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RTL-SDR - an SDR receiver from a cheap DVB-T tuner on a USB connector

Ganjor86 716044 1593
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Can I turn a cheap DVB-T USB tuner into an SDR receiver, and how can I make it receive shortwave too?

Yes: with an RTL2832U-based DVB-T dongle you can use it as an SDR receiver after replacing the stock DVB-T drivers with the prepared Zadig/libusb drivers and running SDR software like SDR Sharp or HDSDR [#11182116] In normal mode these tuners work roughly from 24 MHz up to about 1700 MHz, so VHF/UHF services, airband, CB, ADS-B, etc. are fine [#13168529] [#12073526] For shortwave below that range, do not connect the antenna straight to the RTL chip; direct sampling is possible but is considered risky and can damage the RTL28xx [#12073526] The safer and better-performing solution in the thread is an upconverter on the antenna input, e.g. based on TA7358/LA1185/LA1186, which users report can extend reception down to roughly 100 kHz–40 MHz [#13135481]
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  • #241 13639006
    kriss51
    VIP Meritorious for electroda.pl  
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    I made a few NE602 or 612 converters in a symmetrical configuration, because it has a gain by 3db greater than in a non-symmetrical system. Symmetrical has 3K input and output resistance. I made the adjustment to 50ohm on transformers with a ratio of 7.75: 1. Two-hole cores obtained from baluns of television antennas. Of course, you can use other cores that will work in the range of up to 80MHz, for that at the input of the low-pass filter and the output of the high-pass. Both filters designed in RFSim99 to suck from the net for free. For this 50MHz generator. I recommend it works great. The whole structure complies with all the rules in this field. It is about matching the resistance, which is important because hardly anyone matches the impedance of the mixer to the impedance of the filters. Here you can see what the correct fit of the NE602 cube looks like in various configurations. If anyone wants, I can draw a diagram, but just download the application of this cube and everything will be clear.


    http://www.electronics-tutorials.com/devices/602.htm
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  • #242 13640292
    methyl
    Level 16  
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    If you can find some time, please outline your converter circuit with input and output circuits.
    I would like to do and compare how it works. I have some problems here due to possible lack of matching to the mixer. Maybe this will be the golden mean :)
    And the program, or actually filter design programs, is currently testing but instead of getting clearer, a lot of question marks appear ;)


    Best regards!!
  • #243 13640670
    kriss51
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    Here is a diagram of my project. For the filter coils, I only gave inductances, but this can be easily converted with a calculator for converting inductance to turns, winding length and coil diameter. RTL-SDR - an SDR receiver from a cheap DVB-T tuner on a USB connector

    Filters designed for 50? I / O resistance. The high-pass filter has been calculated for the cut-off frequency of 47MHz. At this point it has -3db attenuation, and the input or low pass filter has a cutoff frequency of 31MHz, here it has -3db attenuation.
  • #244 13641232
    methyl
    Level 16  
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    Thanks for the diagram. I will put it together for sure, maybe even today and let you know about the effects here.
    While the impedance of the mixer and tuner is clear and it is easy to transform it with a suitable circuit, what should be done with an active antenna of the "Mini Whip" type

    Do you think that when designing the low-pass input filter, its impedance other than 50R should be taken into account? And how much of this antenna actually has this resistance seen from the side of the system?

    I am asking because while playing with the filter simulations, you can clearly see that by connecting a different "load" to the input than the 50R for a given filter which had a nice flat characteristic, it becomes uninteresting and according to what is shown on the chart, the filter should be recalculated for this other antenna. This also applies to most of the antennas used by users here, i.e. a piece of wire with an impedance not closer to each other. How to consider it whether to take it into account at all or simply agree to losses by mismatch.

