Radioactive logo.gif ACE HIGH

By Andy Emmerson


Here is a map showing the extent of the system, taken from an STC advertisement of 1961.

Photo:Dish antennas at Stenigot
Photo by David Farrant

Here are two more views of the station at Coldblow Lane taken in 1981. Coldblow was close to Detling Hill, between Sittingbourne and Maidstone, Kent. This first picture fails to give the true scale of the dishes, which looked monstrous—and made a good landmark when seen from the M2 motorway in the distance near Junction 5 (A249).

Photo by Andy Emmerson

The Coldblow site was sold by auction in September 1986. The auctioneer was the firm of Clive Emson, Maidstone. "All that was on offer were some brick one-storey buildings (with no secret bunkers attached!).

A microwave tower on the site was retained by the Ministry of Defence and access rights to the tower were built into the sale agreement. The dishes, a local landmark, had been removed the previous year." [information from David Mapley]

This would indicate the system closed during the early 1980s, which figures because the frequencies in which ACE HIGH operated were needed for the new Cellnet and Vodafone cellular radio systems, which opened in 1985. Television viewers in east Kent of a curious disposition (people like me!) who tuned above channel 68 could easily hear the ACE HIGH transmissions. They sounded just like whistles but some shortwave listeners claimed to have fed the audio into a communications receiver and have resolved individual conversations.

Duncan Campbell's book The Unsinkable Aircraft Carrier provides an insight into the applications for ACE HIGH (pages 188 and 62).

The main NATO international network is Ace High, a troposcatter relay network which has five British Stations in a chain from Sumburgh in the Shetlands to Coldblow Lane, near Maidstone. The Ace High network was built in the early 1960s, primarily in order tolink NATO heads of state together in crisis. Two of twelve US/NATO interconnection sites are in the UK, at Mormond Hill Aberdeen and Coldblow Lane.

From a site at Swingate in Dover, high on the celebrated chalk cliffs and overlooking the busy harbour and medieval castle, US Air Force transmitters beamed signals towards their counterpart networks run by the US Army and Air Force in France. This link ran on to US bases at Orleans and Bordeaux. A second connection to the Continent was made in March 1962, when a new communications station, at Martlesham Heath near Ipswich (Suffolk), was linked to Flobecq in Belgium.

In 1963, a longer-range link direct to Spain was built at Ringstead Bay, near Weymouth in Dorset. The link operated across hundreds of miles to Gorramendi, near Elizondo, in the Spanish Pyrenees.

Using massive billboard-style reflectors to direct enormous amounts of radio energy into the troposphere, novel ‘tropospheric scatter’ communications networks were all over the world.

Billboard reflectors at Swingate, Dover
photo by Bob Jenner

Troposcatter station at Ringstead Bay
With aerials 150 feet high, the Ringstead Bay proposal occasioned considerable local controversy, and the Air Ministry was legally challenged on whether they had the right to compulsorily purchase British land for American defence purposes. Amongst the objectors to the powerful new station was the Royal Navy, one of whose officers pointed out that it would cause ‘serious interference’ to the many RN radio stations operating around nearby Portland Bill. However, the station was built, but it was closed by 1970 and dismantled in 1974.

The Ringstead-Gorramendi link provided the High Wycombe Atomic Joint Co-ordination Centre with a direct connection to US nuclear forces straddling the Mediterranean in Spain itself, Morocco, at Wheelus Field near Tripoli in Libya, and further east. In order to provide the necessary microwave link relay stations, the US Air Force obtained four more facilities at Golden Pot, near Alton, Hants, Dean Hill near Salisbury, Bulbarrow Hill near Shaftesbury, and on Portland Bill.

This would indicate that the Ringstead and Martlesham Heath links were not directly part of ACE HIGH. However, they used exactly the same technologies and frequencies.

Frequencies used by ACE HIGH (taken from the ITU international catalogue of radio frequencies) ranged from 832.56 to 959.28MHz. The emission mode was F9 (frequency modulation, miscellaneous), and output powers typically 10kW to 50kW. Throw in the colossal antenna gain from the 80ft dishes and you can imagine the kind of power they radiated (up to 10 megawatts effective radiated power).

Click here for a picture of one of the 50kW transmiiters.

A stylised map of the routes inside and leaving Britain looks something like this:

Ringstead is in Dorset, between Weymouth and Lulworth. Binbrook is in Lincs., Boulmer in Northumberland.

