Simulcast on Viper

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Ethan1373

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#1
Edgecombe county NC fire dispatch has a frequency of 154.16000 VHF and being on a fire department in Edgecombe county i have a county supplied Minitor 6 that is set to this frequency only allowing you to hear dispatch . the only thing is i want to hear the trucks check in so i bought a Unication G5 to try out, i looked at the frequency to program it and it said simulcast on viper? I realize this may seem simple to most but im not seeing how this whole system works! if you have any input on this i would appreciate it.
 

kc4wsd

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#2
Edgecombe County has a handful of talkgroups on the Viper system. One of those, 17002, is assigned to "Fire." What you hear over the VHF frequency is also broadcast ("simulcast") on the Viper talkgroup. Imagine the two channels being tied together, and transmitting the same traffic.
Not every "channel" operates like this, but there are three of these simulcasted talkgroups in Rockingham County (EMS Dispatch, Rescue Dispatch, and County Fire Departments' Dispatch) on the Viper system.
One of the reasons for this is to allow volunteers (who can't afford a shiny new 800 MHz radio) to continue using their VHF (or UHF) portables to communicate with dispatch.

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Ethan1373

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#3
Edgecombe County has a handful of talkgroups on the Viper system. One of those, 17002, is assigned to "Fire." What you hear over the VHF frequency is also broadcast ("simulcast") on the Viper talkgroup. Imagine the two channels being tied together, and transmitting the same traffic.
Not every "channel" operates like this, but there are three of these simulcasted talkgroups in Rockingham County (EMS Dispatch, Rescue Dispatch, and County Fire Departments' Dispatch) on the Viper system.
One of the reasons for this is to allow volunteers (who can't afford a shiny new 800 MHz radio) to continue using their VHF (or UHF) portables to communicate with dispatch.

Sent from my SM-N920V using Tapatalk

Ok great so all I need to do is setup a p25 trunking system with that talk group 17002 and I will hear the same traffic as the vhf dispatch?
 

kc4wsd

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#4
Sorry for the delay in responding . . .
In theory, the answer to your question is "Yes."
In reality, you should monitor both the VHF frequency, AND the Viper talkgroup at the same time to verify they are indeed simulcasting, and it is tied together for all transmissions, not just the initial dispatch.
Nothing beats actual monitoring.

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troymail

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#5
Sorry for the delay in responding . . .
In theory, the answer to your question is "Yes."
In reality, you should monitor both the VHF frequency, AND the Viper talkgroup at the same time to verify they are indeed simulcasting, and it is tied together for all transmissions, not just the initial dispatch.
Nothing beats actual monitoring.

Sent from my SM-N920V using Tapatalk
Can't say I'm well versed in VIPER operations - haven't been here long enough and even then, it's a big state... however...

From what I've seen on both VIPER as well as other large systems, simulcasting of "local" activity - be it VHF, UHF, or even 700/800 activity - can be hit and miss. In many (newer) systems, the simulcasting might be automated such that if a radio switches to the P25 system talkgroup, the simulcast can/will appear but if that last radio leaves, the simulcast may then end.

In other cases, a "patch" to the P25 system can be dispatcher initiated - for either temporary tactical operations or even extended operations. However, eventually, the simulcast could stop without notice.

Then there is which site or sites a simulcast may appear on temporarily and it can apply to any of these situations.

And then there is my county - Brunswick - which seems to - in general - be fully on VIPER and simulcasting back to non-VIPER frequencies - sometimes.... Fireground operations in many cases here switch to non VIPER (and likely) non-repeater (or local repeater) frequencies.

Bottom line, as was already stated, there isn't a single answer to this question. However, a local regular user may be able to confirm their observations for your county.

These days things just aren't black and white, yes or no -- there's lots of grey.
 
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