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GMRS tone codes between radio manufacturers


Guest Murf'n'surf
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Guest Murf'n'surf

Hey guys and gals!  New to GMRS and tasked with setting up a Rugged Radio GMR45 and Back Country BC Link 2.0 walkies.  As far as documentation goes they both use the same tone codes between the 2.  My problem is that both radios don't seem to  TX and RX on every tone code that I am trying.  When using the straight whole number channel for example 17, they both RX and TX just fine.  If I try any tone code with the GMR45 set on T SQ or SQ DCS(which I'm reading are for TX and RX) there is only TX (usually) on the GMR45.  The BC Link radios RX the GMR45 but the GMR45 does not RX the BC Link walkies.  Sorry if I am rambling and confusing anyone!   

Bottom line.....why cant I use tone codes between the radios? What an I missing?

 

Random info I see from the Rugged GMR45 radio programmer tool:

 462.60000       Simplex    FM Narrow    C 17    T Sql    100.0 Hz    100.0 Hz      

I can change the Simplex to Plus and the FM Narrow to FM

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Not being familiar with your specific radios, here is some general info & considerations.

Unless you are using a repeater between you radios, you will want leave then in simplex mode.  

You will be better off (IMO) changing to wideband instead of narrow.  If the only options are "FM" or "FM Narrow" then select FM.

Do the BC link radios receive each others Tx on the 100.0 Hz tone?

Make sure both GMR45 and BC link are in simplex mode, wideband, and the same Sql Tone. Make sure all other variable remain the same as when they work without the tones and try again. (power level, location, obstructions, etc.) 

Changing from Narrow to Wide band might solve the problem, but if it doesn't there are plenty on helpful operators in this forum.

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The BC Link web pages and manual aren't firm on it, but from the lack of mention of a GMRS license it reads, to me, that these are (2017 FCC) FRS radios, and only operate on 12.5kHz... So using NFM on the GMR45 might be reasonable (otherwise the difference between 12.5kHz and 20kHz [FCC spec for GMRS] may result in some odd sounding voices or clipping). cf: https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-95/subpart-B?toc=1

The GMR45, OTOH, does need a license. Normal GMRS bandwidth is 20kHz on (using the FCC consolidated channel scheme) 15-22 (the original GMRS channels -- from back in the day when a license was only authorized TWO of the channels) AND on GMRS interstitial channels 1-7 (which were available to all GMRS licenses, but at a low power limit, because they were stuck between each primary channel and overlapped). 8-14 weren't part of the GMRS channel line-up -- they were originally FRS (0.5W/12.5kHz) channels snuck between GMRS repeater input frequencies. They are still limited to 0.5W NFM. cf: https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-95/subpart-E?toc=1

I'd concur with the prior respondent: first ensure all radios interoperate with no tone squelch. (Set the GMR45 to its lowest power mode -- and maybe walk a ways down the street; it may be putting out so much power that it is overloading the front-ends of the BC-Link units).

Then, verify that the BC-Link units work when both are set to the same channel and CTCSS code (these are not really "privacy" codes -- any radio /not/ configured for CTCSS can hear you; they just mean you don't hear others unless they are set to the same code). The handhelds appear to be full CTCSS encode/decode. The mobile has options for tone encode only (sometimes used to get into a repeater, but the repeater does not send a tone back) and encode/decode (T vs TSQ on display).

Don't try to use both CTCSS and DCS at the same time (the handhelds don't do DCS). CTCSS is just a subaudible continuous single tone. DCS is a serially encoded "number" that has to be matched by the receiver..

 

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  • 1 month later...
Guest Murf'n'surf
On 6/23/2022 at 7:30 PM, WRDB702 said:

Not being familiar with your specific radios, here is some general info & considerations.

Unless you are using a repeater between you radios, you will want leave then in simplex mode.  

You will be better off (IMO) changing to wideband instead of narrow.  If the only options are "FM" or "FM Narrow" then select FM.

Do the BC link radios receive each others Tx on the 100.0 Hz tone?

Make sure both GMR45 and BC link are in simplex mode, wideband, and the same Sql Tone. Make sure all other variable remain the same as when they work without the tones and try again. (power level, location, obstructions, etc.) 

Changing from Narrow to Wide band might solve the problem, but if it doesn't there are plenty on helpful operators in this forum.

"Unless you are using a repeater between you radios, you will want leave then in simplex mode"

-- Correct, there is no repeater and the radio is set to simplex mode.

 

"You will be better off (IMO) changing to wideband instead of narrow.  If the only options are "FM" or "FM Narrow" then select FM."

