RE: [Repeater-Builder] Re: Zetron 38A not sending reverse burst
The TS-64 also SEEMS to detect STE properly. Well kinda... It loses lock on the CTCSS during the 180 degree phase shift, and then it sees it again not too long after. Resulting in what I've dubbed double bounce unkeying when a TS-64 is detecting CTCSS from a stock GE encoder. Not sure I LIKE that behavior, but I've come up with ways to utilize it and cover up the secondary detect in my applications. -- Nate Duehr n...@natetech.com On Thu, 19 Nov 2009 17:41 -0800, Eric Lemmon wb6...@verizon.net wrote: The TS-64 does indeed encode a reverse burst STE signal. Unfortunately, it has the 180-degree phase shift, because that is really easy to do. It cannot encode a 120-degree phase shift, so that means it is fairly useless with Motorola and a few other radio brands. When I contacted Comm Spec about this a few years ago, the engineer I spoke with seemed not to know that there are two standard reverse burst formats. 73, Eric Lemmon WB6FLY -Original Message- From: [1]repeater-buil...@yahoogroups. com [mailto:[2]repeater-buil...@yahoogroups.com] On Behalf Of wspx472 Sent: Thursday, November 19, 2009 6:47 AM To: [3]repeater-buil...@yahoogroups.com Subject: [Repeater-Builder] Re: Zetron 38A not sending reverse burst I tried that but decided not to go that route for now. The reason is that I need that hang time to tell how well I am hearing the repeater. It is 900 MHz and users are few and far between. If usage picks up, I will probably turn off PL during the hang time. I want to try it a while like it is but I am still thinking about with doing away with the controller and just having a PL decoder and ID'er. The ComSpec TS-64 does send reverse burst. --- In [4]repeater-buil...@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com , Jim Brown w5...@... wrote: I use several Z-38A controllers in ham applications. I get around the squelch crash problem by setting the Z-38A to stop sending a PL tone as soon as a user unkeys. The short tail is still there from the repeater, but the lack of a tone to a receiver lets the audio shut off while carrier is still present, and does not generate a squelch crash. I believe Nate calls this a 'chicken burst' though I have never heard that term before - A second benefit of shutting off the tone after a user unkeys is that it allows in-band links with no ping-pong effects due to the tails talking to each other. 73 - Jim W5ZIT --- On Wed, 11/18/09, Eric Lemmon wb6...@... wrote: From: Eric Lemmon wb6...@... Subject: RE: [Repeater-Builder] Zetron 38A not sending reverse burst To: [5]repeater-buil...@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Date: Wednesday, November 18, 2009, 1:09 PM  You have discovered one of many dirty little secrets that apply to aftermarket tone panels. When designing the 38A tone panel, and many other products, Zetron overlooked the fact that reverse burst is essential in the repeated audio. From a close examination of the 38A manual and schematics, it appears that it will decode CTCSS reverse burst and CDCSS turnoff code, and MAY generate CDCSS turnoff code, but I see no evidence that it can generate reverse burst. That alone is a major shortcoming! Zetron is not the only manufacturer that ignored reverse burst encoding when designing a community repeater controller. Instrument Associates, which produced the i20R On-site Repeater Controller for the Motorola GR1225 desktop repeater, did likewise. I did not realize this until I found that squelch crashes were immediately heard as soon as I put the i20R in service. Although some fans of the old Highway Patrol shows starring Broderick Crawford may enjoy the sound of a squelch crash, I do not, nor do any of my radio users. That i20R was pulled from service immediately, and put on the shelf! There are two different formats for CTCSS reverse burst STE (Squelch Tail Elimination) that are defined in TIA-603-C, the international standard for land-mobile radio performance and design. One format, used principally by Motorola, uses a 120-degree phase shift, while the other format, used by Kenwood and many others, uses a 180-degree phase shift. Since modern radios often use digital signal processing to encode and decode low-speed data (CTCSS and CDCSS), it is all too easy to design a circuit that responds perfectly to 180-degree phase shift but ignores 120-degree phase shift, and vice-versa. Zetron and others couldn't be bothered to create a CTCSS encoder that could be switched between the two reverse-burst formats, so they just ignored the problem. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@ yahoogroups. com [mailto:Repeater-Builder@ yahoogroups. com] On Behalf Of wspx472 Sent: Wednesday, November 18, 2009 10:15 AM To: Repeater-Builder@ yahoogroups. com Subject: [Repeater-Builder] Zetron 38A not sending reverse burst I am trying to get a repeater
Re: [Repeater-Builder] Re: Zetron 38A not sending reverse burst
Eric Lemmon wrote: The TS-64 does indeed encode a reverse burst STE signal. Unfortunately, it has the 180-degree phase shift, because that is really easy to do. It cannot encode a 120-degree phase shift, so that means it is fairly useless with Motorola and a few other radio brands. When I contacted Comm Spec about this a few years ago, the engineer I spoke with seemed not to know that there are two standard reverse burst formats. 73, Eric Lemmon WB6FLY I wouldn't be too worried about it. An awful lot of Motorola's will do OK with 180 shift, especially higher-tier radios. But then there's some that are just weird. I have a Maxar-80 on GMRS. It doesn't like the Com-Spec TP-3200 tone panel. It also doesn't like the P-100 handheld on talkaround. But it does like the GE MPA and Phoenix-SX I have. Go figure. The Micor repeaters with a factory reed decoder however, seem to be pretty liberal on what they respond to. Just about any radio with RB will be at least partially muted. The TK-805D has a really short delay on the STE drop out, so the decoder doesn't get a chance to fully spin down before the transmitter goes away. But just about any other radio worked OK. I'd leave it, frankly.
