Selcall Tones and HF
Submitted: Friday, Oct 16, 2009 at 00:25
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Pete Jackman (SA)
From what I have read the Selcall tones are simply a series of audio tones transmitted to "wake up" a receiver.
Does anyone know if you could program a PC to generate the appropriate tones so that those of use with older HF technology can selcall or
beacon call base stations?
I know Mike Harding was looking at this some time ago.
Pete
Reply By: Member - Mike DID - Friday, Oct 16, 2009 at 08:09
Friday, Oct 16, 2009 at 08:09
The sequence of tones needed is very complex.
I think I have some of the Standards documents on the tone sequence needed, if someone wants to do it the hard way.
--------------------------
A more practical solution is to create the tones you need to Selcal the bases you are likely to call, by transmitting on an
HF radio and record them as MP3 files.
When you want to call a station, play the required file into the Microphone using a Phone or MP3 player.
Once one person records them, they could be easily shared.
AnswerID:
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Follow Up By: Pete Jackman (SA) - Friday, Oct 16, 2009 at 14:19
Friday, Oct 16, 2009 at 14:19
Thanks Mike,
Reading the specs for the
Jenal microphones which can retrofit any HF to provide selcall tones I figure that those microphones simply supply the selcall tones before the microphone amp within the set and selcall does not require some fancy FSK system.
If a selcall is just audio tones that can be fed into a microphone I was thinking of making a set of files for
beacon calls and selcalls for the VKS bases, dumping them onto my MP3 player with the appropriate names then I can call up a VKS station out of sked by playing back the MP3 into the microphone.
I have a tone generator for my PC that can put together the required sequence with tones and pauses of whatever frequency and length is required and save them as a MP3 or WAV file.
I think that we use the CCIR standard with 100 ms tone lengths in Oz for Selcall but I need to find out how the sequences are put together.
If I can get it to work I would be happy to put the MP3's up in the fileswap area for those of us without a selcall HF set.
Pete
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Reply By: Member -Signman - Friday, Oct 16, 2009 at 10:19
Friday, Oct 16, 2009 at 10:19
The preamble part of a 'selcall' is simply to send a tone to alert a receiver that may be in scan mode- and, as there is a signal on that frequency- the scan function will pause. No problems creating and transmitting that tone to (as you say) "wake up' a receiver. Even a whistle or tone will cause such a reaction.
However, the ident part of the 'selcall' tone is exclusive to the 'selcall number' in your transmitter, and the one programmed into the recipients receiver.
There was a mob in WA (jencall or something like that) that had microphones that could do the job and generate full selcalls- and would be compatable with (say) a Codan 8525 and the like.
Cheers,
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Follow Up By: Member -Signman - Friday, Oct 16, 2009 at 10:42
Friday, Oct 16, 2009 at 10:42
JENAL is the microphone with the selcall/telcall facilities !!
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Follow Up By: The Explorer - Friday, Oct 16, 2009 at 10:46
Friday, Oct 16, 2009 at 10:46
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Follow Up By: Pete Jackman (SA) - Friday, Oct 16, 2009 at 15:46
Friday, Oct 16, 2009 at 15:46
Thanks Signman and Explorer - see my reply to MIke above.
Regards
Pete
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Reply By: Member - Mark E (VIC) - Monday, Oct 19, 2009 at 21:42
Monday, Oct 19, 2009 at 21:42
I have used the method mentioned many years ago. I recorded the required tones on a cheapo cassette tape recorder and when I needed to 'wake up' the base set (private network) I would simply play the 'track' over the microphone on the appropriate frequency. It worked quite
well. The biggest problem was no selcall mute at my end....
Cheers,
Mark
Ps Since thrown out the tape.
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