The station noted as Martlesham Heath (Suffolk) has nothing to do with the BT research station but was at the USAF base along the Foxhill road; it had local microwave feeders to/from Great Bromley & RAF Bentwaters. Collafirth Hill is in the Shetlands, where a branch of the network went to Sola in Norway. [Research by G4DYA and G8PTH].

Note corrections too in Andrew Haworth's comments in Feedback section.

Terry Wiseman writes (August 2001):
A minor correction - the link in the East Midlands was not at Binbrook— but was at Stenigot. The four huge dishes were taken down about two years ago—but are still lying on the ground there. There are still signs pointing to NFTSS - NATO Forward Tropospheric Scatter Station. I have a couple of publications about Stenigot because it was part of the Chain Home Low network in the last war and after. I would imagine the technicians could well have been based at RAF Binbrook—the nearest convenient RAF facility.

Thanks Terry; the station is listed as Binbrook in the frequency list but it's clear that terminology was a bit slack. Coldblow is called 'London' in some entries and two names can be found for Collafirth Hill and Mossy Hill.

Terry Wiseman

Many years ago, as a Senior Signals Officer in the Civil Defence Corps, we were about to set up a mobile radio repeater station very near the USAF Signals facility at Golden Pot, near Alton (as mentioned in Duncan Campbell's piece above). I went over the facility and rang the bell on the gate—after explaining what I wanted the airman fetched the Officer out (we spoke through the gate—no way were they going to open the gate) and I asked him if our little repeater station would interfere with his communications.

His reply was: "Sir, if your frequencies are anywhere near ours, we will come over and sweep up the ashes as soon as you switch on your equipment."

From Brian Carter, ex Royal Corps of Signals (

I was extremely interested in the commentary on the ACE HIGH station at Coldblow Lane, especially the photograph taken in 1981. I was in fact the Station Commander at that time - that being my last tour of duty in the Armed Forces prior to retirement. I later attended the decommissioning of the station prior to its "sell-off". I actually left Coldblow Lane in February 1982. Sad really, when I remember how it used to be. I was also Station Commander for the ACE HIGH Station in Cyprus. I have a couple of photographs of that site, not very detailed I'm afraid, but does show the desolation of that particular site. It has gone now - I believe that the Greek Army now uses the buildings. The comms equipment will of course have been taken away or maybe destroyed.

I will dig out the Cyprus photos and send you a scan of them. The Cyprus station was a tail station, situated near Ayia Napa (Cape Greco in fact), "fed" from Turkey and with inland LOS shots to the appropriate agencies. Just down the road from us was a high-powered transmitter site that broadcast in Arabic and was "fed" by LOS link from, I think, Larnaca. Rumour had it then that the programmes originated in France. The station chief was French, of that I am certain. All in all, it made for interesting living over there in Cyprus, what with the political situation between Cyprus and Turkey and the fact that my NATO stores usually arrived through the Cypriot Customs organisation. NATO was a "dirty" word over there then.

Just another comment (well, the memories are flooding back !!!!). In the shots of the Stenigot Station, the transmitter designated UBOZ1 is entitled "Kent Transmitter". That was in fact one of the transmitters on the Boulmer link. Kent (or Maidstone transmitters) were designated UMAZ1 and UMAZ2. The Stenigot Station designation was UBIZ. Stenigot was my first station (other stations were Coldblow and Cyprus), so I feel I can speak with a bit of faded authority. We (the Royal Corps of Signals) took over the system from the RAF. The RAF took over, in exchange, the COMCAN system from the Signals. The comments from another of your "readers" regarding Binbrook are really quite correct. We (the brown jobs as the boys in blue called us) lived on the fighter station, Binbrook. It was a Lightning squadron in those days Stenigot was close to another small "village" called Welton Le Wold (umm, I think!!).

The system utilised quadruple diversity. That is both space and frequency diversity. I am starting to recall many stories - all true, maybe unbelievable. I enjoyed my time on the system. Anyway, time for my cocoa, maybe more later - if you can stand an old soldier recalling the past!

Before I forget. I made a mistake above. I actually took over Coldblow Lane in 1981 and left in January 1984. The Lord Lt. of Kent came up to the site to present some long service medals to some of my technicians the week before I finished.

And some more.....

I have just noted some dates that relate to the closure of the Coldblow Lane ACE HIGH site. I ended my service career there in February 1984. I was the Station Commander there for three years and so do have informed knowledge of the place. When I left in 1984 the station was still operational and I know it was so for at least another three years. So, I think the dates that you have recorded regarding the closure and removal of the antennae (1985?) are a bit out. I also attended the de-commissioning ceremony of the site and I am certain that this took place in the early/mid 1990s. At that time there was a 'skeleton' staff of Royal Signals personnel, although, by that time, the station was non-operational.

