[TheList] Squawking Tones on Police Channel & High Frequency Tone on Channel

Sun Mar 20 11:55:07 AEDT 2022

Everywhere can hear police except Wellington Region, Auckland and
Canterbury.

On Sun, 20 Mar 2022, 13:51 Scott Matthews, <ff.swatty at gmail.com> wrote:

> Personally didn’t think most places could hear the police anymore?
> Unless I am missing something?
>
> On Sun, 20 Mar 2022 at 1:26 PM, Tim Devaney <timdevaneynz at gmail.com>
> wrote:
>
>> Are we not going to be able to receive the police soon ??
>>
>> On Sun, Mar 20, 2022, 12:09 DogSec - Richard <richard at dogsecurity.co.nz>
>> wrote:
>>
>>> Hi BJ,
>>>
>>> Years ago someone did a write-up about it on here, but basically it's a
>>> form of SCADA for monitoring sites remotely.  Some sites are often not easy
>>> to get to and may have access issues such as being helicopter access only.
>>> These sites have quite large battery banks, as mains power may be flaky.
>>> The SCADA allows for inputs and outputs to be monitored remotely.  They are
>>> often polled at specific times, which is why sometimes you may hear the
>>> tones underneath voice comms.  If the controller polls and doesn't get a
>>> response back then it will retry X amount of times (if programmed) then
>>> assumes the site is dead, and alerts get generated.  A variety of things
>>> can be monitored. Often these are only 'analog' inputs so you only get very
>>> specific details..  You could see things like
>>>
>>> Battery Bank A is 100/75/50/25% (maybe not even in that much detail)
>>>
>>> Generator On/Off
>>>
>>> Entry Door OPEN/CLOSED
>>>
>>> Alarm ACTIVATED/DEACTIVATED/IN ALARM
>>>
>>> SOLAR ON/OFF (IE is there voltage coming into the system on the Solar
>>> lines)
>>>
>>> REPEATER POWER ON/OFF  (some repeaters can have an output that's
>>> activated when it's in a certain state)  As Daryl mentioned, it would be a
>>> (probably unreliable) way of determining if a repeater is working or not.
>>>
>>> With the NGCC being implemented, a lot of this will eventually become
>>> redundant as most things like SCADA would be converted to IP based, and
>>> digital radio is also IP based, meaning a lot of this could be sent over a
>>> text message over the radio network.  I assume P25, but DMR will prioritize
>>> voice over messaging.
>>>
>>> As for the screeching, lots of factors could be causing that.  I-band
>>> links shouldn't really be used for monitoring as they're only
>>> point-to-point or point-to-multipoint links meaning you really need to be
>>> in line of the path for it to be received. I'd recommend use the VHF/UHF
>>> frequencies.  Once again, with things turning to digital soon, they'll
>>> probably be redundant with the links will be done over IP.
>>>
>>> Cheers,
>>>
>>> Richard
>>> On 20/03/2022 11:23 am, Darryl Healy wrote:
>>>
>>> Those tones are something to do with the linking with all the VTGs.
>>>
>>> They happen every 4 hours at midnight and so on.
>>>
>>> Someone will no doubt give a more technical explanation of them soon.
>>>
>>> On Sun, 20 Mar 2022, 11:01 BJ, <bjcuizon151 at gmail.com> wrote:
>>>
>>>> Hi all,
>>>>
>>>> Was in Dunedin recently and tuned in to police comms. Anyone know what
>>>> those squawking tones on some police channels are? It doesn't sound like
>>>> fire selcall but more like a really short (~1 sec) burst of what sort of
>>>> sounds like a part of the old dial-up handshake.
>>>>
>>>> Also, was listening to firecom and ambo thru the I-band link in Chch
>>>> and on some link channels there is a really high pitched tone that is
>>>> present when someone keys up. It can only be heard on a radio with no audio
>>>> filtering/DSP as my Tait seems to cancel it out. Does anyone have an idea
>>>> what this is as well?
>>>>
>>>> Thanks in advance,
>>>> BJ
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>>>>
>>>
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