [3]. [1] https://github.com/shaunhey/ea_receiver https://github.com/shaunhey/ea_receiver [2] https://github.com/bemasher/rtlamr https://github.com/bemasher/rtlamr [3] https://github.com/merbanan/rtl_433 https://github.com/merbanan/rtl_433
- robputt796 10y ago
  This is a super cool application for this, unfortunately our water meters and stuff in the UK are very basic mechanical devices in most cases still which sucks so none of this fun for me... This does remind me I probably should check out a few other things though, such as ZigBee protocol on my home automation stuff.
  - pjc50 10y ago
    The flashing light on an electric meter (assuming you don't have the really old dial type) flashes once per watt-hour, which can be used for measuring.
  - TickleSteve 10y ago
    The SMETS1 and SMETS2 smart meters that you will be getting soon will have ZigBee.... but secured and tied down so although you will be able to sniff the comms... everything will be encrypted. ...We're far too privacy and security conscious in the UK to allow plaintext personal data go over the airwaves...
    - graystevens 10y ago
      Been meaning to look into the smart meters here in the U.K. after having them fitted recently. I had horrible thoughts of it all being clear text, so it's nice to know that no one can snoop on my gas and electric usage. I had assumed they were at least working on the 2.4Ghz frequency as it'd dropped out a few times due to interference with other kit.
devereaux 10y ago
I will leap as soon as I can get something like the https://xtrx.io/ https://xtrx.io/ with a mini PCIe interface or expresscard interface. I want to do the processing on my laptop without the limitation of a slow bus. Also I would love some solution to nicely expose the ufl connectors. expresscard would seem a better choice to me that mini PCIe, to connect antennas on the side of the laptop or the back of the desktop when using a PCIe to expresscard adapter.
- gravypod 10y ago
  I could only dream of having this in my thinkpad able to do some cool mesh networking/APRS strait in my machine.
deutronium 10y ago
I really wish there were cheaper Tx capable SDRs, as they look like a lot of fun! The cheapest ones I've seen at the moment seem to be around $200 hackrfs from aliexpress.
- heywire 10y ago
  While not SDR, there are some cheaper alternatives if you're just looking to mix code and radio transmitting. [1] https://www.adafruit.com/products/3076 https://www.adafruit.com/products/3076 [2] http://www.ebay.com/itm/162086931088 http://www.ebay.com/itm/162086931088
  - deutronium 10y ago
    Yeah that's a good point I've got a module which uses http://www.silabs.com/products/wireless/EZRadioPRO/Pages/si446x.aspx http://www.silabs.com/products/wireless/EZRadioPRO/Pages/si4... The chip itself covers 119–1050 MHz, but the modules I have, have filters on to allow only narrower ranges.
    - heywire 10y ago
      I got excited there for a second, I thought you linked the Si468x, which I have been thinking about tinkering around with. It is just a receiver, but it does HD radio which interests me for some reason (it certainly isn't the audio quality :))
- vvanders 10y ago
  Isolated Audio card & PPT signal + HT can probably be done for less than $100 if you go with one of the cheaper HTs. Heck you can pick up a Mobilinkd[1] for ~$60 if you just want to stick with KISS/AX.25 over Bluetooth. They're really awesome little devices for what they do. [1] - http://www.mobilinkd.com/ http://www.mobilinkd.com/
qwertyuiop924 10y ago
...You can totally listen in to HAMs using RTL-SDR. 10m, 6m, 2m, 1.25m, 70cm, 33cm, and 23cm all fall within the ranges mentioned. As much as the HAM radio is traditionally an HF affair, the easiest to obtain licence (Technician class) actually pretty much only allows for VHF and UHF transmission. Not only that, but even among Generals and Extras, 10, 6, and 2 are very popular, especially for local communication (usually through a repeater), whereas HF is more commonly used for DXing. You can even listen in to APRS, which is message stream that carries a lot of interesting data (mostly GPS stuff, but you'll catch a few text, email, or general messages through it every once in a while).
- mmaunder 10y ago
  Yes that's about right. For technician's 2 meters and 70cm are by far the most popular. Just tune into a local repeater using a $50 handheld and you can chat all day. You can also use echolink and IRLP to chat world-wide via your local repeater or even connect to a repeater from your smartphone or PC.
cherryblakes 10y ago
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edejong 10y ago
If you like SDR, you should definitely have a look at GNU Radio Companion (GRC) [1]. A nice introduction into the methods of GRC is given by Michael Ossmann [2], which is really worth checking out. [1] http://gnuradio.org/redmine/projects/gnuradio/wiki/GNURadioCompanion http://gnuradio.org/redmine/projects/gnuradio/wiki/GNURadioC... [2] http://greatscottgadgets.com/sdr/1/ http://greatscottgadgets.com/sdr/1/
- heywire 10y ago
  I can't recommend those videos enough, great stuff!