-- Switched to FM and no change.  The BCA is heard on the Rugged but not vice versa.

 

"Do the BC link radios receive each others Tx on the 100.0 Hz tone?"

--Yes, BCA to BCA comms are good on the 100hz.  There is also good 2 way comms between the Rugged and BCA without tone codes.  Soon as you use tone codes the Rugged can not be heard on the BCA except Channel E21 162.2hz--- that tone code works.

 

"Make sure both GMR45 and BC link are in simplex mode, wideband, and the same Sql Tone. Make sure all other variable remain the same as when they work without the tones and try again. (power level, location, obstructions, etc.) "

--Done....no change.

 

 

Radios were tested apart from each other 50'-100' with no change.

 

I am open to any other ideas. Attached below is the channel list that I have loaded into the Rugged GMRS, perhaps someone will see the problem?

 

 

Receive Frequency    Transmit Frequency    Offset Frequency    Offset Direction    Operating Mode    Name    Tone Mode    CTCSS    Rx CTCSS    DCS    Rx DCS    DCS Polarity    Tx Power    Skip    Busy Channel Lockout    Comment  

 

 

462.56250              Simplex    FM Narrow    1    None    67.0 Hz    94.8 Hz    023    023    Both N    Low    0    Off    
462.56250              Simplex    FM Narrow    1-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    Low    0    Off    
462.56250              Simplex    FM Narrow    1-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    Low    0    Off    
462.58750              Simplex    FM Narrow    2    None    67.0 Hz    67.0 Hz    001    001    Both N    Low    0    Off    
462.58750              Simplex    FM Narrow    2-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    Low    0    Off    
462.58750              Simplex    FM Narrow    2-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    Low    0    Off    
462.61250              Simplex    FM Narrow    3    None    67.0 Hz    67.0 Hz    001    001    Both N    Low    0    Off    
462.61250              Simplex    FM Narrow    3-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    Low    0    Off    
462.61250              Simplex    FM Narrow    3-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    Low    0    Off    
462.63750              Simplex    FM Narrow    4    None    67.0 Hz    67.0 Hz    001    001    Both N    Low    0    Off    
462.63750              Simplex    FM Narrow    4-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    Low    0    Off    
462.63750              Simplex    FM Narrow    4-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    Low    0    Off    
462.66250              Simplex    FM Narrow    5    None    67.0 Hz    67.0 Hz    001    001    Both N    Low    0    Off    
462.66250              Simplex    FM Narrow    5-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    Low    0    Off    
462.66250              Simplex    FM Narrow    5-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    Low    0    Off    
462.68750              Simplex    FM Narrow    6    None    67.0 Hz    67.0 Hz    001    001    Both N    Low    0    Off    
462.68750              Simplex    FM Narrow    6-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    Low    0    Off    
462.68750              Simplex    FM Narrow    6-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    Low    0    Off    
462.71250              Simplex    FM Narrow    7    None    67.0 Hz    67.0 Hz    001    001    Both N    Low    0    Off    
462.71250              Simplex    FM Narrow    7-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    Low    0    Off    
462.71250              Simplex    FM Narrow    7-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    Low    0    Off    
462.55000              Simplex    FM Narrow    15    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.57500              Simplex    FM    B 16    T Sql    82.5 Hz    82.5 Hz    001    001    Both N    High    0    Off    
462.55000              Simplex    FM    A 15    T Sql    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.55000              Simplex    FM Narrow    15-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.57500              Simplex    FM Narrow    16    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.57500              Simplex    FM Narrow    16-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.60000              Simplex    FM Narrow    17    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.60000              Simplex    FM    C 17    T Sql    100.0 Hz    100.0 Hz    001    001    Both N    High    0    Off    
462.60000              Simplex    FM Narrow    17-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.62500              Simplex    FM Narrow    18    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.62500              Simplex    FM Narrow    18-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    High    0    Off    
462.62500              Simplex    FM Narrow    18-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.65000              Simplex    FM Narrow    19    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.65000              Simplex    FM Narrow    19-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    High    0    Off    
462.65000              Simplex    FM Narrow    19-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.67500              Simplex    FM Narrow    20    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.67500              Simplex    FM    D 20    T Sql    123.0 Hz    123.0 Hz    001    001    Both N    High    0    Off    
462.67500              Simplex    FM Narrow    20-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.70000              Simplex    FM Narrow    21    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.70000              Simplex    FM    E 21    T Sql    162.2 Hz    162.2 Hz    001    001    Both N    High    0    Off    
462.70000              Simplex    FM Narrow    21-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.72500              Simplex    FM Narrow    22    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.72500              Simplex    FM    F 22    T Sql    218.1 Hz    218.1 Hz    001    001    Both N    High    0    Off    
462.72500              Simplex    FM Narrow    22-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.55000             Plus    FM Narrow    RPT 15    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.57500             Plus    FM Narrow    RPT 16    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.60000             Plus    FM Narrow    RPT 17    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.62500             Plus    FM Narrow    RPT 18    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.65000             Plus    FM Narrow    RPT 19    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.67500             Plus    FM Narrow    RPT 20    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.70000             Plus    FM Narrow    RPT 21    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.72500             Plus    FM Narrow    RPT 22    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    

