Talkarounds work how?

Ok, for the longest time, I've heard of talkarounds, where mainly LE when they have a repeater, they "talk" on the input frequency I believe it is.

How exactly does this work?

Let's say for a LE the system is 453.650/458.650.

The way I understand it, the radios will normally talk on 458.650, that output will be put into the input of the repeater, and everyone will hear the traffic on 453.650.

Now, when they use the talkaround, 458.650, what stops it from going into the repeater? If they are talking on 458.650, wouldn't the repeater notice, or on talkaround mode, does the power get lower and the repeater can't detect it?

Also, what I'm confused about, is Simplex frequencies, I was told you can't pick them up unless you're close, yet I was told that "Dispatch" monitors those frequencies. How can they pick them up, if you can't?

"Talkaround" for my neck of the woods means the opposite of what you have described.. everyone would transmit on 453.650 to use your example. If they really are talking on 458.650, they could be using a different CTCSS/DCS code than what the repeater expects.

As for simplex, as a dispatcher and a responder, I would find it useless to have simplex channels in our dispatch console. As you say, you have to be close by to receive them. There's no point in being able to pick up signals only within 5 blocks of the comm center.

The idea of a talkaround channel is used for simplex radio to radio communications. A prime example would be fireground communications where the incident commander would remain on the repeater , and all other units upon arrival on scene would switch to the talk around channel. The incident commander can hear all conversations , as well as interior/ exterior crews working. In the case of Law Enforcement a SWAT, or SRT team may use it for entry into a situation, keeping their conversation local (within a mile or so ), however being still able to hear a dispatcher or incident commander on a repeater.

The fire side tends to use simplex channels or talk arounds for fireground communications, simply put its reliable, simplistic to use. Having 16-128 channels in a radio does you no good if your lost or trapped, hence the NFPA and other appropiate, policy makers prefer simplex over a repeater for on scene traffic.

Normally, on a repeater system such as the one you described (453.650/458.650), talkaround would use the repeater output (453.650) in simplex (i.e, transmit frequency is the same as the receive frequency) with either the same or different PL/DPL transmitted by the repeater. Usually the high part of the repeater pair (458.650) is only used to transmit signals that need to be repeated. (Though I've seen instances where this is not true.)

Oh

So just so I understand what you all mean.

If I'm using the 453.650/458.650 pair in normal everyday mode, and I hit the PTT button, am I actually sending out in 453.650 or 458.650?

Does it really make any sense to put in the higher frequency in to your scanner at all then? I mean will you probably ever hear anything?

In your example of a 453.650 Rx, 458.650 Tx repeater channel, the radio would be transmitting on 458.650 and receiving on 453.650 to contact dispatch. Even car to car traffic could be accomplished using the repeater as well. When two units are close enough for direct, or simplex operation, they can both switch to 453.650 transmit and receive. This works as long as the channel is not too busy with repeater traffic. If other units are too far away to hear the simplex traffic, they might key up their mikes and drown out the simplex traffic.

That is why they might want to switch to another channel, often called a tactical channel, to complete their car to car traffic. We had this situation in the U.S. Forest Service where the normal channel one in our radios was the simplex or direct channel. Channel two was the repeater channel. The output frequency was called "forest net." Quite often we would call each other in the simplex mode, labeled as channel one in our radios, and say something like "Patrol 22, Recreation 21, forest net direct." After making contact we would typically say something like "switch to six" or "switch to the work channel." We would then be able to speak to each other without having additional forest net repeater traffic interfere. Quite often we would want to talk in some detail about a situation and did not want to tie up the forest net with the somewhat lengthy conversation we needed to have.

As for programming in 458.650 in a scanner, there is no reason to in most cases. I've been in situations where I did not want to listen to everything on the dispatch channel so I would program in 453.650 and lock it out. I would program in 458.650 and scan it until I heard a unit close enough for my radio to copy. I would then lock out 458.650 and unlock 453.650 so I could listen to traffic concerning something close enough to concern me. I haven't done this very often and normally don't have the repeater input, 458.650 in your example, programmed into my scanners at all. When you listen to the repeater input frequency you will have a lot of noise when the mobile units transmitting are close enough to break squelch, but far enough away so that the signal is very noisy and difficult to copy.

I hope this answers your question.

RedPenguin said:

Does it really make any sense to put in the higher frequency in to your scanner at all then? I mean will you probably ever hear anything?

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You won't hear anything unless the transmitting unit is within simplex range. You do not need to monitor the TX freq. unless you have a special reason. I have heard a few hobbyists say they may occasionally listen to the TX of a local law repeater to know who is in their area, or to know if the local "smokey" is on the prowl in their rural part of the county, etc.

Stick with the receive side of your local repeaters. You'll catch all the traffic and if the repeater goes down or for some reason they switch to talkaround (maybe on a scene in a marginal area or if out of repeater range), you'll still hear them.

Good luck.

I always thought it was this way.

Simplex use only one frequency and when you press the PTT I cannot talk and when I press the PTT you cannot talk and only one can talk at the time.

