Friday, 1 July 2016

RTL-SDR with SDRUno Beginner Guide

Update Nov 22, 2016: SDRuno 1.11 out, primarily for new RSP2. For RTL-SDR dongles, 1.05 starts, so no need to upgrade if that's your latest version. Added new sections as well.
Subscribe on Twitter @rtlsdr4everyone for future updates (blue button on the left).

Many thanks for all who made this guide possible.

An RTL-SDR is an affordable ($10 for unbranded, $30 for premium models)
Software Defined Radio receiver, covering the radio spectrum from 25 to 1800 MHz.
SDRuno is the "software" in SDR, and compatible with RTL-SDR dongles.
Why bother with SDRuno? Because it has the best receive audio I've ever heard.
Previously known as Studio1, used to be expensive software for high-end SDRs, then SDRPlay acquired Studio 1.
SDRuno is completely free and compatible with RTL-SDRs.
Download link for Windows here, detailed installation walkthrough below.
Official cookbook is also available, or visit SDRuno's official forum.


Windows 7 used.
Tested and worked with the following dongles:
- Generic chinese R820T2, you get a similar dongle for less than $10,
- previous v.2 and latest v.3,
- Nooelec dongles: SMArt, Mini, Mini Al+, Mini 2 Plus, Nano, Nano 2, Nano 2+, Nano-P,
- FlightAware ProStick and Pro Stick Plus,
- Soft66RTL3,
- Terratec R820T (representing older generics with R820T).
Image and list above covers most RTL-SDR dongles on the market, and even if your RTL-SDR based receiver is not shown, but specifications say "RTL 2832U" and "R820T" or "R820T2", 99.9% chance it will work with SDRUno.

You still need Zadig

Use if new to RTL-SDR dongles, skip this part if dongle is working fine with SDRSharp or other SDR software.
Zadig tells the computer that an RTL-SDR dongle is not a TV tuner.
First-timers: download and run Zadig in administrator mode (link for download), select all devices, select Bulk 0 from drop-down menu, Install driver.

SDRUno Software Installation Step-By-Step

Go to into square, turns into green checkmark, then click on Download:

Download will save an 8.2  MB file onto your computer:

Double-click downloaded file to start installation, accept the agreement, "Next" becomes available to click on:

Default installation folder is under Program Files, change this if a different folder is desired - I left it alone:

Additonal software might be also installed - I missed this step when upgrading.

After a while, installer finishes with the following screen, uncheck box (DO NOT START SDRuno).

Press Finish.

SDRuno requires a particular file to be placed into My Documents.
This file is available by clicking here, save file into My Documents. Alternatively, visit, then download the EXTIO DLL:

Starting SDRuno

Nearly finished, but to make life easier, create a shortcut of SDRUno.EXTIO Application file - this starts the main software, doing this step and placing the shortcut on Desktop saves time.

Regular file without EXTIO is for SDRPlay users, if you try it, you'll get the following error message:

Connect RTL-SDR dongle, then start SDRuno. You get the following error message without a connected dongle:

Uno will start without a dongle present, but will use soundcard as input. If you see the error message above, it's too late, close, then start SDRuno again.


This may not affect you, but was annoying for me.
SDRuno uses a central menu - which is a fixed size, so on a full HD (1920x1080) screen, text and buttons will be hard to read and operate.
Really small text is not good for you.
See image how much space Menu and Receiver control occupies at different screen resolutions.
Unlike SDR#, changing text size in Control Panel has no effect on this. Adjusting screen resolution to a lower setting improves readability, so I went down to 1366x768 to learn where's what.
On a 15.6" laptop, this is the native resolution anyway.

