Re: [Repeater-Builder] Re: Repeating D-Star
I was hoping that AOR would introduce an outboard modem that would plug into any 9600-capable rig, Micor/Mitrek and enable D-Star (and P25, for that matter...) that way. I tried to e-mail them at the support address on their website, and it bounced. There's no reason why such an approach shouldn't work. George, KA3HSW / WQGJ413 - Original Message - From: hwingate [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Thursday, April 26, 2007 7:47 AM Subject: [Repeater-Builder] Re: Repeating D-Star I have often wondered just how diffucult it would to be to build a D-Star system around a Micor or M2. D-Star is mostly open protocol (except for the software which is propriatry to Icom), the AMBE vocoder chips are available from the manufacturer, and GMSK modem chips are also available. Seems like some smart experimenter (much smarter than me anyway),could build such a system and we would not be stuck with one vendor for D-Star systems. It would also have the bulletproof RF performance of the Micor or M2 radios.
Re: [Repeater-Builder] Re: Repeating D-Star
You'd absolutely, ABSOLUTELY limit the energy you emit (the frequency converted input signal) to fit within the allowable channel you're repeater/transponder is coordinated. That's no different with the FM brand of repeater. You're responsible for your output. The IF is where you'd probably want to limit the frequency excursions of the input signal. We do that now. If the user's off frequency, part of their energy is clipped off by the filtering of the IF bandpass. As to the ID, MCW should suffice. I don't see any requirement that you must ID in the mode your delivering. Otherwise you'd be required to have a voice ID for a FM voice repeater and not CW. I hope no one minds this thread. I'm finding it fun and a good discussion of the merits/problems with doing something a little different. 73 Rod Nate Duehr [EMAIL PROTECTED] wrote: On 4/26/07, Rod Lane [EMAIL PROTECTED] wrote: go through unimpeded ( and undistorted.) One possible minor down side is that the user's radio needs to be somewhat on-frequency. If they come in 1 KHz low, they go out 1 KHz low. In theory, it's not the repeater owner's problem, but can be noticed on the output. Numerous issues there... If they're off-frequency, so is your repeater... and your repeater is only coordinated ON-frequency. This would be a bigger deal in areas (like mine) if you were on VHF with 15 KHz channel-spacing, for example... letting your linear transponder repeater doing digital traffic splatter all over your neighbor's analog output isn't going to win many friends. If they're over-deviating... same thing... unless you brick-wall limit them and cause the waveform to clip, making it useless... but at least they'd know their radio was Foo-BAR'ed up... Etc. Etc. Etc. There be dragons here. I don't think it's good engineering practice to put the end-users that much in charge of the signal you're putting out with your callsign on it. That would be another interesting thing... how to ID it properly... digital? CW? That one's easier than the others... but still a headache. (Come to think of it, now I want to go read the regs on satellite ID's... heh... hmmm... How does that work? The beacon? What if it's off, but the transponder's still on? Interesting campfire question for AMSAT friends... please answer off-list if you're tempted... ha... not here, unless we're going to start discussing linear ORBITING transponders as a form of repeater... GRIN...) Nate WY0X p.s. Want to drive people crazy? Hack up the code in your digital radio to understand received traffic that's been INVERTED by an inverting linear transponder... LOL... no encryption, just mega-geekiness...