 

 

 

 

 

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Guest Solution found.....

I have run across the solution.  For whatever reason the channels above 14 wont work with tone codes except channel 20.  Seems as if the BCA radios are made or programmed that way; to not receive on those frequencies with a tone code.

 

Problem solved and hope this helps somebody in the future.  Over.

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4 hours ago, Guest Murf'n'surf said:

--Yes, BCA to BCA comms are good on the 100hz.  There is also good 2 way comms between the Rugged and BCA without tone codes.  Soon as you use tone codes the Rugged can not be heard on the BCA except Channel E21 162.2hz--- that tone code works.

What type of numbering scheme does that radio use? "E21"???

4 hours ago, Guest Murf'n'surf said:

462.56250              Simplex    FM Narrow    1    None    67.0 Hz    94.8 Hz    023    023    Both N    Low    0    Off   
462.56250              Simplex    FM Narrow    1-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    Low    0    Off    
462.56250              Simplex    FM Narrow    1-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    Low    0    Off    
462.58750              Simplex    FM Narrow    2    None    67.0 Hz    67.0 Hz    001    001    Both N    Low    0    Off    
462.58750              Simplex    FM Narrow    2-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    Low    0    Off    
462.58750              Simplex    FM Narrow    2-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    Low    0    Off    
462.61250              Simplex    FM Narrow    3    None    67.0 Hz    67.0 Hz    001    001    Both N    Low    0    Off    
462.61250              Simplex    FM Narrow    3-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    Low    0    Off    
462.61250              Simplex    FM Narrow    3-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    Low    0    Off    
462.63750              Simplex    FM Narrow    4    None    67.0 Hz    67.0 Hz    001    001    Both N    Low    0    Off    
462.63750              Simplex    FM Narrow    4-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    Low    0    Off    
462.63750              Simplex    FM Narrow    4-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    Low    0    Off    
462.66250              Simplex    FM Narrow    5    None    67.0 Hz    67.0 Hz    001    001    Both N    Low    0    Off    
462.66250              Simplex    FM Narrow    5-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    Low    0    Off    
462.66250              Simplex    FM Narrow    5-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    Low    0    Off    
462.68750              Simplex    FM Narrow    6    None    67.0 Hz    67.0 Hz    001    001    Both N    Low    0    Off    
462.68750              Simplex    FM Narrow    6-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    Low    0    Off    
462.68750              Simplex    FM Narrow    6-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    Low    0    Off    
462.71250              Simplex    FM Narrow    7    None    67.0 Hz    67.0 Hz    001    001    Both N    Low    0    Off    
462.71250              Simplex    FM Narrow    7-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    Low    0    Off    
462.71250              Simplex    FM Narrow    7-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    Low    0    Off    
462.55000              Simplex    FM Narrow    15    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.57500              Simplex    FM    B 16    T Sql    82.5 Hz    82.5 Hz    001    001    Both N    High    0    Off    
462.55000              Simplex    FM    A 15    T Sql    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.55000              Simplex    FM Narrow    15-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.57500              Simplex    FM Narrow    16    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.57500              Simplex    FM Narrow    16-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.60000              Simplex    FM Narrow    17    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.60000              Simplex    FM    C 17    T Sql    100.0 Hz    100.0 Hz    001    001    Both N    High    0    Off    
462.60000              Simplex    FM Narrow    17-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.62500              Simplex    FM Narrow    18    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.62500              Simplex    FM Narrow    18-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    High    0    Off   
462.62500              Simplex    FM Narrow    18-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.65000              Simplex    FM Narrow    19    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.65000              Simplex    FM Narrow    19-10    T Sql    94.8 Hz    94.8 Hz    001    001    Both N    High    0    Off    
462.65000              Simplex    FM Narrow    19-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.67500              Simplex    FM Narrow    20    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.67500              Simplex    FM    D 20    T Sql    123.0 Hz    123.0 Hz    001    001    Both N    High    0    Off    
462.67500              Simplex    FM Narrow    20-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.70000              Simplex    FM Narrow    21    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.70000              Simplex    FM    E 21    T Sql    162.2 Hz    162.2 Hz    001    001    Both N    High    0    Off    
462.70000              Simplex    FM Narrow    21-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.72500              Simplex    FM Narrow    22    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.72500              Simplex    FM    F 22    T Sql    218.1 Hz    218.1 Hz    001    001    Both N    High    0    Off    
462.72500              Simplex    FM Narrow    22-25    T Sql    156.7 Hz    156.7 Hz    001    001    Both N    High    0    Off    
462.55000             Plus    FM Narrow    RPT 15    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.57500             Plus    FM Narrow    RPT 16    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.60000             Plus    FM Narrow    RPT 17    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.62500             Plus    FM Narrow    RPT 18    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.65000             Plus    FM Narrow    RPT 19    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.67500             Plus    FM Narrow    RPT 20    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.70000             Plus    FM Narrow    RPT 21    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off    
462.72500             Plus    FM Narrow    RPT 22    None    67.0 Hz    67.0 Hz    001    001    Both N    High    0    Off   

