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is there anyone knows Repeater Access Control (RAC) feature? Recently, I got confused with RAC, and I have some problems about it.

1. RAC allows the selective access of repeaters in systems covering large geographical areas, where repeater coverage may overlap, is it right?

2. must select one repeater when the radio reaches the overlap area ? But how to know the radio has entered the overlap area, any indication?

3. this feature only works on the those repeaters which are able to support this function?

4. to access the repeater, must know the proper singletone which the repeater is using beforehand? in that case, must know all about the repeaters in system?

5. the repeater will forword the signal if the radio's single tone is matched with one of repeaters? how about other repeaters which isn't matched with?

6. in cps, there are two Repeater Access Button able to config to access two repeaters at most, but in acutal application, it's possible to meet more than two repeaters...how to do that?

I really need your help.

I don't believe you ever stated just what type of system your playing with.

If your talking about conventional repeaters on the same frequency, then if a smart radio engineer
set them up, each repeater would use a different CTCSS tone to open up the selected repeater.
There are a number of ways to do this. One would be to actually program the radio with different
channels. Each channel has the same RF, but the TX tone would be different. You would select
the channel based on your location. A second way would be to program the multi PL feature on
the radio. Just change the tone to select the repeater your trying to key.

If your talking about a trunking system, the type of system your using will dictate how this is done.
On a Motorola Smartzone system, the radio will do it all by itself. This would be based on the
received signal strength. On a Smartnet system, it would depend on how the radio was programmed.

You might want to provide more detailed info so the boys on here can provide more details, based
on your system needs.

Jim

jiang wrote:is there anyone knows Repeater Access Control (RAC) feature? Recently, I got confused with RAC, and I have some problems about it.

1. RAC allows the selective access of repeaters in systems covering large geographical areas, where repeater coverage may overlap, is it right?

2. must select one repeater when the radio reaches the overlap area ? But how to know the radio has entered the overlap area, any indication?

3. this feature only works on the those repeaters which are able to support this function?

4. to access the repeater, must know the proper singletone which the repeater is using beforehand? in that case, must know all about the repeaters in system?

5. the repeater will forword the signal if the radio's single tone is matched with one of repeaters? how about other repeaters which isn't matched with?

6. in cps, there are two Repeater Access Button able to config to access two repeaters at most, but in acutal application, it's possible to meet more than two repeaters...how to do that?

I really need your help.

As commonly used in RSS and CPS, RAC refers to a radio function that sends either an MDC ID or a burst tone, either on the push of a button or (more commonly) on press of the PTT key. As a general matter, repeater access this way is pretty much of an obsolete feature.

I wouldn't be surprised. Around here, the State Police on the Turnpike used burst tones to access whatever receiver was appropriate for the zone they were in, but this was abandonned easily 20 years ago.

It is still a useful tool.

For example, when you have 800 MHz mutual aid repeaters in adjoining systems and the coverage footprints overlap.

Simply use different PL? Oops!. FCC rules specify 156.7 must be used.

RAC to the rescue.

Jim202 wrote:I don't believe you ever stated just what type of system your playing with.

If your talking about conventional repeaters on the same frequency, then if a smart radio engineer
set them up, each repeater would use a different CTCSS tone to open up the selected repeater.
There are a number of ways to do this. One would be to actually program the radio with different
...
I really need your help.

[/quote]

Actually, I am not intending to build a system, I am just for studying this feature in theory. But I hardly have any experence with radio and repeater.

If in a system each repeater uses a different tone to open up the selected repeater, then the radio in this system could select one or two repeater by setting a corresponding tone, is it correct?
If certain radio without setting a proper tone, it will be refused transmission by the repeaters in this system, right?
In this system, the radio could select proper repeater as required. If the repeaters which are not selected by the radio would not serve for radio even the repeaters could receive the radio's signal, is it this way?

RAC is more like a tool if my guess is right, and it just provides an approach to build a system in which radio-users have to select repeater by themself. I believe this work should be done by dispatcher automatically in most of current systems, so it really like what RKG said, this approach is out of date or used less.

Also, I'd like know more about how it works in conventional system.

xmo wrote:It is still a useful tool.

For example, when you have 800 MHz mutual aid repeaters in adjoining systems and the coverage footprints overlap.

Simply use different PL? Oops!. FCC rules specify 156.7 must be used.

RAC to the rescue.

Around here we generally turn these repeaters off until needed, else they become either secondary ops channels (properly forbidden by the rules) or get-the-coffee channels.

jiang wrote:

Jim202 wrote:I don't believe you ever stated just what type of system your playing with.

If your talking about conventional repeaters on the same frequency, then if a smart radio engineer
set them up, each repeater would use a different CTCSS tone to open up the selected repeater.
There are a number of ways to do this. One would be to actually program the radio with different
...
I really need your help.

Actually, I am not intending to build a system, I am just for studying this feature in theory. But I hardly have any experence with radio and repeater.

If in a system each repeater uses a different tone to open up the selected repeater, then the radio in this system could select one or two repeater by setting a corresponding tone, is it correct?
If certain radio without setting a proper tone, it will be refused transmission by the repeaters in this system, right?
In this system, the radio could select proper repeater as required. If the repeaters which are not selected by the radio would not serve for radio even the repeaters could receive the radio's signal, is it this way?

RAC is more like a tool if my guess is right, and it just provides an approach to build a system in which radio-users have to select repeater by themself. I believe this work should be done by dispatcher automatically in most of current systems, so it really like what RKG said, this approach is out of date or used less.

Also, I'd like know more about how it works in conventional system.[/quote]


Most of the time, the scenario in question is a poor-man's voting system: two or more repeaters operating in in-cabinet mode with overlapping coverage, and usually where a dispatcher can reach any of them (either via wireline or via a control station with ooomph). Usually, they will be programmed with split tones, all sharing the same output tone but with different input tones. Subscriber equipment is programmed with separate channels for each repeater, where the channels are the same except for TxPL.

Those repeaters programmed for an input tone other than what the subscriber is using either don't hear him (range issue) or ignore him (receiver never unsquelches because tone wrong). Usually the user is trained to announce the "channel" he is calling on, so that responders can switch channels (or channel cards) appropriately.

An example of this, which is not legal for Part 90 but is legal for telco service, involves repeaters in different locales, which are wireline interconnected. If a user in the area of, say, the South repeater wants to talk locally, he'll use the "South Local" channel. If he wants to talk to someone in the North zone, he'll use the "South to North" channel. This will cause the south receiver's audio to be wirelined to the North's transmitter (plus key tones), and vice versa. This isn't legal for Part 90 because a user cannot monitor for interference in the distant zone.