Monitoring ground repeater

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majoco

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You have to separate Air Traffic Control from all the other users - company offices, ramp marshalls etc. In the UK they run a multicarrier system where, say, the route from Prestwick to London is controlled by one controller on the same frequency all the way. That system has been in use since the mid-60's when I was working for the CAA - a trial was carried out on a back route and worked very well.

I can't find any real technical document on how it works but here's a bit of info...

https://www.pprune.org/atc-issues/512812-multiple-atc-transmitters.html
 
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DaveNF2G

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I think some are becoming confused about the thread because, at least in North America, ATC is not the only permissible use of the VHF aeronautical band.
 

kayn1n32008

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Yet another person who apparently didn't watch the video

You are correct. I did not watch the video. My apologies.

or didn't understand that the ATC in that video was being relayed to a remote transceiver via UHF as is commonly done in the UK.

It has EVERYTHING to do with remote sites and linking to remote transmitters, but apparently you don't understand how the technology works over there, or in general.

I am guessing that ATC is linked on UHF, simply due to the short distances they have to deal with in Britain.

In North America, it can be hundreds, possibly thousands of kilometers from where the ATC's are looking at screens to the ATC transmitter sites. it is just not practical to link on UHF in North America.
 

majoco

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I am guessing that ATC is linked on UHF, simply due to the short distances they have to deal with in Britain.
In the first trials the linking was done with the voice network that ATC used - good old telephones - not dial-up of course. Every control desk had a press-to-talk lever that instantly connected him to the next controller down the track or whichever route the aircraft was taking. The problem of communication was being solved in 1974 when I left with the construction of the massive centre at West Drayton - right by Heathrow Airport. Now there are two major centres which control the upper airspace and the other smaller control centres. Now it loooks like that has been reduced in size now, although the amount of traffic going to/from or over the UK is massive. Swanwick is down by Southampton, Prestwick of course us up on the west coast of Scotland.


NATS Swanwick

This centre started operating in January 2002, when it began handling aircraft flying over England and Wales. The operations room in Swanwick combines:

London Area Control Centre (LACC), which manages en route traffic in the London Flight Information Region. This includes en route airspace over England and Wales up to the Scottish border.
London Terminal Control Centre (LTCC), which handles traffic below 24,500 feet flying to or from London’s airports. This area, one of the busiest in Europe, extends south and east towards the coast, west towards Bristol and north to near Birmingham.
Military Air Traffic Control. Military controllers provide services to civil and military aircraft operating outside controlled airspace. They work closely with civilian controllers to ensure safe co-ordination of traffic.

NATS Prestwick

With the opening of the new Prestwick Centre in 2010, we consolidated our air traffic control centres from four to two – reducing costs, and increasing security and operational efficiency.

The operations room in Prestwick combines:

Manchester Area Control Centre (MACC), which controls aircraft over much of the north of England, the Midlands and north Wales from 2,500 feet up to 28,500 feet.
Scottish Area Control Centre (ScACC), which controls aircraft over Scotland, Northern Ireland, Northern England and the North Sea from 2,500 feet up to 66,000 feet.
Oceanic Area Control Centre (OACC), which controls the airspace over the eastern half of the North Atlantic from the Azores (45 degrees north) to a boundary with Iceland (61 degrees north).
 
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majoco

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At our relatively small airport in NZ, the company ops office ran all the ramp, refuellers, catering, passenger handling etc by Motorola handheld on a UHF trunking network - only had three channels and no connection to the tower on any frequency. Us engineers also had an airband handheld as well with full coverage of frequencies which is why we had to pass our FRTO exams. About the only time we had to call the tower on the ground frequency was to request permission to cross a live taxiway or runway - there was no rebroadcast of any ATC comms into the trunking network. If we wanted to talk to an incoming aircraft we used the company frequency on 131.8MHz. No aircraft had a UHF Tx/Rx, If the aircraft wanted to call ops they used 131.8 too - we could hear their communication as well and sometimes the aircraft would call us direct and maybe go to another company frequency for a discussion of a problem, 133.4MHz.
 

morfis

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This has become one of the most confusing threads I've looked at for a good while.

