CWS - CENTRALISED W/T SYSTEM

CWS - CENTRALISED W/T SYSTEM

Written by Godfrey Dykes

© RN Communications Branch Museum/Library

The introduction into the Fleet of the CCX which was to remain centre stage right through to the ICS2 period.

I have mentioned the CCS (Central Control W/T System) which was engineered to handle W/T equipment and their user as a system rather than individual pieces of kit used in-situ. Very soon after the establishment of the CCS the Admiralty started work on the CWS which was to streamline and widen the facilities offered by CCS and to install such a system in many more ships. The CWS, unlike the CCS, was later given the OUTFIT LETTERS KDA and thereafter, it was a relatively short step to the KH series and after that the KM series extant to the end of our period namely up to (and beyond) 1980.

This picture sets the scene, central of which is the Lower Receiving Room (LRR) and the CCX (Control Circuit Exchange)

Note the transmitter Types 57, 59 and 60 , new sets specifically designed to work with CWS. The older sets (Types 30's, 40's, 55 etc) were modified before they could be used with CCS.

For a general description of the W/T System look here CWS General Description, when fitted, and into what class of ship. Note that all transmitters in the CCS and CWS are British, and this was the state of fit in 1939 at the beginning of WW2 with the American sets yet to be introduced and with them, the need for yet more Control Systems.

Following the axiom that a picture saves a thousand words, we will start by showing the equipment which was used at the operators position

Outfit KDA was a system which was much envied by other Navies. It used existing technology namely that of the GPO Telephone Dialler to send signals down the line, control remote transmitters, or to speak, when necessary, to the operator manning the Transmitter Room (TR) who was called the "TRW", 'W' standing for Watchkeeper. This 'clever' piece of kit can been seen above in picture No3. Picture 17 also shows this unit which is called the W/T CONTROL UNIT. Picture No3 is marked with numerals 1 to 29 (with lapses) and here we explore the device with an explanation.


	NUMERAL		DESCRIPTION
	1		The W/T Control Unit
	2		The Base Unit for the Control Unit
			Morse Key. This was the actual circuit key.
			Control Dial. Two streams of numbers could be dialled namely 1 to 9 or 01 to 09. 1 to 9 were the initial Conditions and 01 to 09 the wave change (frequency change) requests. Look at picture No 22 above. This gives the dial code 1 to 9 reactions. Looking at picture No3 you can clearly see how the dial face is divided for POWER OUTPUT and MODULATION required. For WAVE CHANGE click on this thumbnail to see the Dial results for stream 01 to 09.
	7		A Green indicating Lamp. Has to be lit before any dialling or operating can take place.
	9		The transmitter ON and OFF switch. Note: CANNOT be turned to ON when the slide-bar 29 is to the bottom of its slide.
	18		A Neon Indicating Lamp. Has to be lit before any dialling or operating can take place.
	20		Microphone. This is used only to communicate with other operators plugged to the same circuit and also to the rating(s) in charge of the watch in either of the controlling offices - it cannot be connected to a Circuit. The voice is superimposed on top of the incoming Morse code, and it is claimed that this WILL NOT interfere with signalling !
	24		Microphone on and off switch - press down to talk.
	26		Headphone sockets.
	28		Securing screw to keep the Control Unit firmly anchored to its base.
	29		Piece of metal with a screw which moves in the vertical plane. When it is down (as shown) the words "W/T SILENCE" are shown and the transmitter On position cannot be selected. When it is up and the screw is tightened, the transmitter On switch can be made and transmissions continued.

The functions of the stream 1 to 9 are automatically performed at the transmitter selected. However, the functions of the stream 01 to 09 alert the TRW (Transmitter Room Watchkeeper) and it is he who does the necessary wave or frequency change. Referring again to this thumbnail Click to enlarge

We can see the procedures and actions taken. There were two systems, either the W/T Control Unit (of which we are talking about) and a W.C.O.I. (Wave change order indicator) and either one, depending upon the fit, could be used to order a change of frequency when necessary. Each transmitter had a WCOI which was identical at the operators position and in the TR. When you are ready, click on picture No 1 above which is of the very first CCX built. You will see that it had 7 sockets per horizontal row and 12 horizontal rows each one representing a unique transmitter: a ship with fewer than 12 transmitters had a lot of redundant rows. Along side each row is a slot which accommodates a 'wave indicating tally' and these were duplicated at each separate transmitter in the TR's, in the CCO and in the RCO so that all knew the frequency (wave) plan. To help you understand this simple system have a look at this file WCOI.

