Cobb County TDMA

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b7spectra

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Very interesting in the FCC Database:

YE WQQB804
COBB, COUNTY OF
[RADIOS WILL COORDINATE COUNTY JAIL ACTIVITIES]
9K80D7W P25 Phase II fixed-end 2-slot TDMA (Harmonized Differential Quadrature Phase Shift Keyed modulation - H-DQPSK)

[FONT=&quot]855.9125 FB2 Ant: 1 100p 151e Units: 1 16K0F3E 9K80D7W [/FONT]
[FONT=&quot]856.7375 FB2 Ant: 1 100p 151e Units: 1 16K0F3E 9K80D7W [/FONT]
[FONT=&quot]855.0875 FB2 Ant: 1 100p 151e Units: 1 16K0F3E 9K80D7W [/FONT]
[FONT=&quot]857.9875 FB2 Ant: 1 100p 151e Units: 1 16K0F3E 9K80D7W [/FONT]
[FONT=&quot]856.9875 FB2 Ant: 1 100p 151e Units: 1 16K0F3E 9K80D7W [/FONT]
 

b7spectra

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So, I had a little birdie sit on my shoulder and tell me a few things:

Cobb is in the process of starting to move frequencies over to the TDMA Phase 2 system. Everything is going to be in place by end of year and they will "throw the switch" for all of the county, but NO one in the county has the APX radios yet. The system will be phased in TG by TG. Selected TG's (i.e. SWAT/MCS/EOD) will be encrypted, but that will be it.

As I said, just a little birdie that had my ear for a little bit.
 

K4SVT

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We are screwed.....:(...
 

Casey

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East Cobb County GA
The largest fleets in the system (police, fire) have a large investment in digital phase I radios, so listening shouldn't be affected for quite some time, what I would like to know is if all the existing talkgroup numbers will stay the same or if they will all be new ones in the short-term well before any radios are swapped out.
 
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MTS2000des

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Cobb County, GA Stadium Crime Zone
the fleetmap (talkgroups) won't likely change, adding TDMA is merely a check-box option in the CPS for the APX radios enabling it on a per talkgroup basis.

I would say you are right Casey, most subscriber radios are FDMA only and will be replaced as they fail with TDMA capable ones. Once the majority of each fleet user is TDMA capable, then the talkgroup can be strapped for TDMA only operation.

There is also the issue of interoperability, which the system administrator is very aware of and involved with, as most digital radios throughout the region are currently FDMA only.

FWIW my employer purchased 20 APX4000s earlier this year but we are still using the majority of the older FDMA radios (XTS2500s).

It is important to note that the Astro 25 7.13/7.14 core can support talkgroups being strapped to FDMA only, TDMA only, or dynamic FDMA/TDMA capable. When a talkgroup is set to dynamic, so long as ONE FDMA only radio registers on that TG, all radios are forced to operate in FDMA only. I am not sure how the fleet map will be converted over in time, but I don't think we have anything to worry about for the next year or so.

I suspect the timing of the switch to TDMA will coincide with the need for additional talkgroup capacity for the upcoming Race to Waste stadium, which we are all paying $397 million dollars of our taxpayer money for. It's good to know Tim Lee is looking out for his constituents in Englewood, CO.
 

K4SVT

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this is for mts2000des...i was going to ask you if cobb county is going phase II next week or just going live for testing purposes then merging over...thanks..

Sent via LG G2 on Sprint 4G LTE Spark
 

K4SVT

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Eh oh well i got my information

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KD4YGG

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Running PRO96COM on 856.6125 Mhz while in Austell this morning showed Site 101 of system 17D in site trunking mode.
Looks like a test site is available.

FileVersion:8
-TowerInfo
#This section is here for information only. With the exception
#of the Call Sign(s), This data is not Read back into the program at all.
System ID : 17D
System Name : Cobb County Phase II
WACN : BEE00
Tower Number (Decimal): 1-1
Tower Number (Hex) : T0101
Tower Description : Site 101
Control Capabilities : Voice,Registration
Flavor : Phase 2
Call Sign(s) :
Timestamp : Sat Oct 18 09:35:38 2014

-Tables
#Format: Table ID,Base Freq,Spacing,Input Offset,Assumed/Confirmed,BandWidth,Slots
00,851.00625,0.00625,-45.00000,"Confirmed",0.01250,1
01,762.00625,0.00625,30.00000,"Confirmed",0.01250,1
02,851.01250,0.01250,-45.00000,"Confirmed",0.01250,2
03,762.00625,0.01250,30.00000,"Confirmed",0.01250,2

-Frequencies
#Format: Channel,Usage,Frequency(/Slot),Input Channel,Input Frequency(/Slot),Input Explicit(1/0),Hit Count
"00-0897","c",856.61250,"00-0897",811.61250,0,0
 

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