Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
Hi cutler22, On 6/7/2010 10:33 AM, a cutler22 wrote: It would be the ultimate in $$$ reduction - free! This would *not* happen in HTs, being they're hardware driven. However, for base stations and mobile/laptop setups, or even an HT/Smartphone combo it *would* be possible to drop cost to free. -73, KE7HQY Free?? TANSTAAFL or in this case installing a laptop in my car is not free. For me it needs to be a hardware implementation. I do not mind outboard modems or adapters hooked to the 9600 baud port on my mobile radios. 73, tom n4pzt
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
Hi Jonathan, On 6/8/2010 4:06 AM, Jonathan Naylor wrote: I would also like to see a move away from 4800 Bd GMSK and maybe go to 9600 Bd and using the G3RUH modem, most of our radios would be able to handle it, it'd be easy to distinguish on air, and there'd be extra bits available to add some FEC to the slow data. Would love to play with this as well. 73, tom n4zpt
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
At 01:02 AM 6/15/2010, you wrote: Free?? TANSTAAFL or in this case installing a laptop in my car is not free. For me it needs to be a hardware implementation. I do not mind outboard modems or adapters hooked to the 9600 baud port on my mobile radios. In my case, it depends. For some applications, PC based software is a good solution, as is a hardware modem attached to a radio. In other applications, there is no room for add on boxes of any kind, PC or node adapter. For example, when I take my IC-91AD out, I just want to carry the radio and no additional boxes to make it do D-STAR. For that scenario, an internal hardware implementation of the codec is the only answer. 73 de VK3JED / VK3IRL http://vkradio.com
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
Hi Jonathan, fortunately the AMBE chip is so efficient that we don't have to start running QPSK/OFDM and changing over to ultra linear PAs, like we have for Digital ATV. It seems churlish to suggest that everyone change their radios, repeaters and power amplifiers, just to cope with the deficiencies of open source codecs. The answer to why there's a push for 6.25 KHz, could best be answered during a chat with G4TSN, who will fill you in on how hard it is to get new kit on the air on VHF, especially near conurbations. This problem exists across much of Europe and the US, it's not a local issue. TDM would have the benefit of reusing the precious spectrum (see above) and the valuable hill top sites/equipment, that volunteers spend so much effort financing and maintaining. TDM is also something to experiment with. To say, Why do TDM?, could encourage others to say, Why do sound card based GMSK?. Both of the items above are valid for experimental purposes and self training. There are undoubtedly many amateurs that have not worked on TDM systems professionally and some might enjoy learning about TDM, just as some amateurs like to use a PC, soundcard software to do the job of a GMSK modem chip and a PIC. As it happens, there is already a well developed open source stack for GSM that could be adapted to our needs... but now we're heading rather OT. I agree that Codec2 is a neat project and one to be encouraged. Whether Codec2 has any place within D-Star or even if D-Star will still be the preferred DV mode when Codec2 matures, are entirely different questions altogether. 73 de Darren G7LWT On 11 June 2010 12:59, Jonathan Naylor naylo...@yahoo.com wrote: Getting 9600 Bd into 12.5 kHz isn't too difficult as long as you're willing to sacrifice weak signal performance, Shannons law tells us that. I would imagine OFDM or even m-ary PSK would be capable of providing the required throughput. The big advantage that GMSK has for manufacturers is that they can use the same class C output stages as they do for FM. PSK and particularly OFDM require extremely linear amplifiers. If we go over to TDM then we're in the land of GSM or NexEdge re-implementation and why should we do that? I think the development of codec2 should be encouraged as it represents something fun, rather than just plugging in black boxes which seems all too prevalent these days. BTW why is there a push to 6.25 kHz channel spacing, the 2m band is hardly that busy these days. A better argument for that could have been made in the early-80s when the channels were choc-a-bloc but not now. We almost went 12.5 kHz then (remember S20x?) but we didn't. Jonathan G4KLX
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