From Walter Elkins in Clearwater, FL (

Hi, I am Walter Elkins and I am the webmaster for the US Forces in Austria Veterans website ( I have been doing research on the history and mission of the US Army in Europe for over twenty years and also include in this research the role that the Air Force played in strategic communications and air defense. I have a couple of articles on the ACE HIGH project that I found in SIGNAL (early 1960s), the journal published by the Armed Forces Communications and Electronics Assn. One has a map that shows a little more deatil on the "main routes" and "tails" of the ACE HIGH network.

From John Myers, Pluto webmaster (

Hey, I came across your interesting website, and in particular, to your page devoted to ACE High. I'm doing a website devoted to a NATO site at which I was stationed in northern Italy--near Vicenza--in the mid-1970s. ( We had a communications system there known as the "green box", about which the commo people kept us in the dark. However, I know this was a tropospheric scattering system, and we would have used it, in the event of war with the Warsaw Pact, to receive messages that we would decode using one-time pads. This system did not have the huge antennas described on your website. Can you shed any light on what it might have been? [Please reply direct if you can]

From Linn Barringer (

I was sent your URL by an acquaintance who had an interest in the site at Martlesham Heath. While perusing your website I noted your comments about your picture being faded, so I thought you might like a version that has been 'colour-corrected' by me using Paint Shop Pro. I hope you like it (attached).

Most kind of you and now substituted for the original picture!
You may also be interested to know that I have a civil engineering drawing for the Water System (dated January 1968, with revisions up to January 1976) which also shows two line-of-sight(?) pointers from two of the antennas, showing bearing 334-deg 20' 21" TRUE TO FYLINGDALES and 334-deg 20' 46" TRUE. Among the drawing descriptions are "Martlesham Heath RRL." [RRL=radio relay link?]

I also have some pictures on my web site (which is mainly about the Twin Bases of RAF Bentwaters and RAF Woodbridge) - URL below.

From Andrew Haworth (

Several things to note about the ACE HIGH System:

1. The Tropospheric Scatter transmitters used were of 1kW and 10kW only. The main equipment was provided by REL (Radio Equipment Laboratory) of New York and consited of a two nominal 1kW transmitter coupled to the separated power amplifiers and quad receivers, which used frequency and space diversity. The 10kW power amplifiers where also provided by REL and used a four cavity water cooled klystron. The 1kW amplifiers where provided by Pye UK and were air cooled.

2. The map you show is the initial proposed one and is not correct. In the Shetland Isles the tropo station was Mossy Hill located 7 miles north of Sumburgh. There was then a LOS link relayed through Collafirth Hill ( which over looks the oil terminal at Sullum Voe) to RAF Saxa Vord. The LOS equipment was by NERA of Norway.

3. The Mossy Hill link to the Faroes was never impemented. It was provided by the Americans from Mormond HIll, co-located with the ACE HIGH Station.

4. Mossy Hill also provided the northern Europe link to Norway; this was the longest link in the ACE HIGH system and was over water for over 99% of its path. I suffered from slow speed and high speed fading but never failed, to my knowledge.

5. There was also a LOS link from Mormond hill to RAF Buchan, south of Peterhead.

6. When France left NATO a new link was put in from Cold Blow Lane to a site in Germany whose name I forget. The control centre was also moved the from Paris Nord, which was just outside Beauvais, famous for a cathedral that fell down and the airship R101 disaster. France did not leave the the ACE HIGH system. The new links put in to bypass France operated a 1kW and used a frequency of about 1.5GHz. There was a second link from southern Germany to Italy. The largest station was near Athens with seven links, tropo and LOS (line of sight). There was also a link not often mentioned from Turkey to Cape Greco in Cyprus, just west of the now holiday resort Ayios Nikolias. This was linked into the British forces' LOS system on Cyprus. When NATO started its satellite system it ws connected in a few cases to the ACE HIGH system with a LOS sytem provided by Selenia. The number of speech channels was increase to 60 channels on most links. To 72 of busier routes and up to 120 channels on very busy links, i.e. Brussels to Lammersdorf. The Army took over the running of the British ACE HIGH stations in 1968 from the RAF.

