What is RTL-SDR?

RTL-SDR is a very cheap ~$25 USB dongle that can be used as a computer based radio scanner for receiving live radio signals in your area (no internet required). Depending on the particular model it could receive frequencies from 500 kHz up to 1.75 GHz. Most software for the RTL-SDR is also community developed, and provided free of charge.

The origins of RTL-SDR stem from mass produced DVB-T TV tuner dongles that were based on the RTL2832U chipset. With the combined efforts of Antti Palosaari, Eric Fry and Osmocom (in particular Steve Markgraf) it was found that the raw I/Q data on the RTL2832U chipset could be accessed directly, which allowed the DVB-T TV tuner to be converted into a wideband software defined radio via a custom software driver developed by Steve Markgraf. If you've ever enjoyed the RTL-SDR project please consider donating to Osmocom via Open Collective as they are the ones who developed the drivers and brought RTL-SDR to life.

Over the years since its discovery RTL-SDR has become extremely popular and has democratized access to the radio spectrum. Now anyone including hobbyists on a budget can access the radio spectrum. It's worth noting that this sort of SDR capability would have cost hundreds or even thousands of dollars just a few years ago. The RTL-SDR is also sometimes referred to as RTL2832U, DVB-T SDR, DVB-T dongle, RTL dongle, or the "cheap software defined radio".

There are now many other software defined radios better than the RTL-SDR, but they all come at a higher price. Currently we think that the Airspy ($169) and SDRPlay ($99) SDR's are the best low cost RX only SDR's. There is also the HackRF ($300USD) which can both transmit and receive.

What is Software Defined Radio?

Radio components such as modulators, demodulators and tuners are traditionally implemented in analogue hardware components. The advent of modern computing and analogue to digital converters allows most of these traditionally hardware based components to be implemented in software instead. Hence, the term software defined radio. This enables easy signal processing and thus cheap wide band scanner radios to be produced.

What are some RTL-SDR Radio Scanner Applications?

The RTL-SDR can be used as a wide band radio scanner. Applications include:

Furthermore, with an upconverter or V3 RTL-SDR dongle to receive HF signals the applications are expanded to:

  • Listening to amateur radio hams on SSB with LSB/USB modulation.
  • Decoding digital amateur radio ham communications such as CW/PSK/RTTY/SSTV.
  • Receiving HF weatherfax.
  • Receiving digital radio mondiale shortwave radio (DRM).
  • Listening to international shortwave radio.
  • Looking for RADAR signals like over the horizon (OTH) radar, and HAARP signals.

Note that not all the applications listed may be legal in your country. Please be responsible.

What is the RTL-SDR frequency range?

This is dependent on the particular tuner variant used in the dongle, and the particular implementation. Some dongles, like our RTL-SDR Blog V3 also utilize the direct sampling mode which can enable reception below 28 MHz.

Tuner Frequency range
Elonics E4000 52 – 2200 MHz with a gap from 1100 MHz to 1250 MHz (varies)
Rafael Micro R820T/2 24 – 1766 MHz (Can be improved to ~13 - 1864 MHz with experimental drivers)
Fitipower FC0013 22 – 1100 MHz
Fitipower FC0012 22 – 948.6 MHz
FCI FC2580 146 – 308 MHz and 438 – 924 MHz (gap in between)

Table Source: Osmocom

As you can see from the table, the Elonics E4000 and Rafael Micro R820T/2 dongles have the greatest frequency range.

What is the RTL-SDRs sample rate?

The maximum sample rate is 3.2 MS/s (mega samples per second). However, the RTL-SDR is unstable at this rate and may drop samples. The maximum sample rate that does not drop samples is 2.56 MS/s, however some people have had luck with 2.8MS/s and 3.2 MS/s working well on some USB 3.0 ports.

Dropped samples are okay if you are just visualizing the spectrum, but will cause problems if you want to demodulate/decode signals.

What is the RTL-SDR's ADC resolution?

The native resolution is 8 bits, but the Effective Number of Bits (ENOB) is estimated at ~7. Decimation in software may raise this value.

