Tagged: hdsdr

HDSDR Version 2.75 (Stable) Released

The beta 2.75 version of HDSDR was released about two months ago. Now the stable version has just been released. HDSDR is a free general purpose SDR receiver, similar in nature to other programs like SDR# and SDR-Console. HDSDR can be downloaded from hdsdr.de.

The author of HDSDR emailed us with the following release information:

this morning we released the final version 2.75. Here’s the changelog:

Version 2.75 (January 01, 2017)
- more recording options
- support for 8bit sampling format – ideal for RTLSDR, halving RF recording size
- display level / clipping for RF and AF
- additive noise generator for hiding aliases
- Highpass Filter for AM/FM deactivatable – useful for slow digimodes
- configurable gain for I/Q output – useful for digimode decoding weak signals of SDRs with >16 Bit dynamic range
- Uniform “Calibration” dialog for Frequency/S-Meter/DC Removal/Channel Skew
- “Custom color palette” to customize colors of Waterfall/Spectrum and some more
- output soundcard no longer necessary (e.g. for recording or monitoring)
- support for 8k display resolution (7680×4320)
- some new keyboard shortcuts (see )
- extended ExtIO capabilities
- experimental transmit capability through ExtIO API interface
- many fixes and improvements

Some of the new features were introduced especially for the RTLSDR Dongles:

- 8 bit support, of course

- displaying the RF (ADC) level in dBFS allow working with deactivated Tuner AGC – NOT oversteering/clipping the ADC.
This would also ease making good suitable recordings as used in

Especially for decoding this kind of signals (AM/FM) , deactivating the Highpass filter (Ctrl-H) will make the demodulated Audio clearer:
long periods of positive or negative levels will not fade towards zero.
Find attached recordings and screenshots with active and deactivated highpass filter of a garage door opener demodulated in AM.

- additive noise generator (Ctrl-N) is for hiding some alias carriers in scenarios where the ADC does not see real noise from the antenna.
The noise generators level has to be configured carefully for not hiding real signals. A level between -25 to -10 looked fine for me. But that should be measured in a lab.

Below are the mentioned attached images and .wav files.

Highpass Filter - Active
Highpass Filter – Active
Highpass Filter - Inactive
Highpass Filter – Inactive

Highpass Active .wav file (Download)

Highpass Inactive .wav file (Download)

HDSDR Beta 2.75 Released

A new beta version of HDSDR has recently been released. HDSDR hasn’t been updated since 2013, so it is good to see that the author is back in action. HDSDR is a free general purpose SDR receiver, similar in nature to other programs like SDR# and SDR-Console. It was one of the first programs to work with the RTL-SDR dongle and despite a lack of recent updates is still a very solid piece of software.

The new HDSDR is version 2.75 Beta1 and the changes include:

  • more recording options
  • support for 8bit sampling format
  • HDSDR runs without output soundcard
  • support for 8k display resolution (7680×4320)
  • extended ExtIO capabilities
  • many fixes and improvements

The main visual difference we’ve noticed so far is the addition of a text dBM meter under the S-Units meter. We also discovered some new color palettes.

HDSDR Beta running a new bright grayscale color palette.
HDSDR Beta running a new bright grayscale color palette.

Using a 75 Year old Marconi CR100 Radio to Control an SDRplay RSP

Over on YouTube Jon from SDRplay has uploaded a video showing how he’s used the knobs and interface from a 75 year old Marconi CR100 analogue radio to completely control an SDRplay SDR. This allows you have the feeling of tuning a vintage radio with the old fashioned knobs, whilst enjoying the features of a modern SDR.

Within the old radio enclosure they’ve managed to fit in a full Acer mini computer which runs the RSP on HDSDR. To allow the main tuning knob on the Marconi to tune the SDRplay they’ve used an Arduino controller, and an optical shaft encoder. As they intend for their hybrid to be completely keyboard-less, they’ve also added two UP/DOWN buttons to jump up and down the spectrum, buttons to choose the demodulation mode, and a new knob to control the zoom setting in HDSDR.

The project was sponsored by RS components and is intended to be used in the November 2016 Electronica event in Munich as an exhibit that celebrates the 80th anniversary of the expo. The idea is that the SDRplay-Marconi hybrid combines radio technology which would have been around during the first Electronica expo’s as well today’s modern SDR technology. There is a write up of the project available on the RS components designspark website.


