Introducing RTL-SDR: a $20 SDR

If you don’t want to spend $1,200+ for a USRP SDR to use GNU Radio the crew at OsmoSDR want to help. In addition to their other amazing work, Osmocom team members (notably Steve Markgraf) have been hacking away on an alternative least-cost solution they call rtl-sdr.

So what is rtl-sdr? It is a creative form of using consumer-grade DVB-T USB receivers, turning them into fully-fledged software defined radios.

Those DVB-T receivers supported by rtl-sdr are based on the Realtek RTL2832U chipset plus a tuner IC like the Elonics E4000.

The RTL2832U has some undocumented commands/registers, by which it can be placed into a mode where it simply forwards the unprocessed raw baseband samples (up to 2.8 MS/s 8-bit I+Q) via high-speed USB into the PC, where they are routed into GNU Radio.

At a street price of about USD 20 to USD 25, they are undoubtedly the most capable low-cost SDR hardware that can be bought. So now there is really no more excuse for anyone to not learn GNU Radio. You don’t have to buy a USRP, not even a FCDP or an OsmoSDR: A USD 20 device is all that’s needed for receiving signals like GSM, GMR, DECT, TETRA, APCO25 and many others.

Visit the rtl-sdr page at Osmocom for complete details and links to hardware suppliers.

Join the Conversation


  1. That chip doesn’t seem to be available except from the company that makes it. Anyone else look into this? Did you find something?

  2. Excellent, I’ve been waiting for something like this. Dealextreme here I come!

    @Jay: this isn’t a hardware project per-se, it’s repurposing a cheap digital tv tuner dongle via software. So you don’t need to source the IC, just the right model of dongle.

  3. Okay, so I’ve seen this go around the webs and even looked up Software Defined Radio on wikipedia, but I don’t get it. What do you use this for? What is it useful for? Not trying to be sarcastic or anything, just a bit new to the true ECE stuff and don’t know.

  4. In the old days, you needed a specific kind of radio to transmit and receive a specific signal type. Analog type AM/FM is most common for broadcast, but there is also SSB, FSK and probably thousands of different kinds of digital modulation. With a SDR (Software Defined Radio) you can receive just about any type of radio signal in use, or even brand new ones, just by changing the software.

  5. I had bought a dongle that I also wanted repurposed ( there is no broadcast DVB in South Africa yet) into a scanner radio. This may be the ticket in a small way… although 8 bit samples should be poor dynamic range. The FunCube dongle uses the TI codec for 24 bit sampling.

    I wonder what the processing requirements would be for this? It would be nice to have a Raspberry Pi and a USB dongle making up a low cost portable receiver. I guess both devices may be too limited in practice, but still it could be fun to tinker with these.

  6. This one of the reasons why I keep checking out DP. Now this is what I call a Hack, and I would call it a jem of a find. Have been wanting to get my feet wet in the SDR domain and the prohibitive prices of the USRP has been keeping me away. Now, that is not the case anymore with this RTLSDR. Thanks to Machinegeek.

    Ian, would it be possible to open up a separate channel in the DP forum for people to share their tribal knowledge on SDRs. SDRs are the perfect amalgam of Good Hardware with a Software play. An ideal vehicle for one to dabble with RF,Signal processing and Back end software. I am totally going to order this dongle like right away!.


    P.S. Here is a link to an excellent SDR tutorial that appeared on ARRL a few years ago. PDF alert.

  7. $22 with free shipping is a bargain. AliExpress seems to be a consumer version of Alibaba. I’m always wary plugging a credit card into an unfamiliar retailer… any comments on AliExpress? Are they trustworthy?

  8. @Joe, I cant speak for Ali. Just placed my order on Dealextreme. They are poor man’s Amazon. GOt my ds1105 scope from them a couple of years back for a good deal. The dongle is available for $19.50 on Dealextreme.

  9. @ultrasounder : ah Dealextreme support PayPal, which AliExpress don’t. So placed the order with them via PayPal. $19 incl shipping… not bad!