What is the RTL-SDR input impedance?

Since these dongles are intended for TV, most dongles will have an input impedance of approximately 75 Ohms, although it is unlikely to be exactly 75 Ohms over the entire frequency range.

Remember that the mismatch loss when using 50 Ohm cabling on a 75 Ohm input will be very minimal at less than 0.177 dB.

The 75 Ohm impedance for the R820T can be checked on the datasheet which can be downloaded here.

However, newer dongles that come with SMA connectors will be 50 Ohms.

What are the minimum PC requirements?

Generally, at least a dual core processor of some sort will be required for most general GUI based software defined radio software. Command line tools and ADS-B decoders may work with less powerful hardware. Single board PCs like the Raspberry Pi 3, and Android mobile devices can also run several applications.

What dongle should I buy?

The cheapest, most common and generally best performing dongle at the moment is the Rafael Micro R820T2. It can be bought for about $20 USD.

The Elonics E4000 used to be the most common, but Elonics has closed and ceased chip production, making the E4000 rarer and much more expensive these days. Note that there seems to be a misconception that the E4000 is better than the R820T2 because it costs more - this is not the case, the increased cost is only due to its rarity.

The R820T2 is generally regarded as having better performance and sensitivity for most interesting frequencies compared to the E4000. For ADS-B, the R820T2 is much more sensitive at 1090 MHz. There are now also the R820T2 dongles, which offer increased sensitivity over the R820T. For these reasons, the R820T2 is currently the recommended dongle, unless you need the higher frequencies that the E4000 provides and are willing to pay a premium price.

Be careful when buying a dongle as certain sellers tend to misrepresent their devices (knowingly or unknowingly) as having compatible tuners, when in fact they may send out a device with an incompatible tuner. Also be wary when buying E4000 dongles from auction sites as there are many dodgy sellers incorrectly advertising R820T2 dongles as the rare E4000.

See our RTL-SDR store page for more information about where to obtain dongles from reputable sources. We now sell our own "RTL-SDR Blog V3" dongles which come with several key improvements for the SDR crowd and we recommend these for users who want to mainly use their dongle for SDR.

I already have a USB TV Tuner, is it Compatible?

If your TV tuner contains an RTL2832U chip it is probably compatible. If it does not contain this chip, it is not compatible. A list (somewhat out of date) on compatible and incompatible tuners can be found on this reddit wiki page.

Who owns RTL-SDR?

No person or company owns RTL-SDR and all it's supported software and hardware in it's entirety. However, it was the combined efforts of Antti Palosaari, Eric Fry and Osmocom (in particular Steve Markgraf) who first discovered that certain TV dongles could be used for SDR. Osmocom in particular developed the first RTL-SDR driver which was released as open source.

Since then RTL-SDR has become a community based phenomenon. Certain companies such as us at RTL-SDR Blog have taken it upon ourselves to produce our own flavor of RTL-SDR dongles that perform better than the standard TV dongle. But none of it is possible without the wider community development behind all the free software.

People Behind RTL-SDR:

Original pioneering discoverers: Antti Palosaari, Eric Fry and Osmocom. In particular Steve Markgraf from Osmocom who developed the first driver.
Hardware Sellers: Chinese factories producing and selling generic TV dongles. Sellers of RTL-SDRs improved for SDR use like RTL-SDR Blog.
Community Software/Hardware Devs: Anyone who has created software for the RTL-SDR, or has discovered and documented a hardware hack for the RTL-SDR.
Community Bloggers: RTL-SDR Blog, and other bloggers/content creators who write and popularize RTL-SDR applications.
Wider Community: Anyone using RTL-SDRs.

What is RTL-SDR Blog?

RTL-SDR.com (RTL-SDR Blog) started as a place for us to upload our RTL-SDR tutorials and to curate all other RTL-SDR related content onto a single blog. Since its inception we have continued to expand and have written many tutorials, written a guide book and started the signal identification wiki.