    It is also possible that I am thinking wrong, maybe someone will explain to me?
  • #245 13648177
    kriss51
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    Each antenna is connected via a cable, usually 50?, so the TRX is not converted to other input resistances, but you only need to adjust the cable and the antenna to the TRX. So I am trying to do TRX to the standard resistance. What if someone did not have a suitable antenna and used a cable other than 50? And dismantled the radio to adapt it to the existing antenna system :D . The radio is to have 50 ?, and the antenna system needs to be adjusted, although when it comes to the reception itself, some major mismatch will still pass. If you want to send on a random wire, buy yourself a kilogram of tips, because you will burn them, and as they say, you will fly from the window to the yard :D . In the case of these converters, you will listen to a lot with about 10m of wire, but such wire should be connected via the antenna cable anyway, because the antenna must be away from the computer, TV, etc. Otherwise there is terrible "shot" and it is difficult to catch distant stations, especially at 1.8 and 3.5MHz. It is also worth powering the converter from a transformer power supply, not from USB or, for example, a 5-volt phone charger, because it is very humming.
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  • #246 13648509
    methyl
    Level 16  
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    I made this layout of the converter with a symmetrical input, but for the moment I did not compare with the previous layout because I took my block off the roof, MINI WHIPA and hooked up to the "Long Wire" which I have hung up here and annoying the building maintenance man. I am testing the antenna preselector as part of the fight against QRMs ;)

    I know that TRXs have a standard 50? input as well as antenna cables for this equipment. What ends broadcasting on the antenna with high WFS, I know because about 15 years ago, when CB was more popular, I "exchanged" 2sc2078 2sc2075 and similar, sometimes with a driver, on radio which people broadcast from a curtain rod or bicycle rim, praising it on 11m airwaves ;)

    Maybe I did not express myself well in the question or I was not fully understood, but it is not very important, I already understand the topic myself. I had a bad understanding of how the filter transfer characteristic looks depending on the impedance of the loads.

    I have been supplying the laptop with a transformer power supply for a long time, because I have a "noise-phono" on the original one, I have already mentioned it and I advise others to do so.

    And it is possible to transmit from a random piece of wire quite effectively, without burning silicon, of course through the appropriate ant box. :D

    Coming back to MINI WHIP those who do not have the possibility or want to have washing hangers over 20 m long, go ahead and fold them and look for a pole.
    Antenna properly placed above the roof works very well.
    There are a few modified antennas of this type and I want to test them before I leave the "pole" permanently.
  • #247 13657048
    methyl
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    Sorry with the post, but today I put on a MINI WHIPA on the roof after a slight tuning in the form of changing the transistors to j310 / 2n4427 and the former BF245 / KFW17, plus a change of ceramic capacitors, which apparently work badly on MKP here.

    It is connected to the NE612 converter and the effect is interesting.
    Earlier I had good reception of KF, but going down the frequency, the last thing that could be heard nicely was the PR1 225kHz and a little LORAN at 100kHz.

    Now the PR1 has a signal until it goes out of scale and reception actually starts from scratch.
    Transmissions from ALFA at 10-14kHz can be seen very well, despite the disturbances and crackles from lightning. These are the short vertical lines next to each other ;)
    RTL-SDR - an SDR receiver from a cheap DVB-T tuner on a USB connector