A point to note: the 10kW transmitters in later years mainly ran at a reduced power of 5kW. The amplifiers operated in Class A, which is only 35% efficient at theoetical best, and therefore saved oodles of money. The nominal mid-frequency gain of the 18-metre (60ft) antenna was 43dB. For your interest I was the senior technician at Mossy Hill for four years and an instructor at the NATO Communications school in Latina, Italy, about 30 miles south of Rome to the seaward side of the Appian way. I also worked on the Cyprus LOS system. P.S. The German station and control centre was at Lammersdorf.

From Martin Non (

You noted some discrepancies in the information. I can perhaps add another. The location noted as "Boulmer" was never itself home to an ACE HIGH facility. RAF Boulmer's only telecoms functions have been as part of the air defence radar system but including some civil ATC responsibilities for Border Radar. The main site at Boulmer itself is supported by outstations at High Buston (comm sites for Buchan, Boulmer, Neatishead and London/Scottish Mil), North Charlton and Newton (military navaids).

The ACE HIGH facility in Northumberland was on high ground at Brizlee Wood to the west of the town of Alnwick and was operated by Royal Signals units, i.e. Army. The site was very similar to your pictures of that in Kent and was visible for perhaps 20 miles away in some directions. The facility was dismantled about three years ago and has now been transferred to the RAF who have installed a geodesic dome containing a fixed air defence radar.

From Peter Murdie (

I am a native of Northumberland, having been born in the county some 50 years ago and having served as a Technician at ACE HIGH Brizlee Wood (Boulmer) towards the end of my Army service from 1977 - 1980 would like to comment on the note from Martin Non.

The ACE HIGH facility in Northumberland was indeed physically located at Brizlee Wood to the west of Alnwick, but was always referred to operationally as Ace High Boulmer. The station designation was UBOZ and it was a tropo relay station working to Binbrook (UBIZ) to the South and Mormond Hill (UMOZ) to the North. Historically when the station first opened it was operated and maintained by the RAF, and as the nearest RAF station to Brizlee Wood was RAF Boulmer, so that is where the station personnel and administration would have came from. Hence the name Boulmer was originally chosen for the operational site located at Brizlee Wood.

At some time during the 1960s there was a shake-up of how military radio equipment was split between the RAF and Army, and the Royal Corps of Signals took over the operation of the Boulmer/Brizlee Wood ACE HIGH station. Army personnel serving on the station used RAF Boulmer for quarters and messing and indeed for many years at RAF Boulmer the RAF Sergeants Mess was home to some 14 or so Royal Signals Senior NCOs. Indeed also the Electrical Maintenance personnel for the ACE HIGH stations' generators etc. were also the guys that looked after the power generation at the Boulmer RAF Station.

I can understand the confusion this can create, but Martin's comment in my opinion does not highlight any discrepancy but serves to demonstrate the confusion that could occur from these arrangements. Yes, the station was physically located at Brizlee Wood (the road sign pointing to it off the Alnwick to Rothbury road read 'Royal Signals Brizlee Wood). Operationally, however, it was part of RAF Boulmer, and the station documentation and procedures always referred to the name Boulmer. Indeed when answering the Engineers' Order wire on the station we answered 'Boulmer'. I have many memories of my time at 'Boulmer' and indeed am one of the privileged few on this Earth that know the correct operating procedure for the pair of 'AVO 8' leads which would hang on the front of every REL 10kW RF Tropo transmitter! They were for emergency use only, but that's another story for another day........

Steve Gould ( writes:

We were in charge of all the sites (microwave and tropo), including Uxbridge, Botley Hill Farm, Coldblow (where we were told the first RADAR experiments were conducted), etc. It was amazing to see pictures of places I haven't seen in 30 years. It would be wonderful to hear from others stationed there at the time. It was a wonderful experience, living in England for nearly four years, (I actually came back 10 years later to live there another year) and one I always treasure having had.

It's been a long time ago, but I think the microwave broadband link (this was before the world decided to use the term wideband) went from the US Naval headquarters in London (Grosvenor Square) and High Wycombe (which had the complete operational war plan send over every few days via 9600 baud modems which then cost over $100,000!) to South Ruislip to Uxbridge, to Bovington or Botley Hill Farm, a couple of others sites I don't remember, and then to Coldblow. If I'm not mistaken it finally wound up in Rota Spain (hence the Navy HQ link).

Botley Hill Farm was interesting. At the time we had an airborne command post called 'Silk Purse' in the sky 24 hours a day (out of Mildenhall) much like 'Looking Glass' in the US. It was a group of converted KC135 planes (read Boeing 707) which would have run the war in Europe if ground command centers were destroyed. Botley Hill Farm was the UHF link to the airplane, and then on to the broadband system, while the plane was over the UK. There was always a general officer on board. I flew on it a couple of times (I was mere captain at the time).If you get more interesting stuff up on your site, alert me via e-mail.