I have no idea how you are numbering those channels. What does x-10 & x-25 represent? Other than that you have them set for TSQL (both send and RECEIVE the tone to be active).

You seem to have repeated each simplex channel three times with NO-TONE, TSQL, TSQL with what appears to be randomly selected CTCSS tones. Personally, I'd have clustered the NO-TONE channels first, followed by repeater channels; essentially, the stock bare-bones 30 (less 8-14, so occupying 23 slots) -- and then put any customized tone channels after them.

AS an aside, the BTech GMRS-V1 has 128 channel slots... BUT ONLY 1-30 will transmit on GMRS frequencies! Slots 31-128 are receive only/scanner slots. The -V2 model "fixed" that -- any slot can be programmed for GMRS frequencies, and will transmit on that frequency.

In the 2017 reorganization, the standard channel numbers are...

1-7 FM(wide), up to 5W ERP, interstitials
8-14 NFM, up to 0.5W ERP, 467MHZ (FRS) interstitials (Judging by what is shown, you don't have any of these -- I'll presume a mobile rig that only goes to 5W low-power)
15-22 FM(wide), up to 50W output, main/primary channels
23-30 (alternately some variant of RP15-22, 15-22R, etc.) FM(wide), up to 50W output, main/primary repeater shift.

... which may align with what you are using, but the naming is, as mentioned, confusing.

So... First step is to set ALL the channels you list to FM(wide), just to minimize incompatibilities with REAL GMRS radios. If you want to set up auxiliary channels JUST for NFM for contact with FRS radios, I'd put them at the end of the memory.

Have you confirmed that the HTs aren't just accepting anything -- that is: set different tones on them and confirm that they do not open squelch on the other unit.

TSQL (CTCSS), on most of the programmers I have say the radio will send the specified tone, and requires the specified tone on receive.
TONE (CT), means the radio will send the specified tone, but does not require a tone for receive.
DCS is a totally different system -- digital coded squelch. Rather then sending a single tone, it sends a binary sequence representing the selected number.

 

FYI: in the old days, 462.675/467.675 was an FCC designated emergency/traveller assistance frequency, and many repeaters allowed access using, I think, 141.3 tone. If you can't transmit tones on 15+ (including repeater config) you will not be able to access any repeaters -- pretty much all of them require a tone to access.

 

Having said all that -- it very much sounds more like the fault is in the HTs, not the mobile unit. They seem optimized to be set up for 6 or so "preset"  (A-F) channel configurations (allowing the same frequency to be used multiple times but with different tone settings) rather than allowing direct access to any of the GMRS/FRS channels.

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17 hours ago, KAF6045 said:

FYI: in the old days, 462.675/467.675 was an FCC designated emergency/traveller assistance frequency, and many repeaters allowed access using, I think, 141.3 tone.

Does anyone have a link to this?  I keep seeing this sprinkled throughout various forums, but I can never find the actual FCC document.

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It was on our license back in the day. I'm not sure I have any old copies around. Never specified a PL tone just 462.675/467/675. Then you only got one frequency when you got a GMRS channel. My first one was 462.625/467.625.

Later on a few of the larger GMRS based groups pushed the 141.3 as a traveler code. Our area had a REACT repeater on 131.8 (still active today) but was an old repeater that used reeds. I searched for 2 years and finally gave up. Some history on that is here and is a good read. http://www.nsea.com//index_files/nseainfo.htm

Our REACT team was very involved in GMRS and CB at the time. Sadly it fell apart as soon as most of the guys went to HAM radio. Our SAR team took over the GMRS repeater and have upgraded it a few times. Its on the schedule to be replaced this fall and will incorporate the 141.3 in the list of available PL tones. 

