Joint Communication Exercise – JOCOMEX

Not all 14th Signal Regiment exercises took place in warm, sunny and interesting places. By far the most common were the JOCOMEX. The Regimental Historical Record 1st April 1969 to 31st October 1969 contained the following – 

 JOCOMEX – These joint communications exercises with ships of the Royal Navy are regularly mounted to practice D13 or D11 detachments in CW and FST working and to further joint working.
Each exercise consisted of an opening phase of CW working with stations exchanging questions on procedure, followed by a change to FST for the remainder.”

Whilst this describes a JOCOMEX in a few words, it fails to give any detail.

Firstly, the vessels were usually at sea (although not always!) which meant that they were moving and therefore not exactly in the position that they were expected to be which posed problems when using fairly directional antennas on shore. On one occasion, according to gossip, instead of being on it’s way to Gibraltar, one RN vessel was actually still in dry-dock at Portsmouth.

Another minor drudge with JOCOMEX’s was the initial contact (and lost contact procedure) was in CW (Continuous Wave – Morse). This meant that the on-shift operator had to be proficient in the skill as the RN operators, who used Morse very regularly tended to ‘key’ rather quickly. On poor quality links, the operator (usually only one per 8 hour shift) was a bit ‘stressed’.

Once a reasonable quality ‘link’ was established and both ends agreed, the system was changed to FST (Frequency Shift Telegraph) and handed to the ‘techs’ for engineering. For all D11, D13 and early E21 links this was encrypted using BID 610 ‘Vendor’ equipment. Once the circuit was stable in ‘green’(encrypted), the operator then exchanged ‘traffic’.  This often took the form of the latest football scores especially on a Saturday afternoon! It wasn’t unheard of for the ‘ship’ to off-load any backed-up telegraph traffic that it had not been able to clear over its’ more ‘normal’ links. When this occurred, the received traffic was passed to Norton Barracks for onward transmission.

The duration of these exercises was usually only 2 or 3 days, but with sometimes 3 or 4 in a month and with 3 x 80ft. masts per detachment, the small crews were experts at erecting masts in short order. Mistakes were still made occasionally, with by far the most common being forgetting to put either the antenna pulley and guy, or mast head light pulley and guy, on the top before erecting. Very embarrassing to have to lower the whole thing to fix the mistake. You only ever forgot once! It was on one JOCOMEX (possibly at South Cerney) on an airfield that the mast head light failed requiring the on shift crew to post a man with torch shining up the mast for the whole night.



Initially the HF Radios in the regiment were D13/R234 or D11/R230 stations as the E21/R241 stations had not been issued. Little detail is available in the Regimental History other than the name of the ships.. There is no information available in Regimental Historical Records prior to 1969


The first record of an E21/R241 being used was 11-12 November 1970 working to HMS Andromeda which was operating as Fisheries Protection off Ireland. It is recorded that whilst CW was good, telegraph failed! The second time was to HMS Juno, This also was pretty unsuccessful as even CW was difficult with records showing that this was attributed to the ship using only 1KW via an omnidirectional mast.


On 7-8 September 1971, B Troop worked to HMS Puma off Gibraltar.  A troop member was on board as liaison.


On 19-21 April 1972, Capt C.J. Dakin joined HMS London in Gibraltar on invitation of the Captain to ‘observe the exercise at sea’.

The 1973/1974 Fuel Crisis meant that overseas exercises were greatly reduced and the number of JOCOMEX’s increased (to keep the troops busy?)



Rick Thomas recalls “I did the exchange on JOCOMEX on HMS Antrim with Brian Coombes and A.N.Other. We were treated with great hospitality by the crew and remember staying in No 3 PO’s mess where I was in the top bunk. This needed athletic ability to access. (Which I had then!) Still have the H.M.S Antrim plaque given by the crew and had a brilliant experience enjoying the “entente cordiale” of the locals. A great trip all round! I believe H.M.S Antrim was sold to the Chilean Navy shortly afterwards.”



In the period 1969 to 1976, the Regiment took part in a total recorded 114 JOCOMEXs

Orph January 2018

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