    I think that it will be possible to receive SAQ transmissions on VLF 17.2kHz, it will be the best test.
  • #248 13661882
    Ganjor86
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    It would be nice to see a movie with bandscans and some interesting dxs on commercial stations and ham radio bands. Such a set rtl-sdr + downconverter + mini-whip is an interesting set for a beginner, which is inexpensive for a lot of possibilities and the antenna has a lot of possibilities, small dimensions, it is easy to mask when our neighbors for some reason do not want antennas on a common roof. In case of strong interference to which the mini-whip antenna is sensitive, x-phase is very helpful, which I have recently had and use with mini-whip and de1103. With the help of such a set, it is possible to monitor even in a block where the aether is very cluttered and there are no conditions for a "normal" antenna.
  • #249 13661910
    Jezzman
    Level 21  
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    @methyl and tell me how this antenna behaves, as if I put it on the windowsill on the ground floor of the building, because unfortunately I have no other option :( I just wanted to get one on BF245 eno I am still looking for a rather overwhelmed scheme :D
  • #250 13661933
    Ganjor86
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    The question is not directed to me, but let me answer it. The mini-whip antenna needs space and placing it in the eye is a bad idea as it will have a very weak signal. You could hook this antenna on a tree if it grows near your window. The thin conductor will not be noticeable, and certainly the signal from the antenna placed on the tree, preferably at the top of the tree, but as far as possible from the walls of the buildings, will give a much better effect than placing the antenna on the window.
  • #251 13661968
    Jezzman
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    @ Ganjor86 the problem is that there is no tree near my window, and I can not put the antenna on the roof because the conservator of monuments does not agree ... But I will try something with this antenna as I will have a diagram :D
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  • #252 13662035
    BOOM i ZONK
    Level 22  
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    Jezzman - To see how Mini-whip works, you do not need to watch the movie, you can organoleptically test its operation on the website WebSDR . As the previous speakers say, this active antenna does not like the presence of metal elements that suppress / bend electromagnetic radiation.
    http://wwwhome.ewi.utwente.nl/~ptdeboer/ham/tn/
    Attachments:
    • pa0rdt_whip__1_.pdf (704.84 KB) You must be logged in to download this attachment.
  • #253 13662077
    Ganjor86
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    Maybe on the ground floor, in your conditions, however, magnetic loop would have been better. The mini-whip is a great little antenna, but it needs to be in the right conditions.
  • #254 13662105
    BOOM i ZONK
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    Only that magnetic-loop, as far as I know, is an extremely band antenna, unlike Whip, but it can be transmitted from it.
  • #255 13662941
    methyl
    Level 16  
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    Jezzman, I live on the ground floor myself and sometimes tested the Mini Whip "outside the window".
    If you equip yourself with a 2-3 meter long pipe / fishing rod and after attaching the "Mini Whip" to it, you put it out of the window, eg at night, so as not to scare people, you will hear something accompanied by disturbances and noise. Unfortunately, in order for the antenna to work properly, it must be the highest point within a radius of at least a few dozen meters.
    The antenna reacts to the electric component of radio waves, so the perfect place for it is a tin roof where it will have something to breathe ;)

    I have tested many antennas and if you really want to hear something more from the ground floor, it is just "magnetic loop". Its advantage is that it works even while standing in a room, less efficient but it works. Its narrowband nature is both an advantage and a disadvantage.
    This makes it difficult to search the band but eliminates a lot of interference from strong stations.

    Some people suggest active loop antennas and other inventions, but for me it did not work at all in ground level tests.
  • #256 13678502
    Ganjor86
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    Additionally, magnetic loop is bi-directional, not omnidirectional, and its manufacture is simple and its components are cheap.
  • #257 13679135
    c2h5oh
    Moderator  
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    Ganjor86 wrote:
    Additionally, magnetic loop is bi-directional, not omnidirectional ...


    Are you sure?
    What is the polarity of this antenna when it is placed horizontally above the ground?
  • #258 13679926
    Ganjor86
    Level 21  
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    Then it is ocular but gives a weaker signal.
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  • #259 13681654
    BOOM i ZONK
    Level 22  
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    As a curiosity, it gives a screenshot of the "tracking" frequency of the heterodyne / oscillator of the Philips mini-tower tuned every 50KHz :) . I believe that there was no antenna in the antenna socket and the sensitivity of the SDR was at a minimum ... After all, I know which radio stations the neighbors are listening to ...

    RTL-SDR - an SDR receiver from a cheap DVB-T tuner on a USB connector
  • #260 13682506
    methyl
    Level 16  
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    It's nice to see how the heterodyne is retuning. I recently saw a signal from a wireless mouse by accident. It turned out that it works at 27MHz and draws nice signals on the waterfall when it is working.

