VHF simulcast

[Mark174]

When I look at the frequency listing for Phoenix and Mesa Fire, I see their old VHF-Hi dispatch frequencies (154.190 and 154.280) are still listed. Are the simulcasted from the digital frequencies, or would I need to have a digital scanner to hear anything? Would the same be for PD?

 

[K5mow]

I would think it would be simulcast in regular FM and you should be able to get it on a analog Scanner.


Sent from my iPhone using Tapatalk

 

[KB7MIB]

The VHF side is still analog, conventional narrow FM. No special digital equipment is needed.

154.1900 is the Phoenix FD Regional Dispatch Center VHF-High Dispatch channel A-1. It is multicasted with the K-1 talkgroup 1795 on the Regional Wireless Cooperative P25 trunked system.

154.3400 is the Mesa FD Regional Dispatch Center VHF-High Dispatch channel B-1. It is multicasted with the C-1 talkgroup 3064 on the TOPAZ Regional Wireless Cooperative P25 trunked system.

154.2800 is known as mutual-aid fire 4, since it is usually in the channel 4 slot in the VHF-High radios of any of the fire departments and districts in Maricopa County, and perhaps adjacent counties, as well as the Arizona Department of Forestry and Fire Management. It is not a dispatch channel.

John
Peoria

 

[Mark174]

Thanks for the info. Is there a difference in meaning between the terms simulcast and multicast?

 

[cfsimmont]

You can hear all of the dispatches for Mesa Fire and Phoenix Fire on the VHF channels, however they both only use the VHF Tac channels for hazard calls (working fires, hazmat, etc.). All other radio traffic (MVA, medical calls and so on) are worked on the digital talk groups. All city PD radio traffic is on the digital systems listed in the DB. DPS is still on their UHF system.

 

[radioprescott]

Thanks for the info. Is there a difference in meaning between the terms simulcast and multicast?

SIMULCAST One channel at each of the simulcasting sites transmits the same signal simultaneously at the same frequency

MULTICAST One channel at each of the participating sites transmits the same signal simultaneously at a different frequency

AZ Sate Fire is simulcasting when they transit on all CH 1 repeaters together. You may get a warbling sound when hearing 2 transmitters at once

DPS is multicasting when they link 2 districts together on separate freqs

 

[E5911]

I cant speak to the rest of it but at my center Simulcasting(Patching) is 2 or channels tied together so everyone hears everything. A example would be 2 agencies who do not have a common frequency may simulcast two repeaters so both agencies can talk and hear each other. In a multicasting scenario, the dispatcher can hear both frequencies, or repeaters or sites, and field units can hear the dispatcher but not each other. DPS regularly "multiselects" two districts so they can staff up fewer positions at night, rarely can I hear District 9 mobiles in Dist 4 in Yuma at night but I hear the dispatcher talking to units in District 4 and 9 most nights . Every once in a while I can hear district 4 and 9 cars, for a dispatcher, sometimes its easier to patch than to multiselect. Easier to hear less chance 2 officers in two distant locations would talk over each other.

My console has a folder with six "patches" I can set up, or six "multiselects". I can set them up before I need them and turn them on and off as needed.

There is a bit of a difference between the above example and mine, but the concept is the same, either expanding the users, expanding the coverage or expanding the geographic footprint for a certain dispatcher.

 

[K9DAK]

Then there's the original definition of simulcast, before the advent of what we call "simulcast" P25 systems... "a program broadcast simultaneously on radio and television, or on more than one station, or in several languages, etc." For example WBBM-AM 780 and WCFS-FM 105.9, both called News Radio 780, broadcasting the same programming on AM and FM.