At 11:56 PM 6/11/2010, you wrote: The answer to why there's a push for 6.25 KHz, could best be answered during a chat with G4TSN, who will fill you in on how hard it is to get new kit on the air on VHF, especially near conurbations. This problem exists across much of Europe and the US, it's not a local issue. It is a problem across much of the world. Here, the situation is slightly different, but again one where narrow bandwidth helps. We're pretty much our of 2m repeater pairs here in Melbourne. However, despite there being a bit of spectrum for simplex, as while we have 4MHz on 2m, unlike the US, we don't have any repeaters below 146 MHz. This leaves quite a bit of simplex room from around 145.2 (top of the digital/packet sub band) to 145.8 (bottom of the satellite segment), minus a couple of special purpose frequencies (ARDF/foxhunting, Morse practice beacon, RTTY). However, this simplex room is quite full, with several IRLP/Echolink nodes, as well as various clubs and groups, who regular use simplex frequencies. In fact, the simplex part of the band is often busier than the repeaters down here. Even with D-STAR's (effective) 12.5 kHz bandwidth, we're able to slip D-STAR in between the 25 kHz spaced FM channels. 6.5 kHz bandwidth would make this even neater. TDM would have the benefit of reusing the precious spectrum (see above) and the valuable hill top sites/equipment, that volunteers spend so much effort financing and maintaining. TDM could be particularly valuable for repeaters, especially as sites become more limited in availability, so if one site can carry more than one stream of traffic, that would work to our advantage. TDM is also something to experiment with. To say, Why do TDM?, could encourage others to say, Why do sound card based GMSK?. Both of the items above are valid for experimental purposes and self training. There are undoubtedly many amateurs that have not worked on TDM systems professionally and some might enjoy learning about TDM, just as some amateurs li ke to use a PC, soundcard software to do the job of a GMSK modem chip and a PIC. That's a good enough reason for me to play. In this part of the world, we'd also be looking at playing with methods to increase the coverage area of TDM, such as optimising the duration of the time slices and pre-compensating for propagation delay. This was one of the well known limitations of GSM, the 30-35km cell radius limit (of the basic GSM system, without any cell extenders). Open terrain and low population densities meant this became a real issue in rural areas. As it happens, there is already a well developed open source stack for GSM that could be adapted to our needs... but now we're heading rather OT. That would be a good starting point. Hmm, maybe we need to move to another digital voice experimenters group. ;) I agree that Codec2 is a neat project and one to be encouraged. Whether Codec2 has any place within D-Star or even if D-Star will still be the preferred DV mode when Codec2 matures, are entirely different questions altogether. I agree. I can't see Codec2 and D-STAR having any significant roles together (because of the amount of D-STAR gear already out in the field), but I do see Codec2 as having a lot of potential for experimentation, particularly in new VHF/UHF modes, as well as HF DV, if the developers can get the bitrate into the 1000bps and below region (to make Shannon's Law work in our favour). Codec2 will allow the next generation of DV modes to be developed on a PC, which is a low cost way of getting a lot of people into the mode. Look at what PCs did for PSK-31 and SSTV years ago. 73 de VK3JED / VK3IRL http://vkradio.com
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
Of course we could come up with better network protocols (security, no #...@$# pre-registration of radios -- the callsign is the registration, strong authentication for network connected devices, better discovery and update, classes of traffic with full admin control by rule, ...) the air protocol is basically documented. On Jun 8, 2010, at 10:25 PM, kb9mwr wrote: If we want to drive down costs to help entice other potential manufactures lets start with open documentation of all the repeater network protocols. A few hams have reverse engineered these parts of the system. Yes I know those details aren't essential for a manufacture to build a radio, as the air protocol is well defined. But it would present a good image. --- In dstar_digital@yahoogroups.com, n9aa scott.man...@... wrote: Actually, my point was that the real way to drive down costs was for other manufacturers to jump into the ring. John D. Hays Amateur Radio Station K7VE PO Box 1223 Edmonds, WA 98020-1223 VOIP/SIP: j...@hays.org Phone: 206-801-0820 801-790-0950 Email: j...@hays.org
