[TheList] Sel-Call tones list

Mon Dec 6 08:59:54 AEDT 2010

At last something I can answer with a wee bit of knowledge having spent
15+yrs working with the original Sepac decoders & these tones plus one of
the designers who told all over many a beer.

Here's a bit of background to the selcall format used today.

The NZFS selcall format known as 13tone was originally designed by a few
characters in Auckland and a company called Sepac Industries in Oz. Auckland
was the first area to use these then Wellington later. Auckland used Sepac
Industries while Sigtec keypads were sold to Wellington.

The brief was to have a selcall string capable of delivering:

	* Vehicle Type (0-9) 1=pump, 7=rescue, 0=special vehicle,exec
officer etc
	* Vehicle call sign (3 digits)
	* Status
	* location = patch currently in. 00 = home patch normally but not
always
	* same de-encoder to decode 5+1 station calls and station status

One thing to note is back in the Eighties when Sepac were up against Sigtec
and the rest of the world for selcall domination, someone in the office at
Sepac made a major clerical error and transposed all the  tone frequencies
in the A-F range.

The C you are seeing is actually a D therefore a new CCIR format was
established which the NZFS and Sigtec had to follow.

The starting C (or D) and ending C ( or D) was actually to tell decoders
when to start and stop decoding 13tone else it was a 1 to determine station
call or incoming status update using standard 5+1 (5 digit ID @ 20ms each,
40ms of blank, 40ms of single status 0-9, A-F)

Now days they run 2 Sigtec de-encoders per channel, one for 5+1, the other
for 13tone.

Format for vehicle call sign is as follows using SEPAC format:

Vehicle sending string:

D	(start. Tells decoder vehicle calling)
X	(1st digit ID)
X	(2nd digit ID)
X	(third digit ID)
1	(vehicle type)
C	(C tone)
C
C
1	(start of status)
S	(status)
L	(location 1st digit)
L	(location 2nd digit)
D	(stop) 

Firecom ack string

D
0 	
X
X
X

When the NZFS went to FM around early 2000, the pump type was not needed so
was fixed to 1 and also the vehicle Ack was split with D0 Nth Is & D9 Sth
Is.
Also prior to FM roll out, all call signs were 3 digit numerical only with
no alpha in the string.

Hope that answers the reasons behind the weirdest selcall format used.

Cheers
Neil

-----Original Message-----
From: thelist-bounces at radiowiki.org.nz
[mailto:thelist-bounces at radiowiki.org.nz] On Behalf Of Scott Palmer
Sent: Monday, 6 December 2010 8:08 a.m.
To: thelist at radiowiki.org.nz
Subject: Re: [TheList] Sel-Call tones list

Hi Mike

I say keep adding them.

As for the C9 codes, up to you, put in what you like and the beauty of wiki
is soneone else can add if they like.

Cheers

On 4/12/2010, at 13:53, Mike Trump <zl3tpq at hotmail.com> wrote:

> Hi there guys,
> I've been adding some new Sel-Call tones to the existing list under the
Canterbury part of the site and I have got as far as 
> Little River 4711.
> Now, before I go any further, I want to ask a couple of questions.
> The first being:
> This list could get quite large, does the site owner have a problem with
such a large list (to the extent that it could take over the page)?
> 
> Secondly,
> I question the use of the C9xxx codes at the end of each tone set, all you
need is the first set (radio code) and the second set (Answer back) for a 
> Sel-Call decoder to operate correctly.
> I could be way wrong there, but that's only my opinion.
> 
> Your thoughts?
> 
> Mike T. 
> _______________________________________________
> TheList mailing list
> TheList at radiowiki.org.nz
> http://radiowiki.org.nz/mailman/listinfo/thelist_radiowiki.org.nz

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