  - trapperkeeper79 10y ago
    Pardon me, what videos?
    - awqrre 10y ago
      http://greatscottgadgets.com/sdr/1/ http://greatscottgadgets.com/sdr/1/, probably...
- heywire 10y ago
  I'll add some other software recommendations along the more visual route. For those on Windows, SDR# [1] is pretty great. On Linux and Mac, I really enjoy using GQRX [2]. And finally, when you're digging deep down into a received signal, inspectrum [3] can't be beat. [1] http://airspy.com/download/ http://airspy.com/download/ [2] http://gqrx.dk/ http://gqrx.dk/ [3] https://github.com/miek/inspectrum https://github.com/miek/inspectrum
phkahler 10y ago
Can't you decode OTA TV? I know GNU radio was doing that years ago, but not in real time yet. I would think that's possible now.
- mcpherrinm 10y ago
  The cheap RTL_SDR dongles are actually sold as OTA TV tuners. It's how I watch TV.
  - mcpherrinm 10y ago
    Edit: Apparently I'm wrong, and the DVB-T decoding is actually done in hardware. https://www.reddit.com/r/RTLSDR/comments/368s1n/how_does_a_device_with_32mhz_of_bandwidth_decode/ https://www.reddit.com/r/RTLSDR/comments/368s1n/how_does_a_d...? Nonetheless, you can receive TV with a higher-end SDR, ala https://medium.com/@rxseger/receiving-atsc-digital-television-with-an-sdr-76b03a863fea https://medium.com/@rxseger/receiving-atsc-digital-televisio...
fosco 10y ago
Think this bookmark of an intro to SDR is appropriate https://www.youtube.com/watch?v=kWfU1G3Jq4w https://www.youtube.com/watch?v=kWfU1G3Jq4w
mmaunder 10y ago
SDR is fun and the way of the future. I'd say we're getting close to a very low cost SDR that also brings together usability and excellent RX/TX and filtering capability. We're not there yet and so my Kenwood TS-2000 and Yaesu 857D and 817ND still kicks the butt of low cost SDR's. You'll find as you set up the base station your focus quickly moves to antennas. And then you become obsessed with antennas. Definitely get into amateur satellites. http://amsat.org/status/ http://amsat.org/status/ Go get a cheap handheld arrow dual band antenna with built-in diplexer to get started. I use macdoppler and also Ham Radio Deluxe's Satellite module. They are Mac and Windows respectively - I use them both for different things. Mostly I use macdoppler to make the doppler corrections automatically on my Yaesu 817ND and I use HRD for my TS-2000. Also, build yourself a HF monoband dipole antenna tuned to 14.3MHZ and then listen in to the ham band from 14.00 to 14.150 for digital/cw and from 14.150 to 14.300 for voice. It'll cost you about 20 bucks for the coax and a few bucks for the wire. You don't need a balun if you're using low enough power for TX. If you want to be a bit naughty (this is HN afterall) google around and learn about FLTSATCOM 7 and 8. It's an old US milsat that is basically an open repeater. They're geosynchronous birds that are used for encrypted comms but Brazilian criminal gangs periodically use them for free communication. They build antennas out of spare parts and use down-converters/up-converters to deal with the 250mhz frequency which is outside normal VHF/UHF. With your SDR you can build your own cheap home depot antenna and listen in without a converter. Just do absolutely not broadcast because you'll get arrested - someone already has. You can sometimes pick up used special forces directional portable antennas for a reasonable price on ebay for 250mhz. I'm a radio amateur, callsign WT1J. If you're into this stuff and find yourself able to TX on HF or satellite, drop me a line and we can set up a schedule. Mark.
- madengr 10y ago
  However the high cost SDR will kick the butt of high cost analog rigs.
- trapperkeeper79 10y ago
  I'm a dabbler and I came across a very cool project that seemed a bit out of my league at the moment - but perhaps you and others on this thread will get a kick out of: https://ocw.mit.edu/resources/res-ll-003-build-a-small-radar-system-capable-of-sensing-range-doppler-and-synthetic-aperture-radar-imaging-january-iap-2011/projects/ https://ocw.mit.edu/resources/res-ll-003-build-a-small-radar... Basically, making your own radar system with Coffee cans. As a newbie, I'm a bit surprised by all the modular components that were just fitted together. I knew about Amps and attenuators but didn't know you could get VCOs and mixers like that too. Any books/website recommendations/beginner projects would be appreciated!
metaphor 10y ago
Snapshots depict sub -100dBm noise floor...on a $21 DVB-T receiver...mkay, sure.
madengr 10y ago
I have a KiwiSDR going here on the HF band: http://64.136.200.36:8073 http://64.136.200.36:8073 Also wrote a GNU Radio based scanner that will work with the SDR dongles: https://github.com/madengr/ham2mon https://github.com/madengr/ham2mon
BuuQu9hu 10y ago
https://www.crowdsupply.com/lime-micro/limesdr https://www.crowdsupply.com/lime-micro/limesdr
- gerryk 10y ago
  I look forward to seeing some end-user reviews of this device when it finally ships. I realise that there are plenty of pre-production reviews, but I believe that the final version will have broader matching networks, facilitating better sensitivity on HF and low VHF.