Re: [Repeater-Builder] Re: Repeating D-Star
There's one reason- they would have to purchase rights to the voice decoder designs from DVSI. D-Star is still young so other manufacturers may eventually jump on board once they convince themselves that the upfront engineering and intellectual costs will be worthwhile. By the way, as if there were not already enough digital voice protocols on the market Icom and Kenwood have teamed up and produced another protocol that they are offering through their respective land/mobile lines. This new unnamed digital voice protocol is said to meet the FCC's 6.25Khz emission mask requirements for narrowband ops. We'll see what happens. Gary George Henry [EMAIL PROTECTED] wrote: I was hoping that AOR would introduce an outboard modem that would plug into any 9600-capable rig, Micor/Mitrek and enable D-Star (and P25, for that matter...) that way. I tried to e-mail them at the support address on their website, and it bounced. There's no reason why such an approach shouldn't work. George, KA3HSW / WQGJ413
Re: [Repeater-Builder] Re: Repeating D-Star
They're already using a DVSI AMBE vocoder in their HF digital voice modems. it's certainly not a large leap from there to D-Star. SOMEONE will do it soon enough... I just figured AOR might be the first, since they already have at least part of a foot in the door. George, KA3HSW / WQGJ413 -Original Message- From: [EMAIL PROTECTED] Sent: Apr 27, 2007 10:35 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Repeating D-Star There's one reason- they would have to purchase rights to the voice decoder designs from DVSI. D-Star is still young so other manufacturers may eventually jump on board once they convince themselves that the upfront engineering and intellectual costs will be worthwhile. By the way, as if there were not already enough digital voice protocols on the market Icom and Kenwood have teamed up and produced another protocol that they are offering through their respective land/mobile lines. This new unnamed digital voice protocol is said to meet the FCC's 6.25Khz emission mask requirements for narrowband ops. We'll see what happens. Gary George Henry [EMAIL PROTECTED] wrote: I was hoping that AOR would introduce an outboard modem that would plug into any 9600-capable rig, Micor/Mitrek and enable D-Star (and P25, for that matter...) that way. I tried to e-mail them at the support address on their website, and it bounced. There's no reason why such an approach shouldn't work. George, KA3HSW / WQGJ413
Re: [Repeater-Builder] Re: Repeating D-Star
You'll have to check with AOR on that one. For all we know whatever contract they may have with DVSI may be specific to the modem. I figured two years ago when they introduced the AR-ONE that they would include some decoders, or an expansion port for an option card, or maybe even trunking but no joy. It seems almost no communications receiver manufacturer wants to make the leap and start offering scanner features in their comm receivers. I know, the Wulfbergs do but even I won't spend that much at this time. If I see Taka (from AOR-USA) at Dayton I try to speak with him about this issue. Gary George Henry wrote: They're already using a DVSI AMBE vocoder in their HF digital voice modems. it's certainly not a large leap from there to D-Star. SOMEONE will do it soon enough... I just figured AOR might be the first, since they already have at least part of a foot in the door. George, KA3HSW / WQGJ413
Re: [Repeater-Builder] Re: Repeating D-Star
I don't think you will be able to just plug binary data into a radio transmitter unless there is a made for the purpose FSK input for binary data that would support the DSTAR data rate. Steve On 4/27/07, Gary [EMAIL PROTECTED] wrote: You'll have to check with AOR on that one. For all we know whatever contract they may have with DVSI may be specific to the modem. I figured two years ago when they introduced the AR-ONE that they would include some decoders, or an expansion port for an option card, or maybe even trunking but no joy. It seems almost no communications receiver manufacturer wants to make the leap and start offering scanner features in their comm receivers. I know, the Wulfbergs do but even I won't spend that much at this time. If I see Taka (from AOR-USA) at Dayton I try to speak with him about this issue. Gary George Henry wrote: They're already using a DVSI AMBE vocoder in their HF digital voice modems. it's certainly not a large leap from there to D-Star. SOMEONE will do it soon enough... I just figured AOR might be the first, since they already have at least part of a foot in the door. George, KA3HSW / WQGJ413 Yahoo! Groups Links -- Ham Radio Spoken Here.NU5D Nickel Under Five Dollars
Re: [Repeater-Builder] Re: Repeating D-Star
What do you guys know about the AOR digital modems? I understand that is an open protocol. Seems a little expensive, but if it sounds good maybe we can build some kind of cheap encoder/decoder? On 4/25/07, Bob Witte K0NR [EMAIL PROTECTED] wrote: --- In Repeater-Builder@yahoogroups.com, Bob Dengler [EMAIL PROTECTED] wrote: What would be far more interesting to me would be for one of the ham manufacturers to offer a P25 user radio. How much would adding the vocoder add to the cost of a current analog FM model? If it's comparable in price to Icom's DStar radios (which are substantially more than their analog counterparts - roughly double the cost), it just might be worth it. Something to add to my wish list of radio features to deliver to the reps. at Dayton, along with better IMD performance split CTCSS tone. Bob NO6B I tend to agree...how about a Kenwood or Yaesu ham rig that runs analog and P25? Although used commercial gear is a great option to have, the feature set is, well, commercial. Easy front panel programming on the fly, VFO modes, etc. are usually left out or compromised. Bob K0NR Yahoo! Groups Links
[Repeater-Builder] Re: Repeating D-Star
I have often wondered just how diffucult it would to be to build a D-Star system around a Micor or M2. D-Star is mostly open protocol (except for the software which is propriatry to Icom), the AMBE vocoder chips are available from the manufacturer, and GMSK modem chips are also available. Seems like some smart experimenter (much smarter than me anyway),could build such a system and we would not be stuck with one vendor for D-Star systems. It would also have the bulletproof RF performance of the Micor or M2 radios. --- In Repeater-Builder@yahoogroups.com, DCFluX [EMAIL PROTECTED] wrote: What do you guys know about the AOR digital modems? I understand that is an open protocol. Seems a little expensive, but if it sounds good maybe we can build some kind of cheap encoder/decoder?