  10. Aliexpress has worked for me so far. I’m not in USA. No duds yet but packaging is sometimes inadequate for large items. Several have arrived scratched. suggest you request good packing when ordering… Scratches don’t bother me.

  11. I’ve used Aliexpress a few times and don’t have any regrets. It’s a marketplace in the same way that Ebay is, so you gotta be careful. I tried to buy some tablets on there once only to see a week later other people posting feedback about the tablets never being shipped. The tracking number I was given was bogus also. I opened a complaint with Aliexpress and they cancelled the order. They don’t release your money to the supplier until you say it’s okay or until it’s a week after your item was delivered, so if you get something that’s not as advertised you can make a complaint about it.

    It’s nice to see some cheaper alternatives coming out for SDR. USRP is way too overpriced for what it is. It should be 1/10 of the price WITH at least a receiver module and it’s highway robbery what they are charging. Funcube dongle is $180 and sells out quick last I heard. It might be better hardware than this though. This $20 dongle should be more than enough for lots of people to get their feet wet in SDR. It’s value is only matched by the Softrock kits. All of those kits pack a lot of value, even the ~$80 RXTX. Downside is you have to solder them together. (well… some people, like me, enjoy that sort of thing though.)

  12. Look forward to progress on this. The big chunks of the project seem to be working by command line control. I’ll see about getting a GUI going. Downloading Markgraf’s 83MB FM band binary capture to see what I can make of it. Looks like fun. Ordered a few dongles from Dealextreme and am excited to play. One project in mind is to monitor 70MHz baseband carriers for signal level changes, data log the result and maybe trigger threshold alarms. Could also slow sweep the L-band to build a spectrum picture of satellite transponders from an LNB output. Cool.

    1. Jan 2013 update: To answer the question, “Can I use it for my shortwave listening and Ham radio hobby?”, the answer is No and Yes, and only as a receiver (for now…). As mentioned, the dongles themselves only cover about 50 MHz to 1.7 GHz (+/-, depending on chipset) so shortwave is out. That being said, you can still use it to receive the 6 meter (50-54 MHz), 2 meter (144-148 MHz), 1.25 meter (220 MHz), 70 cm (440 MHz) and 23 cm (1.2 GHz) bands (plus 4 meters – 70 MHz – in Europe), use it as a VHF/UHF spectrum analyzer.

      Late 2012 an article was published in the ARRL magazine “QST” that describes these uses, free open source control software available ( and, and description of an inexpensive HF upconverter (HF to 100 MHz) that can be built and fed into the SDR dongle to cover HF. With this, the answer to your question “Can I use it for my shortwave listening..” is Yes!

      A well made and tested HF Upconverter board called the “Ham it Up” is now available on EBay for around $50. With the dongle available for around $20, and with various connectors and cable adapters to connect the two and an outside antenna, for about $100 total you can have an all mode receiver/spectrum analyzer that covers 500 KHz to +/- 1.7 GHz!

      Now to hook all this up to a Raspberry Pi or A13-OLinuXino ( computer with A13-LCD7-TS 7″ touch screen display…

  13. Mildly off topic: my DealExtreme order for this has been sitting there since 20 March (marked as paid, waiting shipping since that date). Is it normal to take so long?

    1. Yes, DX is pretty slow to process orders. They’ll definitely ship, but they take their time.

    1. Looking at the list of compatibility from here:

      Seems the mini uses a different chipset (IT9130 or AF9135) than the Realtek RTL2832U and is not compatible to this I/Q streaming hack. “Any chipset other than the RTL2832U is unsupported by this project.”

      Seems only a matter of time until some of these other chipsets are figured out. Seems like there is plenty of opportunity to ride this wave of enthusiasm.

