The RTL-SDR is one of the cheapest and easiest ways to start experimenting with Software Defined Radio (SDR). Plug a compatible RTL2832U-based USB dongle into your computer, install some free SDR software, connect an antenna and you can start exploring radio signals on your PC.
RTL-SDR dongles can be used to listen to amateur radio, FM broadcast radio, airband, marine radio and many other signals. They can also be used for projects such as ADS-B aircraft tracking.
This guide covers the basics of choosing an RTL-SDR dongle, setting it up on Windows, getting started with SDR# (SDRSharp), receiving amateur radio signals and solving some common problems.
We’ve been experimenting with these devices for many years. If you’d like to see what we managed to receive with one of the original cheap RTL2832U TV dongles, see our original Realtek RTL2832U SDR experiment, covering amateur radio, FM, aircraft tracking, DAB and Freeview.
What is RTL-SDR?
RTL-SDR is a low-cost type of Software Defined Radio receiver based around the Realtek RTL2832U chipset. The hardware was originally intended for USB digital television receivers, but radio enthusiasts discovered that compatible devices could be used as general-purpose radio receivers.
Instead of much of the radio processing being performed inside a conventional receiver, the dongle sends radio data to your computer. SDR software then lets you tune around the spectrum, change reception modes, adjust filters and see signals displayed on a spectrum and waterfall.
For a radio amateur, shortwave listener or anyone interested in radio, it’s a very inexpensive way to explore what’s happening on the air.
What can you receive with an RTL-SDR?
Exactly what you can receive depends on the RTL-SDR hardware, antenna, location and software you’re using, but possible signals include:
- Amateur radio – including VHF and UHF FM and SSB signals
- FM broadcast radio – 88 to 108MHz in the UK
- Airband – aircraft voice communications
- ADS-B – aircraft position transmissions on 1090MHz
- Marine VHF
- PMR446 and other licence-exempt radio signals
- Weather satellite and other digital signals with suitable software
Some modern RTL-SDR models can also receive HF and shortwave frequencies. Older generic RTL2832U dongles normally require additional hardware, modification or direct-sampling support for useful reception below their normal tuning range.
Remember that an RTL-SDR is a receiver only – it doesn’t transmit.
Which RTL-SDR dongle should I buy?
There are lots of RTL2832U-based USB receivers available. The very cheap generic TV-style dongles can still be useful for experimenting, particularly on VHF and UHF, but purpose-built RTL-SDR receivers generally offer improvements such as better frequency stability, improved filtering, better connectors and metal cases.
If you’re buying one specifically for Software Defined Radio rather than digital TV, it’s worth choosing a unit designed for SDR use rather than simply buying the cheapest RTL2832U TV tuner you can find.
Note: Older versions of this page referred to the original R820T and R820T2 dongles. RTL-SDR hardware has moved on considerably since then, so check the specification of the particular receiver you’re considering.
Which RTL-SDR should I buy?Our pick: NooElec NESDR SMArt v5 See the NooElec NESDR SMArt v5 on Amazon UK | NooElec NESDR SMArt v5 on eBay Established alternative: RTL-SDR Blog V3 See the RTL-SDR Blog V3 on Amazon UK | RTL-SDR Blog V3 on eBay Easy starter kit: NooElec NESDR Mini 2+ See the NESDR Mini 2+ kit on Amazon UK | NESDR Mini 2+ on eBay As an Amazon Associate, Essex Ham earns from qualifying purchases. |
Setting up an RTL-SDR on Windows
There are several SDR applications available. We’ve used SDR# (SDRSharp) extensively, so that’s what we’ll concentrate on here.
If your dongle was originally supplied as a TV receiver, don’t install the television software if your intention is to use it with SDR#.
The general setup process is:
- Go to Airspy Downloads and download the current SDR# software package.
- Extract the downloaded files into a suitable folder on your computer.
- Run install-rtlsdr.bat if included with the current SDR# package. This downloads the RTL-SDR components required by SDR#.
- Connect your RTL-SDR dongle to the computer.
- Use Zadig to install the appropriate USB driver for the RTL-SDR device.
If your RTL device isn’t visible in Zadig, select Options > List All Devices. Depending on the particular dongle, it may appear with a name such as “Bulk-In, Interface (Interface 0)” or another RTL2832U-related device name.
Take care to select the RTL-SDR device rather than replacing the driver for an unrelated USB device.
Starting SDR# with an RTL-SDR
Once the driver is installed, start SDR# and select the RTL-SDR device as your source.