Gain adjustment and MSPS

Again, ExtIo file must be in "Documents" folder, then connect dongle to an USB port (should be the same USB port each time, or needs Zadig driver reinstallation), then start SDRUno from the Start Menu or via desktop icon.
Three windows come up, click into the smallest called Main, then press letter "h" on keyboard for instant access, or with a mouse:
Press on OPT (top left corner),
- then move cursor over "Select Input" (top of list),
- then click on "Generic RTL2832U OEM" (yellow square with dot in it).
Keyboard shortcut again: press letter "h" for instant access to settings screen.
Sample rate (left hand side, third from top) will be 2.4 Msps by default, and cannot be changed. That's the maximum any dongle can reliably do, more than enough.

Correcting offset and drift

Frequency Correction can be also set here, if value is known - not an issue with TCXO dongles, will be a constant value after warm-up with regular dongles.
PPM setup needs to be done only once. Omitting this makes no difference to reception, but displayed frequency will not be accurate.
1. Tune to a known and always-on frequency, such as local airport ATIS.
2. Wait 10-15 minutes for dongle to warm up, time depends on dongle.
3. Check signal on SP1 window, peak of signal should intersect red line.
If not, adjust with Up and Down arrows between "0" and "ppm".

Recent generic chinese dongles are pretty good with a maximum of plus/minus 20 ppm, older dongles can be 70-80 ppm off - this depends and varies from dongle to dongle.
Finished, but leave this window open, as proper gain setting is crucial to good reception (detailed later on).
Gain settings screen will stay on top of any other open window.

No hot-swapping

A.k.a stopping software, then replacing dongle with a different one, will give the following error screen, requires restart:

Grouping Taskbar buttons

Separate windows can take up too much space on Taskbar, if this is not to your liking, right-click an empty space on taskbar, click on Properties (bottom one on list), then adjust settings.

Closing SDRUno Main with the X in the top right corner closes all daughter windows.

Change mouse wheel behavior

By default, mouse wheel behavior is the exact opposite from SDRSharp, rolling down changes to a higher number.
This can be changed in Main window, press SETT (top left corner), select misc, then click on "REVERSE MOUSE WHEEL".

All the numbers

Signals have a number, written in either kHz or MHz. This number is the frequency of the signal. SDRUno displays the whole number/frequency.
The small k, short for kilo, means multiply by one hundred, so 198 kHz equals 198,000 Hertz - the Hz abbreviation is used to honor physicist Heinrich Hertz (Wiki link).
The M in MHz means mega: multiply by million, 14 MHz means 14,000,000 Hertz.
7255 kHz is the same as 7.255 MHz, this is just a custom in the radio world.

Adjusting sliders - example: adjusting sound volume level

All sliders can be adjusted the following way:
1. Left-Click into the slider area, adjustment jumps to the point of clicking, or
2. Bring cursor over the slider, then move mouse wheel up and down for fine adjustment.
SDRUno sound level control applies only to SDRUno, if volume is at maximum, but still no sound when you should be hearing something: 
- adjust system volume with speaker icon next to clock (usually bottom right corner to left of clock), or 
- check mute next to slider (should be white text on blue background as in image above).

Resize and move SDRUno windows

SDRuno windows can be resized to your liking; but not all of them, arrow in bottom right corner indicates if a window can be resized:

Start SDRuno

Press SP1 (Main Spectrum window) and RX (Control), then press the Play button in SDRUno Main, starts reception.
Every window has a SETT button (top left corner), controls that particular window's appearance.
SP1 - Main spectrum below, adjust Spectrum Base (orange in image, height of waves from bottom of screen) if you can't see any visible signal.

Eye candy: spectrum and waterfall can be combined into one window, also try various checkboxes to adjust for personal preferences.
With a bit of tinkering, display(s) will make a CIA station chief happy.
Dwelve into SETT options, checkboxes and sliders: SDRUno rewards with a great visual experience.
Don't forget to save your creation - remember Ctrl and two clicks after reading the next paragraph.

Workspace management

One of the coolest feature of SDRuno: set up different environments for different tasks, then save them. For example, have a separate appearance and windows for shortwave and broadcast listening, accessible with just one click.
Nine individual workplaces are possible.
Simple description: workspace name is at the bottom of Main window, change name with Right-click, Enter to accept. Set up workspace. Hold Ctrl, then click on workspace name and click again to select slot.
Example in image and text creates a workspace called "Demonstration".