    2. they are identical 100% both are the eztv668 (i have one of these)

      there is a smaller one (the ezcap 666) …. only difference is that the 666 has a different coax connector
      and on the 666 there is a double diode on the input missing (for protecting the tuner from tooo high rf signals) …and the parts are on both sides of the pcb instead of only one side like in the 668

      for modding (adding preamp and/or phantom power for lna) the 668 is a bit easier to handle (more room in it) but both have exactly the same performance on receiving

      if you wanna add phatom power to your stick to feed an lna direct from that stick you have to look for these diodes on the input (otherwise the diodes would short out your phantom voltage)

      i have BOTH models and did compare them … both work exactly the same



  14. Has anyone seen their order ship from DealExtreme yet? I’ve been told they are not the fastest, but at 2.5 weeks, money taken and still no shipment I’m mildly concerned.

  15. Mine hasn’t shipped either. I’ve ordered from them before without issue. They may have had too much demand and not enough supply for the amount of orders coming in. I’m a little disappointed that it’s causing me to be left behind a bit with all of the progress other people are making on this project.

  16. I checked my order and they havent shipped yet. Anybody else got their dongle yet? looking for a ray of sunshine here.


  17. No, my DealExtreme order is still marked as paid but not shipped. I did put in a query a few weeks ago and they said they were waiting for stock.

  18. Still no joy from DealExtreme on this item (although I did have an order for another item ship successfully in the interim). Wondering at what point does it make sense to cancel the order… any one else hanging on?

  19. It will come you just have to be patient. Items that are OOS have to be sourced and it can take up to a month. That’s the trade-off with DX — cheap but slow.

  20. I just a pleasant surprise in my inbox. My shipment of the Dongle shipped out. Let the Hunger Games Begin.

  21. Pleased to say it (the ezcap) arrived from DealExtreme this morning. The basic tool compiled easily and I was able to grab a sample at an arbitrary frequency on Linux. However the whole GNU Radio thing lead me down a never ending rabbit hole of dependencies which I still haven’t solved. So tried this howto: and got results reasonably quickly on Windows XP running in a VM.

  22. Deal Extreme, now, is a bit slow, but the two Ezcap EZTV668 dongles arrived in fine shape, retail boxes with all the accessories… Ordered May 14th, Finally shipped May 21, Arrived in San Diego from Hong Kong June 4th…

    Units work a charm, at least once you replace the older 79k sized librtl2832++.dll with the 97kb size one listed as an update on… the software “seemed” to work but no signals would appear until I did that update.

    Have fun SDR’ing!

    1. I guess this model from eBay does not support DAB/DAB+ right?
      I am looking for similar model which supports all modes…does anybody know about it please?
      73 – Petr, OK1RP

  23. I got the first one from DealExtreme, but I had an idea for an experiment needing 3 of these, so I got two more from this guy in Germany.

    When I had a question about tracking the parcel he was *really* fast in replying and was *really* helpful. So I think it’s a good place to order from.

    However he’s only selling the bare device — you don’t get any of the accessories (no antenna, no remote control etc) you get with the normal kit.


  24. Hi,
    Does anyone know of a compatible hardware supplier in the USA that I can call to place an order? I have an aversion to ordering via the web. …Thanks in advance…

  25. please help in below doubts

    1. Can I use rtl-sdr(Realtek RTL2832U chipset) for a LTE eNodeB
    2. Cab I use rtl-sdr(Realtek RTL2832U chipset) for a LTE UE

  26. Has anyone considered the possibility of using RTL dongle to decode the wideband FM video on 23cm Amateur TV frequencies?

    1. How would that work? Isn’t Amateur TV basically just NTSC? That’s 6mhz wide.. You’d need a couple of dongles working together somehow to do that.

    2. I guess it would work with some of the DVB-S based digital amateur tv modes people are experimenting with. If it’s only 1-2mhz wide then it would fit in the bandwidth of the dongle…

  27. How hard would it be to detach the mcx connector and solder in a new chassis-mount f connector?

  28. Hello,

    I just purchased the latest FM+DAB USB DVB-T RTL2832U+R820T. It uses latest RTL2832U/R820T chipset. Also the protecting antiparallel diodes seems to be installed.

    Did anybody tested it and even more > compared to older one?

    Thank you,

    73 – Petr, OK1RP

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