SDR software notes Feb 2018

Those of you who tune into the club net may have heard me saying I was playing around with a TV tuner stick and free Windows SDR software again. Part of the reason for doing this was to see what operation with a proper SDR transceiver such as a Flex or Anan might be like. I ended up trying the latest versions of six different software packages and thought there might be some interest in my notes here on the club website.

The stick I own is an E4000 RTL2832 DTV dongle, which is of course receive-only. As far as I can tell it tunes from around 23.1 MHz to about 1800 MHz with some gaps. Aside from two DAB-specific programs most of the others allowed me to tune into the local 6m beacon, FM broadcasts, air band signals, 2m and 70cm beacons and repeaters, 70cm beacons & repeaters as well as allowing me to see signals from DAB and DTV multiplexes and mobile phone networks. These latter types were all too wide to see anything other than part of the signal at a time.

Most of the programs rely on use of a DLL called ExtIO_RTL2832.dll to control the stick. There appear to be multiple versions of ExtIO_RTL2832.dll written by different authors, supporting different feature-sets of different tuner sticks! You need to use a program called Zadig to replace the standard Windows TV tuner driver too. Fortunately I started at, which helped a lot.

Many of the programs I tried (details below) have amateur-friendly features such as variable bandwidth, noise blankers and squelch. All except the DAB-specific programs show both received spectrum and waterfall charts.
Some programs require you to set a ‘LO’ frequency. This is not a conventional local oscillator but is the mid-point of the frequency band to be received and displayed on the spectrum chart. The user can then tune to any frequency within that range. Another feature most has was a way to correct for any frequency error caused by the stick. GB3UHF was used as a frequency standard and tuning errors successfully corrected for.

All of the programs are either Open Source or Freeware. Some may also have paid-for versions with more features. Although I believe the information is accurate, the programs were all in their different ways a bit unfriendly so it is entirely possible that there are features, or ways of setting the programs up, that I didn’t discover.

SDRuno 1.06 from
Designed for use with wideband SDRplay dongle but will work with RTL dongle (with a reduced feature set). NB The latest software version is v1.22 but the install package for that only has the v1.06 version for use with non-SDRplay tuners.

Click on these screenshots to see full size

Dedicated band buttons for HF amateur bands plus 2m. (But see below.)
Allegedly has other button options but this doesn’t seem to be present on the
Wide FM and Stereo FM modes for broadcast stations
Professional look & feel
Decides on suitable LO frequency itself

Only the 2m band button is any use with an RTL dongle.
Separate, non-dockable windows for software Control, RX Control, Main (passband)` Spectrum, Aux (tuned-in) Spectrum and Memory Panel
Poor memory banks arrangements
Press play button to start decoding

SDR# v1.0.0.1637 from

Now optimised for Airspy SDR radios but still works with RTL dongles.


Wide FM and Stereo FM modes for broadcast stations
Decodes RDS from FM broadcasts
No S-meter
Memory banks don’t seem to remember the transmission mode (eg Wide FM)
Memory banks hidden down at bottom of pop-out sidebar menu
Press play buton to start decoding

HDSDR v2.76 from
As you can see from the URL, HDSDR comes from Germany. The website is in English though! Unfortunately there is no manual, although a few amateurs have posted helpful articles online. HDSDR is based on the much older Winrad and some documentation on that may be helpful.
During testing I discovered that the upper frequency limits on my dongle were:
Highest LO = 1868.545
Highest RX freq = 1869.745

DRM & ECSS?? modes (ECSS is assumed to be Exalted Carrier Single Sideband whose benefits are unknown!)
‘Analogue’ S-meter
‘DC’ spike in centre of passband can be nulled using menu option
No wideband FM mode
No squelch
Confusing dual ‘LO’ (passband centre frequency) & operating frequency tuning
Hammers the CPU. Any other activity maxes out 2.8 GHz E5500 dual-core Pentium
Memories/band change via popup Frequency Manager application

SDR Console v2.3 (aka SDR-radio) from
I really wanted to like this program, which is written by Simon Brown of HRD fame. Unfortunately it was a pig to install, requiring four dll’s to be installed before it worked. Some of these were documented but on installation there was an error message that MSVCR100.dll was missing too. A quick Google turned up the fact that this is a redistributable part of Microsoft Visual C+ + 2010. Fortunately I was able to install the Visual C+ + 2010 redistributables from the Microsoft website.

Unfortunately I also encountered what appeared to be a bug: at one point the frequency was changed but the decoded and displayed spectrum didn’t change. The only solution seemed to be a restart.
v3 of the program is currently available in Beta.

Comes with server software that can be used to allow remote operation. (I haven’t tested this yet.)
Exceptionally good amateur features: integrated PSK and RTTY. Supports CW Skimmer, rig control, satellite operation including rotator control and doppler correction.
Low CPU demand
Works with a wide range of SDR receivers (but currently only the ANAN SDRs for transmit).
Those dll’s and the ‘bug’
Steep learning curve
Some interface elements appeared counter-intuitive in operation
Press start to begin decoding

DAB-specific programs
QT-dab v1.0 alpha
Initially this program seemed prone to audio glitches and decoding errors. Turning AGC off and increasing gain to almost maximum solved this.

Geeky! Charts showing channel spectrum, carrier phase/amplitude and impulse response. The latter shows signals arriving from long path reflections and multiple transmitters in the SFN.
Decodes DAB+ as well as DAB
Crude in operation with basic look & feel. (Starts with a slow-to-boot ‘console’ window followed by GUI elements, which initially overlap.
Need to select ‘Device’ Ext_IO.dll every time
Tuning is by mux channel number eg 12B for the BBC mux, which is pretty unfriendly
No waterfall chart

WELLE.IO v1.0-rc2 from
This was the most user-friendly of the two DAB programs. I did discover one bug however. The program can be used in full-screen or ‘player’ sizes. Mine is stuck in full screen!


Scans bands to find receivable DAB muxes
Builds station list
Decodes DAB and DAB+
Decodes MOT slide shows (allegedly – I haven’t seen any slide show decodes)
Expert mode shows RF spectrum of mux and reception details, errors etc
CPU-hog – lots of audio glitches if other CPU activity
No waterfall chartMisreports stereo DAB+ stations as mono

This wasn’t intended to be a full review of the SDR programs but should give you some idea of their relative benefits. All seem to be under active development so may already be even better than I found. They are all free, so why not give one or two a go today?



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