mrkgnao 10y ago
Apparently antirez is a radio enthusiast. https://github.com/antirez/dump1090 https://github.com/antirez/dump1090
- lorenzhs 10y ago
  Yes, and contrary to the article it has a google maps display, too. Try "./dump1090 --net --interactive" and open localhost:8080. Would be neat if it could query some API to find out the flight's origin and destination, etc (flightradar24 maybe? do they have an API?)
  - jburgess777 10y ago
    The web interface on the dump1090 fork shipped by FlightAware has links to lookup flight information for each aircraft: http://flightaware.com/adsb/piaware/build http://flightaware.com/adsb/piaware/build Google started blocking the mechanism used by the dump1090 map display. It might work if you have used it previously but not for new users: http://discussions.flightaware.com/ads-b-flight-tracking-f21/dump1090-google-maps-not-displaying-publicly-t37546.html http://discussions.flightaware.com/ads-b-flight-tracking-f21... The FlightAware fork now uses an OpenLayers map instead: https://discussions.flightaware.com/ads-b-flight-tracking-f21/announcing-piaware-3-t37681.html https://discussions.flightaware.com/ads-b-flight-tracking-f2...
    - lorenzhs 10y ago
      Thanks for the link, that looks nice! I used dump1090 for the first time this weekend and simply ran it from localhost, it worked fine.
photogrammetry 10y ago
Strange that he couldn't find ADSB# - I used it just a few months ago. Perhaps it's been merged with another repository. If he wants the zip I used for installation I can send it to him, just give me an email address.
buserror 10y ago
Funny that, I've played all week-end with a RTL stick[0], and a £30 'weather station' thing from amazon[1]. Using rtl_433[2] it took no time at all to be able to receive what the sensor pods are sending over, it's really pretty cool! I've also ordered some 433mhz wall/light switches, I hope to be able to receive/transmit and log all of that stuff, from what I can see, with a bit of tweaking you can integrate quite a few vendor's kit, and even integrate it with amazon Alexa for voice control. Also started to 'explore' the spectrum using gqrx/gnuradio, I can see how it could become addictive :-) [0]: http://www.ebay.co.uk/itm/152142033580 http://www.ebay.co.uk/itm/152142033580 [1]: https://www.amazon.co.uk/gp/product/B00SIZZBDK https://www.amazon.co.uk/gp/product/B00SIZZBDK [ whoops sorry went up in price, cyber week is over :( ] [2]: http://www.rtl-sdr.com/using-rtl-sdr-rtl_433-decode-various-devices/ http://www.rtl-sdr.com/using-rtl-sdr-rtl_433-decode-various-...
jonah 10y ago
I just got my Ham license a couple weeks ago and picked up an updated version of the SDR dongle he's using a few days ago[0][1]. I've just started playing with it but even if you're not that into radio, it's worth $20 and a couple hours with to explore the invisible radio frequency world around us. [0] Be sure to get one with a TCXO (Temperature Compensated Crystal Oscillator) which reduces frequency drift. [1] His link actually goes to the newer, improved, Mini 2+.
partycoder 10y ago
On Linux there's Cubic SDR (among others). http://cubicsdr.readthedocs.io/en/latest/ http://cubicsdr.readthedocs.io/en/latest/ Make sure to use it with a supported device. The device in the article is supported I think (by the SoapyRTLSDR module).
periodicfunc 10y ago
For those interested in ADSB#, I believe it was renamed ADSB Spy and is now included with SDR# available at airspy.com. SDR# has a bit of a messy history and at one time was completely open source but was later closed after some dispute between the developers (to the best of my knowledge). If you look hard enough you can still find the source code of the older versions of SDR# and ADSB# which is handy if you want to learn how they work, although its all C# .NET and there is some wild stuff going on to try and squeeze enough performance out of the code. This is where I started learning though being a .NET developer, and from there moved on to GNU Radio and now learning C++. Fascinating subject.
tmescic 10y ago
A fun way to use one of these is to decode images sent from weather satellites. We built a system to decode images from a Russian Meteor-M2 satellite by using a RTL-SDR, home made antenna and GNU radio (image gallery : http://meteor.amphinicy.com/ http://meteor.amphinicy.com/). Unfortunately, we are located in the city center with a lot of RF noise and interference so images are not as clean as they could be.
gbtw 10y ago
The University of Twente SDR is pretty neat too: http://websdr.ewi.utwente.nl:8901/ http://websdr.ewi.utwente.nl:8901/
gerryk 10y ago
I have been through a number of SDRs - Softrock, RTLSDR, HackRF, and more recently I have a Red Pitaya (http://redpitaya.com/ http://redpitaya.com/) and am ICOM 7300 (http://www.icomamerica.com/en/products/amateur/hf/7300/default.aspx http://www.icomamerica.com/en/products/amateur/hf/7300/defau...), which is a traditional looking radio with SDR at its core. The flexibility offered by doing all the work in software is ground-breaking... really only limited by imagination.

