Eric, That is exactly what I've been wondering about. I totally realise that there are lots of gains to be had on the RF side, but for now this could start to show people that a 100% open source digital radio is possible at a price point that anyone could play with it.
As far as frame setup goes I believe DMR is 216bits per 60ms of audio. So the usable bit rate for voice would be 3.6kbps which could probably work quite nicely with the 3200bps version of codec2 without much changes. I would guess it would sound a decent bit better than AMBE at (2450 bps voice + 1150 FEC = 3600 bps) either way it would be 100% open source which would be super awesome. I would imagine leaving the DMR standard (9.6kbps) in favour of a lower phy bit rate would also offer gains as far as power per bit is concerned, but that would be much more involved I would guess. Regards, Daniel Mundall VA7DRM On Tue, Feb 2, 2021 at 2:29 PM <[email protected]> wrote: > Hi David, > > > > In short, yes. I don’t think it is viable to bypass the modem on the GD77, > and as I understand it current OpenGD77 firmware is using much of the > available space. > > > > I’m interested in many things, but in this case whether we can just > replace the codec. > > > > For the code inclined, the C code that uses two block of the original > radio firmware is here: > > > > > https://github.com/rogerclarkmelbourne/OpenGD77/tree/master/firmware/source/dmr_codec > > > > and the source to the tool that extracts the codec code from the original > firmware is here: > > > > > https://github.com/rogerclarkmelbourne/OpenGD77/tree/master/tools/codec_dat_files_creator > > > > I too would love an open radio from the ground up, but being able to drop > firmware into a $70 2m/70cm handheld is still pretty cool. > > > > Cheers, > > Eric > > > > *From:* David Rowe <[email protected]> > *Sent:* February 2, 2021 14:35 > *To:* [email protected] > *Subject:* Re: [Freetel-codec2] Codec2 and OpenGD77 > > > > Hi Danilo, > > I think Eric's proposal was just to swap out the codec, and perhaps using > the existing modem on the radio? > > The current FreeDV modes we have ported to the stm32 (1600 and 700D) are > aimed at HF channels, and the GD77 probably doesn't have the RF hardware to > support them (e.g. a SSB style radio deck). FreeDV includes the modem, > protocol, FEC, and Codec 2 - which may be overkill for this project. > > I can't recall the exact CPU/memory breakdown between Codec 2 and the > other parts of the FreeDV stack, but I imagine Codec 2 alone would require > substantially less resources. > > While a GD77 port would be cool, I lean towards full ground up open source > radio designs like M17 although I'd like to use better modems :-) At some > point I'm going to try my open vhf/uhf PI+RTLSDR based radio project with > voice - it's already running the FreeDV stack and has plenty of CPU. > > Cheers, > David > > On 3/2/21 4:37 am, Danilo Beuche wrote: > > Hi, > > I'd like to share my thoughts on this, as I also have some GD77 and love > the OpenGD77 FW (main reason for getting these). I have some experience > with porting FreeDV to the STM32 arm processor as I was one of the > developers who integrated Codec2 into the UHSDR Firmware a couple of years > ago. > > The hardware in the OpenGD77 GD77 is surely not powerful enough for 700D, > it may be possible to get it to work with 1600D. FreeDV also eats a big > slice of your RAM (~64k at least) of which the GD77's MK22FN512VLL12R has > only 128k. 120 Mhz is also less than the 168Mhz of the SM1000 or the MCHF > with an STM32F4xx processor. As both processor belong to the CORTEX-M4 > family, they should have similar performance per MHZ. > > In measurements for 1600D on the MCHF with the UHSDR software, this takes > roughly 70% load in the signal processing path from 48khz IQ to audio for > 1600D. Doing the math 168/120 * 70% load = 98% load. 2% cycles left. SSB > decoding takes about 10%, the remaining 60% went to FreeDV. Not a problem > in SM1600 as it does less signal processing and doesn't have to run a > graphical UI in addition (which the MCHF does). > > 700D runs ok on the STM32F7 processor with 216 Mhz and processor caches > (CORTEX-M7 design), speeding up code execution quite significantly. The > STM32H7 with 480 Mhz is not concerned about decoding 700D at all, there is > plenty of cpu power left. But those are unfortunately not in those > handhelds. > > But for a different FreeDV mode better suited for