A few years ago we decided to create our own RTL-SDR dongle hardware that has significant improvements that benefit SDR users. Since then we've continued to improve our RTL-SDR hardware and are now at the V3 dongle.

Comparisons with other common Wideband Commercial Software Defined Radios

SDR Tune Low (MHz) Tune Max (MHz) RX Bandwidth (MHz) ADC Resolution (Bits) Transmit?(Yes/No) Price ($USD)
RTL-SDR (R820T) 24  1766 3.2 / 2.56 Stable 8 No ~20
Funcube Pro+ 0.15
0.192 16 No ~200
Airspy 24 1800 10 12 No 199
SDRPlay 0.1 2000 8 12 No 149
HackRF 30 6000 20 8 Yes 299
BladeRF 300 3800 40 12 Yes 400 & 650
USRP 1 DC 6000 64 12 Yes 700

For those who just want to receive a wide range of signals, we recommend the Airspy or SDRPlay as an upgrade to the RTL-SDR. If you are mainly interested in narrowband signals the Funcube Dongle Pro+ may be worth considering.

For a big list of more software defined radios see our roundup here https://www.rtl-sdr.com/roundup-software-defined-radios/.

RTL-SDR Schematics

No official schematic is available, but GGToshi has created his own reverse engineered schematic which is available at http://ggtoshi.at.webry.info/201406/article_6.html. Some application example schematics are also available in the R820T data sheet (see below).


There is no datasheet available for the RTL2832U as it is only available to manufacturers under NDA. The R820T tuner datasheet is available and can be downloaded here.

The Register Description datasheet can be downloaded here.

Useful Links

http://sdr.osmocom.org/trac/wiki/rtl-sdr - Official RTL-SDR Osmocom website

http://www.reddit.com/r/RTLSDR - Reddit RTL-SDR forum

www.rtlsdr.org - RTL-SDR community Wiki (not updated in a while)

http://www.dxzone.com/ - A good ham related database useful for research

http://www.dangerousprototypes.com - A blog about open source hardware projects that often has SDR related posts.

http://www.hackaday.com - A blog about DIY hardware that also often has SDR related posts.

http://radioforeveryone.com/ - Formerly known as "SDR4Mariners". Another blog about RTL-SDR and radio projects.

http://labyrinth13.com/ - Strange Beacons. Radio user who records and makes videos about several interesting signals he finds. Often uses an RTL-SDR.

https://www.elecrow.com/ - Full Raspberry Pi Kit. Probably useful for an RTL-SDR carry kit.

For a comprehensive book about the RTL-SDR you may be interested in our eBook available on Amazon.

The Hobbyist's Guide to the RTL-SDR: Really Cheap Software Defined radio.


    • dl2sdr

      Yes, simple audio interface. But watch out if you use long wire antennas because of static electricity. A Megaohm resistor from wire to ground avoids high voltages,

  1. stamatis

    Hey. I bought an rtl-sdr the other day and it gets extremly hot after a few minutes of using it.
    Is there anything that I can do?

    • Brad Allen

      If it has a metal case, that makes it easy to mate to another metal surface to radiate away the heat. I have one cheap USB dongle that gets extremely hot when alone, but all I do is clamp it onto a piece of metal about one square foot in size, and it conducts all the heat away very well, and it stays room temperature, even though I use it 24/7/365.

      • Brad Allen

        I posted the above reply in consideration of those wanting to understand the physics of radio and how electronics work. However, I agree with freedomf regarding buying Chinese crap. I would like someone to point me to a USA SDR.

      • Barbara Victoria

        What you ‘murican folks fail to understand is that almost all electronics in the world are made somewhere in Asia, whether it’s China, Taiwan, Hong Kong, Japan, Malaysia etc. This is the main reason for an iPhone having a price tag of $1k, instead of $10k.
        So, stop whining about and inventing crazy conspiracy theories and get a grab of some reality. It seems that too much cholesterol and banging your cousins have permanently damaged your brains.

        • James Cathcart

          Barbara, on behalf of all of us in-bred, Oreo-loving Muricans, let me just say thanks for your kind words. Let me clarify a few things for you.