One of the first settings to check is RF gain. If the gain is set too low, you may see very few signals – or none at all.
Don’t automatically turn the gain to maximum. Increase it until signals become clear without raising the noise floor unnecessarily.
The exact SDR# interface and available settings have changed over the years, so your screen may look different from our older screenshots.
Testing your RTL-SDR with FM radio
A simple way to check that everything is working is to try receiving a strong FM broadcast station.
Select WFM (Wideband FM) and tune somewhere between 88 and 108MHz. With even a fairly basic antenna, you should normally be able to find a local FM broadcast station.
If you can see the signal on the spectrum or waterfall and hear the station clearly, your RTL-SDR, driver and SDR software are basically working.
Listening to amateur radio with RTL-SDR
Once you’ve confirmed the receiver is working, try listening around the amateur bands.
For UK amateur radio, the 2 metre band (144–146MHz) is a good place to start. Local repeaters and FM activity can provide relatively strong signals, particularly if you’re using a suitable external antenna.
For conventional FM amateur radio voice signals, select NFM (Narrowband FM). For SSB signals, select the appropriate USB or LSB mode.
Settings such as bandwidth, gain and squelch depend on the signal you’re trying to receive, so don’t be afraid to experiment.
Our older SDR# setup used settings such as NFM, a 12.5kHz tuning step and manually-adjusted RF gain. Modern versions of SDR# may present these controls differently, but the basic principles remain the same.
What antenna do I need for RTL-SDR?
The antenna makes a huge difference to what you’ll receive.
Many inexpensive RTL-SDR packages include a small telescopic or magnetic-mount antenna. That’s useful for getting started and receiving strong local signals, but don’t judge the capability of the dongle solely by the supplied antenna.
For amateur radio reception, an antenna designed for the frequency you’re interested in will normally perform much better. For example, a decent VHF antenna should considerably improve reception on the 2 metre amateur band compared with a tiny indoor whip.
Check the antenna connector before buying adapters. Older generic RTL2832U TV dongles often used small MCX connectors, whereas purpose-built SDR receivers may use other connectors such as SMA.
Our original dongle used MCX. I eventually adapted the lead and fitted a BNC connector so that I could connect it to more useful amateur-radio antennas.
RTL-SDR problems and troubleshooting
Here are some of the common problems we’ve encountered when getting an RTL-SDR running:
No signals received
- Check that you’ve selected the correct RTL-SDR source.
- Check that the RF gain isn’t set too low.
- Try receiving a strong local FM broadcast station between 88 and 108MHz.
- Check the antenna connection.
- Try another USB port.
I can see signals but can’t hear anything
- Check that you’ve selected the correct reception mode – for example WFM for broadcast FM or NFM for conventional amateur FM.
- Check the audio output and volume settings.
- Check that the squelch isn’t set too high.
There’s a large spike in the centre of the display
Some RTL-SDR receivers and SDR configurations can show a centre/DC spike. Older versions of SDR# included options such as IQ correction to reduce this.
The frequency is slightly wrong
Cheap older RTL-SDR dongles weren’t always particularly frequency-stable and could require a PPM frequency correction.
Our original dongle needed a correction of 57ppm, but don’t copy that figure – it was specific to our receiver. Tune to a known accurate signal and determine the correction required by your own dongle.
Better purpose-built RTL-SDR receivers often use a temperature-compensated oscillator (TCXO), which considerably reduces this problem.
Reception is poor
Try a better antenna. The small antenna supplied with many inexpensive dongles is one of the biggest limitations, particularly for weaker signals.
Can RTL-SDR receive HF?
It depends on the dongle.
The original generic RTL2832U/R820T-type receivers were primarily useful at VHF and UHF. Receiving HF generally required an upconverter, hardware modification or a direct-sampling arrangement.
Some purpose-built RTL-SDR models support reception of HF frequencies directly, so check the specification and instructions for your particular receiver.
If HF is your main interest, also consider whether a receiver designed specifically for good HF performance would be more suitable.
What else can I do with an RTL-SDR?
Once you’ve got the basics working, there’s a huge amount to experiment with. Depending on your software and antenna, RTL-SDR can be used for projects including:
- ADS-B aircraft tracking
- Scanning radio channels
- Receiving digital radio signals
- Weather satellite reception
- Monitoring amateur radio activity
- Experimenting with Raspberry Pi-based SDR receivers
For an example of some of the things we’ve tried, see our original RTL2832U experiment, where we tested amateur radio, FM, ADS-B aircraft tracking, DAB and Freeview reception.
RTL-SDR Frequently Asked Questions
What does RTL-SDR stand for?