VHF/UHF usage or a > different signal processing chain it might be an entirely different story. > Thats is where I have to hand over to David and the other experts. > And just for the record: I would love to have a "completely" open source > GD77 with digital voice. > > Danilo > > > > Can't say anything about the DM1801 > > On 02/02/2021 18:21, Daniel Mundall wrote: > > Hi Eric, > > Funny that you mention OpenGD77 as last month I discovered these radios > (Baofeng DM-1801 in my case) and picked up two of them off of aliexpress > with codec2 being the primary reason for my purchase. > > There are 4 reasons why I think they would be great fit for codec2: > > - They're cheap ($65-75) & available which means you could get a > larger adoption. > - They run on an ARM platform either STM32 or similar processor. > - And there's already an open source firmware without inventing that. > - The audio encoding isn't a separate chip (at least on the DM1801) > it's software encoding. > > Interestingly enough original portion of the memory containing the > software audio codec is retained in OpenGD77 to avoid patent issues. > > > > Another cool possibility that I haven't felt out yet but in theory because > of the two slot TDMA setup I think either a repeater mode or full duplex > audio should be possible. > > > > Anyway, I just got the radios so soon as I have a chance I'm going to get > OpenGD77 loaded up and play around with it. > > > > One thing that David or the others might be better suited to answer is how > much hardware functions of the STM32 have been used in the codec2 port. > Because there could be hardware limitations with what is even available as > far a hardware functions on the MCU. > > > > Regards, > > > > Daniel Mundall VA7DRM > > > > > > On Tue, Feb 2, 2021 at 5:59 AM Eric Jacksch <[email protected]> wrote: > > I don't know enough about CODECS to know the right answer (thus must > post here), but right now the OpenGD77 source basically includes an > bit of assembly language to call some binary code lifted out of the > vendor's original firmware. My interest is to drop in a different > CODEC, but I don't know enough about them to understand exactly what > needs to be done. > > On Tue, 2 Feb 2021 at 02:48, Mooneer Salem <[email protected]> wrote: > > > > I'm thinking M17 (based on Codec2) might be better to incorporate since > it's already building in routing type features that DMR, D-STAR, etc. > already have. I'm not really familiar with OpenGD77 but it seems like a > neat project. Unfortunately I don't have a compatible HT (I use a MD-380 > for DMR) but perhaps it'll gain more support in the future. > > > > -Mooneer K6AQ > > > > On Mon, Feb 1, 2021 at 3:21 PM Eric Jacksch <[email protected]> wrote: > >> > >> Greetings, > >> > >> Has anyone looked at dropping Codec2 into OpenGD77? > >> > >> In case anyone is not aware, OpenGD77 is a (mostly) open source > >> firmware replacement for several low cost handheld two-way radios, > >> including the GD-77 (aka TYT MD-760). > >> > >> To work around intellectual property issues, the firmware currently > >> links in the DMR CODEC from the original vendor's binary. > >> > >> While it would break compatibility with other DMR radios, I'm > >> interested in seeing a fork of OpenGD77 that is fully open source and > >> Codec 2 seems like an obvious candidate. A truly open-source amateur > >> VHF/UHF digital mode. > >> > >> The IDE (MCUExpresso) and complete toolchain for OpenGD77 is free and > >> relatively straightforward on Windows, and the firmware is written in > >> C. What's needed is the Codec 2 expertise. > >> > >> Anyone interested? > >> > >> Cheers, > >> Eric > >> > >> > >> _______________________________________________ > >> Freetel-codec2 mailing list > >> [email protected] > >> https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > > > > _______________________________________________ > > Freetel-codec2 mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > > > > -- > Eric Jacksch, CPP, CISM, CISSP > [email protected] > Twitter: @EricJacksch > https://SecurityShelf.com > > > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > > > > > _______________________________________________ > > Freetel-codec2 mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > > > > > _______________________________________________ > > Freetel-codec2 mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 >
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