Re: [Repeater-Builder] Re: Repeating D-Star
I have often wondered just how diffucult it would to be to build a D-Star system around a Micor or M2. D-Star is mostly open I have given thought to buying the controller or at least getting a manual to see if I could use Icom logic with brand X radio. There does not seem to be much info that I can sink my teeth into, though. Anyone have a DSTAR repeater controller manual, drawing, and layout in pdf form that they could share? Steve
[Repeater-Builder] Re: Repeating D-Star
I would hate to see your insightful comment missed. I haven't seen anyone else pick up on the part of your message about the linear transponder. If someone wants to pass many different modes through a repeater, you can't do better than a transponder. I've been on the transmitting and receiving end of them for years with the satellite world, and we haven't had to wholesale change out them with the change from FM video to digital modes. They just work. Not being an expert on designing them, my understanding of the process is as follows. On a block level, they're much simpler than they seem. Take a tightly bandpass filtered IF from just about any quality radio, AGC it really well, frequency convert it to the desired output frequency, run it through a LINEAR power chain, and you now have the transponder. A simple RF envelope detector can act as the squelch so that the output power chain isn't constantly running to amplify ambient noise that wanders into the system's input bandpass. The only other challenge is to be able to ID the repeater. A simple MCW oscillator somewhere in the chain, either at the IF frequency or output fundamental, and you're legal. FM, D-Star, P25, AM, CW, SSB and virtually any mode that'll stay within the bandpass of the IF will go through unimpeded ( and undistorted.) One possible minor down side is that the user's radio needs to be somewhat on-frequency. If they come in 1 KHz low, they go out 1 KHz low. In theory, it's not the repeater owner's problem, but can be noticed on the output. I remember someone a few years back doing mods on a standard repeater amplifier to linearlize it for ATV and SSB with some bias network additions. As long as the PA is reasonably linear, slight distortions in the linearity curve shouldn't create huge issues except with modes like QAM or other modes with serious amplitude-dependent requirements. I wish I had the time. Being an RF guy, not a software type, it sounds like a great project. 73 de N1FNE --- In Repeater-Builder@yahoogroups.com, Kris Kirby [EMAIL PROTECTED] wrote: On Tue, 24 Apr 2007, Steve Bosshard (NU5D) wrote: Took a couple of antique GE Phoenix SX mobile radios. Programmed for 442.0/ 447.0. With TOT. Carrier Squelch - Took Receiver Un Squelched lead to PTT thru a one transistor keying transistor. Took VOL / SQ Hi and ran it thru a single common emitter stage - bipolar amp and applied the collector output to the high side of the TX deviation control and set for +/- 1 Khz TXD. Did have to bypass the emitter leg of the single stage amp and wallah - DSTAR Repeater - sort of. Maybe P25 repeater too? Simple - really do need to regenerate the data signal and key on detected data with a CCD chip to give the preamble tone time to get thru. Excellent work Mr. Bosshard. This is one of the things that I've wanted to explore with D-Star but haven't had the time. This approach also works for most other modes based on FM (9600 BPS packet, Motorola DES, etc.). Truly, to support multiple modes or technologies, we need only look at the world of linear transponders for a clue -- there's really not much of a point in having too much of a radio there when you're just repeating in the input RF. -- Kris Kirby [EMAIL PROTECTED] The illegal we do immediately. The unconstitutional takes a bit longer. -- Henry Kissinger
Re: [Repeater-Builder] Re: Repeating D-Star
There used to be Linear Translators that were land based. There was one around the Pittsburgh area. I'm sure somewhere there are a few left, but they are few and far between. Joe M. Rod Lane wrote: I would hate to see your insightful comment missed. I haven't seen anyone else pick up on the part of your message about the linear transponder. If someone wants to pass many different modes through a repeater, you can't do better than a transponder. I've been on the transmitting and receiving end of them for years with the satellite world, and we haven't had to wholesale change out them with the change from FM video to digital modes. They just work. Not being an expert on designing them, my understanding of the process is as follows. On a block level, they're much simpler than they seem. Take a tightly bandpass