Spectra Tac jumper configuration

[JMINN]

I have a spectra Tac system on a MTR2000 with two spectra tac voting receivers and the MTR`s receiver voting up a storm. I have a question on what is the best way to configure the Command module`s vote lock options. Also instead of being praised for the improved coverage all I get from the officers in the field is complaints about the slightly longer key up delay and the clicks and occasional guard tone, they think it is a roger beep, at the end of transmission. Any thought on this?

Thanks

Joe

[Bill_G]

Vote lock is normally disabled. JU11 is normally out. Let the SQM's do the voting, not the command module.

[d119]

I have a spectra Tac system on a MTR2000 with two spectra tac voting receivers and the MTR`s receiver voting up a storm. I have a question on what is the best way to configure the Command module`s vote lock options. Also instead of being praised for the improved coverage all I get from the officers in the field is complaints about the slightly longer key up delay and the clicks and occasional guard tone, they think it is a roger beep, at the end of transmission. Any thought on this?

Thanks

Joe

You shouldn't be hearing any guard tones or function tones over the air... Something isn't set up right.

As for the clicks, there's nothing you can do about that - it's a natural part of all TAC systems.

As for the keyup delay, that's a training issue and they need to just deal with it.

I've never needed to set up a system for vote lock. It somewhat defeats the purpose of the system. As Bill said, let the comparator do it's job. AFAIK, Vote Lock is for extremely wide-area systems where receivers may be EXTREMELY far apart, or in multicast systems where several channels of audio need to be patched together for several transmitters so everything is in the same place.

[Bill_G]

I wondered what vote lock would be used for especially since the SpectraTAC didn't have transmitter steering like the JPS. The rcvr "bubble clicks" of the SpectraTAC were cleaned up in the DigiTAC. They are mild but normal. Occasionally you can hear a bit of the high level sequence if the repeater/base is already active and people are snappy with a response. Voting systems are not as fast as simplex, but only by tens of milliseconds. Simply waiting one or two vowels was long enough. The latest JPS voters will delay/buffer the audio so that every word goes through. But, then you have an "echo" that confuses users not accustomed to it.

[JMINN]

Thanks for the responses. They have comfirmed what I already though. I will show your responses to the command staff so that they can tell the winny officers to live with it. The improved coverage out ways the slight inconvience.

Joe

[Bill_G]

Some things you can do to improve comparator performance is (a) set your rcvrs for AND squelch, (b) set your rcvr squelch slightly tighter than you might be normally inclined (-116 rather than -120) and the same at each site, (c) measure and record site noise / effective sensitivity at each site - compensate or eliminate if possible, and (d) set all your levels the same to eliminate erroneous switching to "quieter" sites.

[d119]

I wondered what vote lock would be used for especially since the SpectraTAC didn't have transmitter steering like the JPS. The rcvr "bubble clicks" of the SpectraTAC were cleaned up in the DigiTAC. They are mild but normal. Occasionally you can hear a bit of the high level sequence if the repeater/base is already active and people are snappy with a response. Voting systems are not as fast as simplex, but only by tens of milliseconds. Simply waiting one or two vowels was long enough. The latest JPS voters will delay/buffer the audio so that every word goes through. But, then you have an "echo" that confuses users not accustomed to it.

Every DIGITAC I've ever worked with clicks just like a SpectraTAC... Am I missing something?

[Bill_G]

Every DIGITAC I've ever worked with clicks just like a SpectraTAC... Am I missing something?

Even though I built and maintain two systems with Digitacs (a 12 channel, 6 site UHF and a 3 channel, 3 site VHF), the comparators never break. So, I'm working off the back of my head how I set it up. If I recall, there is a soft mute you can apply to eliminate the "cluck" when the rcvr mutes and status tone is restored. I don't recall if it is a jumper or RSS. Even someone with a bad PTT switch / intermittent cord has a hard time getting the system to clucka clucka clucka like SpectraTACs would. Very smooth. I'll try to look it up tomorrow.

[d119]

Every DIGITAC I've ever worked with clicks just like a SpectraTAC... Am I missing something?

Even though I built and maintain two systems with Digitacs (a 12 channel, 6 site UHF and a 3 channel, 3 site VHF), the comparators never break. So, I'm working off the back of my head how I set it up. If I recall, there is a soft mute you can apply to eliminate the "cluck" when the rcvr mutes and status tone is restored. I don't recall if it is a jumper or RSS. Even someone with a bad PTT switch / intermittent cord has a hard time getting the system to clucka clucka clucka like SpectraTACs would. Very smooth. I'll try to look it up tomorrow.

Well I know there is a notch filter that can be turned on and off to quiet most of the "Cheep" you hear when the receivers go idle, but the result of that is just the "click"

Let me know if there is anything that can be done to further clean this up.

