Q: Where can I get the user manual?
There is no official user manual available from HDSDR team. We try to make HDSDR's usage as simple as possible.
All program buttons include ‘pop-up’ tooltips that explain their function. Alan (G4ZFQ) wrote some lines on installing and using HDSDR . French translation v1.0 by Jean Marie Polard, F5VLB. Also Alan (AB1JX) has published a documentation . Dario Bonfanti wrote a manual in Italian . Additionally, you can watch HDSDR on YouTube. For further reading, you can try Alberto di Bene's manual on Winrad. This is the manual written for the original version of Winrad. This may be very useful for new users of this type of software. Unfortunately, we do not have the time to develop the software AND write a user manual. However, we welcome, and are grateful for any contributions made by volunteers.

Q: Why there are two different frequencies (LO / Tune) ?
The LO frequency represents the SDR hardware's oscillator frequency. With an I/Q receiver this is at the centre of the waterfall/spectrum display. [ For IF receivers, e.g. 12 kHz, this is the leftmost displayed frequency in the waterfall/spectrum display. ] Many SDRs do not work quite so well close to the LO frequency, there may be a band of noise there. Soundcard SDRs may show a spike and some noise from ground loop effects. HDSDR's DC removal (Options - Input Channel Calibration for RX) will notch out the spike, normally "Auto" is effective. The tune frequency represents the software oscillator (NCO - Numerically Controlled Oscillator), which is used to tune the signal one wants to hear. Usually LO is set, so that a desired band with multiple signals can be seen and tuned simultaneously. This allows quick tuning to a signal with just single mouse click - without the need to move the LO - provided you can see all the desired band. RF (full spectrum) recordings may be made. You may later replay and tune to every visible signal - one by one. With wideband receivers this allows you to record all the AM (MW) band for example.

Q: TX doesn't work! How do I enable it?
Yes, this can happen. We extended the ExtIO-DLL interface to allow RX/TX switching in HDSDR versions 2.13 and above. TX functionality requires support from your ExtIO-DLL. Without this ExtIO support, HDSDR cannot provide the TX function. You may be able to get TX support for HDSDR by contacting the manufacturer of your radio, or alternatively by contacting the developer of the ExtIO.

Q: What is an ExtIO-DLL?
The HDSDR software doesn't communicate with the SDR hardware directly. It communicates with the SDR radio hardware through an External Input Output Dynamic Link Library (ExtIO-DLL) file, which is a type of plug-in. Alberto di Bene designed the DLL interface so that Winrad can operate with a wide range of SDR hardware. We extended the DLL-interface to support TX switching. Winrad and HDSDR can support new hardware radios using an ExtIO-DLL file without the need to change the HDSDR software. ExtIO DLL files are written by anyone who wishes to provide support for any particular SDR hardware. In this manner, several radios can be used with a single piece of software. The software in this case is HDSDR.

Q: How do I develop an ExtIO-DLL?
At this point, we assume that you are a software developer familiar with C/C++ programming. Here is a “hopefully” well documented header file (updated November 23, 2016), which specifies the interface between HDSDR and an ExtIO-DLL. Here is also an example ExtIO DLL with sources as public-domain, developed with Microsoft Visual C++ 2008 Express Edition.

Q: My radio is not supported by HDSDR. When will it be supported?
Support for a particular radio depends entirely on manufacturers and the HDSDR community. Therefore, it is possible that some radios may never be supported. If the SDR radio is a commercially available product, such as FlexRadio or WiNRADiO, contact the manufacturer and request support for HDSDR. For a non-commercial radio project, you will need to contact a software programmer who is able to develop an ExtIO DLL for that radio.

Q: Can I listen to Wide FM radio stations?
Yes. Currently, this can be achieved by using a workaround procedure as described below. The ‘Bandwidth’ button [F6] may be used to increase the output sampling rate to 96000 Hz. We will endeavor to provide better support for the Wide FM mode in a future version of HDSDR.

Q: Can I change the size of the Spectrum/Waterfall display?
Yes. Click and hold the right mouse button on the frequency scale, and then move the mouse up or down.