300 points by robputt796 10y ago

I am interested in using a SDR for exploring the PHY in software. This includes having to sniff the GSM, bluetooth etc. I have a Nooelec SDR USB dongle but I am yet to experiment with it. I have used to listen to FM radio and that's it. I am thinking of starting decoding FM radio by myself to understand the basics.I do not want to use GNU radio except for better understanding. I would like to learn and have an understanding of things from scratch so that I get an intuitive feel when I am developing sniffers. Is this a good way to start? I really love wireless protocols but have worked from link layer upwards and would love to understand wireless PHY implementations.

w8rbt 10y ago

"I’ll be honest I have always thought radio related stuff is a bit of a strange and boring hobby, the electronics side fine, but sitting and chatting to people in a slow and often poor quality conversation didn’t really seem that interesting to me" --- You can send data over radio links and do other very interesting things... All without using a network! Just two nodes transmitting and receiving data via antennas at the speed of light. You don't have to talk at all. A lot of people don't get this when they think about radio. Radio is not just old, retired guys talking about health problems on VHF/UHF repeaters. Rather, it's a world-wide network, that has no infrastructure dependencies, transmitting data at the speed of light.

qwertyuiop924 10y ago
Yeah, it's full of cool stuff. Like old guys talking about emergency systems over VHF/UHF repeaters. And younger people, too.
mmaunder 10y ago
What many people don't realize is that right now, as you're reading this, you're probably using radio. Either wifi or 4G cellphone. Seems like an obvious statement, but RF engineers have done such a great job at making IP over the air reliable with 802.11X and 4G/LTE that we can forget about the fact that we're using it. The problem with this though is security. We tend to focus as security engineers too much on stuff riding on top of IP and forget about the underlying layer 1 protocols. And so that's for me what makes radio really interesting - especially dark corners that haven't been looked at for some time because they've been forgotten about.
- cortesoft 10y ago
  Nope, good old CAT6 for me ;)
  - TickleSteve 10y ago
    ...which also broadcasts RF. ...and can be quite easily sniffed with the right equipment.
- comboy 10y ago
  If you have proper security on a higher abstraction layer you don't care at all how the data gets transmitted, who can listen to it or modify it.
  - jonah 10y ago
    Note that on the Amateur frequencies, it's illegal to "Obfuscate" your transmissions. You can't even use coded language.
    - comboy 10y ago
      Didn't know that. Surely some people tried steganography? Or is there too much noise to try something like that? (and thanks for the antenna book recommendation)
      - pjc50 10y ago
        That would count as "obfuscation".
        comboy 10y ago
        It's really hard to prove steganography if you are hiding encrypted data (which looks like noise if it's properly encrypted)
  - mmaunder 10y ago