Creating a Long Term Averaged Waterfall on HDSDR with Chronolapse

While tools like rtl_power and rx_power now exist for creating long term averaged waterfalls for many SDR’s, another option is to use a screenshot grabber to grab screenshots of the waterfall every few seconds on an SDR program like HDSDR.

This is what the admin of the coolsdrstuff.blogspot.com blog has done. The author used the program Chronolapse which was set to take a screenshot every 60 seconds. The waterfall in HDSDR was then set to a speed so that the waterfall would complete one cycle every 60 seconds. Then after collecting images all night he used Irfanview to bulk resize all the images to be 1 pixel high. Finally he then combined all the 1 pixel high images into a nice waterfall image.

The waterfall speed in HDSDR can also be set to a very slow update speed, but the problem with this as noted by the author is that this does not average the data, meaning that data in between waterfall updates is lost. 

An overnight averaged waterfall from HDSDR.
An overnight averaged waterfall from HDSDR.

New ExtIO for the HackRF and HDSDR

We’ve received a note from RTL-SDR.com reader Tim about a new ExtIO module available for the HackRF and HDSDR. ExtIO stands for External IO, and is a special DLL file that allows HDSDR and other software to access hardware like the HackRF.

To use it, simply copy the HackRF ExtIO dll file into the HDSDR directory, and select it when opening HDSDR. The module currently supports 2, 4, 8, 10, 12.5, 16 and 20 MSPS sample rates. We tested it briefly on our own HackRF and it ran just fine at all sample rates.

The module is available on GitHub and it’s current binary release can be downloaded here.

The HackRF running in HDSDR.
The HackRF running in HDSDR with the new ExtIO Module.

How to Setup CWSkimmer with an RTL-SDR and HDSDR

Over on YouTube user Brent Crier has uploaded a tutorial video showing how to set up CWSkimmer with an RTL-SDR and HDSDR. CWSkimmer is regarded as one of the best pieces of software that can be used to decode CW a.k.a Morse code.

Morse code is a communications technique still used widely by the amateur radio community in the HF bands. The RTL-SDR can receive HF frequencies and Morse code with an upconverter or direct sampling modification.

In the video Brent goes over the installation of HDSDR, Virtual Audio Cable, and a program called Virtual Serial Port (VSP) manager as well as the needed settings for each program. The set up he shows allows CWSkimmer to automatically change the frequency in HDSDR when tuning in CWSkimmer.


Hak5: Exploring With The PortaPack and HDSDR

In this Hak5 episode Darren discusses the HackRF PortaPack which is a portable LCD screen device that connects to a HackRF SDR and allows portable frequency spectrum visualization. The PortaPack is currently under development and in the future it will allow demodulation of multiple audio modes and possibly digital demodulation and recording capabilities as well.

Later in the episode Shannon presents a tutorial on HDSDR, an SDR GUI alternative to SDR#. She shows how to install and use the HDSDR program.


The BIG List of RTL-SDR Supported Software

There are now dozens of software defined radio packages that support the ultra cheap RTL-SDR. On this page we will attempt to list, categorize and provide a brief overview of each software program. We categorize the programs into general purpose software, single purpose software, research software and software compatible with audio piping.

If you know of a program that is missing please leave a comment in the comments section at the bottom of the page.

13/02/2014 – Added Sodira, gr-wmbus, rtlsdr-waterfall, QTRadio, multimon, sdrangelove, lte-scanner, rtl_tcp, rtl_sdr_FS20_decoder.
17/02/2014 – Updated the Linrad description.
28/04/2014 – Added Modesdeco and Trunk88.
30/05/2014 – Added RTL Panorama, RTL SDR Panoramic Spectrum Analyzer, Chrome Radio Receiver, SeeDeR, DAB Player, RTL SDR Installer, PD/Max Wrapper, SDRWeather, LTR Analyzer, softEOT/softDPU and ScanEyes.
26/07/2014 – Added PiAware, OOK-Decoder, rtl_fm_python, rtl_power heatmap viewer, RTL Bridge, threejs-spectrum, CANFI Software, PNAIS, FLARM Decoder, Xastir, RTLSDR-Airband, SDRTrunk.
13/11/2014 – Added Touchstone, RFAnalyzer, RTL1090 XHSI Interface, Parus Decoder, PlotRTL1090, LRPT Decoder.
05/02/2015 – Added rtl_tool_kit, CubicSDR, OregonWeather, FreqWatch.
15/04/2015 – Added ADSBox, YouSDR, FlightAware Flight Feeder, Frequensea, Track your flight EUROPE, QSpectrumAnalyzer, Doppler & Demod, Redsea, rtl_heatmap, gr-gsm, driveby, SDRecord.
23/12/2015 – Added Remote rtl_udp, AISRec, dump978, AISDeco2, SDRrecorder, OpenWebRX, dsame, RTL-Widespectrum, rtl_ais, rtl_gopow, ham2mon, rtl_ais_android, inmarsatdecoder, spektrum, qtcsdr, rtl_power_fftw, JAERO, GNSS-SDRLIB, SVxLink.