          Most Americans are smarter than you give us credit for. We are not anti-Asia. Products made in South Korea, Japan, Taiwan and other non-Chinese countries are not the problem. We love our Samsung phones and Nintendo gaming consoles. When you buy from China however, you are subsidizing the worst tyranny in the world. Unlike most countries, where companies exist outside of government control (for the most part), ALL Chinese companies are owned and controlled by the state. When you pay those companies, you pay the PRC government. We are aware that it is impossible to avoid buying ANYTHING from China, but we like to keep it to a minimum. We believe it’s the right thing to do.

          Personally, I really like some Chinese companies. They are managed and manned by good, decent people who are stuck in a horrific dictatorship which hangs over all of them like the Sword of Damocles. That’s not a conspiracy theory. It’s a fact.

          So, thanks again for your thoughtful comment. It warms my heart to know that there are grateful people like you out there who know and understand that the freedoms they enjoy in their own countries exist because of the Constitution of the United States, which defined liberty and justice for the free world everywhere.

          • Gregory Stevens

            Take note at how these new Cold Warriors froth and seethe. This is your brain on American propaganda, kids.

          • someone from china

            That’s right. Especially the paragraph ‘Chinese companies are owned and controlled by the state’. Any organization with more than three people has to have a party branch, which is a branch of the party, controlled from above.

      • Done

        The usage of a rtl.sdr from 500kHz – 24MHz with Windows is no Problem. With Windows I can use SDR# and there is no problem to switch to direct sampling (Q-branch, 500kHz – 24MHz). But how can I use this frequency area with my Handy (Samsung S8) when I use the tool “RF Analyer”. Or is there any other tool to make me able to use direct sampling and so to receive 500kHz to 24MHz? I can’t find any option to switch to direct sampling (or Q-sampling) and no useful tool to do this on my Android Samsung S8.

  2. Sandy Johnston

    hi, great product.
    I bought an RTL-SDR V3 (RTL2832u R820T2TCX0+BIAS T+HF) from you over a year ago and it still works well on my old laptop windows 7.
    I have upgraded to HP window 10, but when I try to use it and connect the same way it won’t see the dongle. What am I missing??

      • Walter Hynson

        I have a new all in one win 10 machine and this does not work ,It will not install and zidag does not see it to set up drivers,yes these worked several years ago win 7,but now its all changed so please either update your software or fix these things so they work.

  3. edwar

    how much is the actual sensitivity of R820T dongle? i saw in many articles, people say it is about -110 dBm but when i checked in the datasheet you give in this article it only -97.5 dBm.

    • Timmy

      They produce a lot of chips, and the easiest and cheapest way to stay inside the official specification of any part is to over specify. That way with a normal distribution of parts produced you do not need to throw 20% of them in the bin to stay inside specification.

      The EOL (End Of Life) parts R8002T and R802T2 also had an official frequency range of 42 MHz to 1002 MHz but the PLL can lock down to ~23-26MHz and up to 1800-1850MHz. The high end testing also would add considerable cost, and they are aiming for a cheap TV tuner part, so good enough for TV is good enough to sell. That is where the bulk of their sales were for that part.

      The best example is probably Intel, they produce billions of processors and spend a fortune on testing them, to sell as separate product lines. They used to use one time burnable fuses on the silicon to hardcode the maximum clock speed, number of active cores and product names. But basically they were selling the 10% at high side of the of the normal distribution curve with a fantastic profit margin. The low end parts were produced in the same process, but for whatever reason, failed to fully operate at the higher frequencies.

  4. Nico

    Hi, I have an issue with the FC0013 tuner. AGC Mode isn’t working correctly. When activating AGC Mode the signal drops down to the lowest possible gain and only a view stronger stations are heard.

    After deactivation of the AGC I can regulate the gain manually without problem.. Is there a solution to this problem?

