Code and Cipher Development (continued)

The COMETSYN cipher comprised 60 pages, each containing 30 lines of five figure groups. A distinctive five letter starting point indicator was adopted for the table, which went into operation on 27 February 1942 with replacement every two months. Rapid expansion of the broadcast services, however, soon heavily increased the traffic load on the cipher so that in January 1943 it was increased in size to 100 pages and replaced monthly. Even that proved inadequate to the security task involved, so that, in April 1944, the life of the cipher was decreased to 10 days and security further safeguarded by the allocation of blocks of starting points among offices originating messages. Finally, the use of COMETSYN was discontinued for collective synoptic messages and replaced by the SS frame system on 10 November 1944. COMETSYN was retained, however, for the exchange of meteorological W/T messages between stations and for transmission of station reports by wireless.

Special purpose codes also were designed and put into operation for diverse purposes. There were, for instance, the spotter codes that were compiled for use by guerilla forces and others operating behind enemy lines before the fall of the NEI, Philippine Islands and parts of New Guinea. By these means valuable information was secured of weather conditions in these probable target areas. These codes were necessarily simple, for the men were operating under conditions of the utmost danger and difficulty, relying in the main on loyal native villages, for supplies and shelter.

Codes had also to be provided by the Directorate to meet the needs of essential public services under conditions of security. For example, observers of the lighthouse service which continued their functions throughout the war and weather messages from pedal set radio stations to ensure continuance of the flying doctor service of the inland.

Bureau of Meteorology