Request for some help, want to create an audio base Radio IF Signal Processor [IF SDR]

[pa3akp]

Let me first comment that CSCore is an amazing project, the first one I have ever seen with such details.

What do I want to create. I am an HAM radio operator and want to create in C#, with the help of CSCore, a universal Audio IF (IF = Intermediate Frequency) signal processor to built a IF SDR (software defined Radio). The signal processing is meant to demodulate radio signals converted from the 455kHz IF of my receiver into a 12kHz IF. The modulation types can be AM, FM, USB, LSB,.... whatever.

Next to the IF processing, I would like to create Audio Based signal processing of of signals like SSTV(Slow Scan Television, WEFAX (Weather Fax Maps), APT(Automatic Picture Transmission from weather satelllites), RTTY ( Radio TeleType) etc etc.

Also custom filtering DSP must be one of the features (Low Pass, High Pass etc)

As a first step for help:

At the moment I already can sample the incoming Audio, using one of the samples in CScore, and place them info a buffer with a programmable size. Making use of Zedgraph I can display the sampled time domain and using AlgLib and Zedgraph to create a spectral plot.

In the code below, I store each sample of the single block read in a buffer of 2^n samples. When the buffer has all the points I show time domain or (after FFT) show freq domain.

QUESTION: how can I replay the contents of this (unprocessed) data back again to the audio output of the soundcard?

Thanks Onno de Meijer

private void SingleBlockNotificationStreamOnSingleBlockRead(object sender, SingleBlockReadEventArgs e)
        {
            // Filling of FFT-list to 'totSamples' points
            if (fftBufferPointer < totSamples - 1)         //This statement was < is now !=

            {
                // Array without the Window function for the Scope, no windowing
                fftBufferL.Add(Convert.ToDouble(e.Left));
                fftBufferR.Add(Convert.ToDouble(e.Right));

                // if the form SpectrumAnalyserForm is open, then work on the FFT data points.

                switch (fftWindow)
                // Depending on the sampling winwdow type, fill the Array 'windowedBuffer(L)(R)' with windowed sample points
                {
                case "hamming":
                    windowedBufferL.Add(Convert.ToDouble(e.Left) * (0.54 - 0.46 * Math.Cos((2 * Math.PI * fftBufferPointer) / (totSamples - 1))));
                    break;
                case "hanning":
                    windowedBufferL.Add(Convert.ToDouble(e.Left) * 0.5 * (1 - Math.Cos((2 * Math.PI * fftBufferPointer) / (totSamples - 1))));
                    break;
                case "blackman-harris":
                    windowedBufferL.Add(Convert.ToDouble(e.Left) * (0.35875 - 0.48829 * Math.Cos((2 * Math.PI * fftBufferPointer) / (totSamples - 1)) + 0.14128 * Math.Cos((4 * Math.PI * fftBufferPointer) / (totSamples - 1)) - 0.01168 * Math.Cos((6 * Math.PI * fftBufferPointer) / (totSamples - 1))));
                    break;
                }

                // Increment the fftBufferPointer
                fftBufferPointer++;

            }
            else
            {
                //Debug.Print(windowedBufferL.Count.ToString());

                fftBufferPointer++;

                // Is the ScopeForm loaded?
                Form fc = Application.OpenForms["ScopeForm"];
                if (fc != null)
                {
                    // Call the scope display with the list converted to an array
                    audioToScope(fftBufferL.ToArray());
                }

                // Is the SpecAnForm loaded?
                fc = Application.OpenForms["SpectrumAnalyserForm"];
                if (fc != null)
                {
                    // Call the specan display with the list converted to an array
                    audioToSpecAn(windowedBufferL.ToArray());
                }

                // Clear the audio time-span buffers and the pointer
                fftBufferL.Clear();
                fftBufferR.Clear();

                windowedBufferL.Clear();
                windowedBufferR.Clear();

                fftBufferPointer = 0;
            }
        }

[pa3akp]

To make it more clear : the data which resides in the buffer fftBufferL and/or fftBufferR

Onno

[filoe]

As far as I understood you correct, you would like to do a IFFT on the fftBufferL and fftBufferR, store the samples in a buffer again and play them?

[pa3akp]

Thanks for coming back Florian!

I will compose a good explanation of my needs and come back to you!

Best regards,

Onno de Meijer

From: Florian Rosmann [mailto:notifications@github.com] Sent: Sunday, July 02, 2017 5:49 PM To: filoe/cscore Cc: Onno de Meijer; Author Subject: Re: [filoe/cscore] Request for some help, want to create an audio base Radio IF Signal Processor [IF SDR] (#250)

As far as I understood you correct, you would like to do a IFFT on the fftBufferL and fftBufferR, store the samples in a buffer again and play them?

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/filoe/cscore/issues/250#issuecomment-312499626 , or mute the thread https://github.com/notifications/unsubscribe-auth/AbM8mT_g-u28XS5U0FSxoe9hSZbTQ89Aks5sJ7v4gaJpZM4OEiSs . https://github.com/notifications/beacon/AbM8mfKNze_QyObTSCsqhzkX633_QX20ks5sJ7v4gaJpZM4OEiSs.gif

[filoe]

Any news on that?

[pa3akp]

Hi Florian,

Thanks for the mail!

Not yet unfortunately, sorry for this.

I am working on a large project in Russia at present for work, and free time is a problem, and away from home often.

I will come back on this, but appreciate your reminder!

Best regards,

Onno

From: Florian Rosmann [mailto:notifications@github.com] Sent: Saturday, October 21, 2017 10:34 PM To: filoe/cscore Cc: Onno de Meijer; Author Subject: Re: [filoe/cscore] Request for some help, want to create an audio base Radio IF Signal Processor [IF SDR] (#250)

Any news on that?

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/filoe/cscore/issues/250#issuecomment-338430516 , or mute the thread https://github.com/notifications/unsubscribe-auth/AbM8mbDu-JlBio3dCOoTtX6nF4kcmDkWks5sulU3gaJpZM4OEiSs . https://github.com/notifications/beacon/AbM8mcdZEkkuxF8SR5ftlyqjCBLjTaUmks5sulU3gaJpZM4OEiSs.gif