need help decoding courtesy tone

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kg4ciu
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Joined: Thu Jan 09, 2003 8:11 pm

need help decoding courtesy tone

Post by kg4ciu »

does anybody know the tone frequency and duration in MSEC of the courtesy blip a moto trunking system using spectra tac remote
I have a audio clip
Will
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Joined: Tue Sep 04, 2001 4:00 pm

Post by Will »

. 1760hz for 30ms, 30ms space, 1760hz for 30ms, 30ms space, 1760hz for 30ms.


Your triple NEXHELL tone......
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d119
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Re: need help decoding courtesy tone

Post by d119 »

kg4ciu wrote:does anybody know the tone frequency and duration in MSEC of the courtesy blip a moto trunking system using spectra tac remote
I have a audio clip
Why don't you post that audio clip so we can answer the question...

Doesn't sound like you're talking about a talk permit tone.
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kg4ciu
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Post by kg4ciu »

http://www.scancobb.com/playlists/scanc ... nner3d.asx

here is a live feed -- take notice of the courtsey blip
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d119
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Post by d119 »

If you're referring to the "clicking" sounds heard after a unit unkeys, thats NOT a "courtesy blip".

What you're hearing is a Motorola DigiTAC (theres *nothing* SpectraTAC about that audio clip) comparator.

The sound is a slight cheep of 2175Hz status tone leaking through before the notch filter cuts the audio off.

You may hear it a couple of times depending on how many receivers are unsquelched, and the delay from the signal to disappear from each of those receivers.

I've no idea what the values are, but you'll have a hard time reproducing it without the actual hardware for the system.

The system is a voting comparator system that selects the best signal quality off of several remote receive sites.


Good luck!
SZ$DEF
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Post by SZ$DEF »

Yep - typical of a Motorola SmartNet simulcast system. You will also note the same leak through of the 2175 Hz tone just before a console keys up, too.
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kg4ciu
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Post by kg4ciu »

yes thats what I'm referring to.

I have a controller with dual tone generators if I had the frequncey and duration of the "click" I'm sure I can replicate
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d119
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Post by d119 »

Actually, you'd have a very hard time duplicating it..

The tone is not being turned on / turned off such as your Link Comm (I'm sure that's what you've got) controller does by generating a tone (turning it on) and then inserting silence (turning the tone off)...

The 2175Hz in a DigiTAC is actually being notched out, so there's a certain hollowness and reduction in volume, filterting, and equalization that's occuring...

All you'll end up with out of your Link Comm controller is a couple of very fast beeping noises.

Why the hell do you want to try and imitate something you don't have attached to the system? No offense, typical ham B.S. (I'm a ham, so I'm allowed to make that statement).

If you want it THAT BADLY, go buy a DigiTAC (~$500 on eBay when they show up), some receivers, and set up a system.

Thats what I did. I liked that sound so much I set up a SpectraTAC system on my MSF 5000, all amateur. It has 3 remote receive sites on RF links.
SZ$DEF
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Post by SZ$DEF »

Personally, I like it un-notched where you do get the little ~100 ms blip of 2175 Hz tone :)

Can't do it in SmartNet with consoles since they use a 2175 Hz guard tone to keep the audio going through the DigiTAC and it sounds awful without the notch filter, so you can only get away with it in SmartNet without consoles, or anytime with SmartZONE.
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kg4ciu
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Post by kg4ciu »

I've also heard it on a conventional vhf system.
and I'm using a pacres ri300 and i can vary the volume and pitch of the 2 tone generators which can run simultaneously with they are generating tones
so it sounds like i want to use a 2150hz tone that rises in volume and slightly twist the pitch within 100 msecs maybe 50 msecs volume level 5 then 2150 msecs volume level 10 .
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d119
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Post by d119 »

I still think you're going to be disappointed, but whatever you like.

Good luck.
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