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
At 02:33 AM 6/10/2010, you wrote: Of course we could come up with better network protocols (security, no #...@$# pre-registration of radios -- the callsign is the registration, strong authentication for network connected devices, better discovery and update, classes of traffic with full admin control by rule, ...) the air protocol is basically documented. Agree totally. The network side of D-STAR could be overhauled, and we hams have the experience of running G1 and G2, as well as relevant experience from networks such as IRLP and Echolink (both of which kick D-STAR to death on the network security side of things). 73 de VK3JED / VK3IRL http://vkradio.com
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
At 06:06 PM 6/8/2010, you wrote: I would also like to see a move away from 4800 Bd GMSK and maybe go to 9600 Bd and using the G3RUH modem, most of our radios would be able to handle it, it'd be easy to distinguish on air, and there'd be extra bits available to add some FEC to the slow data. Now, this might be a way to bring codec2 into the fold, by having a new voice/data system, with no RF level compatibility with D-STAR, and learning from D-STAR's shortcomings. Gateways could be built to translate between the two systems, so the D-STAR network is tied to the new network. I know my hotspot radio could handle 9600, it was originally built to handle the G3RUH modem. What would I like to see? Variable voice/slow data bandwidth - bandwidth can be allocated to voice, slow data or a mix (i.e. similar to D-STAR) of the two. Obviously, the protocol will need to be able to signal dynamically whether a frame contains voice or data. being able to smoothly shift between high quality 9600 bps voice to 9600 bps of just data would be handy. 9600 bps is a more useful bandwidth, but I'd also like to see a narrowband version (4800 bps or slower), which could be used where channel bandwidth is limited. 73 de VK3JED / VK3IRL http://vkradio.com
RE: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
So my question is, how long has the G3RUH modem and other CODECs been around that could make a VHF/UHF communications system like D-STAR. From my knowledge, the solution has been available for probably 5+, if not 10+ years. But yet the glorious Amateur Radio Experimentation hasn't come up with a solution that used it. Only now, after Japan got way ahead of the rest of the world, has there even been a slight push in Amateur digital technologies. Sure, I would love for there to be a LOT MORE EXPERIMENTATION. But guys, don't try to just do the same thing as D-STAR, go beyond, well beyond what D-STAR can do. Put the JARL D-STAR specs to shame and let's show the world what's possible, not just another we can too solution. What we need is something like the ability to place hot spots all over the place and the hot spots interoperate and are connected to the Internet (as well as other possibilities) and are smart enough to handle handoffs from other hotspots as you move around. And then the radios are probably similar to today's D-STAR radios, but able to handle the handoffs and can provide 4.8, even 9.6 bps error protected data transfer. Forget about duplexers and use 440 in and 1.2GHz out. Doing D-STAR better than D-STAR, well, sounds more spiteful than innovative! Let's be innovative! Ed WA4YIH From: dstar_digital@yahoogroups.com [mailto:dstar_digi...@yahoogroups.com] On Behalf Of Jonathan Naylor Sent: Tuesday, June 08, 2010 4:06 AM To: dstar_digital@yahoogroups.com Subject: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder A lot of people in this thread are missing the point. This hobby is about experimentation and trying new things, maybe improving on existing commercial implementations, maybe going down dead ends, but so what? If Codec2 comes to fruition then I for one will probably support it in my D-Star repeater software, it'd be fun. Maybe no one will use it, but so what? It's a hobby. I would also like to see a move away from 4800 Bd GMSK and maybe go to 9600 Bd and using the G3RUH modem, most of our radios would be able to handle it, it'd be easy to distinguish on air, and there'd be extra bits available to add some FEC to the slow data. Jonathan G4KLX
RE: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
