[TheList] Sel-Call tones list

Scott Palmer scott at scottpalmer.com
Mon Dec 6 10:00:32 AEDT 2010


Wow, very informative, thanks Neil.


On 6/12/2010, at 10:59, Wobbly <wobblynz at live.com> wrote:

> 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. 
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