Detailed description:
1. On the main screen, find the text "Default Workspace" under the green bars.
2. Left-click on it once, jump-up window comes up with available workspaces. In the images, I use Workspace 5.
3. Left-click on Workspace 5. This step selects it as the actual workspace.
4. Right-click on Workspace 5, becomes blue, means you can change the workspace name.
Enter a name, I use Demonstration in the image.
Saving a workspace:
5. Move windows around, set up workspace to your liking.
6. Hold (push down and and keep it pressed) the Ctrl button on the keyboard (bottom left), then left-click name visible under the green bars in the Main window, THEN LEFT-CLICK AGAIN on the workspace slot you want to use. Used windows and their position is saved now.
That's two clicks, once on the workspace name and once on the slot name.
(Took a while to figure this out... . Anyone emailing that description above is excessive will be jinxed to compulsively watch reruns of early Friends episodes.)

Tuning to a frequency - Direct entry

Press RX in Main menu, window called Receiver control pops up.
Long number in the middle is frequency: left-click with mouse, changes to zero.
Default entry in kHz, three zeros after entered number. For example, to get BBC at 198 kHz, enter 198 and press / click Enter.

Onscreen keyboard has the same number layout as a traditional keyboard, numbers in yellow. Bottom right Enter in blue has same effect as Enter on a keyboard.
Dots every three digit make life and frequency identification easier.

Amateur Bands quick access

White numbers on onscreen frequency entry keyboard refer to amateur radio bands - pressing the button No 5 (yellow) / 20 (white) will tune to the bottom of the 20-meter band.

Amateur "meter band" direct click only works if direct frequency entry is not enabled - should be one long number / tuned frequency in receiver control, not just one zero.

Browsing the spectrum - move cursor over number

Change one unit at a time: in receiver control or Main SP display, arrow changes to a hand and yellow line appears above number.
Move mouse wheel up or down to change number.

Received signal is centered under red vertical (up and down) line, how much received each side is called bandwidth, shown as grey area left and right from red line. This is the same in SDRSharp, but it's possible to move bandwidth directly in SDR# - not in SDRUno.
To do the same, open SP2 from Main menu (rectangle where you click Play to start software).
SP2 looks like the child of Spectrum/Waterfall, smaller area, adjust bandwidth there by dragging grey area edges - main Spectrum/Waterfall grey area will also change.
Bandwidth in numbers is also displayed on top of this smaller window.

Tuning a juicy signal - using Zoom.

Click on the signal, either in Spectrum or Waterfall, then click on Zoom. This will increase the center area of Spectrum/Waterfall, but if the signall falls outside of the enlarged range, move to the number area below, then left-click and hold (grab) to move displayed frequency range.
Setting up COMBO is great, zoom and frequency is closer, less mouse movement required.

Automatic Frequency Control (AFC)

Tunes to maximum signal strength nearby - if the signal looks like a mountain, it will move the red line to the top of the mountain.
From Receiver control, left-click on EXV (left of SDRuno sign), then left-click on AFC (bottom left corner, turns white).

It's a great feature for casual broadcast FM listening.
Won't work if there's no steady signal, so for example, if you're monitoring airplane to airport conversations, takes a few minutes to move to the maximum signal.

Using an upconverter (example for shortwave listening)

An upconverter is called an "up-converter" because it adds a number to the received frequency; for instance, a Ham It Up v1.3 adds 125 MHz to the received frequency number.
Frequencies usually in kHz for shortwave broadcasts, signals below 30 MHz and specific amateur radio channels.
Vatican Radio used for the image below on 15595 kHz will be heard on 125+15.595 = 140.595 MHz with an upconverter.

For other upconverters, the principle is the same, e.g. a 100MHz upconverter adds 100 MHz to received signal.
Offset for external converters can be set under Main => Sett => Offset => Ext Converter Offset when SDRuno is NOT running.