    • charlie

      se te quemo la etapa de entrada agregar un mar 6 de minicircuits con un condensador de 47pf a la entrada y salida del mismo
      charlie lu4dgn

    • AD5NL

      Hi Mohammed,

      This is probably not compatible with RTL-SDR drivers.

      Most dongles that are compatible are advertised for receiving DVB and DAB broadcasting, these are both digital formats. The dongle you link to is for analog reception (probably PAL or SECAM) and looks to be several-generations-old technology given its requirements (Pentium 4).

      You may find that it can receive FM analog broadcasting, as some analog dongles could do that.

  5. barrie kissack

    apart from aircraft dos the pro stick install exactly as any sdr/rtfl
    ln windows which is the best software to monitor aircraft/ with a pro stick and filter?
    thganks barrie

  6. Jerry Parker

    Is there tv software that will use the rtl-sdr on the UHF hd channels.

    I live in the country remote and want to use it for surveying to see what i can
    get here.



  7. Joe

    im usins hdsdr and DSD+1.51 on win xp along with vbcable and I get a lot of hit and target groups decoding mototrbo as always…but on my other computer i have win 7, sdr# with dsd+ 1.51 and vbcable and all i get are errors and no logs or tg groups or anything…i followed the instructions like setting the 12.5 khz . I also hear people talking on my xp but on win 7…all i hear is the normal noises when decoding. I have everything set up the same i think…ive messed with volumes and input audio levels and nothing but errors. Im using the latest rtl-sdr dongle. Will hdsdr work on win 7???

  8. Joe

    According to the R830T data sheet, this chip is also capable of ATSC at 6mhz bandwidth. It lists DVB-T at 6 – 8 Mhz. Why are we limited to a bandwidth of 3.2 mhz ? Has anyone attempted ATSC reception ?

    • Laur

      AFAIK, the RLT2832 chip does the DVB-T demodulation on-chip. The fact that it is also capable of outputting raw IQ is a happy accident for us, but it is not capable of doing it at full ADC bandwidth.

  9. Very Serious Problem

    Has anyone used this to detect electronic harassment transmissions? Possibly pulsed microwaves if that is what is being used.

    • Realist

      Dude, No one is using any kind of radio waves to harass you or your equipment, after countless studies that have been done the research says that humans are pretty much immune to being “mind controlled” etc. via pretty much any means of RF/EM emissions that we know of so just stop being paranoid! If someone is using RF to screw with equipment in your home call the FCC and stop whining.

      • Clint Mclean

        Actually electronic harassment is a very serious problem. I’m a qualified scientist and I can tell you that it is an absolute fact.

        Those that are saying that they’re being electronically harassed experience the same things with the same symptoms. The human body just does not behave in the ways that this technology can cause.

        The symptoms are otherwise unrelated and can only be connected by the use of such technology.

          • eric oyen

            actually, in the early days of UHF research ( around 450 Mhz) some people were blinded by high RF exposure while measuring at the end of an antenna in an anechoich chamber. Also, the cavity of the human eye is resonant at around the 2.5 cm band. Thus, any appreciable radiation at those frequencies can cause heating in the flesh and physical damage.

            • Clint Mclean

              Yeah, the resonant frequency range of the human mind is between 400 and 500 MHz.

              These could be the frequency ranges that they’ve been using on the diplomats in Cuba and China.

              It’s interesting that I’ve been saying for ages that microwaves or electromagnetic waves were used on them.

              I described this scientifically, referencing Frey’s work on the microwave auditory effect, that generates the same sounds that they heard, and how an over exposure to radio or microwaves cause the same symptoms that they experienced. It’s called radio or microwave sickness.

              So these are the same symptoms that the diplomats experienced, and only more recently have those that are officially involved in the investigation have said that it is very likely that electromagnetic waves were used.

              Why have the investigators not been saying the most obvious answer until now, how could they be that ignorant? They weren’t even mentioning it as a probable cause.

              There really isn’t any scientific mystery regarding what happened to the diplomats, it’s established science that an over exposure to radio or microwaves causes those symptoms and the microwave hearing effect produces the same sounds.

