SELCAL and flying Oceanic on VATSIM

Questions and comments about using VATSIM, Sqawkbox, VRoute, ServInfo or VAT-Spy
chriszdc
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SELCAL and flying Oceanic on VATSIM

Postby chriszdc » Mon Apr 04, 2005 5:21 pm

HI guys!

I'm one of those insane controllers in real life as well as VATSIM. With SB3 you now have a built in SELCAL function - no need to run FSSELCAL anymore.

What is SELCAL you ask?

Selcal (Selective Call) was developed in the late sixties as a means of identifying aircraft automatically when flying on HF (where the USB nature of communications makes automatic selcalling difficult).
Selcal works by sending two, two-tone signals, one after the other, chosen from a list of frequencies in the audio range. The frequencies (see list) are not harmonics thereby reducing interference. The SELCAL is send using Single SideBand, Full Carrier AM.
Every aircraft radio set contains an USB transmitter as well as an AM receiver in the same package.
The audio signal from the AM detector is connected to a decoding network that uses PLL (Phase Locked Loops) to identify the signals coming in.

In the aircraft setup page, near the bottom is a SELCAL box. SB3 will include this in your remarks automatically. (man, you gotta LOVE that module) the SELCAL code is a 2 letter group - 2 letter group. each letter represents a tone. two tones cannot repeat and the first must be lower than the second. the second group starts over. e.g.

good SELCALs letters A-S except I, N, O.

AB-AB AS-RS FG-HJ

bad - DA-AG in first set A is lower than D (or an earlier letter)

I control on VATSIM at Washington Center and Oakland Oceanic (most of the Pacific Ocean), I have visiting priviledges at Tahiti FIR.

http://www.csgm.org/kzak/

this website is about the procedures in the Oakland Oceanic FIR (San Francisco Radio). If you have the time and there is a controller on (rare, but we try :wink: ) this can greatly increase the realism of an Oceanic Flight. Gander and Shannwick Radios (North Atlantic Tracks) are usually on occasionally too.

SELCAL is used in real life so the pilots can turn the volume down on the HF radios (don't simulate this in VATSIM :wink: ). If the controller needs the pilot, they send the SELCAL tones for the aircraft causing a chime to sound in the aircraft (an AAL 767 I jumpseated on - it sounded like a gong and blue lights lit up all over the dash). The pilot would then turn up the volume and respond.

in the VATSIM environment, it allows you to leave the 'flight deck' and as long as you remain in range of your speakers, you can hear the klaxon and respond.

We separate everyone out there nonradar. we use the FAA standards for nonradar Oceanic separation. right now it is 10 minutes intrail and 60 miles lateral at same altitude. RVSM applies.

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Pylet
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Postby Pylet » Sun Jul 17, 2005 2:33 pm

FANTASTIC Post Chris!!!! I'll give it a try.
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