[GlennD]

All of our comparators use E & M keying over our microwave network and they have no click. On most channels we vote seven receivers. You really have to be watching the voter display to see receiver changes. There is no audio difference.

[Bill_G]

I went through my notes from both projects, and then through the manuals, and can't find what I was looking for. I know we spent a lot of time refining both to get seamless transitions between rcvrs. It is inaudible. The only click is at the end of transmission when the Digitac dekeys the station, and it is very small. You hear the noise floor change to silence, then the familiar "creak" followed by the sq tail. The "creak" is an artifact of the voter as the last rcvr mutes and status tone is restored. Listening to an old sheriff dept VHF Micor / SpectraTAC versus a newer fire VHF MTR / DigiTAC, the SO is "talk talk talk creaka talk creaka talk talk talk creak" and the FD is "talk talk talk talk creak". Maybe it is how anal we got about setting the levels and the squelch that made the difference.

[d119]

All of our comparators use E & M keying over our microwave network and they have no click. On most channels we vote seven receivers. You really have to be watching the voter display to see receiver changes. There is no audio difference.

Last time I listened to your agency, Glenn, when a unit unkeys, I hear "clickclickclick" when the receiver status tones come back online. What I find most interesting is that you guys run MDC 1200, but you hardly EVER hear it over the air.

[d119]

I went through my notes from both projects, and then through the manuals, and can't find what I was looking for. I know we spent a lot of time refining both to get seamless transitions between rcvrs. It is inaudible. The only click is at the end of transmission when the Digitac dekeys the station, and it is very small. You hear the noise floor change to silence, then the familiar "creak" followed by the sq tail. The "creak" is an artifact of the voter as the last rcvr mutes and status tone is restored. Listening to an old sheriff dept VHF Micor / SpectraTAC versus a newer fire VHF MTR / DigiTAC, the SO is "talk talk talk creaka talk creaka talk talk talk creak" and the FD is "talk talk talk talk creak". Maybe it is how anal we got about setting the levels and the squelch that made the difference.

OK. I thought you were referring to the "end of transmission" clicks as the receivers place status tone back on the line.

Yes our voters make almost no noise as they switch from site to site during a transmission.

You can tell who knows how to properly align a voting system and who doesn't by what happens when the system selects different receivers during a transmission. (read: levels/equalization)

[MassFD]

Last time I listened to your agency, Glenn, when a unit unkeys, I hear "clickclickclick" when the receiver status tones come back online. What I find most interesting is that you guys run MDC 1200, but you hardly EVER hear it over the air.

When we ran SpectraTac we used MDC pre transmission with sidetone enabled, we set a short pre delay (250ms I think) this ate up the voting time and repeater keyup delay while the user was waiting for the sidetone to end before speaking. You rarely heard the MDC over the air unless you were in CS.

Think of the delays involved, Remote Receiver PL detect, vote delay, TX key up via tone remote, Portable PL detect.
Add all the delays and It's a wonder it does not cut off the entire transmission.

Using Data operated squelch in the portables can also add delay if the coast time is set to long, the radio hears the MDC data burst then mutes untill the data goes away and the coast time expires.

I kind of liked the clicks and the tone remote burst geting thru once and a while, grows on you like MODAT

[JMINN]

My three channel Spectra tac votes seamlessly, no difference in audio levels. What officers are bitching about is the front end clipping and the clicks at the end. Not a one of them has noticed the improvement in coverage. I see that used Digitac comparators are now reasonable. Do they make that much of an improvement and are the field repairable like the Spectratac?

Joe

[d119]

In my opinion, if you aren't doing anything with encryption (SECURENET) and your SpectraTAC works properly, there is no need to upgrade to a DIGITAC. The SpectraTAC is much more "field repairable" than the DIGITAC and replacement parts are MUCH more readily available for the SpectraTAC gear.

I see no benefit to you to upgrade.

[GlennD]

Regarding our MDC, It is muted on most channels in the voter. On LG1 and LG2, It is repeated since towing uses button boxes for status. They use lg1 until the refuse gorillas stop using lg2. Then they switch to a clear lg2. Since the refuse people have no courtesy they make the channel unusable for anyone else.

Other channels may repeat MDC since one of the techs is playing with radio kill. I know the splinter that we use as a shop channel does.

As far as the clicks, I will have to listen to the channels with a carrier squelch radio. You may be right.

[d119]

You'll hear the clicks regardless of whether or not you are in carrier squelch or PL. I'm referring to the notched 2175Hz status tones that go over the air when a field unit unkeys.

MDC muting in the voter? Using the voter keyup delay or ?