Example above for Ham It Up v1.3 which - like many upconverters - uses a 125 MHz oscillator. Enter 125000000 (that's six zeros), press on the - sign, then click on OFFS1 right next to it (rightmost arrow in image), becomes white. Now you can start SDRuno.
Automatic station tuning for SWLing is detailed in the official cookbook from Page 18 onwards.

Gain control

Same values available as in SDRSharp Cogwheel setting, but instead of left and right, slider moves Up (more gain) and Down (less gain).
Less overall gain is required for me with SDRUno, e.g. same station sounds better with 20.7 dB in Uno than with 28.0 dB in SDR#.
Using preamps / LNAs on really strong signals e.g. broadcast FM overloaded with SDRuno even with 0dB gain, whereas in SDR# same station was fine. Turn down preamp gain if you can - this happened with Janilab's preamp which has this feature.

Selecting proper mode according to signal

Pushbuttons below direct frequency entry for a particular mode - which one to use depends on frequency.
Selected mode turns white as in image:

Mode settings above the red line determine mode used: NFM, MFM, WFM, SWFM are only subsets of FM mode, clicking WFM will not change the "boss" mode to FM.

Adjusting Waterfall Palette

Main waterfall display color scheme can be changed to your liking, click on SETT in top left corner:

Also play with FFT AVG, right next to this drop-down menu.

Routing output to external software

Such as for weather satellite images, AIS etc.
Click on SETT (top left) in RX panel, OUT tab, select Cable Input / your solution.

Access official help

Main Menu, top left "OPT" button, second from bottom will be User Manual, also found in installation folder.
Opens pdf document in separate window, requires Adobe Acrobat reader (download link).

The official cookbook is also a good read if you get stuck.

Closing thoughts

The SDRUno has great audio. Even on commercial FM stations, the output sounds better, airplane band is clearer, and it's easier to tell how much coffee the taxi driver had that evening.


  1. This is a great guide for RTL-SDR use with SDRuno, Akos! Thank you for writing it. I have not used an RTL based receiver before, only Perseus/Elad/Afedri SDRs. However, a few weeks ago I received a Soft66Q (RTL type). Your blog post has convinced me to try it first with SDRuno. I already own Studio 1 for other SDRs, so it should be a short learning curve.

    1. Thanks, if you want to share your thoughts on the RTL-SDR platform here via other high-end SDRs, with or without your name, I'd love to hear from you.

  2. 4nradio The Soft66Q is a great SDR from Japan but your Elad & Perseus will smoke everything you have or will ever own in the future. Those two SDR'S alone is all you need for HF

  3. Would be nice if you'd also mention HDSDR, from where you copied the ExtIO to your DropBox. Why not link directly to there, where people could also find an alternative ExtIO over rtl_tcp? That one also runs fine with SDRuno.

    1. Thanks for pointing that out, done, I found an ExtIO in my drivers folder which worked and posted it for common use. All credit to HDSDR!!!

    2. I tried the extio_rtltcp.dll from and can't get it to work with sdruno. I can get it to show the extio control panel in sdruno. When I configure it to point to one of my rtl_tcp servers it says "The input Sample Rate exceeds the maximum allowed in this mode". I have tried setting the sample rate to various numbers including 960000 and I get the same message. Has anyone else got it working with sdruno? is there another dll I can try?

  4. Question, I have the RTL.SDR+Upconverter(820T/2832U), the one unit that has the two antenna ports and toggle switch for HF,VHF and up. It works well with SDR#,SDRconsole(2.3 and v3 preview) For HF i must enter -100,000,000 offset in SDR#, 100,000,000 in SDRconsole. Works well also in Linrad and GQRX. But for the life of me, HF is deaf in SDRUNO, VHF and up work in SDRUNO. Ive placed the EXTIO dll's appropiately, and they are recognized, but nothing for HF but noise(which does vary with RF-gain. This puzzles me and i've scoured the manuals and internet to no joy. Any ideas or references? TNX

    1. I forgot to mention that i tried the 100,000,000 and -100,000,000 offsets.

    2. I don't know what upconverter you got, with the Ham It Up I tune 125 MHz plus frequency. For example, 7 MHz becomes 125+7 = 132. I find it easier, no need to adjust software.