A Duplex use one frequency to talk and one to hear the communication .So you could hear 1 or 2 or even 3 talk at the same time .

I never found out what half duplex is.

The FD use talkaround when the radio get too bad in apartments or underground where radio is too weak.You will hear Mississauga fire or Brampton fire say go to talkaround 8 .

They use it in underground parking too if the radio is too bad here.

RedPenguin said:

Does it really make any sense to put in the higher frequency in to your scanner at all then? I mean will you probably ever hear anything?

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I used to monitor a system that used a particularly crappy repeater and I had the input in one radio and the output in another so I could pick the best signal.

nec208 said:

I always thought it was this way.

Simplex use only one frequency and when you press the PTT I cannot talk and when I press the PTT you cannot talk and only one can talk at the time.

A Duplex use one frequency to talk and one to hear the communication .So you could hear 1 or 2 or even 3 talk at the same time .

I never found out what half duplex is.

The FD use talkaround when the radio get too bad in apartments or underground where radio is too weak.You will hear Mississauga fire or Brampton fire say go to talkaround 8 .

They use it in underground parking too if the radio is too bad here.

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Okay I think you have the idea here but lets just make sure.

• Simplex - One frequency is used, all communication is on that one frequency shared among all users.
• Duplex - Two or more frequencies are used where all communication is heard by all parties at the same time and can talk at the same time; this is pretty uncommon in radio communication (as we are used to) but is exactly what a telephone circuit is.
• Half-Duplex - This is where everyone talks on one frequency shared and listens on a second frequency. This is the typical repeater set up and also is used quite frequently in public safety usually on wide spread agencies like the state police. Texas DPS uses this method, as does the California HP.

Hope this helps.

I don't think so Lou, the subject has been talked to death and they still haven't figured it out.

RedPenguin said:

Also, what I'm confused about, is Simplex frequencies, I was told you can't pick them up unless you're close, yet I was told that "Dispatch" monitors those frequencies. How can they pick them up, if you can't?

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Because they have an antenna on top of a high building or tower and you don't.

If the site can pick up comms on the repeater inputs, why couldn't it hear simplex frequencies?

Simplex - One frequency is used, all communication is on that one frequency shared among all users.

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But only one person can talk at a time?

Duplex - Two or more frequencies are used where all communication is heard by all parties at the same time and can talk at the same time; this is pretty uncommon in radio communication (as we are used to) but is exactly what a telephone circuit is.

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So would the base station have frequencies like that say 851.15 Mhz 852.25 Mhz and the portables and mobiles?

Half-Duplex - This is where everyone talks on one frequency shared and listens on a second frequency. This is the typical repeater set up and also is used quite frequently in public safety usually on wide spread agencies like the state police. Texas DPS uses this method, as does the California HP

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So they talk on one frequency and hear on the other frequency ..

nec208 said:

Simplex - One frequency is used, all communication is on that one frequency shared among all users.

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But only one person can talk at a time?

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Yes, that is correct...well not quite, nothing stops two people from talking at the same time but only one will be heard by each receiver (depending on who is closest).

nec208 said:

Duplex - Two or more frequencies are used where all communication is heard by all parties at the same time and can talk at the same time; this is pretty uncommon in radio communication (as we are used to) but is exactly what a telephone circuit is.

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So would the base station have frequencies like that say 851.15 Mhz 852.25 Mhz and the portables and mobiles?

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Err, no not the way you are thinking. In fact, you would probably never hear such a thing on any radio you have; think more of multi-channels on each path.

nec208 said:

Half-Duplex - This is where everyone talks on one frequency shared and listens on a second frequency. This is the typical repeater set up and also is used quite frequently in public safety usually on wide spread agencies like the state police. Texas DPS uses this method, as does the California HP

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So they talk on one frequency and hear on the other frequency ..

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Yes, just like every repeater operation. In "common" usage, all repeater setups are half-duplex. Some other systems (like the ones I mentioned) are not repeated, just half-duplex.

Jay911 said:

"Talkaround" for my neck of the woods means the opposite of what you have described.. everyone would transmit on 453.650 to use your example. If they really are talking on 458.650, they could be using a different CTCSS/DCS code than what the repeater expects.

As for simplex, as a dispatcher and a responder, I would find it useless to have simplex channels in our dispatch console. As you say, you have to be close by to receive them. There's no point in being able to pick up signals only within 5 blocks of the comm center.

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I worked for a security company with this type of system. We actually made good use of it. We only had one dispatcher on duty and she couldn't leave the office. Whenever the patrol supervisor was close to the station, we would contact her on the talkaround and ask her what she wanted for lunch and get that for her.

Just a side note concerning the input frequency. I always keep the repeater input frequencies in for our local LE. I do this because there are dead spotss in the county where either mobiles or especially handhelds are difficult if not impossible to hear. If a LEO needs assistance and dispatch can't hear them then I can call and tell them what is happening or just let them hear my radio through the phone. (I only do this in true emergency situations and I work with our county agencies on a routine basis). I am not suggesting everyone do this, however, if an officer needed help and dispatch couldn't hear them then I doubt anyone would be opposed to letting dispatch know of the situation. I am not too far from one of the "dead spots" where dispatch frequently has trouble hearing officers who are out of the car on traffic stops or investigations.

