command function ofr spectra tac voter

[efc]

Hi,

Have an interesting situation. A cust. wants lights to go off at a location in an ER room when there is traffic on a homeland security channel. Problem is, that this channel is shared by the local county pd. , which normally does not use this channel except when their main channel has issues.When the lights were installed,one hour later they went to channel 2 causing the ER people nuts. The equipment in the system is as follows:
1. Spectra tac Voter
2. 7 Quantar tac receivers, one spectra tac
3. Quantar 350 watt base.

I thought about sending a command through the tac receivers to the voter then to the base to go to a second PL. I figured I could program a second PL in all the receivers which would trigger this command which would go through the voter ahead of the audio to "tell" the base to transmit on PL number 2. So far no luck. Any ideas?

Thank you

[psapengineer]

John,

What's unclear is how the receivers know which carrier RF needs to set off the alert and which carrier RF doesn't need to set of the alert. It kind of reads like the receivers have to be clairvoyant and, of course, they aren't. What is it about the two different kinds of co-channel signals that differentiates them?

What types of circuits are used to transport the receivers to the Voter and/or Hospital?

Regards, Bob

[efc]

Bob,

Thank you for the reply. Let me explain. What I thinking of trying was one channel with multi PL. In other words, 7 Quantars tac receivers with DPL 054 AND DPL lets say, 612. 054 will be for the cops and 612 ,when seen by any receiver would not only pass audio to the Spectra tac voter but also some code,maybe DTMF or whatever would work in the programming,to the Spectra tac voter which would then pass audio and the code which would tell the Quantar base to tranmit on 612 which would only be seen by the hospitals and trigger lights.Otherwise what happens is that all audio triggers lights at the hospital, not just homeland security.

Thank you again for the response,

[psapengineer]

John,

and, how does the audio get from the receivers to the voter? What kind of transport or circuits are in use?

[efc]

Bob,

Sorry, I assumed, which you know the saying. Copper wire lines, voice grade.

[xmo]

The reason that the type of connectivity matters is related to its ability to support out of band signaling, for example E&M circuits would be ideal for this application to send the PL status back to the comparator site. An 'E' lead closure from a remote receiver could cause the comparator to send an F2 transmit function to which would switch the Quantar to use the second PL.

When you say you are using "Copper wire lines, voice grade" - if you mean leased voice grade lines - those might not actually be "copper" since the carriers often use plant facilities that do not provide DC continuity. If you know that the circuits can pass DC, that could be an alternative way to get the PL status to the comparator site.

WIth only VF paths to work with you have a much more difficult project. If that is the case, I would recommend a simple approach. Make the transmit PL selection happen at the main transmit site based on the PL code its local receiver hears. This would be accomplished with a Quantar wildcard action based on the enhanced wildcard state "MCS User". In that way, you can configure the station to transmit the code of the current channel user so long as the local receiver hears some sort of signal. The other receivers can hear better and be voted for the repeat audio, but if the local receiver hears at all, the wildcard function will work. That isn't an unreasonable expectation since the main site should be in range of most users - after all - they have to hear the transmitter. Also, since the law agency only uses the channel as a backup, their use is infrequent and the default transmit PL would normally be the code for the homeland security users.

You would still equip every receiver to respond to both PL codes but you would not have to pass that information to the comparator. The Spectra-TAC will simply select the best audio signal and pass it to the transmitter regardless of which user is on the channel

You do have another issue to consider. The Quantar MCS feature does not support multiple DPL codes. With the Quantar MCS you can have multiple PL tones and one DPL. If multiple DPL is a requirement you will require an outboard device, but if one PL and one DPL will meet your requirements, you can accomplish the project without third party hardware.

[efc]

Hi

Thank you for your responses. That has been very helpful.

[RKG]

I'm not sure I fully understand, but what I think you're saying is this:

Voted system, using Quantar receivers (except one SpectraTac receiver).

Receivers come back to comparator via voice-grade lines.

Two users, using same freq but different PLs.

You want a light function to go active when system keyed by one user's subscriber, but not when keyed by the other user's subscriber.

You intend to program the receivers to "qualify" on either user's subscribers. For Quantar receivers, you can either program two channels and have the receivers scan or (better approach) use the Quantar MPL feature and live with its limitations. I don't know how you're going to do this with the SpectraTac receiver.

However, there is no way that the receiver(s) can tell the comparator which PL they qualified on.

What you can do, though, is to use a burst tone on the subscribers of the user whose traffic is to activate the light. One way is to program the subscribers' radios to send the burst tone on keyup. Alternatively, via wildcard programming I believe you could program the Quantar receivers to send a defined burst tone down the wireline when qualified on one channel (or on one PL); then parallel a burst tone decoder on the console Rx line coming out of the comparator and use the burst tone decoder's relay to trigger your lights(with a timer). Again, the SpectraTac receiver would be left out in the cold.