At 11:34 PM 6/8/2010, you wrote: So my question is, how long has the G3RUH modem and other CODECs been around that could make a VHF/UHF communications system like D-STAR. From my knowledge, the solution has been available for probably 5+, if not 10+ years. But yet the glorious Amateur Radio Experimentation hasn't come up with a solution that used it. I'd say 10+ years. The reason I say this is: 1. The G3RUH modem was around over 20 years ago, though it was harder getting one on the air than it is now (more radios with suitable interfaces brought out to a connector nowadays). 2. Speak Freely (which IRLP is heavily based on, and Echolink is a more distant cousin of) has had open source implementations of LPC, LPC-10 and CELP (4800 bps), all of which could easily be carried over 9600bps. I was running Speak Freely in 1995 over 14.4k dialup. What we need is something like the ability to place hot spots all over the place and the hot spots interoperate and are connected to the Internet (as well as other possibilities) and are smart enough to handle handoffs from other hotspots as you move around. And then the radios are probably similar to today's D-STAR radios, but able to handle the handoffs and can provide 4.8, even 9.6 bps error protected data transfer. Hmm, a low speed voice data network, meshed by a mixture of Internet based and RF based high speed backhaul links? That could be interesting. Forget about duplexers and use 440 in and 1.2GHz out. That would simplify the engineering considerably! All we need is cost effective 1.2 GHz radio hardware (440 will be a piece of cake). 10m/6m 4800bps nodes would be interesting to play with as well. 73 de VK3JED / VK3IRL http://vkradio.com
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
On Jun 8, 2010, at 1:31 AM, Tony Langdon wrote: Obviously, the protocol will need to be able to signal dynamically whether a frame contains voice or data. It already does. The only difference in the D-STAR wrapper between encapsulated Digital Voice and encapsulated Ethernet Frames is one bit in the header. (There is some additional info in the payload, but that's it for the header.) John D. Hays Amateur Radio Station K7VE PO Box 1223 Edmonds, WA 98020-1223 VOIP/SIP: j...@hays.org Phone: 206-801-0820 801-790-0950 Email: j...@hays.org
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
Reduce the $$$ barrier? The D-Star chip costs about $25. No one is going to be able to manufacture an open source vocoder chip for less than that. It would be the ultimate in $$$ reduction - free! This would *not* happen in HTs, being they're hardware driven. However, for base stations and mobile/laptop setups, or even an HT/Smartphone combo it *would* be possible to drop cost to free. -73, KE7HQY
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
Not to mention, any manufacturer who wanted to implement Codec2 *wouldn't need* a pre-manufactured vocoder chip. They'd implement the vocoder algorithm into their existing firmware on the onboard processor -73 de Anthony, KE7HQY From: a cutler22 acutle...@yahoo.com To: dstar_digital@yahoogroups.com Sent: Mon, June 7, 2010 7:33:42 AM Subject: Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder Reduce the $$$ barrier? The D-Star chip costs about $25. No one is going to be able to manufacture an open source vocoder chip for less than that. It would be the ultimate in $$$ reduction - free! This would *not* happen in HTs, being they're hardware driven. However, for base stations and mobile/laptop setups, or even an HT/Smartphone combo it *would* be possible to drop cost to free. -73, KE7HQY
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
Hi Anthony, *HQY They'd implement the vocoder algorithm into their existing firmware on the onboard processor* That sounds like another 30 MIPS or so, of soft DSP budget. The CPUs in D-Star HTs eat the batteries quickly enough already; does free Codec2 come with free batteries too? 73 de Darren G7LWT On 7 June 2010 15:40, a cutler22 acutle...@yahoo.com wrote: Not to mention, any manufacturer who wanted to implement Codec2 **wouldn't need** a pre-manufactured vocoder chip. They'd implement the vocoder algorithm into their existing firmware on the onboard processor -73 de Anthony, KE7HQY -- *From:* a cutler22 acutle...@yahoo.com *To:* dstar_digital@yahoogroups.com *Sent:* Mon, June 7, 2010 7:33:42 AM *Subject:* Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder Reduce the $$$ barrier? The D-Star chip costs about $25. No one is going to be able to manufacture an open source vocoder chip for less than that. It would be the ultimate in $$$ reduction - free! This would *not* happen in HTs, being they're hardware driven. However, for base stations and mobile/laptop setups, or even an HT/Smartphone combo it *would* be possible to drop cost to free. -73, KE7HQY
