[TheList] Christchurch Ambulance now digital

Wed Aug 3 15:04:58 AEST 2011

In reply to the coverage question, I believe its due to the digital 
nature of the signal. The information I have shows a considerable range 
increase.

As for bandwidth, there's a new "version" of P25 due out which is 
6.25khz bandwidth, but NZ Police are using 12.5khz I believe.

I don't think you'll see Police allowing any other group to use their 
network, even though yes it could be done. Part of this will be due to 
the nature of the repeater sites. Most sites will contain 4 repeaters 
(this is the minimum they will install at one site too) - one for 
control and 3 for actually passing conversations. While yes this could 
hold more than 3 actual channels, the channels are a heck of a lot 
busier now than before, as most info that was passed by cellphone now 
doesn't need to, and can go out over the radio. As such, your average 
two channels covering an area are in use most of the time. When there's 
also AOS, CIB, and the Proactive groups to consider that will need a 
channel as well, that won't leave much, if any, room for anyone else.

On 3/08/2011 4:48 p.m., nivick at vodafone.co.nz wrote:
>
> Is P25 narrow bandwidth? Trunking allows more groups to use less 
> spectrum allocation, ambo could use the allocated channels for police 
> and no one would be
> the wiser.  Control Channel is not picky who it allocates talk 
> channels too.
>
> On Wed, 3 Aug 2011 16:34:19 +1200, Scanhead <scanhead at gmail.com> wrote:
>
>     Has coverage improved purely because its a digital signal? Or
>     because the bands have changed or more equipment is installed
>     (larger network etc)? Is it like comparing AMPS to GSM coverage wise?
>
>     On Wed, Aug 3, 2011 at 3:27 PM, Mike Bailey <tahiini at gmail.com
>     <mailto:tahiini at gmail.com>> wrote:
>
>         "So what are the advantages of P25 over analog if secure
>         communication is not an issue? "
>
>         Coverage is improved. Also, on the fringe areas, you either
>         have full coverage, or none at all - not the sometimes
>         scrambled guff we can hear now and then. Also, the radio
>         itself can tell you if you're in coverage or not.
>
>
>         On 3/08/2011 2:54 p.m., Scanhead wrote:
>
>             Perhaps the confusion is because the police are using ESB
>             band with P25 trunking as the replacement for ESA... Which
>             is normally (and probably still) where ambo operates.
>
>             Can anyone confirm that current digital scanners are still
>             not able to follow tait P25 trunked? From memory it was to
>             do with the data rate of the control channel (could be
>             wrong). I could get unencrypted voice with my uniden
>             digital but was never able to follow the conversation.
>             Thats why I started looking at software radio etc.
>
>             It is ironic that the P25 system came into being because
>             of a need for radio systems and services to
>             inter-communicate, and now it is what separates them. Some
>             will argue that P25 radios can communicate with the old
>             analog systems (mixed mode), but I've been told this is
>             not possible with a trunked system. (again, could be wrong)
>
>             So what are the advantages of P25 over analog if secure
>             communication is not an issue?
>
>             Scanhead.
>
>             On Wed, Aug 3, 2011 at 12:17 PM, Neill Ellis
>             <tgsnoopy at gmail.com <mailto:tgsnoopy at gmail.com>> wrote:
>
>                 Hi Grunter,
>
>                 I think you might be on to something. I'm pretty sure
>                 the media would have let us know if Ambo's were
>                 trialling or had gone secure digital.
>
>                 Regards,
>
>                 Neill.
>
>
>
>                 On 3/08/2011 11:50 a.m., Grant Carroll wrote:
>
>                     Hello,
>                     I am still listening to ambos on the same
>                     frequencies in the ESB band they have been on for
>                     ages. This is on an analogue scanner and my
>                     digital scanner with no "P25" coming up to suggest
>                     the transmissions are digital and obviously if I
>                     can hear them on an analogue scanner they aren't.
>                     Am I missing something here? Are they being
>                     simulcast on analogue and new digital frequencies
>                     for now or is their going digital just a vicious
>                     rumour?
>                     Cheers guys.
>                     Grunter1.
>
>
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