Selcal Success

[Mango3]

HF is a fact of life for our field of operations. Selcal checks come good sometimes, and other times no joy. Some blokes request ATC to "send a longer signal" after a failed Selcal check. Viola! This seems to work. Any clues as to why, and does this actual phrase have any valid meaning to those working in ATC?

[Spodman]

Haven't come across "longer signal" before. Can't on our equipment, duration of tones preset. Our guys just push a button. I have heard operators send a series of tones and get a response. Don't know if it helped.

Do ATC anywhere directly use HF/SELCAL? Done by FSO's (whats left of them) here.

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I am not an animal, I am an ATC.

[10W]

HF SELCAL is used on the North Atlantic for most of the traffic. Though with datalink and FANS, the number using it should slowly decrease.

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10 West
UK ATC'er
[email protected]

[Dan Winterland]

Mango 3, a double pulse works sometimes. The system relies on a Heath-Robinson designed system of vibrating reeds which resonate in sympathy with a coded tone. The fist pulsed tone gets the reeds vibrating, the second makes them vibrate that bit more and hopefully enough to trigger the alert.

This was covered by a recent thread in much detail.

[karrank]

REEDS???

You are joking surely. Tones have been generated electronically here since early '80s.

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"Station calling Centre, grow a head..."