P25 alert tone

[jaaredmond]

Anybody know of an audible tone that passes clear enough to not sound distorted on a P25 conventional channel? I was wondering if I could get a old zetron (4018) to send a clear tone as an attention getter only.

I know that the newer Centracom's can send a solid and warble that sound fine. Not sure what protocol or Hz they use. I have heard that a 1011 and 511 Hz tone might work.

Any thoughts?

Thanks

 

[scanningisfun]

I know that it is possible. On the KC MARRS system, the KCPD sends out tones over P25 that sound clear.

Jacob

 

[dcr_inc]

Most of the P25 consoles send a wav file that was generated to sound good on P25 for each alert tone..

 

[jaaredmond]

Anyone have a raw sample if what is sent that I can listen to? I would like to decode it and see which tones pass through the DIU with stability.

 

[KB1UAM]

My city pd is p25 on uhf they send tones out for weather alerts street closures and BOLOs the tones sound pretty clear to me.

 

[rapidcharger]

I think the key here is BRIEF tones. My county does very short beeps and the county next door that I listen to uses a hi-lo warble. I guess the longer the tone, the more you notice P25 wasn't optimized for anything other than the male voice. And for that hi-lo, I would image you're pretty close with that ~500/1000. Don't know for sure.

 

[scanningisfun]

The KCPD uses a five second alert tone when 'clearing the air'.

Jacob

 

[Jay911]

The 700MHz P25 trunked system being developed here is using 1000hz tone generators on NAC 293, RID 1, TG 1, on some of the voice channels, while the system is being built out. I have no idea why (it's not talkgroup grants thru the system, they're manually activating the repeaters) - unless they care not for the actual tone being generated, more for the strength of the signal.

 

[GTR8000]

The 700MHz P25 trunked system being developed here is using 1000hz tone generators on NAC 293, RID 1, TG 1, on some of the voice channels, while the system is being built out. I have no idea why (it's not talkgroup grants thru the system, they're manually activating the repeaters) - unless they care not for the actual tone being generated, more for the strength of the signal.

Sound like they're using a 1K tone to test the repeaters individually in conventional mode, either for range testing or audio levels or failsoft or who knows what. It's not being used for an alert tone, though, if it's not a TG grant through the system, because no subscriber unit would ever hear it otherwise.

 

[Jay911]

It's not being used for an alert tone, though

Never said it was.

if it's not a TG grant through the system, no subscriber unit would ever hear it

I'm extremely familiar with how trunk systems work.

 

[GTR8000]

Calm down, Jay. I'm extremely glad that you're extremely familiar with how trunked systems work...however you did clearly state "I have no idea why..." My apologies for offering a few ideas as to what they're up to, I didn't mean to question your extreme expertise.

 

[inigo88]

For what it's worth, in the case of the older Centracom Gold Elite consoles, the alert tone played through the dispatcher's headset sounds quite a bit more shrill and crisp than the resulting (slightly warbly) P25 tone. I always assumed they continued to use the stock Centracom alert tone, and the IMBE vocoder just distorts it into what it is today. It might be a wav file on the newer MCC7500 consoles, but I'm pretty sure the Centracom Gold Elite just uses an analog tone converted to digital.

 

[jaaredmond]

Thanks everybody for you response!