    Why do you have such a strange SHIFT set in SDR # ??
  • #261 13683904
    Tommy82
    Level 41  
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    General curiosity
    I recently installed Ubuntu 14.04 and
    pros
    - there is a packet rtl-sdr
    https://launchpad.net/ubuntu/trusty/+package/rtl-sdr

    - Gnu radio is now in the repositories
    https://launchpad.net/ubuntu/trusty/+source/gnuradio

    - GQRX is in the repositories.
    https://launchpad.net/ubuntu/trusty/+source/gqrx-sdr

    minuses
    You have to turn off the standard driver either permanently or before using the dongle in sdr mode.
    sudo rmmod dvb_usb_rtl28xxu rtl2832

    There is no native support for SDR going from kernel 3.15
    http://www.rtl-sdr.com/rtl-sdr-native-support-coming-linux/
  • #262 13686726
    jarekm27
    Level 18  
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    Hello....
    I would like to try to hear what squeaks on low frequencies as an amateur
    below FM, therefore planning to buy a receiver to receive RTL-SDR, first however
    I want to ask about the antenna, I have this antenna http://www.dipol.com.pl/antena_radiowa_dipol_1ruz_pm_b_A0221.htm in the passive version, will it be suitable for
    beginning to receive SDR?
  • #263 13686832
    Tommy82
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    jarekm27
    Two wires, a piece of concentrate, possibly a broomstick to eject from the balcony and the plug and you have the antenna. The length of these wires is adjusted to the frequency.

    The second question is how low do you want to go down because you may need an upconverter.
    There is also a lot to listen to above
  • #264 13686953
    Ganjor86
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    http://www.rtlsdr.com/2013/07/fractal-antenna-for-use-with-rtl-sdr-or-your-hdtv/ " target="_blank" rel="nofollow noopener ugc" class="postlink inline" title="" > http://www.rtlsdr.com/2013/07/fractal-antenna-for-use-with-rtl-sdr-or-your-hdtv/ Anyone tried this before? Apparently it is supposed to work from 50MHz to 1GHz or at higher frequencies.
  • #265 13687024
    jarekm27
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    All in all, I would like to test the whole band as much as the receiver would allow ...
    I live in a single-family house, I would have no problems with this stick
    screwed to the mast, maybe you have some schematics for these antennas,
    what would you do yourself ...
  • #266 13687038
    Tommy82
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    The easiest way to start is an open dipole. Of course, it is matched to the frequency.
  • #267 13687078
    Ganjor86
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    SDR with the r820t tuner allows you to listen to frequencies from 24MHz to 1850MHz so there is plenty to listen to and using the upconverter you can listen from really low frequencies, i.e. 10KHz (and maybe even lower using the appropriate parts) to 1850MHz. There is something to listen to. And so, out of curiosity, what is interesting to listen to from 500MHz to 1850MHz and whether it is possible to build a downconverter with e.g. 1800MHz and then it would be possible to receive frequencies up to 3600MHz but something feels that it is impossible because someone would have already figured it out.
  • #268 13687088
    lysy1980
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    There was something mentioned somewhere with the down-converter, probably even on this subject. There was also a link I think.
  • #269 13687097
    Tommy82
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    ASDB works on 1030 interrogators and 1090 replies from planes.
    As for the downconverter, the sat converter is a down converter.
  • #270 13687110
    BOOM i ZONK
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    jarekm27 -As you can on the mast, the J-pole antenna is a two-band 144 / 433MHz
    or even a single stranded one, it can be scraped from the copper pipes and elbows of the CO installation, or from the old 300 Ohm symmetrical cable.
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Topic summary

✨ The discussion centers on using inexpensive DVB-T USB tuners, particularly those based on the RTL2832U chipset combined with various tuner modules like the R820T and E4000, as software-defined radio (SDR) receivers. These devices, originally intended for digital TV reception, can be repurposed for wideband SDR reception from approximately 25 MHz up to 1.7 GHz, covering amateur radio bands, FM broadcast, airband, ADS-B, and more. Modifications such as direct antenna connection to the RTL2832U chip pins enable reception of lower frequency bands (below 30 MHz), including shortwave, though precautions against electrostatic discharge and signal surges are necessary. Upconverter circuits based on chips like LA1186, LA1185, and TA7358AP are commonly used to extend reception down to HF and VLF bands by frequency shifting signals into the tuner's range. Various software solutions including SDR# (SDR Sharp), HDSDR, and dump1090 are recommended for Windows and Linux platforms, with driver installation often requiring tools like Zadig to replace default DVB-T drivers with RTL-SDR compatible ones. Users report challenges with driver installation, device recognition, and antenna selection, especially for frequencies outside the FM broadcast band. Amplifiers such as the FP6L and antennas like Discone or long wire are suggested to improve reception quality. Mobile and embedded platforms like Raspberry Pi and Android devices with USB OTG support are explored for portable SDR setups. The community shares detailed schematics, installation guides, and troubleshooting tips, emphasizing the cost-effectiveness and versatility of RTL-SDR dongles for radio experimentation and monitoring.
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FAQ