RE: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
Anthony, You totally miss the point, most manufacturers WANT a PRE-MANUFACTURED VOCODER chip. Adding the AMBE chip to a radio is relatively cheap and easy. It would be a lot cheaper if Icom started placing it on the main board instead of a daughter board. This is the same history as PL encoders/decoders. Initially they were $100-$150 add-ons (1970 dollars), now they are on the main board. Oh, and something as simple to program as a PL decoder, AFAIK, they are still implemented in hardware, it’s too cheap, too easy, and MUCH more reliable than just about any other solution. And like Darren mentioned, radios just don’t have CPUs capable of CODECs, they tend to run more at key press speeds. Ed WA4YIH From: dstar_digital@yahoogroups.com [mailto:dstar_digi...@yahoogroups.com] On Behalf Of a cutler22 Sent: Monday, June 07, 2010 10:40 AM To: dstar_digital@yahoogroups.com Subject: Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder Not to mention, any manufacturer who wanted to implement Codec2 *wouldn't need* a pre-manufactured vocoder chip. They'd implement the vocoder algorithm into their existing firmware on the onboard processor -73 de Anthony, KE7HQY From: a cutler22 acutle...@yahoo.com To: dstar_digital@yahoogroups.com Sent: Mon, June 7, 2010 7:33:42 AM Subject: Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder Reduce the $$$ barrier? The D-Star chip costs about $25. No one is going to be able to manufacture an open source vocoder chip for less than that. It would be the ultimate in $$$ reduction - free! This would *not* happen in HTs, being they're hardware driven. However, for base stations and mobile/laptop setups, or even an HT/Smartphone combo it *would* be possible to drop cost to free. -73, KE7HQY
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
Anthony, that would be well and fine in a totally perfect world. BUT we do not have that place and we are not sure what dream world you are living in but it is not this real one.. Time to wake up and head down to the greasy spoon on the corner where you can tell the waitress that you need a whole pot of black coffee. N6UYB Jack E. Foster - Original Message - From: a cutler22 To: dstar_digital@yahoogroups.com Sent: Monday, June 07, 2010 10:40 AM Subject: Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder Not to mention, any manufacturer who wanted to implement Codec2 *wouldn't need* a pre-manufactured vocoder chip. They'd implement the vocoder algorithm into their existing firmware on the onboard processor -73 de Anthony, KE7HQY -- From: a cutler22 acutle...@yahoo.com To: dstar_digital@yahoogroups.com Sent: Mon, June 7, 2010 7:33:42 AM Subject: Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder Reduce the $$$ barrier? The D-Star chip costs about $25. No one is going to be able to manufacture an open source vocoder chip for less than that. It would be the ultimate in $$$ reduction - free! This would *not* happen in HTs, being they're hardware driven. However, for base stations and mobile/laptop setups, or even an HT/Smartphone combo it *would* be possible to drop cost to free. -73, KE7HQY
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
And zeal drives my point over the cliff - You're quite correct - a dedicated DSP chip is much more battery-friendly. So in terms of manufacturing costs, it would be similar to AMBE's usage of TI chips, and DVSI's market share gives it a bulk-cost advantage today... Hobbiest wise it would be free, because the imperviousness of extraordinarily powerful consumer CPUs in Smartphones, Netbooks etc. etc. In 5 years we'll have Dick Tracey watches that sync bluetooth to HTs... -73, KE7HQY From: Storer, Darren darren.sto...@gmail.com To: dstar_digital@yahoogroups.com Sent: Mon, June 7, 2010 8:28:14 AM Subject: Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder Hi Anthony, HQY They'd implement the vocoder algorithm into their existing firmware on the onboard processor... . That sounds like another 30 MIPS or so, of soft DSP budget. The CPUs in D-Star HTs eat the batteries quickly enough already; does free Codec2 come with free batteries too? 73 de Darren G7LWT On 7 June 2010 15:40, a cutler22 acutle...@yahoo. com wrote: Not to mention, any manufacturer who wanted to implement Codec2 *wouldn't need* a pre-manufactured vocoder chip. They'd implement the vocoder algorithm into their existing firmware on the onboard processor... . -73 de Anthony, KE7HQY From: a cutler22 acutle...@yahoo. com To: dstar_digital@ yahoogroups. com Sent: Mon, June 7, 2010 7:33:42 AM Subject: Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder Reduce the $$$ barrier? The D-Star chip costs about $25. No one is going to be able to manufacture an open source vocoder chip for less than that. It would be the ultimate in $$$ reduction - free! This would *not* happen in HTs, being they're hardware driven. However, for base stations and mobile/laptop setups, or even an HT/Smartphone combo it *would* be possible to drop cost to free. -73, KE7HQY
