Dane County: P25 VHF trunking

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biglaz

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Dane county is currently considering making the shift to a P25 capable VHF trunking system. This will be backed by a homeland security grant. The final decision will, supposedly, be made later this month. Obviously this would require a long transition period beginning with updating a lot of equipment county-wide.

Discuss.
 

OpSec

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Cool. As long as it's not another snake-oil "miracle cure" 800 TRS I'm happy.

(mocks the Sam Adams commercial)

VHF...always a good choice!
 
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MMIC

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Yes - i'm glad to see that someone out there is going to something other than 800 MHz. VHF will cover pretty well, but the only concern with that band is the inefficiency of the antennas on the portable radios, which will degrade portable coverage. Mobile coverage will be exceptional.

Where are they going to get the frequencies for the system? VHF is typically a tough band to acquire frequencies from.
 
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N_Jay

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MMIC said:
. . . . . but the only concern with that band is the inefficiency of the antennas on the portable radios, which will degrade portable coverage. . . . .

. . .. . Where are they going to get the frequencies for the system? VHF is typically a tough band to acquire frequencies from.
Looks like portable radio antennas is not the "only concern". :roll:

As you pointed out channel availability is a big concern, as is co-channel and adjacent channel interference, man made RF interference, and several other issues.

Sometimes 700, or 800 are the better solution. Sometimes not!
 

ffemtbland

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why would portable radio antennas be a concern?
and most importantly - even if a homeland security grant is gonna cover the rebanding, etc, who will help pay for all of the new radios, etc. for fire / ems departments that are already struggling for cash?
Lars
 

MMIC

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Portable radio antennas in the VHF band have significant loss, or they are said to have "less than unity gain" and are very inefficient compared to UHF (better) or 700/800 MHz (better yet). With an inefficient antenna, the range of the signal that is transmitted will be degraded. This degredation is most noticible in VHF where a full wave is about 2 meters long, as opposed to about 35 centimeters long on 800 MHz. 800 MHz portable antennas aren't the answer to all problems, but they will be more efficient in the band.
 

ffemtbland

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the word on the street in terms of cost ... anywhere from 40-60 million ... that's what i've heard ... hopefully that includes compatible equipment for ems, pd, and fds ...
Lars
 

ffemtbland

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i mispoke - i'm "guessing," not assuming. i think i'll try and get down there later today ... i'll let you all know whats up.
Lars
 
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N_Jay

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ffemtbland said:
i mispoke - i'm "guessing," not assuming. i think i'll try and get down there later today ... i'll let you all know whats up.
Lars
I would "assume" most government committee meetings are open unless I had a good reason to "guess" they were closed.
 

bc780l

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Open Meeting

I actually called and confirmed that this was supposed to be an open meeting. My past experience has been that they'll indicate in advance in the announcement that it's a closed meeting. Attendees may be asked to identify themselves, generically. Hmm. Communications consultant ...
 
N

N_Jay

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bc780l said:
. . . Attendees may be asked to identify themselves, generically. Hmm. Communications consultant ...
"Interested constituent" may get more attention from the political people.

"Communications Consultant" will just makes them think you are out of work and fishing for a contract.
 

ffemtbland

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im planning on going ... and please ... let's drop the "assuming" "guessing" issues ... although the comments have been intriguing ...
Lars
 

bc780l

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To provide interoperability on VHF with surrounding communities, the Madison/Dane Co trunking system, and the future State VHF/800 P25 Hybrid trunking system, Dane County's public safety communications system will be upgraded to a hybrid VHF/800MHz P25 system. Next [significant] steps will be funding approval [starting at $46M], an RFP, and lots of coordination. Minutes of the meeting will be published at Dane County's public web site, under Public Safety Communications Center Board, at http://www.co.dane.wi.us/committees/agendas.asp This is a waaaays down the road.
 
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MMIC

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If they are going with a 9600 baud system, I would imagine that the City of Madison would want to migrate some of their 800 MHz equipment to the 9600 baud system so that they don't have to buy all new VHF equipment. A 9600 system will support trunking across these bands - it's just that the radios won't support roaming between the bands. The question is whether or not Madison has equipment that will migrate forward to the 9600 platform. I would guess that the answer will be "yes" since they are not planning on dumping the 800 MHz side completely.

The rest of the State can operate on the same system on VHF without any problem. The VHF and 800 MHz sides could share talk groups and interoperate just fine.
 
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