From Jay Clark (

Back in the mid 1960s, when France bailed on NATO, a continuation of the ACE HIGH system was the ACE HIGH relocation project. Basically the project installed new sites bypassing the French portion of the system, starting in Belgium, it shot to Landstul in Germany, on to another German site and ended up at Dosso dei Galley in Italy, where it connected by microwave to an existing NATO site in the north. I was the commsissioning engineer for for Landsthul site, and went on to be the OJT instructor for a year at Dosso Dei Galley (spelling is probabaly not correct).

From Jay Clark again!:

I worked on Ace High Relocation as a contractor for Marconi out of Chelmsford, I am also volunteer web master for www.ExReps.Com ExReps is all about former and current tech reps, any company, any project, any time, and their friends and families. WWW.ExReps.Com - On Line Community for Tech Reps, Ex Reps, their families and friends. For those who worked abroad as Tech Reps, Expatriates, Adventurers, World Travelers, Globe Trotters, and job-shoppers.

From Pat Shediack Chief Master Sergeant, USAF (Retired) (

When you get a chance, stop by my web site, Bluejeans' Place, and check out my pages on TUSLOG Detachment 150, the US Air Force tropo communications site at Sahintepe, Turkey.If I am correct, we were part of the Aces High network. Can you confirm? 80% of the voice and data going in and out of Turkey for NATO, the US and Turkish General Staff came through our circuits. Visit the TUSLOG Detachment 150 (USAF) unit history on Bluejeans' Place at

From Willibert Wilkens (

I´m a former ACE-High-technician and I served on the NATO ACE High Station, AFEZ Feldberg.With interest I read your historical information about ACE High. Please visit our homepage about the former ACE High Station Feldberg. Comments are welcome.

The site is in German but the excellent photographs are international. German speakers will see that a CD-ROM with further images and information is available. AE.

From Wingenet (no name given)—make of this what you will:

"Ace High operated on frequencies from 832 to 959MHz"

Certainly not a hard and fast rule given the various types of equipment in use across the network. Some of the LOS equipment operated across this band but the Tropo equipment did not. As a side note to this and just to muddy the waters a bit, the Royal Corps of Signals is still using mobile (that's vehicle mounted not cellular) LOS equipment that operates in several ranges between 225 - 960MHz. Triffid, one equipment with variations of RF top box, was introduced to my unit in BAOR between 1980 & 1983 after which I left for colder climes. The RA site shows several applications allocated space within this spectrum but it shouldn't be assumed that the MoD no longer uses these frequencies or any other. Just because the RA says it SHOULD be so, doesn't necessarily mean it IS so.

And "some military radiolocation" is just what it says—military radio location not military communications or even military radio re-location.

As I have already said, the ACE High network was originally operated by the RAF. RAF Binbrook, RAF Boulmer, Coldblow Lane (also associated with the RAF but I don't know in what capacity). Do we see a thread running through this I wonder? Stenigot (so called by my contemporaries) was originally manned by the RAF from Binbrook and so I am not in least surprised that it might be called Binbrook.

You will note that Mossy Hill is several miles from Sumburgh (on the south island or Mainland) whereas Collafirth Hill is located in the north of Mainland, close to the Sullom Voe Oil Terminal. There is no confusion on the part of those familiar with ACE High as a whole, with or without local knowledge. These were two seperate stations within the organisation. A ladies' dinner night at Collafirth was anticipated with some relish by those of us from Mossy who usually had to make do with the odd lunchtime binge at the British Airways club at Sumburgh airport (to their credit they did serve Theakston's Old Peculiar). The spur created by the link from Mossy to Collafirth eventually fed RAF Saxa Vord (theres that RAF thing again AND they had the only NAAFI on Shetland) which can be found near Haroldswick on Unst (the northernmost island).

I suppose the power output from the various stations would be different dependant on circumstance (path length etc). During our training and familiarisation at the NATO School of Comms in Italy, we were not particularly made aware of any differences. We were certainly not fed any site specifics, this information only being available to me when I arrived in the sun-drenched paradise that was Shetland.

From James Dougan (

Visit and enter 'radio' as a search word. Nice picture of a USAF antenna, captioned as:

Microwave Aerials, Mormond Hill Radio Stations, Near Fraserburgh, Aberdeenshire.
Photo number: jd10001-7
Taken: 18/03/02

To continue the feature on Ace High click here

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Last updated 14th December 2003

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