Re: [Repeater-Builder] Re: Zetron 38A not sending reverse burst
I've gone so far as to make a couple of changes to a Motorola MSR2000 to not send reverse burst, and hold the transmitter a little longer than a normal reverse burst -- that is to say, chicken burst. That was a different application, what I'll do next time I deal with a Micor or MSR with a Zetron (which may be never) -- that is to say, use a factory card just to get the extra carrier hang with no reeds in it and jumpered as if there were no card :) On Nov 20, 2009, at 9:24 AM, wspx472 wrote: Thanks for the useful info. Very interesting. On a somewhat similar topic, we ran into a situation where the local Motorola shop sold a local entity a repeater and several portables using a DPL code that only certain models of Motorola have. We checked every Kenwood, Vertex, and even some other Motorola models and none could do this particular code. I found a work around for the lack of reverse burst. I am using a Tait exciter which has its own hang timer. I just set that timer to hold the carrier up for a fraction of a second after the 38A drops out. This gives the PL decoder in the mobiles/portables time to close the squelch before the carrier drops. --- In Repeater-Builder@yahoogroups.com, wd8chl wd8...@... wrote: Eric Lemmon wrote: The TS-64 does indeed encode a reverse burst STE signal. Unfortunately, it has the 180-degree phase shift, because that is really easy to do. It cannot encode a 120-degree phase shift, so that means it is fairly useless with Motorola and a few other radio brands. When I contacted Comm Spec about this a few years ago, the engineer I spoke with seemed not to know that there are two standard reverse burst formats. 73, Eric Lemmon WB6FLY I wouldn't be too worried about it. An awful lot of Motorola's will do OK with 180 shift, especially higher-tier radios. But then there's some that are just weird. I have a Maxar-80 on GMRS. It doesn't like the Com-Spec TP-3200 tone panel. It also doesn't like the P-100 handheld on talkaround. But it does like the GE MPA and Phoenix-SX I have. Go figure. The Micor repeaters with a factory reed decoder however, seem to be pretty liberal on what they respond to. Just about any radio with RB will be at least partially muted. The TK-805D has a really short delay on the STE drop out, so the decoder doesn't get a chance to fully spin down before the transmitter goes away. But just about any other radio worked OK. I'd leave it, frankly. -- Cort Buffington H: +1-785-838-3034 M: +1-785-865-7206 Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: repeater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: Zetron 38A not sending reverse burst
wspx472 wrote: Thanks for the useful info. Very interesting. On a somewhat similar topic, we ran into a situation where the local Motorola shop sold a local entity a repeater and several portables using a DPL code that only certain models of Motorola have. We checked every Kenwood, Vertex, and even some other Motorola models and none could do this particular code. I found a work around for the lack of reverse burst. I am using a Tait exciter which has its own hang timer. I just set that timer to hold the carrier up for a fraction of a second after the 38A drops out. This gives the PL decoder in the mobiles/portables time to close the squelch before the carrier drops. That'll work on nearly all radios. I found my wife's VX-1 won't even respond to that. I checked-once the decoder opens, it stays open until the carrier squelch closes-forever. It does do DPL turn-off code though. Jim
Re: [Repeater-Builder] Re: Zetron 38A not sending reverse burst
Anybody have a 38Max they want to sell me cheap? (he he... now that we're on an anti-Zetron thread :) :) On Nov 19, 2009, at 9:13 AM, wb0vhb wrote: From my experience, the Model 38 and 48 will not do reverse burst. I did however use a Arcomm audio delay board and accomplished the same results. http://www.arcomcontrollers.com/rc210/rad.html Then I decided I want a repeater controller capable of additional ports and dropped the Model 48 I was using and went with the Arcom RC-210 and Com Spec SS-64 encoders with reverse burst built-in. http://www.com-spec.com/ss64.htm Randy --- In Repeater-Builder@yahoogroups.com, wspx472 wpxs...@... wrote: I am trying to get a repeater going using a 38A and find that it doesn't send reverse burst. I thought I saw that it did in the manual but upon looking again, all I see is where it responds to reverse burst. Does anyone know for sure if it is supposed to send reverse burst? If so, how do I get it to do it? -- Cort Buffington H: +1-785-838-3034 M: +1-785-865-7206 Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: repeater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] Re: Zetron 38A not sending reverse burst