Tempest1981 10y ago

How do Ham radio operators feel about SDR? (In general) Do they think it's interesting and cool, or do they reject it for being different and inferior vs. more expensive and sensitive equipment?

vvanders 10y ago
Generally favorably, most of the mid-high end HF rigs are about 50% SDR based anyway. As far as I can tell the average user doesn't tinker with them much however.
- Johnythree 10y ago
  The other side of this coin is the reason that high-end Receivers don't use SDR techniques in their front end is because the intermodulation characteristics of current A/D converters fall a long way short of conventional Superhet technology. It will be a long time before an A/D converter chip can equal the performance of a high-level mixer. In fact it will probably never happen, as any advances will apply equally to both technologies. But yes, I agree with you that few hams are building SDRs. This was my biggest disappointment with SDR. Five years ago I thought that SDRs would usher in a new area of home-brew, but it's evolved into yet another bunch of appliance operators who have little interest in writing the software. So sad, because it's such a fascinating field..
w8rbt 10y ago
It depends on who you ask. The younger generation who have ECE/CS degrees love SDR. So does the military and the commercial/corporate radio industry. Some of the older generation frown upon SDR as voodoo magic with too many computer/network dependencies. There is a general distrust (among older hams) of computer/network technology and especially anything that depends on a non-human (computer program) to modulate or demodulate a message. For example, you can send Morse Code with a Carrier Wave and a simple switch (on and off) that you built from wood scraps and copper. You don't need an external thing (program, software, device, etc.) to do that for you. So there are less dependencies and in general it is much simpler to reason about and use. When the shit hits the fan, you want simple, reliable things. The problem is, most humans don't know Morse Code. So they can't decode a message anymore. Thus the reliance on computers and software. The efficiency gains are hard to argue with as well. You can do things with SDR that would be impossible or far too costly in hardware... Like resurrecting and communicating with a 36 year-old satellite http://www.rtl-sdr.com/rebooting-isee-3-usrp-software-defined-radios/ http://www.rtl-sdr.com/rebooting-isee-3-usrp-software-define...

heywire 10y ago

SDR has been an endless source of fun for me. I have a half a dozen different rtl dongles hooked up to raspberry pis and my laptop at any one time. Most recently I wrote a program to read the 900MHz broadcasts from my electric and water meters [1]. I'm also using an existing program to monitor our gas meter [2]. rtl_433 is another fun one [3]. [1] https://github.com/shaunhey/ea_receiver https://github.com/shaunhey/ea_receiver [2] https://github.com/bemasher/rtlamr https://github.com/bemasher/rtlamr [3] https://github.com/merbanan/rtl_433 https://github.com/merbanan/rtl_433

robputt796 10y ago
This is a super cool application for this, unfortunately our water meters and stuff in the UK are very basic mechanical devices in most cases still which sucks so none of this fun for me... This does remind me I probably should check out a few other things though, such as ZigBee protocol on my home automation stuff.
- pjc50 10y ago
  The flashing light on an electric meter (assuming you don't have the really old dial type) flashes once per watt-hour, which can be used for measuring.
- TickleSteve 10y ago
  The SMETS1 and SMETS2 smart meters that you will be getting soon will have ZigBee.... but secured and tied down so although you will be able to sniff the comms... everything will be encrypted. ...We're far too privacy and security conscious in the UK to allow plaintext personal data go over the airwaves...
  - graystevens 10y ago
    Been meaning to look into the smart meters here in the U.K. after having them fitted recently. I had horrible thoughts of it all being clear text, so it's nice to know that no one can snoop on my gas and electric usage. I had assumed they were at least working on the 2.4Ghz frequency as it'd dropped out a few times due to interference with other kit.

devereaux 10y ago

I will leap as soon as I can get something like the https://xtrx.io/ https://xtrx.io/ with a mini PCIe interface or expresscard interface. I want to do the processing on my laptop without the limitation of a slow bus. Also I would love some solution to nicely expose the ufl connectors. expresscard would seem a better choice to me that mini PCIe, to connect antennas on the side of the laptop or the back of the desktop when using a PCIe to expresscard adapter.

gravypod 10y ago
I could only dream of having this in my thinkpad able to do some cool mesh networking/APRS strait in my machine.

