RFS: P25 Transmissions on TG10055 off Chullora & Horsley Pk

[Mike Alpha]

Yesterday I heard NSWFB on TG43568 in digital on GPT, but on the 3600 GRN. I heard a pumper 3xx asking comms if RFS were attending an incident.

What's that about?

Mike

[rustynswrail]

Yesterday I heard NSWFB on TG43568 in digital on GPT, but on the 3600 GRN. I heard a pumper 3xx asking comms if RFS were attending an incident. What's that about? Mike

Mike,

I think that is their old(?) 3600 baud digital test channel. Most departments had one, obviously still in place.

Russell

[matthewn1983]

yeah i heard that today off GPT whilst in Artarmon. on the 3600 as well.

[ivahri]

Mike,

It is a test patch between analogue & astro to test effects of link compression on digital audio quality... there is actually 2 astro tgs- one connected without link compression, the other with it. The people testing switch between the two. The active traffic you are hearing is Newcastle PMR traffic via our RoIP service at Werris Creek then rebroadcast to the GRN either at Newcastle (compressed) or Alexandria (uncompressed).

Cheers,


Richard

[citabria]

Hi Richard,

When you say compression, is that compression of the digital signal? or is it compression on the RoIP link?

Am a bit confused here with all the jargon etc

[Mike Alpha]

Thanks Russell & Richard. In all the time I've been listening to the GRN, that was the first time I'd heard it .

Mike

[ivahri]

Hi Richard,

When you say compression, is that compression of the digital signal? or is it compression on the RoIP link?

Am a bit confused here with all the jargon etc

Compression currently occurs between the Comms Centres and the CEB. This is done primarily due to the cost of bandwidth- with the current analogue audio compression down to 9.6k is used but what has been found is that P25 audio requires greater bandwidth (ie less compression) to maintain lifelike sounding audio. The tests were (partly) to test the configurations required. Times have changed & the cost of bandwidth has plummeted so compression is less necessary- we don't use any compression on our PMR RoIP links (they run at 56k) so the audio tends to be very good. Pardon my explanation... I'm an RF guy!

Cheers,

Richard

[citabria]

Yeah, no worries that makes sense to me! Cheers..

[jaskel]

Mike, i have sucessfully got both my Pro96's working on the new GRN. i just got home from sydney. works very well and tracks quite well. im picking up horsley park from all the way out at douglas park and right up thru campelltown and ingleburn worked quite will. even in my grandmothers loungeroom in Belfield i got horsley park no problrm.
its crap audio but its no worse than the old G60 ops com 3 (TG54864).

ive been working with russell on this one and managed tro have a win
pm me if you would like the details.

cheers
Matt

have u got a database file or anything u can email to me, im interested to see how u have set it up for GRN as I can get jack on mine..lol

can anyone that has pro96 programming file please email to specialchicken@gmail.com