66. Examinations were also conducted for the Radiotelephony Certificate with the following results:
R/T (Restricted) Certificate R/T (General) Certificate
Candidates
74
15
Pass
54
10
67. Staff were made available to the Director of Marine for inspect- ing and surveying ship radio stations for ensuring compliance with the International Convention for the Safety of Life at Sea and to advise on the installation of equipment on new vessels. 200 ship radio stations were surveyed for the issue of Safety Certificates and 92 vessels were inspected. The Direction Finding equipment on 51 vessels was also recalibrated.
Radio Monitoring and Interference Control
68. During the year 250 cases of interference were reported and high frequency plastic welding machines remained the greatest single source of interference affecting telecommunication services. In the course of investigations 339 visits were paid to factories employing this type of machine and a total of 150 unlicensed units were found in 58 different factories.
69. Routine measurements of civil aviation beacons and ground/air systems were carried out at regular intervals. The frequencies of 731 mobile radio system transmitters were measured to ensure that they were operating within prescribed tolerances. Similarly, the transmitters of 191 ships undergoing radio survey were checked.
70. Local radio communication systems were subjected to super- visory monitoring and investigations were conducted to ascertain the suitability or otherwise of proposed channel allocations.
Government Telephone Services
71. The Division plans and makes arrangements for the provision of telephone services for Government Departments. The number of telephone facilities in operation at 31st March, 1971 is listed below:
Exchange Lines
Official Residential Telephones
Extensions
Private Wires, Tie Lines and Long Line Extensions Switchboard Extensions
Intercommunication Units
Total ...
4,317
1,212
1,811
392
6.225
1,060
15,017
11