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
I'm just finishing my second cup-o-joe and brewing a whole new pot to wake up HIHI -KE7HQY From: Jack jack.mrfixit...@gmail.com To: dstar_digital@yahoogroups.com Sent: Mon, June 7, 2010 8:38:36 AM Subject: Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder Anthony, that would be well and fine in a totally perfect world. BUT we do not have that place and we are not sure what dream world you are living in but it is not this real one.. Time to wake up and head down to the greasy spoon on the corner where you can tell the waitress that you need a whole pot of black coffee. N6UYB Jack E. Foster - Original Message - From: a cutler22 To: dstar_digital@ yahoogroups. com Sent: Monday, June 07, 2010 10:40 AM Subject: Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder Not to mention, any manufacturer who wanted to implement Codec2 *wouldn't need* a pre-manufactured vocoder chip. They'd implement the vocoder algorithm into their existing firmware on the onboard processor... . -73 de Anthony, KE7HQY From: a cutler22 acutle...@yahoo. com To: dstar_digital@ yahoogroups. com Sent: Mon, June 7, 2010 7:33:42 AM Subject: Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder Reduce the $$$ barrier? The D-Star chip costs about $25. No one is going to be able to manufacture an open source vocoder chip for less than that. It would be the ultimate in $$$ reduction - free! This would *not* happen in HTs, being they're hardware driven. However, for base stations and mobile/laptop setups, or even an HT/Smartphone combo it *would* be possible to drop cost to free. -73, KE7HQY
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
From: Joel Koltner zapwire-gro...@yahoo.com OK, but there's nothing wrong with extending the current protocol and calling it D*Star+ or just D*Star Compatible or whatever. It's looking more like it would be a competitor to AMBE in a seperate market, vs overrunning it on the same radio (I.E. reprogramming IC-92ADs, etc.) (I think he's intending for CODEC2 to be implemented in whatever processor you already have around in your PC or radio anyway, though, so the cost is effectively free. The AMBE chip is just a pre-programmed TI DSP, after all, and pretty much any contemporary PC has plenty of CPU cycles around to implement the algorithm; it's in the form of a chip so that it isn't just pirated rampantly.) Unless Alinco, Kenwood or another major radio manufacturer hopped on board, it'd *have* to start as a soundcard mode. The to-market cost of soundcards is nil, compared to DSP chip burning and implementation, as in the case with AMBE... Heck, there are already some freely available CODECs out there anyway that seem to perform pretty well (although weren't specifically designed for wireless usage): Speex and the Skype-CODEC come to mind. (I'm not up on the specific licenses, however -- they're free as in beer at least, though.) David Rowe, VK5DGR was one of Speex's initial developers, so he's got a *lot* of prior experience in the way of vocoder programming. However, Speex doesn't like lossy mediums like radio. It does wonderfully over TCP/IP, but that's because it's a LOSSLESS format. Bruce Perens, K6BP notes on his site (www.codec2.org): existing Open Source codecs, like Speex, are designed for VoIP rather than an imperfect radio link, and are not generally able to cope with single-bit errors. Thus, they don't match the performance of AMBE over the air. One thing to keep in mind is that, since most hams operate D*Star through repeaters anyway, one approach here would be to have the *repeater* have both AMBE and CODEC2 (or whatever) capabilities, and just translate between them on-the-fly. (This approach is used with public service radio systems, since there lots of different companies decided to build their own proprietary protocols and used different CODECs as well.) I would wager that repeater usage probably accounts for more than 90% of D*Star voice traffic, and getting repeater builders to incorporate a backwards compatible radio into their system (that has the same interface as the current Icom boxes) is nowhere near as daunting as getting everyone with an HT or mobile D*Star rig to buy something new. Now THAT is a brilliant idea!! Of course, CODEC2 to AMBE simplex would be nil. However you are quite correct - dual-codex repeaters would make the issue null! Plus, it would translate to and from AMBE over the gateway - I LOVE this idea! ---Joel KE7CDV -73, KE7HQY
