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FDNY Repeaters in Reverse

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#1
Okay Radio Folks,

Help me out here.

Handheld Tactical Radio Channels

11 IN-BLDG RPTR
12 MOBILE RPTR
13 SUBW RPTR F1
14 SUBW RPTR F2

Can operate in the REVERSE mode. (see attached Picture)

To quote the FDNY Operational Reference Book "9th Edition" that just came out

http://www.fire-police-ems.com/books/bf1119.shtm (highly recommend it for anyone interested in the FDNY)

"...plus four "reverse" channels for use in the event of repeater failure. For channels 11-14 there 17-20 labeled REV"

These are sometimes referred to as "Talk Around".

See attached picture.

So ... just for my radio in my vehicle and at home, is the channel I see on the Motorola Mobile Unit just the UHF frequency with a different PL Tone to handle the "Reverse" side?

Not looking to transmit here, just looking to make sure my scanners at home and in the truck are programmed correctly. Not being a radio person, was hard for me to get my head wrapped around this.

My kind thanks,

JR
 

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#2
The URL you cited seems to be unavailable.

For reference, a "talkaround channel" in common parlance means this:
Repeater usually transmits A and receives B.
Talkaround transmits B and receives B.

Until you see the actual frequency assignments it's difficult to tell what exactly the "reverse"
setup means. However, we have FDNY people on this Board who will probably clear this up for you.
 
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#4
I am not familiar with FDNY specifics but I know that I have seen Med channels programmed as "reverse" to allow units to hear the mobile side. This allowed a unit to talk mobile to mobile by talking on the RX freq and listening on the TX freq. Example: 463.0000 TX, 468.0000 RX would allow the two radios to communicate in a pinch if the repeater went down and they dont have a true talkaround (463.0000 rx/tx). The downside is its pretty much limited to 2 users due to the different frequencies. I can't speak to the actual usefulness of this but I have seen it.
 
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#5
We were just talking in the house today, and a true "talk around" is the same as some departments call "DIRECT" which converts the radio from Duplex to Simplex. We are wondering if essentially that is all this is or is there more to it. The FDNY Operational Reference book states that and i'm paraphrasing here "... Units will be able to receive the transmission but the Command Post will be unable to hear the units..."

Looking forward to someone with some more knowledge providing input.
 

tbendick

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#6
OK. Here it is. Reverese is programmed the same way the repeater is. So in the event the repeater fails tge radio can act like a manual repeater. This to broadcast a message to switch back to channel 1. The reason we didn't use a talk around approach is that we can hear the units in case they didn't switch or get trapped.
 
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#8
I think tbendict is on the right page. The way I understand the "Reverse" side was to get a quick message out to units.

Do you have a frequency pair or can u list it here along with PL so I can program my radio.

Thanks
 

tbendick

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#9
Reverse is only on ht11 and 12 used in hirise buildings. Ht14 and 15 used in the subway.
program in the normal channels and then add an additional one which is 3megs up from each.

There is no mixer or mixer off with these. Subway repeater is on all the time and hirise is activated with a key at the fire command station. If these fail while in use we can use a post radio or battalion car radio on reverse to broadcast a message. Its simply switch back to channel 1. If a guy can't switch then we do have a chance of hearing them.
 
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#10
TBendick
You're spot on.

So what do I put in my radio at home and in the truck ?

Thx on this. Just not a radio guy. I can barely make my XTS5000 work right !
 
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#11
okay, lets break this down

Ch I.D. .........................freq out.....PL.........freq in......PL
11 IN-BLDG RPTR .........483.0125 PL 173.8..486.0125 PL 173.8
12 MOBILE RPTR.......... 484.7625 PL 173.8..487.7625 PL 173.8
13 SUBW RPTR F1........ 460.575 PL 110.9....465.575 PL 127.3
14 SUBW RPTR F2.........460.625 PL 103.5...465.625 PL 91.5

so in REVERSE (assumption here...)

17 REV BD RPTR...........486.0125 pl 173.8..483.0125 pl 173.8
18 REV MB RPTR...........487.7625 pl 173.8..484.7625 pl 173.8
19 REV SUBW F1..........465.575.. pl 127.3..460.575...pl 110.9
20 REV SUBW F2..........465.625...pl 91.5...460.625...pl 103.5

confusion points:

a) some colleagues believe it states in manuals that REV channels only transmit on the RX side and thus become a DIRECT / SIMPLEX frequency.

b) some documentation states that this provides only ONE-WAY communication and members can not talk back to the IC in SIMPLEX mode. Okay, that rules out that REV channels are "DIRECT" or "SIMPLEX" -- right ?

You can see in this example:

11 IN-BLDG RPTR .........483.0125 PL 173.8..486.0125 PL 173.8
17 REV BD RPTR...........486.0125 pl 173.8..483.0125 pl 173.8

The IC is transmitting on: 483.0125 allowing him to get a message out to units. Note that if all radios are programmed the same (they are) there is no way for the units to say to CMD, "we hear you, switching to HT-1 TAC-1"

Is this a flaw / does it make sense ?
 

GTR8000

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#12
I'm not sure what the confusion is over this, it's pretty simple. REVERSE does just that, allows the radio to mimic a repeater. That means it will transmit on what is normally the output, and will receive on what is normally the input. Why? Because if the repeater takes a dump, the units inside may not know to switch to a simplex frequency. By reversing the frequencies on one radio (generally would be done at the Command Post), they can be sure everyone who is still on the repeater channel will get the message, and will be heard if they key up on the input.

Tbendick isn't just "on the right page", the guy is on the job and knows what he's talking about.

Anyway, here it is illustrated so there's no confusion, using the In-Building repeater as the example:

Normal Operations with Repeater Active:

- Radios transmit on 486.0125 and receive on 483.0125

- Repeater transmits on 483.0125 and receives on 486.0125

Failed Repeater Operations with a radio at the Command Post in Reverse mode:

- Radios are still transmitting on 486.0125 and receiving on 483.0125

- Radio at Command Post mimics repeater and transmits on 483.0125 and receives on 486.0125


So, as we see from that example, when one of the radios at the Command Post is in Reverse Mode, they can hear any radio that keys up on the repeater input because they're monitoring that frequency, and likewise any radio still on the repeater channel will hear the Command Post because they are transmitting on the repeater output.

It's basically a full duplex system at that point, Base to Mobile and Mobile to Base. It's really not that complicated.

Just program the outputs and inputs and you'll hear both sides of the conversation no matter what channel they're on. Problem solved.
 
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