Proposed GRN Expansion

[ivahri]

Of the roll-out... don't hold your breath for the other.

Cheers

It's being tested in the USA and the specs are in the preliminary phase - basically the protocol is a mixture of P25 and dPMR style TDMA. I'm sure it will happen one day (might be a long way off though!)

I realise it is well advanced in the US, my doubts are more to do with NSW ever being able to afford the upgrade to both bases & terminal equipment. Maybe in around 2020 but I doubt anytime before then. Mother Hubbard's (read Kenneally) cupboard is pretty bare!

Cheers

Richard

[ivahri]

Ah no.

1 "translator" (total 35k) [actually translator is my term, it s really a clever DSP BDA that can do more than a simple BDA] replaces up to 8 bat bases (30k each).

So for your 6ch site you have saved 145k.

Regarding frequencies: the translators are at a site where there is no signal at all from the original site, so reusing the same frequencies is achievable (also neccessary) and is within a tunnel / building and doesnt leak outside (well may be a tiny bit with no detriment) and is in fact clever reuse of existing frquencies rather than needing new ones.

Hi Mal,

I think I need to clarify my comment on them being inefficient use of spectrum. The actual base channels used is efficient, it is the use of multiple link channels (one for each voice channel) that is awfully inefficient. Any other network would use a dedicated link to do this which would allow these voice channels to be compressed in to one link channel (be it 2Meg or 200kHz wide) within a properly assigned link band (ie. 900MHz or above). It shouldn't matter if there are 5 channels or 20 channels at a site, the link should occupy one link assignment, and not consume perfectly valuable 500MHz spectrum particularly in a high density area like Sydney.

Cheers,

Richard

[Bigfella237]

~ If you think I'm guessing .. no ... my team is commisioning 3 such sites this week.

[see if you can find them ]

And there are already similar sites in existance .. clue go to Central Railway main concourse and see which GRN site your radio affiliates to.

So... did anyone go hunting?

Andrew

[system_tech]

Well that was the case when the tunnel/buildings used leaky coax... but then some genius decided that a coverage problem outside could be fixed if the leaky coax was combined with an external antenna. Those in the know where I am referring to! These systems are great, even if hideously expensive (even with the RFI device) for the load that they carry, so long as those tinkering with them know what they are supposed to do (and based on what I've seen they don't have a clue). Maybe they will fix the audio quality problem & heterodyne issue I've been screaming about for some months... at least before P25 Phase II arrives in Australia.

Cheers,

Richard

yes indeed I know where you mean .. not the way it should have been done!

[system_tech]

Ah no.

1 "translator" (total 35k) [actually translator is my term, it s really a clever DSP BDA that can do more than a simple BDA] replaces up to 8 bat bases (30k each).

So for your 6ch site you have saved 145k.

Regarding frequencies: the translators are at a site where there is no signal at all from the original site, so reusing the same frequencies is achievable (also neccessary) and is within a tunnel / building and doesnt leak outside (well may be a tiny bit with no detriment) and is in fact clever reuse of existing frquencies rather than needing new ones.

Hi Mal,

I think I need to clarify my comment on them being inefficient use of spectrum. The actual base channels used is efficient, it is the use of multiple link channels (one for each voice channel) that is awfully inefficient. Any other network would use a dedicated link to do this which would allow these voice channels to be compressed in to one link channel (be it 2Meg or 200kHz wide) within a properly assigned link band (ie. 900MHz or above). It shouldn't matter if there are 5 channels or 20 channels at a site, the link should occupy one link assignment, and not consume perfectly valuable 500MHz spectrum particularly in a high density area like Sydney.

Cheers,

Richard

I agree with the linking inefficiency.

The ones I am working on currently use fibre to connect slaves to host. No RF links! Of course fibre can't be used if there is not a fibre path btween sites.

[ivahri]

Hi Mal,

I can't help it... I will always prefer an RF link for a network such as this. Fibre gets cut (particularly the "last mile" piece), but RF links can be designed with significant redundancy. The thought that emergency services depend on a network significantly tied together by fibre scares the poop out of me. Of course SRA uwave links don't count...

Cheers,

Richard

[system_tech]

Hi Mal,

I can't help it... I will always prefer an RF link for a network such as this. Fibre gets cut (particularly the "last mile" piece), but RF links can be designed with significant redundancy. The thought that emergency services depend on a network significantly tied together by fibre scares the poop out of me. Of course SRA uwave links don't count...

Cheers,

Richard

Ah well ... and how is Telstra connected .. mostly fibre thse days so .. got a Telstra link?

Apologies for being cheeky!

[Bigfella237]

~ If you think I'm guessing .. no ... my team is commisioning 3 such sites this week.

[see if you can find them ]

And there are already similar sites in existance .. clue go to Central Railway main concourse and see which GRN site your radio affiliates to. ~

OK, I'm gunna take a guess at Sutherland, Hurstville and Kogarah railway stations?

Andrew

[rustynswrail]

~ If you think I'm guessing .. no ... my team is commisioning 3 such sites this week. [see if you can find them ]
And there are already similar sites in existance .. clue go to Central Railway main concourse and see which GRN site your radio affiliates to. ~

OK, I'm gunna take a guess at Sutherland, Hurstville and Kogarah railway stations?
Andrew

Redfern Underground Station if memory serves me correctly.

R

[cartman]

According to those infamous documents that were floating around a couple of years ago Central Station Underground is suppose to be a site repeater of Redfern Station Underground in the analogue network.

Grant