Re: [Freetel-codec2] codec2 modes and sm1000 PTT

Faisal, I've not yet done any work to port 2400A or 2400B to the SM1000 or STM32F4. The FMFSK modem used by 2400B will probably run without issue, as it doesn't use a whole lot of memory as is, but I'm not sure about FSK. The big issue I see for you is that 2400A and 2400B operate at a 48Khz

Re: [Freetel-codec2] new FreeDV 2400A VHF Modem

Hi Brady, David, Thank you very much for sharing the GRC flowgraphs. This will help me a lot setting up a similar test. Regarding the performance, I was just surprised to see such a big difference between a modem which runs through analog FM and your new modem. I would have expected something in

Re: [Freetel-codec2] new FreeDV 2400A VHF Modem

Hey Adrian, The gnuradio-companion pipelines I used for the test are attached. These grc pipelines are only meant to get 16-bit 48k samples in and out of the HackRF and rtlsdr for testing. The meat of the FSK is done with the C fsk modem, used in freedv_rx, freedv_tx, fsk_mod, and fsk_demod. We

Re: [Freetel-codec2] new FreeDV 2400A VHF Modem

Hi Adrian, I think Brady's going to get back you with his GR code. Not sure if the FSK modem is still outboard of GR, or if he has a GR module for it. Note we are not running our modems through the analog FM modulator/demodulator, as that's how you throw perfectly good dB away. I'm looking

Re: [Freetel-codec2] new FreeDV 2400A VHF Modem

Did I hear that right? Works with non linear amplifiers, competitive with SSB, replaces all your multi carrier modems? On Thu, Mar 17, 2016, 11:51 David Rowe wrote: > Hi Adrian, > > Getting the modem right can be really critical. It's good that we are > discovering this and

Re: [Freetel-codec2] new FreeDV 2400A VHF Modem

Hi David, You are right, it was measurement error. With the help of Brady's GRC flowgraphs, I was able to set up a more reliable test. The chain was: gnuradio DBPSK modem on laptop -> Yaesu FT60 set on narrow deviation -> USRP B200 -> Gqrx The USRP has fine adjustable gain, between 0 and 70 dB.

Re: [Freetel-codec2] new FreeDV 2400A VHF Modem

Also, for comparison purposes, here is my 2000 bit/s modem running through a Yaesu FT60 handheld radio: https://www.youtube.com/watch?v=bsmGYWxjfjU The filter in Gqrx is adjusted for wide deviation (5 kHz) but the signal is only really about 3 kHz wide. Please note how the signal is 15-16 dB

Re: [Freetel-codec2] new FreeDV 2400A VHF Modem

I think in the case of coherent vs non-coherent for 4FSK, the plot of EbN0(dB) vs BER for ideal coherent and non-coherent says it all. If we find that we really need that extra dB, It'd be easier to switch to non-coherent 8FSK than write and test coherent 4FSK (and at 8FSK, coherent and