This is a debate some of us have been having for 20 years!
Forget about Smartzone- it isn't long for this world (at least in NSW), but even so your argument is not correct. Trunking is far more spectrum "efficient" than PMR because you need to consider how much use agencies make of each channel. The NSWFB and RFS PMRs can go quiet for extremely long periods when there aren't fires. Same with ambos. We talk about "duty cycles" to determine how much use they get & most of these run between 10 and 20% duty cycle. Now the beauty of trunking is that it allows a radio channel to be shared- so that in the 80-90% of the time these agencies aren't operating, someone else gets to use it. In periods of peak load, like during fires & storms it allows these agencies to take up more channels than they normally would- again something you can't do in PMR. So no, trunking is MORE spectrum efficient than PMR- and that is why the ACMA strongly encourage trunking and have done so for the last 20 odd years.
I agree with you on backhaul- but I've just implemented a Telstra based RoIP system that gives me 512/2M throughout NSW & that can easily be shared by multiple agencies. We use other agencies microwave bearers & more shared backhaul will happen over time as bandwidth drops in price. That makes backhauling PMR much cheaper.
The only real issues are (1) Coverage and (2) Politics. The RFS & NP&WS have a unique need for coverage in non-urban, mountain goat country. Providing trunking in to these areas, particularly at UHF and off solar powered sites, is hard & extremely expensive. I personally think the argument is overstated & there are many places where the GRN would work far better than poorly engineered PMR systems (though I know both are working on improvements) but then (2) comes in. Both agencies are fiercely independent & extremely political. They don't play well in other kids' sand pits & like to steal other kids toys... They like to jump up & down & stomp their feet to get what they want... even if it means others go without. So they tend to complain about the GRN even if the complaints aren't that factual, and government prefer to leave the kiddies alone...
For all that I am 100% pro-PMR for areas where trunking is not needed. Like having GRN in Lightning Ridge & Bourke- that was a total waste of money that could have been spent better.
PTT over celular... are you kidding? For life threatening comms? No way in the world- do you know how reliable ptt over celular is? I've tried it- total garbage for anything more than non-essential traffic. The key up delays are unpredictable & determined by network traffic. No serious user would go down that road today. But watch for P25 phase II & TETRA in some of those high security applications in the future.
Your GST money has already bought much of this hardware. Did you feel the pain?
Of course these are my views and mine alone & boy will I cop a flogging (but most people I work with know my views already!).
Cheers,
Richard
criten wrote:centralcoastscanman wrote:
If the RFS combined all of their repeater sited onto the NSWGRN then there would be no reason at all why rfs would need to have their own PMR system across the state.
I know its a bit off topic and playing with fire but Dept of Health(at a hospital level) is another example of an agency using pmr where they could move over to NSWGRN in the city areas.
GRN uses Moto SmartZone II which enables multiple repeater sites with telephone & radio backhauls between repeaters. If you're using two repeater sites, you're using two or three times the radio spectrum licensing than a single repeater site. Fact is, backhaul & widespread coverage isn't free, so moving to GRN potentially costs more.
Then theres all the radio equipment to buy.
Not sure why a hospital would go PMR or even GRN today... when there are services like Push to Talk over Cellular. Also becomes illegal to intercept with a radio scanner as intercepting phone calls is a federal crime.
But sure, organizations like the RFS should primarily use the GRN. Just who pays for all the radio equipment required for the move? I hope I don't with my tax dollars because their current system seems to work fine?