Q: How do I set the ‘Waterfall’ display for extreme low-speed?
Click the ‘Speed’ label for the ‘Upper Display’ RF waterfall with the left mouse button. The adjustable ‘Speed’ slider will disappear. Click the ‘Speed’ label again with the right mouse button and a window will ‘pop-up’ allowing you to enter a ‘Total Time Period’ in minutes. This is the time span value, and it determines how much time is displayed on the vertical axis (height) of the waterfall. If you need to configure how much of the ‘Spectrum’ and ‘Waterfall’ is displayed, you can adjust the ratio between them by clicking and holding the right mouse button on the ‘Frequency’ scale, and then moving the mouse up or down as required. You may then proceed to set the time span value.

Q: What does the ‘Despread’ button do?
‘Despreading’ is a type of radio signal processing designed for CW signals, where the received energy is spread over a frequency range. This spreading effect is primarily produced by Earth Moon Earth (EME) reception. The ‘Despread’ button provides a type of filter that collects the spread radio energy and tries to reproduce a clean radio carrier. This program feature was developed by Alberto di Bene, and he provides a short explanation of this function at the end of the webpage found at http://www.sdradio.eu/weaksignals/winrad/index.html with audio samples available that are recorded before and after use of the ‘Despread’ filter. More EME sample recordings can be found at IZ1BPN's and G4CCH's webpages.

Q: What is ‘RBW’?
‘RBW’ is the Resolution BandWidth of the spectrum and waterfall displays. Basically, it determines how much detail or ‘resolution’ is displayed. Very fine frequency resolution can be achieved with smaller values, but at the expense of time resolution. The result is that time resolution is degraded. Larger ‘RBW’ values will lead to a finer time resolution, but now at the expense of frequency resolution. The result is that frequency resolution is degraded and the display will appear ‘coarser’. There is no optimum value. It depends on modulation and how much detail the user wishes to observe. Mathematically, (RBW = Sample Rate / FFT-Length). Therefore, they are closely related.

Q: There is a feature I would like included. Which forum can I post my request?
Please do not post your requests or wish-lists in any forum. We do not monitor or track any such forums. Simply contact us directly by e-mail. Feature requests for future versions are considered during the planning and prioritization stages of the software's development.

Q: The software does not work. What can I do?
If the HDSDR software does not meet your expectations, it may be the case that it is unsuitable for your purpose. In this case, alternative software may be suitable for your SDR radio. If you would like to contribute to the enhancement of HDSDR, please contact us by e-mail with a detailed report describing the problem. Please include details such as: PC used, Operating System version, CPU type, RAM used, Sound Card type, Rig model, SDR hardware model, ExtIO-DLL used, and all details regarding the antenna and/or IF connections used. Please don't forget to mention at what point the problem occurs, and any other information that can help us try to reproduce the problem. Screenshots and screen recordings are generally preferred as they help us to ‘see’ and understand the nature of the ‘bug’ problem.

Q: Can I run HDSDR on my Mac?
Alain De Carolis build a simple Mac bundle for RTLSDR and SDRPLAY. HDSDR on OSX - The easy way

Q: Where can I download the source code for HDSDR?
Source code for HDSDR is not available. HDSDR is not ‘Open Source’, and is licensed as ‘Freeware’;.
However, Alberto di Bene did release the source code for Winrad v1.32 as public domain software.

Q: What features will be available in the next version? When will it be released?
We cannot provide this information due to the variability of enhancements being added. However, when a new version is released, it is listed on the HDSDR webpage under the heading ‘What's New’.

Q: Can I donate money to HDSDR?
We do not accept any donations. Thank you.

Q: But I really want to donate money!
https://sharethemeal.org Thank you.

Q: Is there any way I can help to enhance HDSDR?
Yes. There are several ways you can help...
a) Writing software documentation.
b) Translating any existing documentation into other languages.
c) Writing a clearly prioritized wish-list of features that could be added to the software.
d) Developing an ExtIO DLL (for use with new or unsupported hardware).
e) Hardware Manufacturers can provide test hardware, allowing us to test new HDSDR versions.
    This way, we can reproduce and correct software ‘bugs’ that may exist with this hardware.