deutronium 10y ago

I really wish there were cheaper Tx capable SDRs, as they look like a lot of fun! The cheapest ones I've seen at the moment seem to be around $200 hackrfs from aliexpress.

heywire 10y ago
While not SDR, there are some cheaper alternatives if you're just looking to mix code and radio transmitting. [1] https://www.adafruit.com/products/3076 https://www.adafruit.com/products/3076 [2] http://www.ebay.com/itm/162086931088 http://www.ebay.com/itm/162086931088
- deutronium 10y ago
  Yeah that's a good point I've got a module which uses http://www.silabs.com/products/wireless/EZRadioPRO/Pages/si446x.aspx http://www.silabs.com/products/wireless/EZRadioPRO/Pages/si4... The chip itself covers 119–1050 MHz, but the modules I have, have filters on to allow only narrower ranges.
  - heywire 10y ago
    I got excited there for a second, I thought you linked the Si468x, which I have been thinking about tinkering around with. It is just a receiver, but it does HD radio which interests me for some reason (it certainly isn't the audio quality :))
vvanders 10y ago
Isolated Audio card & PPT signal + HT can probably be done for less than $100 if you go with one of the cheaper HTs. Heck you can pick up a Mobilinkd[1] for ~$60 if you just want to stick with KISS/AX.25 over Bluetooth. They're really awesome little devices for what they do. [1] - http://www.mobilinkd.com/ http://www.mobilinkd.com/

qwertyuiop924 10y ago

...You can totally listen in to HAMs using RTL-SDR. 10m, 6m, 2m, 1.25m, 70cm, 33cm, and 23cm all fall within the ranges mentioned. As much as the HAM radio is traditionally an HF affair, the easiest to obtain licence (Technician class) actually pretty much only allows for VHF and UHF transmission. Not only that, but even among Generals and Extras, 10, 6, and 2 are very popular, especially for local communication (usually through a repeater), whereas HF is more commonly used for DXing. You can even listen in to APRS, which is message stream that carries a lot of interesting data (mostly GPS stuff, but you'll catch a few text, email, or general messages through it every once in a while).

mmaunder 10y ago
Yes that's about right. For technician's 2 meters and 70cm are by far the most popular. Just tune into a local repeater using a $50 handheld and you can chat all day. You can also use echolink and IRLP to chat world-wide via your local repeater or even connect to a repeater from your smartphone or PC.

cherryblakes 10y ago

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edejong 10y ago

If you like SDR, you should definitely have a look at GNU Radio Companion (GRC) [1]. A nice introduction into the methods of GRC is given by Michael Ossmann [2], which is really worth checking out. [1] http://gnuradio.org/redmine/projects/gnuradio/wiki/GNURadioCompanion http://gnuradio.org/redmine/projects/gnuradio/wiki/GNURadioC... [2] http://greatscottgadgets.com/sdr/1/ http://greatscottgadgets.com/sdr/1/

heywire 10y ago
I can't recommend those videos enough, great stuff!
- trapperkeeper79 10y ago
  Pardon me, what videos?
  - awqrre 10y ago
    http://greatscottgadgets.com/sdr/1/ http://greatscottgadgets.com/sdr/1/, probably...
heywire 10y ago
I'll add some other software recommendations along the more visual route. For those on Windows, SDR# [1] is pretty great. On Linux and Mac, I really enjoy using GQRX [2]. And finally, when you're digging deep down into a received signal, inspectrum [3] can't be beat. [1] http://airspy.com/download/ http://airspy.com/download/ [2] http://gqrx.dk/ http://gqrx.dk/ [3] https://github.com/miek/inspectrum https://github.com/miek/inspectrum

phkahler 10y ago

Can't you decode OTA TV? I know GNU radio was doing that years ago, but not in real time yet. I would think that's possible now.

mcpherrinm 10y ago
The cheap RTL_SDR dongles are actually sold as OTA TV tuners. It's how I watch TV.
- mcpherrinm 10y ago
  Edit: Apparently I'm wrong, and the DVB-T decoding is actually done in hardware. https://www.reddit.com/r/RTLSDR/comments/368s1n/how_does_a_device_with_32mhz_of_bandwidth_decode/ https://www.reddit.com/r/RTLSDR/comments/368s1n/how_does_a_d...? Nonetheless, you can receive TV with a higher-end SDR, ala https://medium.com/@rxseger/receiving-atsc-digital-television-with-an-sdr-76b03a863fea https://medium.com/@rxseger/receiving-atsc-digital-televisio...

