MARCS Affiliation Question

[Volfirefighter]

Sandy Creek Fire's home tower is the Minerva stand-alone site. I understand that when their ems units transport to Canton hospitals they would affiliate with the Stark simulcast and we would hear their traffic there as well. How long does this affiliation last? Will their units always affiliate with the Stark simulcast even when in station due to proximity to the tower in Paris Township? If so, what is the point of a stand-alone site?

 

[mtindor]

The standalone site is covering not only SCJFD but also Minerva PD and OSP / other state agencies through that particular area. Minerva coverage has always been mediocre on MARCS-IP until the Minerva site came online. OSP would have problems in that area. I imagine that even if SCJFD didn't join MARCS, there would still be a Minerva tower to support Minerva PD and state agencies.

SCJFD would likely be affiliated with Minerva by default when they at / around home. But as soon as they roam away from the Minerva site's coverage area, they are going to end up on the Stark Simulcast or one of the Columbiana sites or perhaps even Dellroy on occasion if they are down south for some reason.

 

[phask]

The standalone site is covering not only SCJFD but also Minerva PD and OSP / other state agencies through that particular area. Minerva coverage has always been mediocre on MARCS-IP until the Minerva site came online. OSP would have problems in that area. I imagine that even if SCJFD didn't join MARCS, there would still be a Minerva tower to support Minerva PD and state agencies.

SCJFD would likely be affiliated with Minerva by default when they at/around home. But as soon as they roam away from the Minerva site's coverage area, they are going to end up on the Stark Simulcast or one of the Columbiana sites or perhaps even Dellroy on occasion if they are down south for some reason.

Similar question, I notice when Lifefligh is parked at my local Hospital it will affiliate, but sometimes for several minutes or up to an hour I still am receiving LF comms.

I'm sure it's left the area as I both copy it and am often in the flight path at 400' Is there some actual timer also going on or just physical location?

 

[mtindor]

Similar question, I notice when Lifefligh is parked at my local Hospital it will affiliate, but sometimes for several minutes or up to an hour I still am receiving LF comms.

I'm sure it's left the area as I both copy it and am often in the flight path at 400' Is there some actual timer also going on or just physical location?

I've never touched a P25 radio / system myself, so I'm only going on what i've seen. Basically they will stay affiliated with a particular site until some RSSI threshold is met -- if the RSSI drops below a certain point they start looking at neighboring sites that will fit the bill and eventually move. For a helicopter, obviously they will have extended range compared to a vehicle on the ground or a handheld in a building. So they can "hang on" to a site for a longer period of time before having to switch to another site closer to them.

 

[Volfirefighter]

I only asked because Sandy Creek got toned this morning (tone out is still on UHF) and when the ambulance went enroute from the station in Minerva, I heard the traffic on Stark Simulcast and the Minerva stand alone site. I have these on two different scanners. At the time, no other Sandy Creek ambulance was at a Canton or Alliance hospital.

 

[GTR8000]

Assuming there's only one radio affiliated with a particular talkgroup at the site, which is causing that talkgroup's traffic to be carried at said site:

• If the radio registers at a different site, the default behavior is for the system to immediately stop carrying the talkgroup's traffic on the previous site
• If the radio does not register at a different site for a reason such as being abruptly powered down before it gets a chance to de-register, the traffic will remain active at the last site the radio was registered on until it times out. The timeout length can be set by the system admin, but the default is probably 3-6 hours for most systems.
• It's also possible that the radio is not able to get inbound to the system for some reason. A helicopter might take off and remain registered at that site, but if they change the channel from trunking to a conventional frequency, and the radio is unable to de-register first, the system won't know that it's no longer registered at the site. Essentially the same condition as the radio being abruptly powered down in the previous example.