One frequency, multiple users...

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One frequency, multiple users...

Postby Wiggy » Thu May 31, 2018 3:16 am

Hi folks,
Ive been listening to a frequency that i came across while searching and it seems to be local taxi firm, but while they are going about their business, i then heard blokes talking about wagons, and other bits and pieces, and that sounds like a builders firm, then tonight i heard two foreign men, which could be a pizza place but how are they all on the same frequency and how would i go about separating them? The taxi's are on DMR, not sure about the others. Anyone got any ideas?

I get bits of conversations like, can you pick up jack from the bingo, yeah just stick it on the wagon, would you like fries with that.... :tongue:

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Re: One frequency, multiple users...

Postby m0lsx » Thu May 31, 2018 8:37 am

Many repeaters have multiple users, that is two or more users.
What happens is, you will hear a beeping noise. This beeping is what is called, a time out. So each user has a set amount of time before their access to the repeater is cut off for a certain amount of further time.
Each user has a CTCSS tone on transmit & receive so they are both recognised going into the repeater & do not hear other radio traffic coming out.
The reason we (scanner users,) hear all the traffic through a repeater is. We do not normally use CTCSS on receive, if we did we would limit ourselves to one user, per frequency, repeater or no repeater.
But sometimes, using CTCSS on a repeater can be beneficial. For example I use to work at a recovery company & we shared a repeater with a Taxi company. I do not listen to Taxi's or amateur radio repeaters, as you get the same kind of mindless talk on both. So using CTCSS, I get what I want on that repeater & avoid the fools. HOWEVER, if a new user popped up on that repeater, I would miss it, as it would be silent to me as I am using CTCSS.
During the summer band conditions can mean some VHF & occasionally UHF signals can travel for 100's of miles. We call this a lift & during lift conditions using CTCSS would mean you loose a lot of stations.
As an example of lift conditions. I live in Norwich & the recovery trucks could access the repeaters from about 30 to 40 miles away most days. But during the Summer, on occasions I made contact with base from the bottom of the M6, about 150 miles away.
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Re: One frequency, multiple users...

Postby G4RMT » Thu May 31, 2018 9:09 am

Yep - Alan's absolutely right. I have 3 light users on my repeater, totally unaware the others exist. The only time it is an issue is when two call at the same time, and they have a bit of a fight. They just put it down to occasional interference. I'd be worried about sharing with a taxi firm however, because they would use it too much to share effectively. Usually these users have a comms package - they probably rent the radios, and part of the deal is the repeater time. One of my users I hardly ever hear, and it's very much something they use when their phones go flat I think - I charge them less than the others. On my repeater, when they let go of the PTT button, there is a short pause, then a beep, and if they don't reply, it then shuts down - which is how most people set them. Repeaters don't have to do this - some simply shut down as soon as the PTT is released. The beep gives them confidence that the repeater can hear them.
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Re: One frequency, multiple users...

Postby m0lsx » Thu May 31, 2018 9:34 am

G4RMT wrote: On my repeater, when they let go of the PTT button, there is a short pause, then a beep, and if they don't reply, it then shuts down - which is how most people set them. Repeaters don't have to do this - some simply shut down as soon as the PTT is released.


Wiggy. On amateur radio repeaters, you will often hear a Dah Dit Dah at the end of an over, this is the letter K & in in morse code shorthand it means listening.
It is VERY poor practice but all too often you will hear badly educated radio amateurs just keying up a repeater. That is just keying their mike. To see if the repeater answers them. That is, does the repeater come to life & gives a letter K or it's callsign & tone (CTCSS) code.
A properly trained & competent ham, key's the mike, gives their call sign & says checking access.
When I used VHF repeaters, I use to find checking access properly often got me a good QSO. As it shows it's someone who operates properly & thus it's more likely to be someone you want to talk to to & not the usual amateur repeater type of operator.
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Re: One frequency, multiple users...

Postby Minus1 » Thu May 31, 2018 10:20 am

Could be a common base station (they'll be a corresponding mobile input freq); or it could be a Simple UK freq.
In either case they will have a different CTCSS or DCS (or Talk Group if digital).
I reserve the right to ignore people who have made no attempt to the read the manual, and expect others to do it for them.
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Re: One frequency, multiple users...

Postby G4RMT » Thu May 31, 2018 5:02 pm

Pedant mode on.
K & in in morse code shorthand it means listening

K is an invitation to transmit - as on "over" - it doesn't mean you are listening (which of course you are waiting for them to reply. It concludes with AR. Some people actually use KN, rather than K, for the "over" because that signifies a specific station to reply - so two people can go back and forth a few times, passing info, without somebody else cutting in, or thinking it might be for them. Other people on the net hear the KN and just stand by.
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Re: One frequency, multiple users...

Postby GalaxianFive » Thu May 31, 2018 5:54 pm

Sometimes once you have identified the CTCSS codes to the various users it can be really interesting. There are at least 2 main repeaters in the Norfolk and Norwich area. One is 164.4375 and the codes I have ID are 110.9 breakdown co. 151.4 slot machine maintainers, 250.3 a cab co [don't know which]. The other is 164.875, codes are, 94.8 Herbert Woods broads boat yard mechanics, 103.5 Taxis, and 110.9 Broads Tours passenger boats at Wroxham. I have these programmed in to consecutive channels in order with another channel programmed with CTCSS on search in case a new user shows up.
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Re: One frequency, multiple users...

Postby Chris P » Thu May 31, 2018 7:25 pm

G4RMT wrote:Pedant mode on.
K & in in morse code shorthand it means listening

K is an invitation to transmit - as on "over" - it doesn't mean you are listening (which of course you are waiting for them to reply. It concludes with AR. Some people actually use KN, rather than K, for the "over" because that signifies a specific station to reply - so two people can go back and forth a few times, passing info, without somebody else cutting in, or thinking it might be for them. Other people on the net hear the KN and just stand by.




Nothing wrong with being pedantic , if those in the know dont pass on their knowledge to those who dont know they will never progress
Regards Chris aka G8FFF nipper or tazmin88
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Re: One frequency, multiple users...

Postby Wiggy » Thu May 31, 2018 9:52 pm

Cheers for all the info... now i'll have to go and read up about all this ctcss stuff :)
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Re: One frequency, multiple users...

Postby m0lsx » Thu May 31, 2018 10:24 pm

G4RMT wrote:Pedant mode on.
K & in in morse code shorthand it means listening

K is an invitation to transmit - as on "over" - it doesn't mean you are listening (which of course you are waiting for them to reply. It concludes with AR. Some people actually use KN, rather than K, for the "over" because that signifies a specific station to reply - so two people can go back and forth a few times, passing info, without somebody else cutting in, or thinking it might be for them. Other people on the net hear the KN and just stand by.


Thanks for that.
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