The TS-64 does indeed encode a reverse burst STE signal. Unfortunately, it has the 180-degree phase shift, because that is really easy to do. It cannot encode a 120-degree phase shift, so that means it is fairly useless with Motorola and a few other radio brands. When I contacted Comm Spec about this a few years ago, the engineer I spoke with seemed not to know that there are two standard reverse burst formats. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of wspx472 Sent: Thursday, November 19, 2009 6:47 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Zetron 38A not sending reverse burst I tried that but decided not to go that route for now. The reason is that I need that hang time to tell how well I am hearing the repeater. It is 900 MHz and users are few and far between. If usage picks up, I will probably turn off PL during the hang time. I want to try it a while like it is but I am still thinking about with doing away with the controller and just having a PL decoder and ID'er. The ComSpec TS-64 does send reverse burst. --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com , Jim Brown w5...@... wrote: I use several Z-38A controllers in ham applications. I get around the squelch crash problem by setting the Z-38A to stop sending a PL tone as soon as a user unkeys. The short tail is still there from the repeater, but the lack of a tone to a receiver lets the audio shut off while carrier is still present, and does not generate a squelch crash. I believe Nate calls this a 'chicken burst' though I have never heard that term before - A second benefit of shutting off the tone after a user unkeys is that it allows in-band links with no ping-pong effects due to the tails talking to each other. 73 - Jim W5ZIT --- On Wed, 11/18/09, Eric Lemmon wb6...@... wrote: From: Eric Lemmon wb6...@... Subject: RE: [Repeater-Builder] Zetron 38A not sending reverse burst To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Date: Wednesday, November 18, 2009, 1:09 PM  You have discovered one of many dirty little secrets that apply to aftermarket tone panels. When designing the 38A tone panel, and many other products, Zetron overlooked the fact that reverse burst is essential in the repeated audio. From a close examination of the 38A manual and schematics, it appears that it will decode CTCSS reverse burst and CDCSS turnoff code, and MAY generate CDCSS turnoff code, but I see no evidence that it can generate reverse burst. That alone is a major shortcoming! Zetron is not the only manufacturer that ignored reverse burst encoding when designing a community repeater controller. Instrument Associates, which produced the i20R On-site Repeater Controller for the Motorola GR1225 desktop repeater, did likewise. I did not realize this until I found that squelch crashes were immediately heard as soon as I put the i20R in service. Although some fans of the old Highway Patrol shows starring Broderick Crawford may enjoy the sound of a squelch crash, I do not, nor do any of my radio users. That i20R was pulled from service immediately, and put on the shelf! There are two different formats for CTCSS reverse burst STE (Squelch Tail Elimination) that are defined in TIA-603-C, the international standard for land-mobile radio performance and design. One format, used principally by Motorola, uses a 120-degree phase shift, while the other format, used by Kenwood and many others, uses a 180-degree phase shift. Since modern radios often use digital signal processing to encode and decode low-speed data (CTCSS and CDCSS), it is all too easy to design a circuit that responds perfectly to 180-degree phase shift but ignores 120-degree phase shift, and vice-versa. Zetron and others couldn't be bothered to create a CTCSS encoder that could be switched between the two reverse-burst formats, so they just ignored the problem. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@ yahoogroups. com [mailto:Repeater-Builder@ yahoogroups. com] On Behalf Of wspx472 Sent: Wednesday, November 18, 2009 10:15 AM To: Repeater-Builder@ yahoogroups. com Subject: [Repeater-Builder] Zetron 38A not sending reverse burst I am trying to get a repeater going using a 38A and find that it doesn't send reverse burst. I thought I saw that it did in the manual but upon looking again, all I see is where it responds to reverse burst. Does anyone know for sure if it is supposed to send reverse burst? If so, how do I get it to do it?