RTL-SDR refers to Software Defined Radio receivers based on the Realtek RTL2832U chipset. The devices became popular after it was discovered that inexpensive USB TV tuners using the chipset could be used as general-purpose radio receivers.
Can RTL-SDR transmit?
No. RTL-SDR dongles are receivers. They can be used to listen to and analyse radio signals but don’t transmit.
Do I need an amateur radio licence to use RTL-SDR?
You don’t need an amateur radio licence simply to own and use an RTL-SDR receiver. What you may legally listen to and what you can do with information received depends on the applicable laws and regulations.
What is the best frequency to test an RTL-SDR?
A strong local FM broadcast station between 88 and 108MHz is a useful first test because the signals are normally strong and easy to identify.
Can I listen to amateur radio with RTL-SDR?
Yes. RTL-SDR is useful for receiving amateur radio signals. In the UK, the 2 metre band between 144 and 146MHz is a good place for a beginner to start exploring.
Does RTL-SDR work with a Raspberry Pi?
Yes. RTL-SDR receivers can be used with a Raspberry Pi and suitable SDR software. See our RTL-SDR Raspberry Pi guide.
More RTL-SDR resources
- Our original Realtek RTL2832U SDR experiment – FM, amateur radio, aircraft tracking, DAB and Freeview
- Using an RTL-SDR dongle with a Raspberry Pi
Having a problem we’ve not covered? Add a comment below and we’ll try to help.
Great Help Pete, I was up early this morning configuring SDR. Your simple plain talking instructions made it easy to configure and be up and running.
So thanks for that !!!
Really glad to hear it was useful Ricky – Thanks for the feedback, and enjoy the dongle!
Hi,do you know of a way to run the RTL dongle on Linux,linuxmint17 ubuntu derivative,.
I do have Win7,but do my VHF/UHF on Linux and use Cqrlog.
Jon. G8CCL
This may be of use:
http://linuxtracker.org/index.php?page=torrent-details&id=cf412240ffcaad6edaace0a2bca0ca410d2ac353&_m=3n.004f.1425.ea0ao00hou.t5w
Using Mint 19.x just install any of the Ubuntu methods.
Hello, I bought a similar dongle from Amazon USA some time ago and never used it until recently. Yesterday I installed both SDR# (with Zadig drivers) and the supplied BLAZE software (with Realtek DVB drivers). The two applications seem to neuter each other. If you install zadig, you can’t watch tv, if then you install the realtek drivers you can’t use it as an SDR tuner.
Is it something I have to live with or is there a solution?
Thanks
Ottavio
Something you have to live with – Windows can only have one driver per active USB device.
Hi there,
I downloaded the program SDR radio Pro. Downloaded the three dll’s as well, as per your instruction. Program starts up alright. Alas I cannot add my newly arrived Realtek USB dongle. I cannot get it installed. SDR Radio Pro says : “nothing found, sorry” when I try tp add the Realtek in the “radio definitions / search / RTL SDR USB menu. Windows also says that the “new found device” might not be installed properly.
Can you be of any assistance ?
T.i.a.
Paul.
sorry, wrong email subscription. Should be pauljennner@live.nl
i need binary file eeprom this dongle my dongle damege removed in use.
Tank!
Hi, Have managed to get the dongle “recognised” and can tune in broadcast radio stations, on the “tail” of the dongle antenna. ( chopped it off and put a tv joiner on, to connect to my HF antenna, or to a Digital TV antenna)
Have managed to get digital tv working… BUT..
cannot get any M.W. or S.W. broadcast or Amateur radio signals on my long wire.. Got a “proper” communications receiver that works well on the long wire. Find signal on Rcvr, then go to RTL dongle (sdr) and no movement on the waterfall, nor sound from the same frequency.
Rtl dongles don’t do such low frequencies. You need some sort of step up device to get the signal into the area where the rtl has it’s sensitivity.
Hi Pete et al,
I have set up the dongle as per your instructions and all appears to be correct. Unfortunately even when trying your WFM suggestion, I get peaks showing and when I place the tuner on them they give a VFO etc message, but I cannot get any station sound. I can get background hiss elsewhere. I have tried your suggestions to date, but still no station sound. I am running Windows 10. Any other suggestions for a complete novice?. Thanks, John.
If you’re local to Essex, I can take you through setting up the dongle at Monday’s Skills Night in Danbury. Alternatively, tinker with the SDRSharp settings under Audio and AGC – it’s probably something in there.
