Analog EDACS and properly setting up Scan / Favorite Lists

[batdude]

This discussion is surrounding this system:

Brevard County Government Trunking System, Brevard County, Florida

Brevard County Government Trunking System Profile

www.radioreference.com

Probably one of the last analog (ProVoice capable) public safety systems left on the air.

The system architecture can best be described as having three Simulcast cells; North, South and Beachside. Please do not get wrapped around the term simulcast with this particular system. This system does not operate like a modern-day P25 simulcast system (where each site would have the exact same frequencies). Totally different on this system.....

A few things up front.

I never was, and do not claim to be, an EDACS expert.

I am aware that EDACS can be set up to make an individual TG (or entire Agency / Fleet / Subfleet) to operate in "Wide-Area" mode - which will key the talkgroup across all of the simulcast sites of the system (in this case, all 3 of the sites would be simulkeyed if a group was set to W/A. I do not think that very many of the TGs on this particular system are configured this way.

So here is the dilemma / question.

In my example, I will say that I have just imported the ENTIRE system and TGs into Sentinel.

At the bottom of the favorites list, you will see the 3 simulcast sites, North, South and Beach - along with all the various municipalities associated with Brevard county.

I am going to use two extremes for examples.

1. Titusville - this city is at the north end of the county. There is no reasonable probability that a radio affiliated with this city would be "roaming" onto the beach or south towers.

2. Palm Bay - similar situation. This city is at the extreme south end of the county, and none of their radios should ever be on the North system.


so - for these two examples, what I would want to do is limit the systems that would be scanned for those particular entities. In other words, there is no reason for my scan list associated with Titusville to scan the south tower - and no need for the Palm Bay talkgroups to scan the north tower.

What's the best solution here?

Is it to create a "new" system for these two examples and delete out the non-applicable sites?

or

is the best way to just dump everything into a single favorites list and "let the radio figure it out"?


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I >think< my current method - a single system entry and favorites list with all cities - is causing loss of some traffic.

Then again, the more systems I create, wouldn't there be a potential to slow down the overall time it takes to scan the TGs I want to hear.... (?) - because the radio has to swap over to a "new" (aka different) system for those "other cities"....?


TIA


doug

 

[GTR8000]

Keep it simple. One system, all sites, all talkgroups. Assign a quick key to each site. Turn them on and off as needed, based on your location in the county. Done.

 

[GTR8000]

By the way, there are still numerous EDACS public safety systems on the air: https://www.radioreference.com/apps/db/?rpt=3&sType=5

I'm also not sure why you think these three sites are not simulcast cells comprised of multiple physical sites operating on the same set of frequencies. That seems to be exactly what they are, which EDACS is perfectly capable of. The North cell is comprised of 4 sites, the other two are comprised of 2 each.

North cell: Titusville, Rockledge, Mims, Cocoa
South cell: Palm Bay and Melbourne
Beach cell: Indian Harbor Beach and Cocoa Beach

 

[batdude]

By the way, there are still numerous EDACS public safety systems on the air: https://www.radioreference.com/apps/db/?rpt=3&sType=5

I'm also not sure why you think these three sites are not simulcast cells comprised of multiple physical sites operating on the same set of frequencies. That seems to be exactly what they are, which EDACS is perfectly capable of. The North cell is comprised of 4 sites, the other two are comprised of 2 each.

North Simulcast cell: Titusville, Rockledge, Mims, Cocoa
South Simulcast cell: Palm Bay and Melbourne
Beach Simulcast cell: Indian Harbor Beach and Cocoa Beach

thanks for the reply.

I'd say that 80% of your dB list of EDACS systems aren't public safety tho ... so maybe 20 or so left? Regardless, your point is taken. Funny how a several of those still on the air are in Florida...

I think my reluctance on the use of the word simulcast is that it's night and day compared to how ... let's call it "modern day" simulcast systems operate. Like I made clear, I'm no EDACS expert ;-) but your description is accurate. However, it does make me wonder why EDACS does not suffer the same problems as Simulcast P25 networks.... is that b/c of analog vs. P25? (there is >some< ProVoice activity on this system - primarily a few tac channels for the SO, Titusville and Palm Bay - but I am comfortable saying it's 99% analog, 0.9 % ProVoice and 0.1% encrypted as far as day-to-day operations are concerned.

since this particular system is 30+ years old now... it has never really had (to my knowledge) ... a "full system refresh" ... it's my understanding that any upgrades were all done piecemeal over time.... repeaters here and there, controllers, portables, etc.... never upgraded all at one time. I actually heard a story that one of the techs at CII who installed this system retired recently. He had maintained it since day 1.

regardless, I've set up the 536 as you described and have it sitting next to an SDS-200 sitting on a single TG to see if any calls are being missed by the 536 while it's in scan.

Thanks!

 

[GTR8000]

Analog simulcasting tends to be more forgiving than digital simulcasting, albeit in areas of overlap it won't sound as good as digital, with the simulcast distortion being noticeable in the audio. What causes issues receiving P25 simulcasting is not that it's digital per se, but rather the specific type of modulation being used (Linear Simulcast Modulation aka LSM and other forms of QPSK modulation). In fact, certain type of P25 simulcast (C4FM in particular) would not cause as many issues with reception, but C4FM simulcasts are fairly rare for modern P25 trunked systems. There is also the separate issue of multipath/reflected signals, whereby the receiver is getting hit with signals that are out of sync, which can make it tough for the receiver to piece back together...especially if it was never designed to handle the modulation.

There is no real fundamental difference between a modern day digital P25 simulcast cell, or an analog EDACS cell, or a mixed analog/digital SmartZone cell. They all utilize multiple distinct and geographically separate physical transmitter sites (aka subsites) operating on an identical set of frequencies.

Back to the original question. The reason you were missing traffic is almost certainly because the scanner was cycling through the three cells, pausing ~2 seconds on each control channel checking for grants. If you happen to be in range of all three cells, that's ~4 seconds it might be on two cells that aren't carrying traffic you want to hear, assuming that particular talkgroup's traffic isn't being carried across all three cells.

Manually toggling on/off sites that you don't care about and/or are not in range of is the simplest way to reduce missed traffic.