fosco 10y ago

Think this bookmark of an intro to SDR is appropriate https://www.youtube.com/watch?v=kWfU1G3Jq4w https://www.youtube.com/watch?v=kWfU1G3Jq4w

mmaunder 10y ago

SDR is fun and the way of the future. I'd say we're getting close to a very low cost SDR that also brings together usability and excellent RX/TX and filtering capability. We're not there yet and so my Kenwood TS-2000 and Yaesu 857D and 817ND still kicks the butt of low cost SDR's. You'll find as you set up the base station your focus quickly moves to antennas. And then you become obsessed with antennas. Definitely get into amateur satellites. http://amsat.org/status/ http://amsat.org/status/ Go get a cheap handheld arrow dual band antenna with built-in diplexer to get started. I use macdoppler and also Ham Radio Deluxe's Satellite module. They are Mac and Windows respectively - I use them both for different things. Mostly I use macdoppler to make the doppler corrections automatically on my Yaesu 817ND and I use HRD for my TS-2000. Also, build yourself a HF monoband dipole antenna tuned to 14.3MHZ and then listen in to the ham band from 14.00 to 14.150 for digital/cw and from 14.150 to 14.300 for voice. It'll cost you about 20 bucks for the coax and a few bucks for the wire. You don't need a balun if you're using low enough power for TX. If you want to be a bit naughty (this is HN afterall) google around and learn about FLTSATCOM 7 and 8. It's an old US milsat that is basically an open repeater. They're geosynchronous birds that are used for encrypted comms but Brazilian criminal gangs periodically use them for free communication. They build antennas out of spare parts and use down-converters/up-converters to deal with the 250mhz frequency which is outside normal VHF/UHF. With your SDR you can build your own cheap home depot antenna and listen in without a converter. Just do absolutely not broadcast because you'll get arrested - someone already has. You can sometimes pick up used special forces directional portable antennas for a reasonable price on ebay for 250mhz. I'm a radio amateur, callsign WT1J. If you're into this stuff and find yourself able to TX on HF or satellite, drop me a line and we can set up a schedule. Mark.

madengr 10y ago
However the high cost SDR will kick the butt of high cost analog rigs.
trapperkeeper79 10y ago
I'm a dabbler and I came across a very cool project that seemed a bit out of my league at the moment - but perhaps you and others on this thread will get a kick out of: https://ocw.mit.edu/resources/res-ll-003-build-a-small-radar-system-capable-of-sensing-range-doppler-and-synthetic-aperture-radar-imaging-january-iap-2011/projects/ https://ocw.mit.edu/resources/res-ll-003-build-a-small-radar... Basically, making your own radar system with Coffee cans. As a newbie, I'm a bit surprised by all the modular components that were just fitted together. I knew about Amps and attenuators but didn't know you could get VCOs and mixers like that too. Any books/website recommendations/beginner projects would be appreciated!

metaphor 10y ago

Snapshots depict sub -100dBm noise floor...on a $21 DVB-T receiver...mkay, sure.

madengr 10y ago

I have a KiwiSDR going here on the HF band: http://64.136.200.36:8073 http://64.136.200.36:8073 Also wrote a GNU Radio based scanner that will work with the SDR dongles: https://github.com/madengr/ham2mon https://github.com/madengr/ham2mon

BuuQu9hu 10y ago

https://www.crowdsupply.com/lime-micro/limesdr https://www.crowdsupply.com/lime-micro/limesdr

gerryk 10y ago
I look forward to seeing some end-user reviews of this device when it finally ships. I realise that there are plenty of pre-production reviews, but I believe that the final version will have broader matching networks, facilitating better sensitivity on HF and low VHF.

