NSWGRN is now Phase 2, and has 467MHz bandplan added

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Bigfella237
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Re: NSWGRN is now Phase 2, and has 467MHz bandplan added

Post by Bigfella237 » Mon Dec 17, 2018 5:33 pm

So it looks like they're compounding the problem by forcing the radio to an input channel that doesn't conform to the bandplan?

I have read and re-read the RALIs associated with the government spectrum assignments and they clearly show segment O covers 420.0000 - 430.0000 and it has no paired segment (meaning both TX & RX freqs must be contained within those limits).

If the TELCO are pairing a frequency within segment O with a frequency from segment I (412.8375 in the example above) then they are not complying with the government spectrum, unless as you say, there is some loophole I'm not aware of, but it seems pretty cut 'n dry to me?

Andrew

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Bigfella237
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Re: NSWGRN is now Phase 2, and has 467MHz bandplan added

Post by Bigfella237 » Mon Dec 17, 2018 5:54 pm

The other stupid thing is, why have a 6.25KHz spacing with a 12.5KHz bandwidth?

It just means you can only use every second LCN in the bandplan (which is how it is at the moment).

Andrew

citabria
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Re: NSWGRN is now Phase 2, and has 467MHz bandplan added

Post by citabria » Mon Dec 17, 2018 6:30 pm

Bigfella237 wrote:The other stupid thing is, why have a 6.25KHz spacing with a 12.5KHz bandwidth?

It just means you can only use every second LCN in the bandplan (which is how it is at the moment).

Andrew
"It's how we've always done it" is probably the reason. The newer ranges are correctly spaced at 12.5kHz.

They aren't pairing frequencies across bands - The 420MHz sites are using the upper 425-430MHz band for the inputs as per the correct frequency assignments. Check my previous post and look at the control channel grant. It specifies (04-1498) - 421.8375MHz as the base transmit frequency, and (04-2330) - 427.0375Mhz as the bast receive frequency - so all that is correct and valid as per the frequency assignments.

It's just they're not using bandplan 5 for those frequencies, even though that's obviously what it's there for.

I guess this is why they're using explicit mode P25 trunking. The bandplans don't work because they're misconfigured, so implicit trunking doesn't work...

It's the explicit channel grants that make it work - this is the "intricacy" that I rightly thought we had missed.

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Bigfella237
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Re: NSWGRN is now Phase 2, and has 467MHz bandplan added

Post by Bigfella237 » Mon Dec 17, 2018 7:33 pm

So the question is, why go to all that trouble and not just configure the bases using bandplan 05 to start with and have everything working as it's supposed to? Is there something in the existing radio profiles that needs to change to make use of a new bandplan (there's nothing that I can see)?

If they need to sit down and re-configure the entire system from start to finish, that's a job I could really get my teeth into!

I'd start by changing bandplans 00 & 01 to duplicate 04 & 05 except with 12.5KHz spacing and a 12.5KHz bandwidth (creating new bandplans allows time to work while the rest of the system remains operational).

Then I'd work my way through each site and reassign the new LCNs to all the bases. Sites could be switched to the AltCC while the main CC base is reassigned and vice versa. That way each individual repeater would only be out of action for the few seconds it takes to change it's assigned LCN.

I'd think all that could be done remotely from the NOCC without even visiting a site and with very minor service disruption? It would just take a LONG time to complete!

Andrew

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Bigfella237
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Re: NSWGRN is now Phase 2, and has 467MHz bandplan added

Post by Bigfella237 » Mon Dec 17, 2018 11:54 pm

citabria wrote:So, naturally the bandplans are incorrect, and of course there is another kludge that has been put in place to work around it.

Check out the channel grant opcodes from the sites control channel, and you can see that it's explicitly giving the input frequency as an extension of bandplan 4 as well.

The radios are getting the correct input/uplink freq form the SU to the base using the explicit grants.

Image
So I just downloaded Pro96Com and (finally) figured out how to get it working on my BCD996XT's (using COM over Ethernet no less), and tuned into site 003-029 Mt Wandera, but my channel grant data doesn't have three-quarters of the guff that yours shows...

Image

Andrew

citabria
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NSWGRN is now Phase 2, and has 467MHz bandplan added

Post by citabria » Tue Dec 18, 2018 4:54 am

Try running it again on a 420MHz site. The site you’re monitoring works fine on the 04 bandplan, as it respects those frequencies and splits.

It’s only the 420MHz sites that require the explicit channel grants - which then in turn require the multi block trunking messages.

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Bigfella237
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Re: NSWGRN is now Phase 2, and has 467MHz bandplan added

Post by Bigfella237 » Tue Dec 18, 2018 5:10 am

Unfortunately I don't have any sites within range that are running those bogus LCNs, but that just adds to the mystery... there must be some reason they're doing these freqs this way and not using bandplan 05?

Andrew

citabria
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Re: NSWGRN is now Phase 2, and has 467MHz bandplan added

Post by citabria » Tue Dec 18, 2018 10:55 am

Bigfella237 wrote:there must be some reason they're doing these freqs this way and not using bandplan 05?
Yeah, and we have gone full circle now and are back to the start. This question is the exact reason I posted about this thing in the first place...

I don't know if we will ever find an answer or if it will remain an curiosity...

Wonky
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Re: NSWGRN is now Phase 2, and has 467MHz bandplan added

Post by Wonky » Wed Dec 19, 2018 9:32 pm

In relation to the new 467MHz band plan, do not be surprised if you start seeing control channels in this band plan at some stage, specifically from 467.7625 to 469.4125.

I have seen an APX codeplug (genuine GRN profile) that has 53 control channels listed from this band plan...

Image
control channels.PNG
(33.48 KiB) Not downloaded yet

citabria
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Re: NSWGRN is now Phase 2, and has 467MHz bandplan added

Post by citabria » Thu Dec 20, 2018 9:46 am

Thanks Wonky, that all makes sense.

Any chance you can get the rest of that list? It might be handy when searching for new sites etc..

Cheers,
Citabria

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