filtered IF from just about any quality radio, AGC it really well, frequency convert it to the desired output frequency, run it through a LINEAR power chain, and you now have the transponder. A simple RF envelope detector can act as the squelch so that the output power chain isn't constantly running to amplify ambient noise that wanders into the system's input bandpass. The only other challenge is to be able to ID the repeater. A simple MCW oscillator somewhere in the chain, either at the IF frequency or output fundamental, and you're legal. FM, D-Star, P25, AM, CW, SSB and virtually any mode that'll stay within the bandpass of the IF will go through unimpeded ( and undistorted.) One possible minor down side is that the user's radio needs to be somewhat on-frequency. If they come in 1 KHz low, they go out 1 KHz low. In theory, it's not the repeater owner's problem, but can be noticed on the output. I remember someone a few years back doing mods on a standard repeater amplifier to linearlize it for ATV and SSB with some bias network additions. As long as the PA is reasonably linear, slight distortions in the linearity curve shouldn't create huge issues except with modes like QAM or other modes with serious amplitude-dependent requirements. I wish I had the time. Being an RF guy, not a software type, it sounds like a great project. 73 de N1FNE --- In Repeater-Builder@yahoogroups.com, Kris Kirby [EMAIL PROTECTED] wrote: On Tue, 24 Apr 2007, Steve Bosshard (NU5D) wrote: Took a couple of antique GE Phoenix SX mobile radios. Programmed for 442.0/ 447.0. With TOT. Carrier Squelch - Took Receiver Un Squelched lead to PTT thru a one transistor keying transistor. Took VOL / SQ Hi and ran it thru a single common emitter stage - bipolar amp and applied the collector output to the high side of the TX deviation control and set for +/- 1 Khz TXD. Did have to bypass the emitter leg of the single stage amp and wallah - DSTAR Repeater - sort of. Maybe P25 repeater too? Simple - really do need to regenerate the data signal and key on detected data with a CCD chip to give the preamble tone time to get thru. Excellent work Mr. Bosshard. This is one of the things that I've wanted to explore with D-Star but haven't had the time. This approach also works for most other modes based on FM (9600 BPS packet, Motorola DES, etc.). Truly, to support multiple modes or technologies, we need only look at the world of linear transponders for a clue -- there's really not much of a point in having too much of a radio there when you're just repeating in the input RF. -- Kris Kirby [EMAIL PROTECTED] The illegal we do immediately. The unconstitutional takes a bit longer. -- Henry Kissinger Yahoo! Groups Links
RE: [Repeater-Builder] Re: Repeating D-Star
A linear translator for something like D-Star wouldn't work out real well since you are dealing with mobile users. The first issue to overcome is the constantly-varying amplitude of the incoming signal - on the order of tens of dB's in level change doezens of times per second at highway speeds (60 MPH @ 2m = around 15 wavelengths per second). The second is that there is no opportunity to error-correct at the repeater before retransmission, unlike a real (digital) repeater. So, in a mobile environment, the bit error rate at the receiving station is always going to be higher than it was at the repeater site. If all of the users were at fixed locations where the AGC issue wasn't a big deal, and likewise, if they were all solid into the receiver such that the BER was low enough, then a translator might work. But for mobile-to-mobile use, probably not the way to go... --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Rod Lane Sent: Thursday, April 26, 2007 11:02 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Repeating D-Star I would hate to see your insightful comment missed. I haven't seen anyone else pick up on the part of your message about the linear transponder. If someone wants to pass many different modes through a repeater, you can't do better than a transponder. I've been on the transmitting and receiving end of them for years with the satellite world, and we haven't had to wholesale change out them with the change from FM video to digital modes. They just work. Not being an expert on designing them, my understanding of the process is as follows. On a block level, they're much simpler than they seem. Take a tightly bandpass filtered IF from just about any quality radio, AGC it really well, frequency convert it to the desired output frequency, run it through a LINEAR power chain, and you now have the transponder. A simple RF envelope detector can act as the squelch so that the output power chain