 

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7 hours ago, back4more70 said:

Does anyone have a link to this?  I keep seeing this sprinkled throughout various forums, but I can never find the actual FCC document.

Unfortunately, I don't think FCC Part 95 archives exist on the net. We're talking regulations from before 1995. My reference is "General Mobile Radio Service National Repeater Guide 10th Edition" from the (defunct) "Personal Radio Steering Group".

From Wikipedia https://en.wikipedia.org/wiki/International_distress_frequency#Other_frequencies

Quote

GMRS: 462.675 MHz is a UHF mobile distress and road information calling frequency allocated to the General Mobile Radio Service and used throughout Alaska and Canada for emergency communications; sometimes referred to as "Orange Dot" by some transceiver manufacturers who associated a frequency with a color-code for ease of channel coordination, until the creation of the Family Radio Service, in 1996, "GMRS 675" or Channel 6/20 on mobile radios today. Its bandwidth can vary between 12.5, 25 and 50 kHz, and is also allocated to Ch. 20 on 22-channel FRS/GMRS "blister pack" radios. It can have a repeater input frequency of 467.675 MHz, and a tone squelch of 141.3 Hz. After FCC deregulation of simplex FRS/GMRS radios, FRS users may transmit up to 2 watts on the GMRS emergency channel 20 (462.675 MHz) with 141.3 Hz CTCSS, or channel 20-22.

In those days, a GMRS license authorized one to use TWO (out of 8, selected by licensee on application) main Frequencies (one didn't refer to channel numbers, but to the .XXX part of the frequency). Most all GMRS radios (part 90 business types) just had an A/B toggle to select between the two frequencies. It was recommended that one include the .675 frequency as one of the channels.

The Maxon GMRS 210+3 HT was somewhat hot in 1994/1995 as it had 10 channels -- the somewhat recently created interstitials (what are now channels 1-7), channel 8 was the .675 frequency as it was legal to use that frequency for emergency/traveller assistance even if it was NOT one of the two frequencies listed on one's license, and channels 9&10 -- which were to be programmed by a radio shop for the two frequencies on one's license (but Maxon shipped the 6 page programming manual with the radio; programming consisted of taking the back cover off the radio, pressing a micro-button switch, then dialing up the first frequency for channel 9, then pressing the button again to dial up the frequency for channel 10). Duplex/Simplex was handled by a front-panel button.

If .675 was listed on the license, the licensee could use it for routine traffic, not just emergency/traveller assistance.

 

 

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On 8/23/2022 at 7:21 PM, back4more70 said:

Then I guess we should push the FCC to create one more GMRS frequency for emergencies lol.  That should start a fight somewhere.

I'd favor pushing Congress to renegotiate the Line-A restrictions with Canada as their GMRS service includes the two frequency (pairs) that can't be used in half of Michigan. It may have made sense back before Canada created a GMRS service (granted, theirs is closer to our FRS service: <2W power, NO REPEATERS) and they recommended that former users of the "GMRS" frequencies should move to different bands, or put up with interference by GMRS. That implies that our usage of the Line-A frequencies for GMRS should not be a true conflict with other users on the Canadian side if they selected to retain the frequencies for their "other service" license. The only sticking point is that, with no repeaters, the 467MHz input frequencies are hanging in the air and might be a problem if that segment gets assigned to some other usage (Okay, so we have no /repeaters/ on the Line-A group, but simplex should be allowed in the 462 segment).

The Amateur band restrictions on Line-A probably still remain.

Oh, I also found, somewhere a recommendation suggesting:

  • 01 as a simplex calling channel
  • 03 as simplex emergency channel
  • 17 as an emergency channel (I presume simplex and repeater)
  • 20 (the original emergency/traveller assistance channel) as... Emergency/Traveller Assistance (again simplex and repeater)

and I labeled 19 and 21 as Line-A exclusion. (also managed to discover the repeater that seems to cover much of Grand Rapids -- by using a radio with tone scan, I locked onto a tone for it. The repeater on that frequency/tone is listed in my near 20-year old GMRS repeater directory... Belongs to the City of Grand Rapids -- and is available to general users only for Emergency/Traveller Assistance (prior permission needed for other uses [at the time of the book -- suspect they'd be shocked to get a phone call or letter asking for permission to use the repeater these days]).

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