Hello,
What would be the easiest way to pass keying tones from a radio console ,through a UHF RF LINK,to a voter.Point is,I could use a CPI tone inter face to radio,but it will strip off keying tones I think.So I need to be able to key up a UHF radio,and pass the tones from the console,to be received by another UHF radio,and in turn,pass that to a voter to key up an MTR 3K.The voter is a SNV 12.
THANKS!
Passing keying tones
Moderator: Queue Moderator
Passing keying tones
John
Re: Passing keying tones
If you want to do tone control of a remote radio over a UHF link, you need a hot link. One that is always up. And it will need to have RSL in the -80dbm or better region so that there is little or no hiss from the link. You'll essentially need two low power continuous duty repeaters with duplexers into yagis at each end so that it acts like a quiet phone line. My suggestion is to use E&M keying through the link to cause the voter to give tone control to the MTR. Then you don't have to worry about tone timing, tone levels, or a hot link.
Re: Passing keying tones
You're welcome.
Before low cost wifi links, we used to use UHF and 72mhz links all the time. Motorola even sold them made from a pair of HT's. You had to use a hot link to pass the tones because the near end key up and far end decode attack times ate into the HLGT and function tone times causing intermittent no key up of the station you were trying to control. Every millisecond counted.
The link had to be up all the time to faithfully pass the tones, but that put wear and tear on the little HT rfpa. Plus, you had to have sufficient quieting for the LLGT to be properly decoded, or the station would drop out when the link noised up. Royal pain. We had a much more reliable link if we did everything with PTT and COR (E&M). It might sound noisy sometimes when the path faded, but it always worked, and the HT's didn't wear out as often.
UHF worked great if you had LOS, and 72Mhz would crawl the hills and valleys to reach places miles away back in the sticks. That's how I got volunteer pagers to tapout in the far away corners of the county. Poor man's simulcast. Some of the hamlets were so isolated, they couldn't hear the primary VHF channel. So, I could reuse the same freq in several places without worry of self interference. The console would key up with silence for about 500mS to heat up the link followed by the paging tones to light up the pagers. Dispatch could talk. They could talk back on their portables and mobiles. The link relayed it back and forth. Worked fine.
Before low cost wifi links, we used to use UHF and 72mhz links all the time. Motorola even sold them made from a pair of HT's. You had to use a hot link to pass the tones because the near end key up and far end decode attack times ate into the HLGT and function tone times causing intermittent no key up of the station you were trying to control. Every millisecond counted.
The link had to be up all the time to faithfully pass the tones, but that put wear and tear on the little HT rfpa. Plus, you had to have sufficient quieting for the LLGT to be properly decoded, or the station would drop out when the link noised up. Royal pain. We had a much more reliable link if we did everything with PTT and COR (E&M). It might sound noisy sometimes when the path faded, but it always worked, and the HT's didn't wear out as often.
UHF worked great if you had LOS, and 72Mhz would crawl the hills and valleys to reach places miles away back in the sticks. That's how I got volunteer pagers to tapout in the far away corners of the county. Poor man's simulcast. Some of the hamlets were so isolated, they couldn't hear the primary VHF channel. So, I could reuse the same freq in several places without worry of self interference. The console would key up with silence for about 500mS to heat up the link followed by the paging tones to light up the pagers. Dispatch could talk. They could talk back on their portables and mobiles. The link relayed it back and forth. Worked fine.
Re: Passing keying tones
If I recall correctly, there was a way to do this where the link didn't have to be up all the time, and it involved "extended keying tones" from the console. In other words, HLGT would be extended long enough to bring up the link transmitter, then it, followed by FT + LLGT would go out over the air. I think Centracom Series II + supported this, and perhaps Gold Elite, but I'm not sure if any other manufacturers supported it.
Re: Passing keying tones
Yep. That was the problem - not everyone used a Centracom. I had PD's on the coast using plain old T1300 and T1600 remotes. By the time they were consolidating dispatching to single county wide centers with modern consoles, we had also moved them to repeaters (so the console controlled a local radio) and/or microwave links that carried all their traffic for multiple stations.