Frequency standards provided the accuracy and the stability for modern communications and led to synthesisers and unattended W/T equipment.

  Apart from internal standards in receivers such as the CJK in the COMIST fit of the early 1960 period (which could also supply other equipment which needed a standard but didn't have one built in), the Type 633 SSB transceiver, and more modern equipment like the FTA, which used either an external standard or its own built in standard, the vast majority of equipments in the surface Fleet used an external standard. In the submarine world, the old equipments of the transmitters 623/619 (or TCS) and of receivers CDW/CDY (B40D/B41) were replaced in the first place by a Dutch Van der Heem system which was called SSA. Outfit SSA was a transceiver (the transmitter part was called an exciter) and this unit had its own internal 1MHz frequency standard. Later on, submarines were fitted with ICS (and RATT outfit RWC) an had a traditional ICS frequency standard fitted as shown below.

  The first standard to be fitted was the FSB and it provided the standard for the transmitter Type 640 (and the CJK) in the COMIST fit (see Transmitter page). By comparison to all the others, the FSB was a tiny piece of equipment and used the 1MHz output for transmission and the 100kHz output for reception only.

  With the introduction of the Integrated Communication System (ICS) (see Transmitter page) came the FSA Series of standards which continued to use the 1MHz output (although less so than for COMIST), the 100kHz output (but now for both transmitters and receivers) and the 5MHz and 1kHz outputs, the former used for the FTA (recently mentioned above) and the latter for the Control System KMM.

  When first introduced and installed in the Fleet, various procedures were laid down as to their routine maintenance and accuracy checking procedures which were to become W/T operators functions. However, as time went by, it became obvious to all that these machines were so ultra efficient that few if any procedures were necessary over and above those carried out by the Weapons Electrical Branch on a quarterly basis. For operators, complacency set in, which turned out to be justified, and the daily/weekly checks were abandoned. FSA outfits were generally fitted in a compartment free from of 'turmoil' or excessive use, and the 5MHz Crystal (which was the standard) was routed to the Communications Control Room (CCR) where it was divided into the various outputs mentioned above.

  The Table below shows where the types of Standards were fitted and below that are links to the different types.
FSA 1 and 2
FSA 3, 5, 6 and 7