Sel Call

Submitted: Thursday, Apr 03, 2003 at 18:18
ThreadID: 4209 Views:2404 Replies:5 FollowUps:3
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Can someone please explain exactly what the ins & outs of Sel call on UHF Radio is please? A friend of mine recently asked and I couldn't help so here I am.
Much appreciatedDo or Do Not - there is no try !
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Reply By: Member - Peter (WA) - Thursday, Apr 03, 2003 at 18:33

Thursday, Apr 03, 2003 at 18:33
a digital system of calling another persons radio .most radios have a selcal number assigned, which uniquely identifies the radio ( just like a telephone number . (Extract from HF radio for travellers).This book is avalible from the shop on this site ,a very good book for those new to HF radio like myself Born to drive a 4x4 , not a keyboard

Peter York 4x4

AnswerID: 16810

Reply By: kissyeah - Thursday, Apr 03, 2003 at 18:34

Thursday, Apr 03, 2003 at 18:34
Allyn, this is a very basic explanation, SELCAL stands for Selective Calling.
It is a type of automatic monitor that listens for a paticular combination of tones for the radio. When it gets a properly coded transmission the SELCAL decodes it and you get a tone come through (you may have heard it when you have been in a taxi). It alerts you that a message may be for you. In HF it means you don;t have to listen to constant noise while you monitor the radio.
AnswerID: 16811

Reply By: Old Soldier - Thursday, Apr 03, 2003 at 20:21

Thursday, Apr 03, 2003 at 20:21
Not much to add to the above except that the Selcall system is nothing new.

To my knowledge Selcall has been around in one form or another for over 45 years.

One of the original uses was on H.F. radio on jet aircraft on long international flights. As explained above the selcall was a tonal system, with each tone assigned a letter of the alphabet. On approaching each new Flight Information Region [F.I.R] the pilot would call the distant land station, report in, and then advise his selcall which was always checked by the ground operator. They would then test the selcall, and the aircraft crew would have the comparitive luxury of flying through the region without having to wear headphones all the time.

When the land base station wanted them he simply transmitted the selcall coding for that particular aircraft which would active a visual and audible warning on the target aircraft's flight deck.

A simple and very effective invention, though I am yet to be convinced of the need for such a system in CB radios in the bush.

Enjoy the bush

DennisN

AnswerID: 16820

Follow Up By: Member - dolfn - Friday, Apr 04, 2003 at 07:26

Friday, Apr 04, 2003 at 07:26
Being in the Airline industry,

I can confirm the Aviation operation of Selcall.

It's exactly like have in a telephone attached to the HF.

As everyone knows listening the all the static and Hash on HF is so enoying. On long trans oceanic flights, HF is the only means of contact to maintain reporting enroute (this is a requirement for all commercial operations). So like you said, when you first contact a new agency, you pass onto them you selcall alpha-numeric code. Then you only need to monitor the HF when ever you make a report or the selcall has gone off(which is like a phone ringing). Keeps you sane on those long dark nights ;)
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FollowupID: 10436

Follow Up By: Old Soldier - Friday, Apr 04, 2003 at 09:53

Friday, Apr 04, 2003 at 09:53
G’day Dolfn,

I don’t want to hijack Allyn’s thread, but with your background in aviation I though you might find this yarn amusing [or otherwise]

My background is a professional radio operator, and many years ago in Singapore [back in the sixties] we had the habit of keeping a spare receiver [speaker turned on] tuned to the ICAO frequency of 8870Khz to help while away the boredom during quiet evening shifts.

One night there was a British Airways flight en route from Darwin to Singapore, and he announced himself to Singapore with his “Speedbird” callsign, gave his position, and requested permission to descend to a certain height as part of the pre-approach for his eventual descent into Singapore.

Singapore’s answer was to tell him that as he was currently in Indonesian air space that permission would have to come from Jakarta.

Duly noted the skipper of the BA flight called Jakarta with the same request.

Jakarta’s response was to ask his final destination – to which he was told “Singapore”

Jakarta then responded by telling him he had to get permission from Singapore.

Back to Singapore with the same request.

Confusion building – remember, this poor bugger is closing on Singapore at a fair speed while these blokes are arguing the toss.

End result – somebody used their initiative. Darwin stepped in [I think from memoryDarwin was FIR controller] gave the BA flight permission to descend, and then ordered both Singapore and Jakarta to contact him immediately via “other means” [obviously to slip them a few choice words]

One very relieved BA Captain thankful for the Aussie presence in the region.

:) :) :)

Enjoy the bush

DennisN

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FollowupID: 10448

Follow Up By: Member - dolfn - Friday, Apr 04, 2003 at 12:06

Friday, Apr 04, 2003 at 12:06
I agree that we should not Hijack this Question,

But I like the story thanks.

There are many little stories like this "over the air bands" from years past.

Some of which definitely bring a tear to the eye.

One that I recal vividly is about a United 747, which has just landed in Frankfurt. The Captain, who was a fairly senior chap paused briefly on the taxiway, just checking his Chart to make sure he knew exactly which way to go to the Gate. As quick as a flash, the German ground controller, got on the United Aicraft's case and asked, "United 622 haven't you been to Frankfurt Before?" The Captain, took offence to the contoller's tone, responded, "Yeah I was here in 1945, but I didn't stop".

There are many more!

Maybe see you out there sometime.

;)
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FollowupID: 10454

Reply By: Member - Rohan K - Thursday, Apr 03, 2003 at 22:05

Thursday, Apr 03, 2003 at 22:05
Allyn, further to the above, a UHF radio uses the same Selcall process as HF.

Each radio has a unique Selcall ID number. It is usually part of, or recorded next to, the serial number. Just like a mobile phone, if you wany to call another person (radio) specifically rather than just going "on air" to see if you can find them, you need to know their Selcall ID. If you want someone else to Selcall you, they need your Selcall ID.

You can program most modern UHF radios with several Selcall IDs, a bit like speed dial, so your set can monitor for transmissions to you (Selcall) from any one of them. Some even have a "message forwarding" function where you can have your set retransmit the Selcall to another set (hand held or another vehicle or base station). All sets will have the ability to enter any Selcall ID manually. It will be visible on the display.

The Selcall ID is is transmitted/received as a code and when the code is received the set will issue a sound (differs between sets) to alert you that there is someone trying to call you. Just like a mobile phone, you accept the call, then continue the conversation as per normal radio use.

The UHF manual will clearly explain the sets Selcall features and how to use them. Have fun.Be good, or be quick.

Rohan
AnswerID: 16829

Reply By: Allyn (Pilbara) - Friday, Apr 04, 2003 at 12:40

Friday, Apr 04, 2003 at 12:40
Many thanks to all.
I shall duly pass on the information.Do or Do Not - there is no try !
AnswerID: 16869

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