CharMeck TRS Question

[kg4pbd]

Can someone explain this to me? If Charlotte's TRS has multiple tower sites does that make this a multicast system and if so does that mean that I'm dropping one tower (i.e. Park Rd/Fairview Rd. for Monroe/Hwy51) for another as I move around? (I believe those are approximate tower locations).

Part of my reason for asking is I don't understand why when I'm at work, right near the tower at Monroe & Hwy 51 I get great signal strength on all the trunked frequencies except 858.9875. It's like that one particular frequency is on another tower. I've also heard of the issues with multicast systems on a 396 however I've never had any issues that I'm aware of.

I know this may be a very basic question but I never have really understood how this works.

Thanks in advance,

 

[CFDtracker]

It is a multicast system, or simulcast to be correct. Simulcast is where all the towers are broadcasting at the exact same time on the same frequency. i.e. If a transmission is assigned to, lets say frequency 858.2375, it will be broadcast on that frequency at all the tower sites throughout the county. So, I wouldn’t say that your scanner is dropping one tower for another, because the frequencies and the control channel are remaining the same. Your scanner is just receiving the closest signal.

As far as that one particular frequency, 858.9875, it could be that the repeater for that frequency has gone dead at that one particular site, and your signal is now coming from the next nearest site.

That’s what’s great about a simulcast system, if one frequency drops out at a site, there are other sites to transmit the information, super redundancy.

Is this something you’ve noticed recently, or is this a continuing problem?
If it’s a continuing problem, I don’t think it would be the repeater, the techs would have had it fixed within a couple of weeks.

I don’t know about any scanner specific problems with simulcast systems.

 

[kg4pbd]

Thank you, that was exactly the explanation I needed.

858.9875 has been a problem out here for along time, at least the last six months or so. It may simply be that the tower site out here near Monroe & Hwy 51 isn't repeating that particular frequency. I can just about monitor the system from here without any antenna. It's just that one frequency.......

Or I suppose it could be cell tower interference. I didn't suspect that b/c it just sounds like a typically weak signal as opposed to interference. At home I have no problems at all with that one frequency but I believe there I'm receiving off the tower near Park Rd & Fairview.

 

[jeffmulter]

>> Or I suppose it could be cell tower interference. I didn't suspect that b/c it just sounds like a typically weak signal as opposed to interference.

Which is what would occur if the receiver was experiencing desense from something tansmitting on a frequency adjacent to the intended frequency.

Nextel has two towers in the area ... on Independence at Crown Point, and in downtown Matthews ... that are licensed for 1000 watts ERP on 859.0125 MHz. That doesn't necessarily mean the frequencies are in-use at those sites, but it's one possibility.

 

[kg4pbd]

It could be the cell tower. I'll try parking on 858.9875 to see if it always comes in weak. Typically it only catches my attention when I hear it. There may be just as many times when it comes in fine.

Thanks,

 

[bonus1331]

Scott,
I'm just South of 485 and Lawyers Rd and am not having any difference in the sound quality of that frequency.

 

[Yaris07]

can anyone tell me which county's are digital in indiana. when looking at the map i do not understand where to find the info which is active

 

[kg4pbd]

Hi David,

This occurs when I'm at my office. It's in the McAlpines business park off Monroe Rd.

It's only that one frequency that seems to be affected. If you aren't having the problem then it must be local cell tower interference like Jeff described.