Soft Rock 40 Software

Latest Soft Rock 40 Software

Flex-Radio PowerSDR distribution now has SoftRock 40 support built in!

Update 30 October 2005 - The PowerSDR distribution from Flex-Radio now contains the modifications I've done for the SoftRock 40. You can take PowerSDR Beta 1.4.5 preview 2 or later from Flex-Radio's download site and use it directly with the SoftRock 40.

I will continue to use this page to publish experimental Soft Rock software.

Previous Soft Rock 40 PowerSDR versions

I've modified Flex-Radio's PowerSDR software to work with the Soft Rock 40. The combination of the relatively simple Soft Rock 40 hardware with the PowerSDR software results in a low cost receiver with some very nice features. It is a very effective demonstration of the capabilities of the software defined radio approach.

The changes I've made to the PowerSDR software are fairly minor. Basically all one needs to do is to change the software to work as if the DDS is fixed at the frequency of the SoftRock 40 QSD and to ignore most of the parallel port or USB hardware control inputs . To use the software with a Soft Rock 40, go to the Tests page in the Setup dialog. Enter the frequency of the Soft Rock 40's QSD (nominally 7.056 MHz) and check the 'Fixed HW Osc' check box. You will now be able to tune +/- 24 kHz of the QSD frequency. You can also use this feature with an SDR 1000 if you want to experiment with pure software tuning - the software will set the SDR 1000's DDS to the frequency entered.


To use this code you will need to first install an appropriate binary release of PowerSDR from Flex-Radio Systems and then overlay that installation with the changed binaries I've provided.

Chuck Carpenter (W5USJ) wrote up a good post on QRP-L that provides more detailed instructions on how to do the overlay and install.

To enable the code to work with the Soft Rock 40 use the 'Soft Rock' tab on the Setup menu and enter the center frequency of the receiver (nominally 7.056 MHz for the Soft Rock 40) and enable the 'Fixed HW Osc' check box on the page. You will also have to use the Audio tab on setup to tell PowerSDR what sound card the Soft Rock 40 is attached to.

You will need to manually calibrate for level and IQ Balance using the setup notebook. If you also have an SDR 1000, I'd suggest copying your existing installation to a new directory so your're using separate PowerSDR.mdb database files with the Soft Rock 40 and SDR 1000.

Most Recent Release: 20050917 - for PowerSDR 1.4.4

This released is based on PowerSDR 1.4.4. This release fixes a number of bugs that had crept in over the last couple of updates. Specifically:

  • Fixed problem using an SDR 1000 in fixed freq mode
  • Fixed a potential glitch/hang in level calibration with a SoftRock 40
  • Fixed smooth panadapter scrolling when in fixed freq mode Code can be downloaded from:



    If you already have a 1.4.4 PowerSDR based install (either a stock PowerSDR from Flex-Radio, or a SoftRock modified 200050827 setup) you can install this update by just unzipping the binaries and copying them on top of the existing install.

    Release: 20050827 - for PowerSDR 1.4.4

    This release is based on PowerSDR 1.4.4. In this release I've added code to blank the spectrum display in aliased areas (the areas above/below the +/- 24 khz around the central frequency. Code can be downloaded from:



    Release 20050718 - for PowerSDR 1.4.1

    PowerSDR for Soft Rock 20050718 based on PowerSDR 1.4.1. The source changes (from PowerSDR) and binaries can be downloaded from:



    The new feature in this code is that the settings for the Soft Rock 40 have been moved to their own tab in the Setup menu notebook and the settings are persistent.

    Release 20050710 - for PowerSDR 1.4.0

    Release 20050710 for PowerSDR 1.4.0 can be downloaded from:



    There are some limitations with the 20050710 level of the code. It does not save the Soft Rock 40 enablement and frequency setup so you need to re enable it each time you start the program. Also the left channel only option (needed for the KB9YIG's earlier SDR Sampler transceiver is not currently enabled). I do plan to fix these in the not very distant future, but wanted to get our a new release to support the Soft Rock 40 because a number of folks are currently completing those kits.

    The binary files need to be copied on top of an existing Flex-Radio PowerSDR installation. The source files are just the source files I modified to produce the Soft Rock 40 distribution.


    The GPL licensed release of PowerSDR by Gerald Youngblood (K5SDR) of Flex-Radio Systems has made this project possible. Bob Mc Gwier (N4HY) and Frank Brickle (AB2KT) have licensed their DttSP code (the DSP engine in PowerSDR) uner the GPL. My thanks to these people for their contribution to advancing the radio art and for making their code available under a license that allow others to extend and build on their work, and preserves that work for others.

    Other Software

    There are a number of other software radio projects that can probably be setup to work with the SoftRock 40. Phil Covington N8VB is working on adapting his SharpDSP based console for the SoftRock 40. I2PHD's SDRadio works with the SoftRock and one should be able to get it working with GNU radio as well.

    I've also go some more information on things I've done with the Soft Rock 40.

    Comments to: Bill Tracey (

    Last Updated 30 October 2005

    Copyright © Bill Tracey 2005