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Radio1950 · 11th Apr 2019, 8:38 am

Australian Civil Aviation used SSB (USB supp carrier) for point to point (ATC centre to centre) from early 1960s to about 1984, supplemented by some HF RTTY. The SSB voice circuits had audio tone selcall to set up a voice call, so as not to waste ATC operator time.
It was rather elegantly engineered, and worked well.
Multiple frequencies for best time-of-day operation, (typically 2, 5, 8, 17, 23 MHz), feeding dedicated antennas, a lot of which were rhombics.
Some ATC centres had multiple groups of SSB circuits called NETs.

Australian Civil Aviation Air Ground Air used SSB, (again USB supp carrier) from 1982 onwards, for both domestic and international, and is still using it, although it is remoted from stations at optimised HF locations, rather than being installed at ATC centres.

Very interesting Thread; thanks to all.
I have also enjoyed reading the attachments very much.
.

11th Apr 2019, 8:38 am	#74
Radio1950 Hexode Join Date: Apr 2017 Location: Buderim, Queensland, Australia. Posts: 428	Re: ISB Receivers Australian Civil Aviation used SSB (USB supp carrier) for point to point (ATC centre to centre) from early 1960s to about 1984, supplemented by some HF RTTY. The SSB voice circuits had audio tone selcall to set up a voice call, so as not to waste ATC operator time. It was rather elegantly engineered, and worked well. Multiple frequencies for best time-of-day operation, (typically 2, 5, 8, 17, 23 MHz), feeding dedicated antennas, a lot of which were rhombics. Some ATC centres had multiple groups of SSB circuits called NETs. Australian Civil Aviation Air Ground Air used SSB, (again USB supp carrier) from 1982 onwards, for both domestic and international, and is still using it, although it is remoted from stations at optimised HF locations, rather than being installed at ATC centres. Very interesting Thread; thanks to all. I have also enjoyed reading the attachments very much. .