You will have read about the evolution of Wireless Telegraphy equipments and how, on the transmitter side, we moved from SPARK to ARC to VALVE to SOLID STATE CIRCUITRY, and on the receiver side, from COHERER to CATSWHISKER to CRYSTAL to VALVE to HETERODYNE to SOLID STATE, and all evolutions dealing with pieces of kit with their own unique way of being controlled/used by operators, local or remote.

In the 1930's the Admiralty designed the first of the many control systems which would deploy equipments to their users as a SYSTEM rather than as separate pieces of kit, and this was named as


abbreviated to


In its day, it revolutionised the way in which the ships were managed and fought, giving the Command a flexible and versatile communications 'tool'.

The system was an arrangement of W/T equipments in which transmitter were grouped in one or two transmitter rooms [TR's] remote from, but normally controlled by the Central Receiving Room [CRR] in which all the main receivers were fitted.  The object of the arrangement, in conjunction with separated aerials and aerial filter units, was to reduce the interference caused by a ship's transmitters to her own reception and hence to reduce the necessity of detailing W/T guards [other ships whose reception was not interfered with keeping a watch for the ship whose reception was so affected].

At the same time the System was to expedite the handling of messages, making arrangements for coding and distribution of messages to be carried out in one office adjacent to the CRR.

Arrangements were made also to enable the operator at any receiver in the CRR or, with certain limitations, for any operator in any remote control position to control any transmitter.

Local change-over boards and an emergency receiver were fitted in the TR's to enable transmission and reception to be carried out at local control positions in the TR's.


The following nomenclature was used for ships in which the above arrangements were made:-

{a}   Central Control W/T System [C.C.S]   The system under which all W/T transmitters are controlled from, but separated from the Central W/T Receiving Room [CCR]
{b}   Number One Transmitting Room [No1 TR]  The compartment which contains:-
        {i}   The highest powered MF set
        {ii}  A medium power HF transmitter [may be part of {i}
        {iii} Low power transmitters for auxiliary and fire control purposes
        {iv} An emergency receiver
{c}   Number Two Transmitting Room [No2 TR]   The compartment which contains:-
        {i}  A medium power MF transmitter
        {ii} A medium power HF transmitter [may be part of {i}
        {iii} Low power transmitter for auxiliary purposes [stand by]
        {iv} An emergency receiver
{d}   Central Receiving Room [C.R.R.]  The compartment which contains all general purpose receivers, and from which all transmitters can
        be controlled.
        Note: The warning telephone [Wa/T] set may be adjacent to {d} or {h} but not inside the former
{e}   Automatic [High Speed] Receiving Room [H/S R.R.]   The compartment which contains apparatus for automatic high speed reception.
        High speed reception may be included in the CRR
{f}   Automatic [High Speed] Transmitting Room [H/S T.R.]   The compartment which contains apparatus for automatic high speed control
       of transmitters
{g}   Remote Control Office [R.C.O.]   The compartment, adjacent to the plot, from which any transmitter or receiver may be controlled
        through the CCS
{h}   Central Communications Office [C.C.O]    The office in which both coding and distribution of messages were carried out in.  This office
        is situated immediately adjacent to the CRR and combines the functions of SDO {Signal Distribution Office} and MCO {Main  
        Communications Office if more than one Office fitted, otherwise "the W/T Office"] as previously fitted in ships.  The CCO may be
        combined with the CRR
{j}    Signal House   When a CCO is fitted, a small signal house is provided on the signal deck for the use of the signal personnel on watch
        instead of him using the old style SDO


The following transmitters could be used with C.C.S.:-

Types 36C, 43C, 48C, 49C, 51CFL, 51CFH, 52CFH, 55CH, 57C, 73C, 75C.  These, as you will see as your read through the site, were fitted into HEAVY SHIPS and ALL MODERN [post 1930] CRUISERS [Heavy and Light], so it was not a pan-Navy revolution.  The normal arrangement for fitting this equipment was as follows:-

No1 TR = 48C or 36C - 43C or 51CFH/CFL or 52CFH [1 or 2] - 75C
No2 TR = 55CH or 57C - 49C - 43C or 52CFH
CCO ANNEXE = Type 73C Modulator - Wa/T Set - A.C. Supply Outfit


1.   The transmitters are modified so that their master keys, and a magnetic key for switching on filaments [except for Types 73C and 75C]
      can be operated by circuits carrying rectified unsmoothed A.C., taken from the CRR A.C., supply.  A.C., is used to eliminate key clicks
      and commutation noises in the CRR.  The A.C., lines are run in twisted pairs to avoid interference, and are screened from D.C., in
      the various control boxes.
2.   Types 57C, 48C, 49C, 36C are fitted with coupled aerial circuits to reduce harmonic emission.
3.   Type 43C has the aerial continuously connected to the transmitter to prevent alterations to tuning of other transmitting aerials in the
      vicinity which would occur if the aerials were keyed.
4.   Type 49C is given duplicated machines and starters, as in small vessels where it is the main set.
5.   Type 36C uses the delay action filament switch and the key safety unit normal to Type 48C.
6.   Type 43C has new design power boards [i.e., board 2EP, supply for HT and LT motor generator] embodying auto-start. For the Type 43C
       fitted in No 2 TR only one machine and starter is fitted.
7.   Types 73C and 75C are fitted with a special key for remote control, but the filaments must be switched on at the set.
8.   The lamp indicating box associated with Type 48C [and Type 36C] showing machines running and Nos 1 and 2 D/F Offices earthed, is
      duplicated in No1 TR and CRR.
9.   To embody these alterations for CCS and enable the TX to be controlled locally [i.e, in the TR's] new boards "Local Control Change-
      Over" have been designed for each set except Types 73C and 75C.

Click on this file to see an overall block diagram of a typical  CCS.pdf

This file shows you the main controlling panel CCS BOARD 2S CENTRAL CONTROL.pdf

A file to show the overall detailed block in simplified form ccs simplified.pdf


These pictures are self explanatory.  The horizontal rows are the ships transmitters sited in their respective remote TR's.  The vertical rows are the users of the equipment.  Over on the right hand side of the matrix panel you will see switches [off to North West {as drawn} and on to North East] which are outlined in white.  These are non-communicator user positions.  All transmitters are remotely started from this control panel each circuit having its own voltmeters or pilot lamps. Once started, any transmitter can be switch on {on the matrix above} and keyed from a desired position.  At each key, a neon lamp lights when the key is connected to a set and the filaments are lit. The output of all receivers [except the emergency receivers fitted in each TR] is taken to the Board Central Control which enable any remote control position to be plugged into any receiver, with certain limitation in the case of the gunnery control positions.

.........from little acorns big oaks grow......

and this first system opened the doors to many new and better control system.

These are shown in other files and the next logical file to view is that covering the concept know as the Centralised W/T System [CWS].