              Citizen scientists have been the first to provide the answers, Professor James Lin and Dr. Beatrice Golomb have written scientific papers on this.

              I’m also a qualified scientist and I’ve been saying it almost a year before those officially involved in the investigation.

              The New York Times, CNN and others have now also started saying this.

              Why would it take so long? How could I and others have the answer before the CIA, FBI, NSA or anyone else officially involved in investigating this?

              There’s a very interesting answer to that question.

        • Clint Mclean

          It wouldn’t, it can’t even prevent a mobile phone from receiving a signal. Radio frequency engineers and anyone else that does some research on this knows know that it could actually amplify the signal.

    • Clint Mclean

      I’ve actually created a program with that exact objective of finding the electronic harassment transmissions using this RTL2832 dongle.

      It turns it into a spectrum analyzer and can record the data over a range of frequencies and process it to find signals that could be interesting.

      You should try find me on facebook and I’ll send you the program.

    • Ron Dumont

      I’m a ham radio operator. Have not used any radio communications in years. But the electronic herassment is in the wi-fi band .
      Around 2.4 GHz microwave s. I took a wifi detector apart and extended its antenna out of the case. I bought the wifi detector from horbor grate. I detected the herassment it also will detect a microwave oven from 15 feet. Test it, it works, for a hole $20.00 USA dollars. Horbor grate..They just named me… Good luck
      16 years of the same bull shit.

      • Clint Mclean

        The frequencies are likely in the biologically resonant frequency range of the human mind, that’s between 400 and 500 MHz.

        I’ve actually detected using the rtl sdr and some code that I wrote a fascinating signal at a very specific frequency in that range that I’m reradiating.

        If I’m reradiating a resonant frequency in that range it would mean that the original transmitted signal is reaching me, creating oscillating or resonating electrical currents within my mind and then those are creating the reradiated signal, just like an antenna receives and creates radio waves from oscillating currents.

        So it wouldn’t be reflecting off of the surface because signals at this frequency don’t do that.

        That’s a signal that could create the electronic harassment effects that we experience.

        I can detect it from more than 10 meters away using a subscription satellite television dish and those dishes aren’t even designed for this frequency range. I use it mostly for directionality, although a yagi antenna would probably be better.

        It can also be detected with just the basic antenna supplied with the rtl.

        This is proof of something very serious because I should not be reradiating a signal like that and I’m saying this as a qualified scientist.

        Here’s a link to the code at github:


          • Clint Mclean

            Actually I have been specializing in this area for a while now.

            Note what I said above about how I determined that it was microwaves that were used on the diplomats in Cuba and China before the official investigators started admitting that.

            I know because of years of research in this area and I was also referencing the scientific research that was later referenced by others, such as the New York Times article that was essentially the first to say that it’s most probably microwaves.


            I was saying it scientifically long before that.

  10. ben

    What sdr hardware (R820T RT2832U dongles) is the best platform at the moment? SDR#? Portable SDR (PSDR)?

    Is it possible to use such a dongle to record/analyze any RF signal, from like a remote control light switch? Can it also play AM/FM radio?

  11. Curt Rowlett - Strange Beacons

    Thank you very much for the link to my website. I owe much to your blog and website. It was because of the great “Quick Start” guide you provide that I was able to easily setup and configure SDR for my computer. Thank you very much for that and for continuing to post interesting stories about the many uses of this technology. Regards.

  12. M M Iqbal

    Could you plz let us know whether you may provide a solution for;

    1. Detecting and auto recording of real time particular speech or voice passed over mobile phone conversation;
    2. Detecting the mobile phone number(s) which were active at a specific place of abduction/Kidnapping.
    These to be used by govt law enforcement authority.
    Hope to Hearing from your end.

    Thanking you,

    With Best Regards,

    Dr. Muhd M. Iqbal
    Pentagonal Advanced Technologies
    House # 04, Block # A, Mamudpur
    Bhuigar, Narayanganj, BANGLADESH
    Tel: 01748 041104 / 01977 770101
    E-Mail: [email protected]

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