Tibor Bece and George Karan are collaborating with me on the baseband FM (BBFM) project. Tibor and George are veterans of the land mobile radio (LMR) industry, having worked together for many years and helped develop commercial VHF and UHF radio hardware with over 2 million units manufactured. They are pretty excited about the Radio Autoencoder work and what it could mean for LMR.
George has managed to build the RADE V1 stack, and run the ctests on a variety of embedded platforms, including AM625 – this is a high end embedded processor with enough power to run RADE (including the FARGAN stack); and a Librem 5 phone!
Tibor has been interfacing the BBFM ML stack to a COTs LMR radio, using a modified conventional digital voice frame structure to carry the “analog” BBFM symbols. Unlike my passband demo, this implementation has direct access to the FM modulator and discriminator so it’s a “DC coupled” arrangement – closer to what a real world, commercial implementation would look like.
Like me, Tibor was initially thinking the speech quality and low SNR performance of this technology was in the “too good to be true” category. However he has now performed controlled experiments on his (very well equipped) RF work bench, as was quite surprised to be getting high quality speech at RX signals levels down to -125dBm, several dB lower than analog FM or digital LMR systems like P25 would allow. At this low RF level the cut off is due to framing of the RADE symbols (not BBFM), as he never dreamed it would be necessary to operate at such a low SNR.
Tibor writes:
The 11dB SINAD point (around -121dBm) is where the squelch would normally fail to open, and a P25 frame would start dropping out. The RADE decoder munches through this with great ease, there is some barely perceptible degradation.
All I can say – WOW!
Here are samples (over the same radios) of analog FM and BBFM at various RF input levels from Tibor’s workbench:
All I can say too is, WOW, as well! What is the range of that communication at minus 124 db? Can you let me, and others know? 73, Trippy, AC8S
Mind blown – truly amazing work. This FM mode could give other proprietary modes a good run for their money. Don’t stop what you’re doing! Open source ’till the end!
On HF, I just had a nice QSO between Texas and Los Angeles at 25 watts on RADE, fading in and out but maintaining the connection with barely a burble. THAT’s the future.
Congratulations on your grant and all of the exciting work you’ve been doing. Concerning your original project plan, I noticed “WP5000 Commercial Radio Integration” and immediately thought of my FlexRadio, and its built-in “Waveform” capability, which appears to be a potential marriage made in heaven.
However, in reviewing past post comments, I noted your response concerning FlexRadio Waveform integration. You stated this was handed off to TAPR, citing the ezDV product as the solution.
While ezDV is an interesting product, I’m not thrilled about adding yet another piece of hardware/software to my shack, when my Flex has the same potential capability, with superior integration.
Do you intend to adhere to your original WP5000 project plan, and provide true commercial radio integration, including Flex?
Thanks and 73
Hi Bill,
Thanks for your enthusiasm about our grant work. The FreeDV project leadership team (PLT) all agree that the ideal solution is to have our new RADE waveform integrated into commercial radios. We are happy to work with Flex and any other radio company at any time. However – their engagement is necessary – it is not something we can make happen alone. You can help here – please reach out to Flex and express your wishes to see RADE in their products.
Thanks,
David