Hi. I was looking for a sdr dongle to receive our hf ham bands, as I see it with the RTL sdr I would nead to use a up converter If this is the case what would you suggest. Many thanks for your help.
Best 73′
Keith Middleton.
G4EJH.
I have an RTL.SDR, not a ‘stick’ but a little black box with 2 SMA sockets, one marked UV the other HF, sold as covering 100kHz to 1.7GHz. I followed your instructions and it seems to work fine on VHF, but when I try to tune HF or medium wave with a long wire in the HF socket I get nothing. Any ideas? Also I can’t find what the change-over frequency is between the two sockets.
Thanks for your most helpful instructions.
Chris.
Hi, I just bought one of these off Ebay. Installed all the same software as you that came on the disc. I can get some Radio channels but no TV whatsoever. What can I do? I’m in South Essex btw
Hi,
When I press the start key (black triangle) all I get isa message saying can not start air spy? any ideas??Please TIA
Ok, so trying to make this work on a Raspberry Pi 3. Did all the downloads and followed the instructions, but my Pi will not install the drivers for this device. I’m using Rasbaian made form Noobs, and so think I need the Linex version of the drivers. These I have tried for both the 32 and 64 bit files but still no luck. every time I try to run the setup files, it opens them in Geney, a compiler. One compiles, the other is missing a part, but after this neither will run and install, both crash and give an error in the command line box, execute format error. then go no further.
Can you help in any way please
73s Vaughn
Hi Vaughn,
Try this tutorial for getting the RTL running as an SDR… https://www.essexham.co.uk/raspberry-pi-as-an-sdr.html
Pete
Pete M0PSX.
Hi there. You are doing a great job helping people out there with the use of SDR dongles.
I kept insisting to my grandson to take in every thing he was taught at school and at home. It obviously sunk in. He reads a lot of these comments and express grief at some peoples questions. He ask’s me why they have asked that and another question. I then tell him because they have not learned to read. He is only 6 years old and can see now why it is so important that he did as asked in his education.
73 de John – G0WXU
Sorry am a bit perplexed about this.
You say buy one of these Dongle Sadr then you say but do not install any of the software that comes with
And instead download airspy.c/download and Windows software package then want is the pinot in buying the Dongle. And later you say get the portable Mac adapter cable at marlin sorry maplin is no more in 2020 and replace the plug with a bunc
Can you tell me what I am to buy
Andy 2e0pas
Hi can anybody help when i plug the dongle in windows 10 it sets up its self. i follow instructions for airspy but when i open Zadig.exe it says about replacing driver which is a system driver. if i do that some of my usb devises dont work any more ie keyboard (wireless ) so when i try to run airspy and select my dongle “RTL-SDR / USB” it says cannot access RTL device any ideas ??????????? John.
Got it going now on funcube dongle pro setting
All i can hear on funcube is my self when i talk lol
No signal ? buy a usb extansion cable & try that – I found there was too much QRM from my ( replacement) laptop power brick – but once I could get the usb stick further away – bingo !
Hi, I’m struggling with the dongles. I have the nooelec smartee with bias t and ham-it-up nano converter. I’ve also got nooelec push button balun. What exact length of wire aerial should I be using for HF (Do I use dipole or end-fed) as I don’t have access to swr and atu? I’ve adjusted -125MHz and have cubesdr installed on apple, gprx and openwebrx on raspberry pi. Struggling with configuration on openwebrx with two dongles, as above with smart??? No bias t in addition.
Thank you. Hope this makes sense to someone.
Funny I should come across this (and you Pete) :-) I just came off your recent course.
I’ve been struggling with these dongles too.The LimeSDR and ADALM Pluto ones seem to behave. For some reason the rtl8232u/R802T2 mix are a nightmare with noise.
I might be doing something wrong, but I believe that the Rafael R802T2 is a quirky, but I’m probably overlooking something causing the inherent noise.
Anything between 20k – 40M (using direct sampling as well as tuning) and ~50 – 70Mhz is noisy as heck. It sounds like there’s a noisy motor nearby causing it. When I pop past the ~500 Mhz area it sorts itself out, but then Freeview etc… bands kick in…
I’m running out of them myself, as well as coil wire, ferrite rings, caps and the rest. I’m pretty sure that the noise is locally generated? Or I have a setting wrong (one or the other).
Any ideas?
Cheers,
Ade
@mw7cbw I didn’t notice your post there a moment ago? Weird…
I’m in the same boat. Only different is I’m not using an upconverter. I’m literally using direct sampling on the lower bands and back to IQ.