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
At 12:40 AM 6/8/2010, you wrote: Not to mention, any manufacturer who wanted to implement Codec2 *wouldn't need* a pre-manufactured vocoder chip. They'd implement the vocoder algorithm into their existing firmware on the onboard processor I doubt the onboard processor would be up to the job. The codec would most likely be implemented in a DSP chip (much like AMBE is). The only onboard processors that might be up to the job would be those in the latest smartphones. Radios tend to use less powerful processors (they don't have the need for the grunt). 73 de VK3JED / VK3IRL http://vkradio.com
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
At 01:43 AM 6/8/2010, you wrote: OK, but there's nothing wrong with extending the current protocol and calling it D*Star+ or just D*Star Compatible or whatever. 2 words: backwards compatibility. There would have to be a LOT of money spent to make this work. Heck, there are already some freely available CODECs out there anyway that seem to perform pretty well (although weren't specifically designed for wireless usage): Speex and the Skype-CODEC come to mind. (I'm not up on the specific licenses, however -- they're free as in beer at least, though.) Speex is free (as in freedom), same as codec2. However, it operates at a higher bit rate, which was one reason codec2 was developed. Skype is only free as in beer, and I'm not sure what codec(s) they actually use. One thing to keep in mind is that, since most hams operate D*Star through repeaters anyway, one approach here would be to have the *repeater* have both AMBE and CODEC2 (or whatever) capabilities, and just translate between them on-the-fly. (This approach is used with public 2 problems: 1. The repeaters currently have no audio hardware on board. They are simple bit regenerators, so we're talking about adding up to at least 3 voice transcoding modules (one for each band) per stack, to make this possible. 2. What about the case where radios on air are running incompatible codecs. Current Icom (AMBE only) and home brew PC based SDR (Codec2 only). I see a lot of potential for this sort of breakage. The only way around this would be to enforce AMBE in any situation where older radios could intercept the signal. This means adding codec2 would be totally pointless, since AMBE would still be required anyway. service radio systems, since there lots of different companies decided to build their own proprietary protocols and used different CODECs as well.) I would wager that repeater usage probably accounts for more than 90% of D*Star voice traffic, and getting repeater builders to incorporate a backwards compatible radio into their system (that has the same interface as the current Icom boxes) is nowhere near as daunting as getting everyone with an HT or mobile D*Star rig to buy something new. I can think of a lot of corner cases that wouldn't work, unless you mandate the repeater transmits in AMBE (which renders Codec2 pointless in D-STAR). :) 73 de VK3JED / VK3IRL http://vkradio.com
Re: [DSTAR_DIGITAL] Re: Codec2 development - open source vocoder
On Jun 7, 2010, at 2:02 PM, e_l_green wrote: If ICOM had chosen something other than AMBEC, none of this would be a problem... but apparently they felt taking a short cut and gluing an extra chip into their designs was worth more to them in terms of quicker design turnaround than the alternative of finding a provider who was willing to license an algorithm for a reasonable cost that could be integrated into the main CPU of the radio. JARL chose AMBE as part of the D-STAR protocol definition. If Icom, or any other manufacturer wanted to meet the specification (which is required for DV on Amateur Radio in Japan, and that is why Kenwood sells rebadged Icom radios in Japan) they had to use AMBE. AMBE is the best, cost effective, publicly available vocoder on the market and probably the best choice for now. John D. Hays Amateur Radio Station K7VE PO Box 1223 Edmonds, WA 98020-1223 VOIP/SIP: j...@hays.org Phone: 206-801-0820 801-790-0950 Email: j...@hays.org