Can't say whether there are tower-ground repeaters in the USA as I don't really listen to such things. Dave mentions that he has monitored similar use in the USA and to me it would seem a very useful facility and likely to be commonplace.

However, it is normal at large airports (civil and military) in the UK to have repeaters for use AT the airfield. They allow ground vehicles to monitor the tower and ground traffic movements as necessary using the repeaters so they can remain situationally aware. Those repeaters are NOT to link different ATC sites or even different airports. The chap in the video is talking about monitoring it from the fence-line at Ringway but in some directions it can be picked up from several miles away.
At smaller airfields (an example near the guy in the video would be Barton Aerodrome) the ground vehicles usually carry a handheld airband transeiver as well as their own UHF ops transeiver.

From memory the UHF link frequencies are around 455MHz and can easily be found for each airfield on the days that OFCOM's licence database is actually working (the database doesn't show which frequencies are repeated).
 

SCPD

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I know a couple air force bases in the US that will simulcast AM tower, ground, approach to its federal trs. Though the talkgroup system end is encrypted on them they do, do this. AM side clear obviously but the trs strapped. Seems to be at certain points they will patch or simulcast. I couldn't say more to why or if it's during peak or certain operations.
 

737mech

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KALB follow up

Ok confirmed it with SWA KALB. Crossband repeater at KALB brings the Aircraft VHF 131.8 to the Ops Agent's handheld UHF 464.8875. When they need to they can switch to channel 2 and talk back to the aircraft. Convenient for a small station that has few flights and few personel. The rampers and customer service only have the uhf they cannot hear aircraft on their handhelds. Most of the larger stations have an operations coordinator that sits at a desk with two radios. KALB does not have a coordinator. The very busy stations in the system are moving to Cap Plus DMR radios for RAMP/OPS/Provo/CSA/and Maintenance. The aircraft are only VHF as expected.

These guys set it up https://www.acgsys.com/
 
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ATCTech

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Well done 737mech, that confirms what Dave is hearing on UHF.

Cheers!
 

majoco

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Are you sure that what you hear on 131.8MHz is actually ATC or a company frequency? That info that 737Mech explained doesn't sound that much different to the ops system that I experienced above, except there was no UHF rebroadcast from the 131.8 company frequency - note "company" not ATC. Every other company had their own UHF channel on the trunking system and their own VHF frequency for aircraft to their ops office. All us ramp engineers had a VHF chat channel between companies - can't remember what it was now, 129. something.
 

alcahuete

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Nice job 737mech! Thanks for doing the research with company.

It was exactly as we both knew and said on Page 1. It is NOT ATC, it is ops, and there are no UHF radios on the aircraft.
 

nr2d

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At ACY the FAA Tech Center has a VHF FM to VHF AM Comm translator. The Am side is for ground control. This system was installed many years ago in order to provide a convenient way for ground vehicles can talk to the ground control with out having to carry multiple radios. No aircraft that I know of use this link.

The link is used on a daily basis. The FM side is in the US Government VHF FM band 162 - 174 MHz.
 
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PrivatelyJeff

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Reminds me of something similar my local navy air base had. My dad was a civilian paramedic and they could monitor flight/tower communications via a mil-air/uhf repeater (EMS is uhf here). They could talk back to the tower to on the frequency but I don’t believe it went out to the pilot. Someone also set up (without the navy actually knowing it) a tower to FM radio broadcast.
 

AirScan

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Sort of related, I remember many years ago Syracuse, New York (SYR) used to re-broadcast the Tower transmissions on a FM commercial broadcast frequency so people watching planes from their cars could monitor the Tower on their car radios. The FM frequency was posted on a sign on the parking lot fence by the runway. Anyone know if they still do this ?

AS
 

majoco

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There must be a market for these things:

and

where the ground crews are not likely to have airband radios.

Icom wouldn't make a device for which there was no market.

You can't have any one walking around with an airband transmitter who has not passed his FRTO - Flight Radio Telephone Operator - course and exams.
 
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