TL;DR: A US$13 RTL-SDR dongle with an R820T tuner covers 24-1762 MHz “Band 24-1762 MHz (no holes)” [Elektroda, zabex, post #12073526] and can be pushed to ≈100 kHz with a 50 MHz up-converter [Elektroda, sb8gapi, post #13074101]

Why it matters: One stick lets hobbyists scan HF, VHF, UHF and ADS-B without big radios.

Quick Facts

• R820T native span: 24–1762 MHz [Elektroda, zabex, post #12073526] • Direct-Sampling mod: ≈0.1–28 MHz [Elektroda, methyl, post #13657048] • Typical dongle cost: US$13–15 incl. whip [Elektroda, Ganjor86, post #12076142] • PC spec: USB 2.0 + ≥1.2 GHz CPU [Elektroda, Serwis1, post #13206155] • TA7358 up-converter parts ≈ PLN 15 [Elektroda, sb8gapi, post #13074101]

What frequencies can an un-modified RTL-SDR with R820T cover?

About 24 MHz to 1.76 GHz without gaps [Elektroda, zabex, post #12073526] That spans airband, AIS, ACARS, ADS-B, VHF FM, UHF trunked, LTE and more.

How do I install drivers on Windows XP?

  1. Plug dongle, let Windows load Realtek driver.
  2. Run Zadig v2.1 XP, Menu → Options → List All Devices, choose "Bulk-In Interface 0".
  3. Click Install WINUSB driver. After 5 s SDR# sees “RTL-SDR/USB”. [Elektroda, lysy1980, post #13511327]

I get no DVB-T after installing SDR drivers—normal?

Yes. WINUSB replaces Realtek’s TV driver. Switch USB port or reinstall OEM driver when you need DVB-T reception [Elektroda, lysy1980, post #13511327]

What’s the simplest way to receive 0–30 MHz?

Add a 50 MHz HF up-converter using TA7358 or LA1185. It mixes HF to 50–80 MHz, cost under PLN 15 and sensitivity beats direct sampling [Elektroda, sb8gapi, #13074101; Elektroda, zabex, #12073526].

Can overheating freeze the dongle?

Yes. R820T can reach >60 °C and USB disconnects appear. Resoldering the USB plug and adding small heatsinks stopped lock-ups [Elektroda, mkpl, post #13635115]

Which antenna works best for wideband scans?

An outdoor TV log-periodic or discone on 50 Ω feed covers 50–1300 MHz. For HF add Mini-Whip or 20 m long-wire plus the up-converter [Elektroda, methyl, post #13657048]

Edge case: why does FM broadcast appear at 30 MHz?

Strong local FM images alias into 26–40 MHz when the front-end overloads. Use 88–108 MHz notch or reduce RF gain [Elektroda, mkpl, post #13583266]

Can I scan automatically like a hardware scanner?

Yes. Install the ‘Frequency Manager Scanner’ plug-in for SDR#; it hops user lists at 20 channels /s and logs activity [SDRSharpPlugins].

Is spectrum-analysis possible?

RTL-SDR plus ‘RTL-Power’ or ‘Spektrum’ sweeps 24 MHz–1.7 GHz, 2 MHz steps, ~30 dB dynamic range—handy for EMC checks [majek, 2013].

How do I add HF direct sampling without removing the tuner?

On R820T boards, wire a 1:10 transformer to RTL pins 4-5, select “Direct Sampling Q” in SDR#. This keeps VHF/UHF intact [Elektroda, BOOM i ZONK, post #13914702]
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