isn't constantly running to amplify ambient noise that wanders into the system's input bandpass. The only other challenge is to be able to ID the repeater. A simple MCW oscillator somewhere in the chain, either at the IF frequency or output fundamental, and you're legal. FM, D-Star, P25, AM, CW, SSB and virtually any mode that'll stay within the bandpass of the IF will go through unimpeded ( and undistorted.) One possible minor down side is that the user's radio needs to be somewhat on-frequency. If they come in 1 KHz low, they go out 1 KHz low. In theory, it's not the repeater owner's problem, but can be noticed on the output. I remember someone a few years back doing mods on a standard repeater amplifier to linearlize it for ATV and SSB with some bias network additions. As long as the PA is reasonably linear, slight distortions in the linearity curve shouldn't create huge issues except with modes like QAM or other modes with serious amplitude-dependent requirements. I wish I had the time. Being an RF guy, not a software type, it sounds like a great project. 73 de N1FNE --- In Repeater-Builder@yahoogroups.com, Kris Kirby [EMAIL PROTECTED] wrote: On Tue, 24 Apr 2007, Steve Bosshard (NU5D) wrote: Took a couple of antique GE Phoenix SX mobile radios. Programmed for 442.0/ 447.0. With TOT. Carrier Squelch - Took Receiver Un Squelched lead to PTT thru a one transistor keying transistor. Took VOL / SQ Hi and ran it thru a single common emitter stage - bipolar amp and applied the collector output to the high side of the TX deviation control and set for +/- 1 Khz TXD. Did have to bypass the emitter leg of the single stage amp and wallah - DSTAR Repeater - sort of. Maybe P25 repeater too? Simple - really do need to regenerate the data signal and key on detected data with a CCD chip to give the preamble tone time to get thru. Excellent work Mr. Bosshard. This is one of the things that I've wanted to explore with D-Star but haven't had the time. This approach also works for most other modes based on FM (9600 BPS packet, Motorola DES, etc.). Truly, to support multiple modes or technologies, we need only look at the world of linear transponders for a clue -- there's really not much of a point in having too much of a radio there when you're just repeating in the input RF. -- Kris Kirby [EMAIL PROTECTED] The illegal we do immediately. The unconstitutional takes a bit longer. -- Henry Kissinger Yahoo! Groups Links -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.446 / Virus Database: 269.5.7/771 - Release Date: 4/21/2007 11:56 AM
[Repeater-Builder] Re: Repeating D-Star
Do you know what gear they were using? I think I do remember using one near Indio, CA years ago, and it sounded great. Just like simplex (which it should.) 73 de N1FNE --- In Repeater-Builder@yahoogroups.com, mch [EMAIL PROTECTED] wrote: There used to be Linear Translators that were land based. There was one around the Pittsburgh area. I'm sure somewhere there are a few left, but they are few and far between. Joe M. Rod Lane wrote: I would hate to see your insightful comment missed. I haven't seen anyone else pick up on the part of your message about the linear transponder. If someone wants to pass many different modes through a repeater, you can't do better than a transponder. I've been on the transmitting and receiving end of them for years with the satellite world, and we haven't had to wholesale change out them with the change from FM video to digital modes. They just work. Not being an expert on designing them, my understanding of the process is as follows. On a block level, they're much simpler than they seem. Take a tightly bandpass filtered IF from just about any quality radio, AGC it really well, frequency convert it to the desired output frequency, run it through a LINEAR power chain, and you now have the transponder. A simple RF envelope detector can act as the squelch so that the output power chain isn't constantly running to amplify ambient noise that wanders into the system's input bandpass. The only other challenge is to be able to ID the repeater. A simple MCW oscillator somewhere in the chain, either at the IF frequency or output fundamental, and you're legal. FM, D-Star, P25, AM, CW, SSB and virtually any mode that'll stay within the bandpass of the IF will go through unimpeded ( and undistorted.) One possible minor down side is that the user's radio needs to be somewhat on-frequency. If they come in 1 KHz low, they go out 1 KHz low. In theory, it's not the repeater owner's problem, but can be noticed on the output. I remember someone a few years back doing mods on a standard repeater amplifier to linearlize it for ATV and SSB with some bias network additions. As long as the PA is reasonably linear, slight distortions in the linearity curve shouldn't create huge issues except with modes like QAM or other modes with serious amplitude-dependent requirements. I wish I had the time. Being an RF guy, not a software type, it sounds like a great project. 