FLDOT - lowband still active?

[PJH]

Are the lowband channels listed still active with regular use or are they long gone?

 

[bravo14]

I heard some active talk one day last year. I believe need to be close to the trucks to hear them. This was in Bay County.

 

[W4KRR]

Are the lowband channels listed still active with regular use or are they long gone?

Still active, just not very much traffic. The state DOT actually has a VHF low band repeater system up and running. Well, at least in South Florida. Repeater outputs are in the 47.xx range, and inputs are in the 45.xx range.

 

[kd4efm]

Yes, they still have low band. The radio tech for FDOT also runs the ham sarnet system. The vhf low band also uses the same microwave system state wide.

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[RFI-EMI-GUY]

I think there is a system wide radio test the last Thursday of every month.

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[RFI-EMI-GUY]

I heard some active talk one day last year. I believe need to be close to the trucks to hear them. This was in Bay County.

It is a multicast repeater system.

In each district the mobiles talk in on a common frequency used only in that district and the signals are voted and multicast from every site in the district on separate frequencies. The mobiles scan for a signal that has the correct tone and a signal above a certain squelch threshold.

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[PJH]

Sounds good - I've heard comms from FL, and would be nice to test conditions on lowband if they are decently active and/or have a good blowtorch power output. Missouri still takes 1st place on that but..

 

[RFI-EMI-GUY]

Sounds good - I've heard comms from FL, and would be nice to test conditions on lowband if they are decently active and/or have a good blowtorch power output. Missouri still takes 1st place on that but..

Yeah, Missouri was licensed for 5 kilowatts at one time! Florida FDOT repeaters are 100 watt Midland repeaters coupled with Raytheon/JPS SNV-12 voters.

Mobiles were Maratrac, but I think those have been superseded with Midlands and some VHF crossband vehicular repeaters. It's been years since I was involved , I know some changes were made.

Initially the system utilized E&M signalling for the COR. And PTT control logic and TX and RX PL tones were paired for consistant and short access time. These decisions were made so that the repeater would activate quickly and the audio was intentionally delayed somewhat in the voter chassis. This way mobiles scanning to receive a site would not miss any first syllables.

The original intent was to put in stand alone repeaters , however the noise floor at low band is rather high and unpredictable, plus there are not enough frequencies to provide a discrete TX and RX pair for so many repeaters.



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[bravo14]

If I don't forget next month when I'm out towards SJC area I'll try to see if FDOT is active there. When I lived there from 91-2012 I did hear them on/off