  5. Akos,

    Great reviews thus far.
    However the rtl-sdr route doesn't work for receiving TV channels via cable or OTA, DVB- T or DVB-C, due to low RTL bandwidth.

    So is there any good info out there to build cheap DVB- C or -T STB receivers using modern knowledge? Most market STBs are proprietary, expensive and have 20 year old designs.

    1. I'm not getting what you mean rtl-sdr doesn't wor for DVB-T. It works fine as a tv tuner.

    2. This comment has been removed by the author.

    3. if you are using generic drivers you will be able to recieve DVB-T (you won't be able to recieve DVB-C and DVB-S) I think the best software for DVB-T,C and S is DVBDream but remember RTL Dongles are terible for DVB-T and you won't recieve a lot

    4. It might be different for you, with a discone, I get DVB-T without any problems. Don't expect DVB-T with chinese supplied stock antenna thought.

    5. Akos and Mitja,

      Thanks for your quick replies !

      My question was about building a cheap set top box for DVB-C ( and then maybe DVB- T) but I read that the rtl-sdr has only about 3 Mhz bandwidth, while a TV channel is 6-8 Mhz. Are there any compression/ encoding possibilities?

      Maybe Mitja can talk a bit more about Dream DVB?

      I was also wondering if a cheap $2 QAM+ ADC chip, e.g., STM model STV 0297E could be used as decoder for cable TV signals on a Raspberry Pi?

      There must have been some SDR improvements over last 2 decades!

  6. The examples look great ,but having this issue when I start SDRUno.
    The input Sample Rate exceeds the maximum allowed in this mode.
    VRX#0:The Specified com device doesn't exist or is already open.
    User error on my part or incompatibility with my Noolelec nesdr smart dongle?

  7. User error, SMArt works fine with SDRUno.
    1. Input sample rate exceeds... You need to set sample rate to 0.96 MSPS, happened to me lots of times.
    2. Doesn't exists or open: probably you have another software open, like SDR#. Close it, restart SDRUno, will work.
    Thanks for commenting and enjoy,


  8. Hello Akos,

    Apparently the setting to 0.96 is not being saved. As for the issue with Doesn't Exist, there is nothing running except one instance of Omni-Rig. I rebooted the computer just in case something was still running in the background. After the reboot I had the Doesn't Exist and then I had to reenter the 0.96.

    Thanks again

  9. Great tutorial. Unfortunately, though, I keep getting the "The input Sample Rate exceeds the maximum allowed in this mode" error that other users have mentioned. Yes, I've tried to change sampling rate but the ONLY option that appears in the drop-down menu is 2.4MSPS, which is over the max limitation. I tried the ExtIo supplied in the Dropbox link and also the one that works for me in HDSDR. Incidentally, I can change the sample rate to various values well below 1 MSPS in other programs with my RTL2832U dongle. Why would SDRUno not allow the same?

    1. Updated the post, and added a video.
      Click on the arrow, then press the UP key on your keyboard, works like a charm.

  10. Hi Bruno,
    After you select the 2.4MSPS, press the down arrow on the keyboard.
    The problem on my end it does not save the 0.96, so when you start the program you have to make the change again.

  11. I'm running a Yaesu FT-857.
    I'm still having the issue "VRX#0:The Specified com device doesn't exist or is already open"
    After checking through task manager in windows 10, I have nothing open or running pertaining to any radio control or usb/com activity except the NOOElectric dongle.
    Still no rig control, but at least the receive is running.

  12. Came across your blog and thank you so much for helping me get set up in this hobby. Just purchased your book and cant wait to read...but first let me play with my SDRuno :)