Taken from Communicator Magazine - 1955

By the time this article appears many of you will probably have seen and operated the new RATT equipment shortly to be fitted in ships of the Home and Mediterranean Fleets; for those who have not, the photograph will give an idea of what it looks like.

This shows a standard RATT bay as it is hoped to be fitted in Ocean Minesweepers, Frigates and above, but when space does not permit this there are alternative layouts. The equipment consists of two teletypewriters Model TT 69A/UG or TT 70A/UG (lower left), which work with standard B.41 receivers and slightly modified B.40 receivers (middle and upper right), and the ships standard UHF set, type 691 (not shown), in conjunction with the other RATT units, the 'converter/comparator' (middle right), and 'two tone modulator' (upper left) and their associated switches, plugs and power supply units. An important point for operators is that it is nearly all mounted on desk level or above, which allows plenty of leg room unless it has been fitted over a mass of electric cables or steam leads!

A ship fitted with the standard bay will be capable of simultaneous RATT reception of an HF/LF broadcast and transmission/reception of a direct UHF net. If only one of these is required the HF/LF receivers or UHF set are available for other uses, and the second teletypewriter becomes a standby, or is used to double up the first one if additional copies are required.

It is not intended to describe the technical working of the shipborne equipment in great detail, since this is available in the handbook and in the A.T. film strip.

The operating of shipborne RATT should come easily to anyone who has operated line teleprinters since the radio procedure is largely based on normal T/P procedure. The exact uses of which RATT will be put are of course not yet known, and will develop with experience. It is likely that a UHF Net will replace the present Harbour Voice Intercom in most major ports, and that a similar net will become standard for use in a force at sea for administrative traffic and long messages which can not be passed by V/S. A great advantage of UHF RATT over its voice counterpart is the far higher rate of transmission of encrypted messages. Further uses for tactical UHF RATT will undoubtedly be found.

The Home and Mediterranean Fleets are likely to copy a RATT ship broadcast, and the greater traffic capacity thus achieved may well enable some revision of peacetime broadcast routines, and allow a reduction in the number of lines manned.

Finally, however a word of warning. The prime advantage of RATT is that it replaces the human operator and speeds up signalling. For example, a RATT broadcast operator will be able to cope with two to three times as much traffic as was previously handled by a morse broadcast operator and his callsign breaker. This is unfortunately only achieved by sacrificing the reliability of the human being, who can discriminate between the wanted signal and the unwanted interference in a way that no machine can ever do, and as a result RATT is very susceptible to interference. The RATT bay cannot be left unattended and the operator must keep a constant eye on the cathode tube to make sure the receivers are correctly tuned. There are likely to be occasions when the interference is too great for satisfactory RATT communication but when morse communication is possible.

Morse operators therefore should not get the idea that life will be a bed of roses once the shiny new machines arrive onboard, for it is certain that we shall have our full measure of teething troubles in the early stages of

shipborne RATT. Telegraphists have a lot more typewriter bashing ahead of them yet, perhaps a great deal more than some people expect.

W.T.T.P