Another reason to listen is if the radio system console or the repeater itself goes out and LEOs can't contact dispatch. I can relay info. if needed to dispatch.

I am on top of a hill and my antenna is about 35' up. Just thought I would pass along why I listen to the input.

n9zek said:

Just a side note concerning the input frequency. I always keep the repeater input frequencies in for our local LE. I do this because there are dead spotss in the county where either mobiles or especially handhelds are difficult if not impossible to hear. If a LEO needs assistance and dispatch can't hear them then I can call and tell them what is happening or just let them hear my radio through the phone. (I only do this in true emergency situations and I work with our county agencies on a routine basis). I am not suggesting everyone do this, however, if an officer needed help and dispatch couldn't hear them then I doubt anyone would be opposed to letting dispatch know of the situation. I am not too far from one of the "dead spots" where dispatch frequently has trouble hearing officers who are out of the car on traffic stops or investigations.

Another reason to listen is if the radio system console or the repeater itself goes out and LEOs can't contact dispatch. I can relay info. if needed to dispatch.

I am on top of a hill and my antenna is about 35' up. Just thought I would pass along why I listen to the input.

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This is a good point and one a lot of people probably overlook. Aside from relaying information to dispatchers(i'm not even going to comment either way on that... although i'm sure fifty other people on here will), there will be times where you are on the fringe of coverage by the repeater but close to the officer thus getting a clearer signal on the repeater input as opposed to the output. Unless you are a diehard listener and want to get every word said then it probably doesn't make any difference to you. However, i still monitor the input frequencies, and can always just manually change the channel if the input is full of static.

In the past year i believe every agency around me has had a problem with a repeater and therefore had to shut it down for sometime, usually no more than 24hours. The city where i live had to shutdown its entire repeater system because 1 tower was having problems. A city nearby had a repeater issue and just shutdown the problem tower and kept everything else online. Not sure what the cause was, but in either case depending on your location you were screwed if you only monitored the output.

Another point i would make is to always have the secondary and tactical channels programmed, those are normally the ones that suddenly become active when the repeater goes down, or when something major happens.

What?

From the replies here I figured that in a case like 453.350RX/468.350TX that you would use a Talkaround on 453.350.

I noticed this for my state police:

http://www.wpascanner.com/wiki/index.php?title=PA:Commonwealth

and http://www.radioreference.com/apps/db/?aid=744 and it's listed on both sites the same way so I know it's not some kind of strange mistake.

I'm confused because if you look at say Chan A it says Tx 154.950 and Rx 155.580 yet Mon A or Talk Around A, it says Tx/Rx 154.950. Both sets have a 186.2 tone. So when using the "Talk Around" frequency, how would that bypass the repeater in this case?

RedPenguin said:

From the replies here I figured that in a case like 453.350RX/468.350TX that you would use a Talkaround on 453.350.

I noticed this for my state police:

http://www.wpascanner.com/wiki/index.php?title=PA:Commonwealth

and http://www.radioreference.com/apps/db/?aid=744 and it's listed on both sites the same way so I know it's not some kind of strange mistake.

I'm confused because if you look at say Chan A it says Tx 154.950 and Rx 155.580 yet Mon A or Talk Around A, it says Tx/Rx 154.950. Both sets have a 186.2 tone. So when using the "Talk Around" frequency, how would that bypass the repeater in this case?

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I would guess that they do it so that they don't hear the repeater but only what is being said very close. In fact you will bring up the repeater based on what is in our DB and that other link you provided, unless the repeater is shut down.

RedPenguin said:

From the replies here I figured that in a case like 453.350RX/468.350TX that you would use a Talkaround on 453.350.

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No - for talkaround you transmit on the frequency you and every other mobile or portable is ALREADY listening to (the repeater's transmit frequency).

RedPenguin said:

I noticed this for my state police:

http://www.wpascanner.com/wiki/index.php?title=PA:Commonwealth

and http://www.radioreference.com/apps/db/?aid=744 and it's listed on both sites the same way so I know it's not some kind of strange mistake.

I'm confused because if you look at say Chan A it says Tx 154.950 and Rx 155.580 yet Mon A or Talk Around A, it says Tx/Rx 154.950. Both sets have a 186.2 tone. So when using the "Talk Around" frequency, how would that bypass the repeater in this case?

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The info is correct.

The repeater won't hear you - you're transmitting on the same frequency it is. All the mobiles within range of you WILL hear you - in this instance again the talkaround frequency is what all the mobiles/portables are already listening to from the repeater. You will be competing to be heard with the repeater, whoever has the stronger signal at the other radio's receivers gets heard.

-edit update-

Just read loumaag's response and realized that the mobiles are still going to hit the repeater in this instance - and a mobile radio programmed as above won't hear the repeater, just the other radios. Guess this will work for instances where you can't understand what's being sent via the repeater - you'll only hear local radios - but the dispatcher may be able to still receive your transmissions. You just won't ever hear the dispatcher.

Interesting.