73 de N1FNE --- In Repeater-Builder@yahoogroups.com, Kris Kirby kris@ wrote: On Tue, 24 Apr 2007, Steve Bosshard (NU5D) wrote: Took a couple of antique GE Phoenix SX mobile radios. Programmed for 442.0/ 447.0. With TOT. Carrier Squelch - Took Receiver Un Squelched lead to PTT thru a one transistor keying transistor. Took VOL / SQ Hi and ran it thru a single common emitter stage - bipolar amp and applied the collector output to the high side of the TX deviation control and set for +/- 1 Khz TXD. Did have to bypass the emitter leg of the single stage amp and wallah - DSTAR Repeater - sort of. Maybe P25 repeater too? Simple - really do need to regenerate the data signal and key on detected data with a CCD chip to give the preamble tone time to get thru. Excellent work Mr. Bosshard. This is one of the things that I've wanted to explore with D-Star but haven't had the time. This approach also works for most other modes based on FM (9600 BPS packet, Motorola DES, etc.). Truly, to support multiple modes or technologies, we need only look at the world of linear transponders for a clue -- there's really not much of a point in having too much of a radio there when you're just repeating in the input RF. -- Kris Kirby kris@ The illegal we do immediately. The unconstitutional takes a bit longer. -- Henry Kissinger Yahoo! Groups Links
Re: [Repeater-Builder] Re: Repeating D-Star
On 4/26/07, Rod Lane [EMAIL PROTECTED] wrote: go through unimpeded ( and undistorted.) One possible minor down side is that the user's radio needs to be somewhat on-frequency. If they come in 1 KHz low, they go out 1 KHz low. In theory, it's not the repeater owner's problem, but can be noticed on the output. Numerous issues there... If they're off-frequency, so is your repeater... and your repeater is only coordinated ON-frequency. This would be a bigger deal in areas (like mine) if you were on VHF with 15 KHz channel-spacing, for example... letting your linear transponder repeater doing digital traffic splatter all over your neighbor's analog output isn't going to win many friends. If they're over-deviating... same thing... unless you brick-wall limit them and cause the waveform to clip, making it useless... but at least they'd know their radio was Foo-BAR'ed up... Etc. Etc. Etc. There be dragons here. I don't think it's good engineering practice to put the end-users that much in charge of the signal you're putting out with your callsign on it. That would be another interesting thing... how to ID it properly... digital? CW? That one's easier than the others... but still a headache. (Come to think of it, now I want to go read the regs on satellite ID's... heh... hmmm... How does that work? The beacon? What if it's off, but the transponder's still on? Interesting campfire question for AMSAT friends... please answer off-list if you're tempted... ha... not here, unless we're going to start discussing linear ORBITING transponders as a form of repeater... GRIN...) Nate WY0X p.s. Want to drive people crazy? Hack up the code in your digital radio to understand received traffic that's been INVERTED by an inverting linear transponder... LOL... no encryption, just mega-geekiness...
Re: [Repeater-Builder] Re: Repeating D-Star
mch wrote: There used to be Linear Translators that were land based. There was one around the Pittsburgh area. I'm sure somewhere there are a few left, but they are few and far between. Yup, K3PGP had it in his house. I seen it several times, in person. Kevin
[Repeater-Builder] Re: Repeating D-Star
--- In Repeater-Builder@yahoogroups.com, Bob Dengler [EMAIL PROTECTED] wrote: What would be far more interesting to me would be for one of the ham manufacturers to offer a P25 user radio. How much would adding the vocoder add to the cost of a current analog FM model? If it's comparable in price to Icom's DStar radios (which are substantially more than their analog counterparts - roughly double the cost), it just might be worth it. Something to add to my wish list of radio features to deliver to the reps. at Dayton, along with better IMD performance split CTCSS tone. Bob NO6B I tend to agree...how about a Kenwood or Yaesu ham rig that runs analog and P25? Although used commercial gear is a great option to have, the feature set is, well, commercial. Easy front panel programming on the fly, VFO modes, etc. are usually left out or compromised. Bob K0NR
