RFS: P25 Transmissions on TG10055 off Chullora & Horsley Pk

[sw sydney scanner]

i just hoocked the scanner up to uasd when i looked in scanner view this is what it shows
Band Plan P25
Base0 851.006250MHZ
Spacinging0 6.250KHZ
Base1 762.006250MHZ
Spacing1 6.250KHZ
Base2 851.012500MHZ
Spacing2 12.500KHZ
Base3 762.006250MHZ
Spacing3 12.500KHZ
Base4 412.47500MHZ
Spacing4 6.250KHZ
Base5 420.012500MHZ
Spacing5 6.250KHZ
Base6 0.000000MHZ
Spacing6 0.000KHZ
Base7 0.000000MHZ
Spacing7 0.000KHZ
ECT
does this seem right i have not programed any of these all i have done is enterded the cc channels and let the scanner search for a couple of weeks.

[Bigfella237]

The actual data being broadcast on the control channel is:

3D 00 03 22 D0 32 0A 25 10 A2 63 A0 Identifier Update 0 Base 851006250 Spacing 6250 Tx Offset 45000000
3D 00 13 25 E0 32 09 15 75 62 1B 36 Identifier Update 1 Base 762006250 Spacing 6250 Tx Offset 30000000
-BD 00 23 22 D0 64 0A 25 15 84 9F 1A Identifier Update 2 Base 851012500 Spacing 12500 Tx Offset 45000000
-BD 00 33 25 E0 64 09 15 75 62 5C DD Identifier Update 3 Base 762006250 Spacing 12500 Tx Offset 30000000
34 00 45 17 A0 32 04 EA C6 18 44 8F Identifier Update 4 Base 412475000 Spacing 6250 Tx Offset 378000000
34 00 55 91 80 32 05 01 C6 C4 6A 6A Identifier Update 5 Base 420012500 Spacing 6250 Tx Offset 280000000

These are the bandplans used on the system although we only seem to be using bandplan 4 which is:

LCN 04-0000 BaseTX 412.47500 BaseRX 403.02500
LCN 04-0001 BaseTX 412.48125 BaseRX 403.03125
LCN 04-0002 BaseTX 412.48750 BaseRX 403.03750
LCN 04-0003 BaseTX 412.49375 BaseRX 403.04375
LCN 04-0004 BaseTX 412.50000 BaseRX 403.05000
etc. in 6.25 KHz steps to
LCN 04-4095 BaseTX 438.06875 BaseRX 428.61875

except that I doubt you will ever see an LCN over 04-1204 (BaseTX 420.00000) because they are outside the band already in use by the old Type II Omnilink system? Also, you will noticed that at the moment we are only using every second LCN (the even numbered ones) as they correspond to the 12.5 KHz steps of the old frequency licences.

Andrew

[Bigfella237]

BTW, I don't know if it's already been mentioned but P25 TGID 10055 is "GD58 OP COM1" (NSW Rural Fire Service - Operations Communications 1)

Andrew

[Longreach]

does this seem right i have not programed any of these all i have done is enterded the cc channels and let the scanner search for a couple of weeks.

yep thats the correct bandplan, have the same one popping out of my PSR500. and yes we only use bandplan 4 right now. the offset i have is 16384 for bandplan 4 but it may not be required.
cheers

[ivahri]

Na, I also heard it Friday as well and the transmission quality was very poor, the P25 was dropping in and out not like the clear crisp transmissions I have heard up to now by the GRN Tech’s and others so far and I was in a good receive location as well.

If I had to give it a rating, it would have been around 2 out of 5.

Hi Grant,

From what you describe it was the input, the analogue sig, that was dropping out. That was exactly the test that was being done (maybe they were deliberately doing it). The previous tests you heard were "pure" P25 system audio which is what users will hear normally when listening to other appliances. Operator audio is a big issue & we have been working on that aspect as things like compression (on links) can have a big impact on quality. RFS & other agencies have devices called "Smartbridges" that link PMR bases/networks to the GRN- some I hear want to retain them even after the P25 GRN starts up and this could cause some agencies some grief.

Cheers,


Richard

[rustynswrail]

The actual data being broadcast on the control channel is:

3D 00 03 22 D0 32 0A 25 10 A2 63 A0 Identifier Update 0 Base 851006250 Spacing 6250 Tx Offset 45000000
3D 00 13 25 E0 32 09 15 75 62 1B 36 Identifier Update 1 Base 762006250 Spacing 6250 Tx Offset 30000000
-BD 00 23 22 D0 64 0A 25 15 84 9F 1A Identifier Update 2 Base 851012500 Spacing 12500 Tx Offset 45000000
-BD 00 33 25 E0 64 09 15 75 62 5C DD Identifier Update 3 Base 762006250 Spacing 12500 Tx Offset 30000000
34 00 45 17 A0 32 04 EA C6 18 44 8F Identifier Update 4 Base 412475000 Spacing 6250 Tx Offset 378000000
34 00 55 91 80 32 05 01 C6 C4 6A 6A Identifier Update 5 Base 420012500 Spacing 6250 Tx Offset 280000000

These are the bandplans used on the system although we only seem to be using bandplan 4 which is:

LCN 04-0000 BaseTX 412.47500 BaseRX 403.02500
LCN 04-0001 BaseTX 412.48125 BaseRX 403.03125
LCN 04-0002 BaseTX 412.48750 BaseRX 403.03750
LCN 04-0003 BaseTX 412.49375 BaseRX 403.04375
LCN 04-0004 BaseTX 412.50000 BaseRX 403.05000
etc. in 6.25 KHz steps to
LCN 04-4095 BaseTX 438.06875 BaseRX 428.61875

except that I doubt you will ever see an LCN over 04-1204 (BaseTX 420.00000) because they are outside the band already in use by the old Type II Omnilink system? Also, you will noticed that at the moment we are only using every second LCN (the even numbered ones) as they correspond to the 12.5 KHz steps of the old frequency licences.

Andrew

All,

Matt and I have pondered this setup with it making no sense. Interestingly, I have programmed the 396XT and 396T with P25 GRN and they work without offsets, base frequencies or anything else. Enter the control channels, select P25 standard, they track away without any problems.

Which brings me to my next theory, try the GRE500 on P25 GRN without any base frequencies or offsets and see if it works. Just a thought.

Russell

[citabria]

It just works on a GRE500.

I'm willing to bet that the bandplans aren't even used on P25 GRN - they could be set to anything and have it still work.

[rustynswrail]

It just works on a GRE500.
I'm willing to bet that the bandplans aren't even used on P25 GRN - they could be set to anything and have it still work.

They are not. As I understand pure P25 has a sub audible transmission at every press of the PTT which establishes all the system parameters. That is why I cannot understand why the GRE500 and now the PRO96 need the band plans.

Russell

[Mike Alpha]

G'day Russell, good to see you're back dabbling in radios

I can't get the DTS96 to track P25 systems. I haven't entered a bandplan in the ARC96 software. Have you or anyone else on the forum with a PRO96 or a DTS96 got them tracking any sites?

I've currently got a 996 in custom search stopped on Chaullora 417.000 CC and it is tracking the RFS TG 10055 fine. The DTS96 is on the same CC set for Motorola and in open scan mode with not a thing happening.

Mike

[scanSydney]

I was hearing 10055 off GPT on Friday evening as well. I had full bars (obviously, hearing it from Kirribilli) and the audio was shocking. The 'firecom' operator sounded OK, but the unit in the field who may have had bad reception was virtually unreadable via digital.