SDR Television Beta #4
Simon Brown • June 30, 2025
Unexpected Beta #4
I wasn't planning to release another beta, but there was an error with a download link in the Blog port for Beta #3, also a few worthwhile improvements have been made, so here I go.
SDR Television
- Improved matched filter (root-raised cosine).
- Changed LDPC algorithm to use the Offset-Min-Sum (self-corrected) layered schedule', constant factor = 2.
- Fine tuned the receiver constellation.
- Changed the default transmit bandpass shaping filter roll-off to 0.25. Please look at the image below and apply the change.
Known Problems
- Switching from a transmission using short frames to another transmission using normal frames and a lower sample rate may cause the program to abruptly exit. The good news - I have a data recording I can replay to reproduce this.

SDR Radio
No changes.
Download
This new kit does not require a new version of SDR Radio, the links below are for the kit released with beta #3 on June 16th, 2025.
SDR Television
Download from either:
- OneDrive: SDR Television V1.0, 64-bit, 2025-06-30_1338.exe
- Dropbox: SDR Television V1.0, 64-bit, 2025-06-30_1338.exe
SDR Radio
Download from either:
- OneDrive: SDR-Radio V3.4, 64-bit, 2025-06-16_0559.exe
- Dropbox: SDR-Radio V3.4, 64-bit, 2025-06-16_0559.exe
New Paragraph

SDR Television Found and fixed an unused massive memory allocation (up to 10GB), may have caused systems to freeze. Fixed fatal bug in matched filter array allocation. Changed the default transmit bandpass shaping filter roll-off to 0.20 in transmit and receive. Please look at the images below and apply the change. SDR Pluto Now show the AGC gain and RSSI. Added Default link to select the recommended gain - Fast Attack, 0dB visual. Known Problems Add support for tracking transmissions with (?) non-standard PCR data, example is G8GKQ. Using Pluto & variants, sensitivity is not as good as a NIM (hardware tuner). Will compare with SPECTRAN ECO in a week or so.

After too much grief, I've decided to stop using Wi-Fi to connect the small NUC systems in the computer room to my network: DX Cluster (Ubuntu) SDR Server (Windows) User Forums (Windows) These servers are in constant use, causing the wireless transmitter on my TP-Link AX50 to fail. By switching over to a wired network there's less demand on the wireless transmitter and the whole network has become far more reliable. In future I will only use Wi-fi when there's no alternative. I'm keeping a spare router ready just in case the AX50 fails.