mrkgnao 10y ago

Apparently antirez is a radio enthusiast. https://github.com/antirez/dump1090 https://github.com/antirez/dump1090

lorenzhs 10y ago
Yes, and contrary to the article it has a google maps display, too. Try "./dump1090 --net --interactive" and open localhost:8080. Would be neat if it could query some API to find out the flight's origin and destination, etc (flightradar24 maybe? do they have an API?)
- jburgess777 10y ago
  The web interface on the dump1090 fork shipped by FlightAware has links to lookup flight information for each aircraft: http://flightaware.com/adsb/piaware/build http://flightaware.com/adsb/piaware/build Google started blocking the mechanism used by the dump1090 map display. It might work if you have used it previously but not for new users: http://discussions.flightaware.com/ads-b-flight-tracking-f21/dump1090-google-maps-not-displaying-publicly-t37546.html http://discussions.flightaware.com/ads-b-flight-tracking-f21... The FlightAware fork now uses an OpenLayers map instead: https://discussions.flightaware.com/ads-b-flight-tracking-f21/announcing-piaware-3-t37681.html https://discussions.flightaware.com/ads-b-flight-tracking-f2...
  - lorenzhs 10y ago
    Thanks for the link, that looks nice! I used dump1090 for the first time this weekend and simply ran it from localhost, it worked fine.

photogrammetry 10y ago

Strange that he couldn't find ADSB# - I used it just a few months ago. Perhaps it's been merged with another repository. If he wants the zip I used for installation I can send it to him, just give me an email address.

buserror 10y ago

Funny that, I've played all week-end with a RTL stick[0], and a £30 'weather station' thing from amazon[1]. Using rtl_433[2] it took no time at all to be able to receive what the sensor pods are sending over, it's really pretty cool! I've also ordered some 433mhz wall/light switches, I hope to be able to receive/transmit and log all of that stuff, from what I can see, with a bit of tweaking you can integrate quite a few vendor's kit, and even integrate it with amazon Alexa for voice control. Also started to 'explore' the spectrum using gqrx/gnuradio, I can see how it could become addictive :-) [0]: http://www.ebay.co.uk/itm/152142033580 http://www.ebay.co.uk/itm/152142033580 [1]: https://www.amazon.co.uk/gp/product/B00SIZZBDK https://www.amazon.co.uk/gp/product/B00SIZZBDK [ whoops sorry went up in price, cyber week is over :( ] [2]: http://www.rtl-sdr.com/using-rtl-sdr-rtl_433-decode-various-devices/ http://www.rtl-sdr.com/using-rtl-sdr-rtl_433-decode-various-...

jonah 10y ago

I just got my Ham license a couple weeks ago and picked up an updated version of the SDR dongle he's using a few days ago[0][1]. I've just started playing with it but even if you're not that into radio, it's worth $20 and a couple hours with to explore the invisible radio frequency world around us. [0] Be sure to get one with a TCXO (Temperature Compensated Crystal Oscillator) which reduces frequency drift. [1] His link actually goes to the newer, improved, Mini 2+.

partycoder 10y ago

On Linux there's Cubic SDR (among others). http://cubicsdr.readthedocs.io/en/latest/ http://cubicsdr.readthedocs.io/en/latest/ Make sure to use it with a supported device. The device in the article is supported I think (by the SoapyRTLSDR module).

periodicfunc 10y ago

For those interested in ADSB#, I believe it was renamed ADSB Spy and is now included with SDR# available at airspy.com. SDR# has a bit of a messy history and at one time was completely open source but was later closed after some dispute between the developers (to the best of my knowledge). If you look hard enough you can still find the source code of the older versions of SDR# and ADSB# which is handy if you want to learn how they work, although its all C# .NET and there is some wild stuff going on to try and squeeze enough performance out of the code. This is where I started learning though being a .NET developer, and from there moved on to GNU Radio and now learning C++. Fascinating subject.

tmescic 10y ago

A fun way to use one of these is to decode images sent from weather satellites. We built a system to decode images from a Russian Meteor-M2 satellite by using a RTL-SDR, home made antenna and GNU radio (image gallery : http://meteor.amphinicy.com/ http://meteor.amphinicy.com/). Unfortunately, we are located in the city center with a lot of RF noise and interference so images are not as clean as they could be.

gbtw 10y ago

The University of Twente SDR is pretty neat too: http://websdr.ewi.utwente.nl:8901/ http://websdr.ewi.utwente.nl:8901/

gerryk 10y ago

I have been through a number of SDRs - Softrock, RTLSDR, HackRF, and more recently I have a Red Pitaya (http://redpitaya.com/ http://redpitaya.com/) and am ICOM 7300 (http://www.icomamerica.com/en/products/amateur/hf/7300/default.aspx http://www.icomamerica.com/en/products/amateur/hf/7300/defau...), which is a traditional looking radio with SDR at its core. The flexibility offered by doing all the work in software is ground-breaking... really only limited by imagination.