Johnson County VHF NXDN

Last year Johnson County issued a bid packet for a "digital" VHF backup radio system. It appears as though ECS out of Bloomington has won the bid. Pending application for KSA914 is on file in ULS. In the pending application they are adding NXDN emissions designators for the two existing VHF repeaters on 155.61 and 159.15 (and deleting all the old wideband analog designators). It looks as though the narrowband analog designators are also remaining on all frequencies.

It will be interesting to see this system come online.

Now that is smart... But... They will have to replace the APX with an NX variant or have to carry 2 radios around.... They utilize the VHF that they already have, but upgrade it to NXDN...

So if they go with say...
NX-5200_5300_5400 VHF/UHF/700-800MHz Digital Transceiver P25(I&II)NXDN Multi-Digital & FM Analog Portable Radios - NEXEDGE KENWOOD
It can do the analog for the Fire Dispatch and interop... And SAFE-T & IDPS.. and NexEDGE.... If the radio is IPSC approved that is.

And surprising as I thought they had killed the whole backup system thing in council tabling it multiple times.

I would imagine this might be a type of nxdn vhf simulcast system.
I am curious to see how the scanners handle this one??
I have some conventional digital vhf systems over here by me and they cause some strange rx issues.
Sometimes confusing the scanner, the scanner parks on it, and acts like it is decoding but nothing heard.
The systems have 2, 3, or more tower sites throwing out the same digital causing a simulcast trunking phenomenon!
Although some of the issues are different than that of trunked simulcast.

So far I have never heard of NXDN SIMULCAST. We have a 7 county 24 site UHF NXDN TRUNKING SYSTEM ALL USING DIFFERENT CHANNELS.
Not the same 8 frequencies in all 24 sites. I work with a Kenwood Dealer and have never heard of NXDN SIMULCAST (as in the problem of multiple sites using the same frequency) information link below.
http://www.simulcastsolutions.com/userfiles/file/simulcastforums/motorola_simulcast_part4.pdf

No biggie. Johnson co, Being a countywide radio system, there would have to be some form of transmitters linked together somehow for countywide coverage. I am just curious, thats all.
I dont know for sure if these nxdn systems here are simulcast as we know it, but they are linked together and tx together somehow. There is something that icom uses for linked sites, too. Curious to see if anybody has some insight on how johnson county will be set up?

Nope just the high power VHF repeaters SO has always had there in Franklin. Just now will use NXDN. No simulcast, no trunking, just NXDN digital conventional. They have had the VHF repeaters forever. Now they are going to switch out the analog only gear for the dual mode NXDN stuff. (And yes they could just update the stuff that is already in place and use it, but someone put the (MUST BE DIGITAL) bug in the Sheriff ear....) Could have just kept it analog, put it in the APX8000 and not had to buy a buttload of new radios etc....

Last I looked many personnel were still carrying the XTS 2500i portables they bought about 10 years ago. I know IPSC and DPSC have allowed at least some Kenwood P25 gear. I believe Martinsville and several other agencies in Morgan County have some Kenwood P25 gear in service.

I believe this particular bid package was to include portable radios. Seems like more work than what its worth to switch manufacturers and go with Kenwood gear that does all of the above, P25 and NXDN on both 700-800 and VHF. Seems they could have gone P25 on the VHF repeaters and gone with the APX 8000 portables..... but since when did anybody care about maintaining an interoperable standard?

Because with the NX5000's you can have NXDN, P25 and Analog all in one radio that sounds better on P25 than the APX8000 and that comes from APX8000 users. The APX8000 can not do more than one digital format.

buddrousa said:

Because with the NX5000's you can have NXDN, P25 and Analog all in one radio

Click to expand...

Yeah, if its all on the same band. At least that's how I read the Kenwood specs: http://comms.kenwood.com/special/nx_5000/common/pdf/nx_5000_brochure_2016.pdf

The SAFE-T/IPSC system is on 800 MHz and the county "backup" NXDN is on VHF high. It doesn't appear Kenwood makes a radio that does both VHF and 700-800 MHz in the same package.

About the only way they could accomplish this is two mobile RF decks connected to the same control head, one on VHF and one on 700-800. But again, that's two radios. No solution for portables.

They should have just put up their own 700 MHz conventional repeaters for backup purposes on the 7TAC, 7LAW, and 7FIRE channels. Nobody around here that I know of has repeaters up there, and they would have saved a lot of money because they could use their existing 700-800 MHz gear.

Lots of idiots that think they know what’s best. They listen to these radio reps, and go along with anything. Johnson County has lost all of their radio gurus that actually understand the systems and how they work.


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