General Purpose RTL-SDR Software

We define general purpose SDR software as programs that allow the RTL-SDR to work like a normal wideband radio receiver.

SDR# (Windows) (Free)


SDR# (pronounced “SDR Sharp”) is the most popular free RTL-SDR compatible software in use at the moment.  It is relatively simple to use compared to other SDR software and has a simple set up procedure. We have a full overview of the installation procedure on our Quick Start Page. SDR# is designed to be use with the $199 Airspy SDR, but works just fine with the RTL-SDR.

SDR# is a simple to use program that also has some advanced features. It has a useful modular plugin type architecture, and many plugins have already been developed by third party developers. The basic SDR# download without any third party plugins includes a standard FFT display and waterfall, a frequency manager, recording plugin and a digital noise reduction plugin. SDR# also decodes RDS signals from broadcast FM.

HDSDR (Windows) (Free)


HDSDR is based on the old WinRAD SDR program. HDSDR supports the RTL-SDR through use of an ExtIO.dll module. To install HDSDR, download the program from the link on the main HDSDR page, then to use the RTL-SDR you will need to download the ExtIO_RTL2832.dll file an place it into the HDSDR folder. When opening HDSDR, select the newly copied ExtIO_RTL2832.dll. The other dlls that come with HDSDR will not work with the RTL-SDR, even though they have RTL-SDR in their filename. The official installation instructions can be found here.

Along with a FFT display and waterfall, HDSDR has some extra advanced features. Users will also find an Audio FFT and waterfall display on the bottom of the screen. The output audio can also be bandpass filtered by dragging the filter borders on the display. Bandpass filtering the audio can really help clean up a noisy signal. The audio processing also supports placing of notch filters either manually or automatically. There are also noise reduction and noise blanker features and an automatic frequency centering algorithm which will automatically center the signal, so you don’t need to click exactly in the center of a signal. Traditional ham radio users will also enjoy the S-units signal strength meter and the built in frequency manager.

SDR-RADIO.COM V2 (Windows) (Free)


SDR-RADIO.COM V2 is a popular SDR program with many advanced features. As such is it a fair amount more difficult to learn and use compared to SDR# and HDSDR. Be sure you install version 2 and not V1.5 as only V2 has RTL-SDR support.

Once sdr-radio is installed, to get it working with the RTL-SDR you will need to compile or download three .dll files (SDRSourceRTL2832U.dll, rtlsdr.dll and libusb-1.0.dll) and place them into the sdr-radio folder. To compile your own dlls see the instructions here, otherwise download the dlls directly from the bottom of this link. If the dlls were placed in the correct folder you will be able to add your RTL-SDR as a receiver by clicking on the +Definitions button, and then finding and adding the RTL SDR (USB) option under the search drop down menu.

Like HDSDR, not only does sdr-radio have a RF FFT signal and waterfall display, but also an optional audio spectrum FFT and waterfall display. Built in are also several DSP features like a noise blanker, noise reduction filter, notch filter and squelch options. The EMNS noise reduction filter is particularly good at automatically cleaning up and clarifying voice signals.

To add to the feature list, sdr-radio also has built in PSK, RTTY and RDS decoders, and also comes with a satellite tracker. Furthermore, sdr-radio has an excellent remote server which will allow you to easily set up and connect to a remote RTL-SDR server over a network or the internet. Finally, sdr-radio is capable of listening to up to 6 signals in the same chunk of visible spectrum at a time.

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