Funnily enough I’m mainly on apple too and have struggled with VMWare + etc… but had to resort back to an older HP Windows laptop, but same issues.
Also about the RPI, they aren’t very RTLSDR friendly if they’re not a RPI 3 or 4+ When a higher sample rate is demanded from USB, the RPI can’t keep up with the power drain for starters, then even with a powered hub, it can’t handle the number of buffers (and the sheer size of them) so the kernel keels over.
I did see an article about rtl_tcp and a few mods adding/altering ring-buffers which make a HUGE difference, but still strain the raspberry. Google up “rtl_tcp ring buffer” and you’ll see it’s the first post. When I get some time, I’ll play with that too.
Hi I’m thinking about getting the dongle. Do I need to get a small antenna as I seen other dongles on Amazon come with small mad mount antenna’s
Most of the ones I’ve seen on Amazon do come with a small mag-mount, but for better results, a larger /better antenna is advised
Pete,
Can you tell me if the Rtl-sdr.com or nooelec a better buy and worth the extra cash ?
After reading through most of the comments, it appears that users do not understand the basic principles of the importance of the correct antenna for the use on a particular frequency band. For a wide band coverage, a “Disk-cone”style or type of antenna is very useful. It does not however give any signal gain to were you want to receive. They are made for a set frequency bands. The larger they are. Then the wider range they have. Another important thing is not to overload the dongle with too strong a signal. Trial and error will tell you where you are going wrong. Keep experimenting and trying new ideas. A great deal of fun can be had with this type of receiver for the price. Make sure you read the setup instructions and totally ignore the driver provided on the mini disk. That is to use the device for its original intended purpose as a TV tuner. The latest ones appear to have been improved well for stability on the tuning. i.e the accuracy the actual receiving frequency . They are more costly but you gets what you pay for.
73 de John – G0WXU.
I’m getting excellent results with the Nooelec NESDR SMArt v4 SDR. About £30 but it’s frequency stabilised (0.5 ppm). Also, it’s built into a decent aluminium case which helps with heat dissipation (these things can get quite hot). I use mine mainly for the civil aircraft band and have a half wave dipole in the loft tuned for 127.5 MHz.
Pertinent comments from John.
We do need an external antenna to the dongle, such are far more efficient than the internal antennæ that are fitted inside mobile telephones, or the far more limited antennæ inside WiFi and Bluetooth dongles, or in Bluetooth headphones.
And yes we do need to tailor the size of the antenna for the frequency(ies) we wish to receive or listen to, for better response. Something like 5-20metre of wire is OK for reasonable short wave reception, and one can be even more specific for certain of those bands. For VHF/UHF bands one really needs to think of the very wide coverage one can have, and maybe find room for a discone.
As is stated elsewhere an active antenna can be used to cover reception of wider swathes of spectrum, these are useful even with the compromises made in them, and the ground or counterweight they use.
Hi, I’m a bit of a newbie to all of this. My RTL-SDR arrived. Plugged it and and got started without any problem. What I don’t understand is the NFM settings suggested. I’m confused by the bandwidth 7500. What unit is that. How does that relate to NFM frequency.
Regards
Ed
Amateur transmissions are normally NFM (narrow). Broadcast radio stations would be WFM (wide). Bandwidth depends on the signal you’re decoding so will vary.
Hi, I have just bought and installed the ‘Updated Realtek RTL-SDR (R820T2)’ Dongle, came delivered as NESDR mini 2 R820T2 SDR & DVB-T, on Windows 10.
I ran install-rtlsdr.bat as above, and configured, though my screens are different.
There is no ‘Order’ setting.
I have tried both NFM and WFM but only get radio hiss, with very small blips shown on the Broadcast chart.
If I disconnect the aerial from the dongle, the gain is reduced, so I think it is installed, but just doesn’t pick up anything.
Any ideas please,
Pete
Hi, I have just bought and installed the ‘Updated Realtek RTL-SDR (R820T2)’ Dongle, came delivered as NESDR mini 2 R820T2 SDR & DVB-T, on Windows 10.
I ran install-rtlsdr.bat as above, and configured, though my screens are different.
There is no ‘Order’ setting.
I have tried both NFM and WFM but only get radio hiss, with very small blips shown on the Broadcast chart.
If I disconnect the aerial from the dongle, the gain is reduced, so I think it is installed, but just doesn’t pick up anything.
Any ideas please,
Pete
Hi. Can this be set up on Mac using Tahoe?
Thanks
Graham
The best results for hf that I have found have been with an rtl-sdr blog v4.
It includes an upconverter for frequencies below 28MHz