Still referring to picture No1, note at the bottom of the CCX Upper there are two strips of indicator lamps side by side. These also were lit to inform all in the know which of the likely frequencies (those indicated on the tallies just mentioned) the set was actually tuned to at any moment in time. If we take out one of the pages in the WCOI file just viewed you will immediately understand. Consider this section for example:

Let us assume this is Transmitter No 1 of 12 and it has its own horizontal line on the CCX Upper. The set has been assigned for a specific function (or an "individual service") and the name of that service is called "STATION HF WAVE" which could be say in Portsmouth, where all ships in or around the harbour set watch on this circuit. The Tally is pre-made and whoever made it has consulted a book which lists all the frequencies that can be ordered to maintain watch. On this day, or for this watch, No 3 selection, 8290 kc/s, has been set on the transmitter. The TR Watchkeeper (TRW) has switched on the the necessary No3 light to tell all users that transmitter No1 is tuned to 8290 and is ready for use (i.e., no defects and no W/T silence). Now let us assume that for some reason, Portsmouth Control has informed all ships that the frequency to use is 5700 kc/s. The operator(s) plugged to that transmitter by marrying a CCX Lower PLUG to one of the SOCKETS on TX No1, now tells the TRW to shift frequency on TX1. He does this by dialling into his W/T Control Unit 02 and the TRW takes the transmitter down, (lights flash and go out), re-tunes, and puts the transmitter back up for use, with the lights re-appearing to tell the operator that the change-over has been successful. Everybody in the W/T organisation can now see that TX 1 has No2 Tally light burning.

In the next case say, Transmitter No2 of 12, the set is available for "General Use". Let us assume that we are the operator plugged via the CCX to this transmitter and that we are going to send a signal on a ship-shore link to a W/T shore station. Traditionally, the shore station listens for ships calling in on a pretty wide band of frequencies, and once the station acknowledges a ships call, the ship will be shifted to a new frequency to send his signal(s) without interference from other ships waiting to send their traffic. We are going to call our targeted shore station by calling on 2650 kc/s. However, because this transmitter is given over to General Use, we see by the light sequences that TX No2 is showing a light at position 8, used by the previous operator. We will therefore use our W/T control unit and dial in the double digit number 02. Very soon (as explained above) the transmitter is ready for use with No2 light burning. To make sure all is OK, we dial into the W/T Control Unit a single digit number 3 (for full power) followed by a single digit 6 for CW (Morse Code). The call is made on ship-shore (calling); the shore station answers us and we tell him that we intend to shift to 2333 kc/s to send our signal(s) which is called (working). The shore station agrees, and we dial in a double digit number 01 into our W/T Control Unit. The TRW prepares our transmitter and gives it back to us for our sole control. We re-call the shore station and our signals are passed. We can now switch off on our W/T Control Unit indicating to all others that the transmitter is available for other uses for General Service working.

This tally comes to us via a Naval Stationery Order, along with our pencils and paper etc. Here we can add the frequencies we require, the name of the Service or Circuit, and when ready, place it on the CCX upper and at all other user position and in the TR's.

Still with picture No1 from above in mind, along side the CCX upper you will see a box. This box, shown in picture 21 above, is the Microphone Exchange. It routes microphones as shown in picture No 11 above (and not those built-into the W/T Control Units as in picture No3) to transmitters capable of R/T operation.

KDA is a very big subject and did have enhancements for controlling fighter aircraft. Nevertheless, I think we have covered it enough for you to see that even as WW2 started we in the Navy were quite posh and sophisticated with our W/T equipment and Control Systems.

However, not all ships were fitted with CCS/CWS and anyway, with the onset of WW2, the Royal Navy were being supplied with transmitters and receivers which were not compatible with existing systems so a fresh look was required.