scanSydney

I have seen this article doing the rounds on social media lately so I thought I would share here.. Of note the NSW Police get a mention - maybe they will finally get a nice little push to join the GRN

https://www.itnews.com.au/news/nsw-govt ... aul-465721

The project kicked off with a $9.2 million pilot integrating 10 existing networks across 25 sites, which ran until January this year.

Sounds like the CCEP pilot in the north-west is done & dusted, time for that road trip Wonky!

So I wonder, did the police actually move to the GRN in the north-west during the pilot? Doesn't seem like it would've been a valid trial if they didn't.

The rollout will begin on the north coast of NSW, the government said. It has estimated the total cost of the program at $190 million.

Future road trip? We'll have to keep an eye on the ACMA for these sites, there are already a heap of single frequency registrations up the North Coast, I'm guessing a lot of these same sites will be expanded upon?

Andrew

Some more links to supplement the budget announcement

Site Council Pack
https://www.telco.nsw.gov.au/sites/defa ... 20V1.6.pdf

Motorola in $30 million boost to GRN
http://www.govnews.com.au/motorola-solu ... o-network/

Sites FAQ
https://www.telco.nsw.gov.au/sites/defa ... 0EMAIL.pdf

CCEP Pilot Sites
https://www.telco.nsw.gov.au/ccep/ccep-delivery-0

Will the pilot program be GRN Phase 2??

Mike

I haven't seen it mentioned anywhere but I'd be very surprised if any new sites / upgrades weren't phase II? Can you even buy infrastructure that isn't these days?

AFAIK all Motorola APX family radios are TDMA capable (don't know about any other brands), but some agencies are still using VERY old radios that aren't, and ALL radios on a talkgroup (per site) have to be phase II or the talkgroup reverts to phase I.

If it was me, I'd only be programming TDMA radios with the GRN profiles, that way you ensure that all your radio traffic is phase II (where available), but the problem is that you still have different agencies programming the radios to those doing the networks, and cooperation isn't necessarily guaranteed.

Bigfella237 wrote:I haven't seen it mentioned anywhere but I'd be very surprised if any new sites / upgrades weren't phase II?

That's what I found interesting about all the articles I've read, the technical detail is avoided. The best they could manage was "enhanced GRN"

With so many agencies being squeezed onto each site, 6.25KHz spaced channels would be the obvious way to go.

Mike

P25 Phase II is more than just narrowbanding. The original Project 25 Phase I standard used FDMA (Frequency Division Multiple Access), which is just a fancy way of saying each "talk path" (or channel/talkgroup/mode, whichever you like to call them) uses a unique frequency.

The newer P25 Phase II (along with DMR (aka MotoTRBO), TETRA, etc.) employs TDMA (Time Division Multiple Access), which allows multiple talk paths on the SAME frequency, but now divided by time "slots". IIRC, P25 and DMR have two time slots per frequency, and TETRA has four time slots per frequency.

The huge advantage is that one "base" (aka repeater, the actual hardware at the site) can now handle two distinct talk paths, so a five base GRN site switched from P25 Phase I to Phase II instantly becomes a virtual ten base site. Twice as much bang for your buck!

But the caveat, as I mentioned above, is that EVERY radio affiliated with each talkgroup on a site must be operating on TDMA, if even one radio jumps on and says "I'm too old for this shit" then every radio on that talkgroup must also drop back to FDMA (one talk path per base), kinda like gearing something to the lowest common denominator.

So there is a definite advantage in ensuring all the radios on your network are TDMA capable, such as the QLDGWN, where (I believe) they aren't allowing agencies to use any pre-TDMA radio equipment whatsoever, the benefit to the network provider is that they only have to build the infrastructure with half the resources that they'd need if they had older radios being used, like the NSWGRN.

Andrew

Mike Alpha wrote:With so many agencies being squeezed onto each site, 6.25KHz spaced channels would be the obvious way to go.Mike

P25 Phase 2 transmissions are still physically 12.5khz wide... It's just that you can fit two users in one 12.5kHz channel.

The marketing weenies manage to confuse the issue by inventing a new term "6.25e" or 6.25 equivalent - which doesn't really convey the fact that a phase 2 transmission is still 12.5khz wide..

citabria wrote:

Mike Alpha wrote:With so many agencies being squeezed onto each site, 6.25KHz spaced channels would be the obvious way to go.Mike

P25 Phase 2 transmissions are still physically 12.5khz wide... It's just that you can fit two users in one 12.5kHz channel.

The marketing weenies manage to confuse the issue by inventing a new term "6.25e" or 6.25 equivalent - which doesn't really convey the fact that a phase 2 transmission is still 12.5khz wide..

That's interesting. I hadn't heard of that. So TDMA is the key then?

Mike

Yep - two slot TDMA is part of the key - the other part is the "half rate" AMBE2+ vocoder that only requires half the bandwidth of the Phase 2 IMBE vocoder.

Each 20ms slice of voice in Phase One IMBE requires 88 bits. Each 20ms slice of voice in Phase Two AMBE2+ only needs 49 bits.

There is a noticeable loss in voice quality in Phase 2 - much the same as comparing DMR to P25 Phase One.

Cheers,
Matt