RE: [Repeater-Builder] Zetron 38A not sending reverse burst
Just catching up on RB mail after a couple of weeks... For the record, I learned that turn of phrase (chicken burst) from reading things here on RB over the years. I don't know the history of the phrase. Chicken to implement true reverse burst/squelch tail elimination, etc? I have no idea. -- Nate Duehr, WY0X n...@natetech.com On Thu, 19 Nov 2009 06:10 -0800, Jim Brown w5...@yahoo.com 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...@verizon.net wrote: From: Eric Lemmon wb6...@verizon.net Subject: RE: [Repeater-Builder] Zetron 38A not sending reverse burst To: Repeater-Builder@yahoogroups.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? References 1. mailto:w5...@yahoo.com?subject=re:%20[Repeater-Builder]%20Zetron%2038A%20not%20sending%20reverse%20burst 2. mailto:repeater-buil...@yahoogroups.com?subject=re:%20[Repeater-Builder]%20Zetron%2038A%20not%20sending%20reverse%20burst 3. http://groups.yahoo.com/group/Repeater-Builder/message/95820;_ylc=X3oDMTM1ZHZxMDF1BF9TAzk3MzU5NzE0BGdycElkAzEwNDE2OARncnBzcElkAzE3MDUwNjMxMDgEbXNnSWQDOTU4MzMEc2VjA2Z0cgRzbGsDdnRwYwRzdGltZQMxMjU4NjM5OTAzBHRwY0lkAzk1ODIw 4. http://groups.yahoo.com/group/Repeater-Builder/members;_ylc=X3oDMTJlc2RhOTllBF9TAzk3MzU5NzE0BGdycElkAzEwNDE2OARncnBzcElkAzE3MDUwNjMxMDgEc2VjA3Z0bARzbGsDdm1icnMEc3RpbWUDMTI1ODYzOTkwMw--?o=6 5. http://groups.yahoo.com/group/Repeater-Builder;_ylc=X3oDMTJkaGkyMG5hBF9TAzk3MzU5NzE0BGdycElkAzEwNDE2OARncnBzcElkAzE3MDUwNjMxMDgEc2VjA3Z0bARzbGsDdmdocARzdGltZQMxMjU4NjM5OTAz 6. http://groups.yahoo.com/group/Repeater-Builder/post;_ylc=X3oDMTJkN21pdnVmBF9TAzk3MzU5NzE0BGdycElkAzEwNDE2OARncnBzcElkAzE3MDUwNjMxMDgEc2VjA2Z0cgRzbGsDbnRwYwRzdGltZQMxMjU4NjM5OTAz 7. http://us.ard.yahoo.com/SIG=14k9c4lda/M=493064.12016295.13793596.10835568/D=groups/S=1705063108:MKP1/Y=YAHOO/EXP=1258647103/L=/B=F2eDAkPDhEE-/J=1258639903754764/K=KOR8qtxekTH7Rxozg8rs_w/A=5898843/R=0/SIG=11kkq36go
RE: [Repeater-Builder] Zetron 38A not sending reverse burst
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...@verizon.net wrote: From: Eric Lemmon wb6...@verizon.net Subject: RE: [Repeater-Builder] Zetron 38A not sending reverse burst To: Repeater-Builder@yahoogroups.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?
RE: [Repeater-Builder] Zetron 38A not sending reverse burst
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-buil...@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?
