396XT Differentiating between Smartzone sites using same CC?

[novascotian]

I listen to the Nova Scotia Smartzone system which has more than 60 sites. There are 16 sets pf CC's shared but usually spaced well apart geographically. Sometimes however when I am moblle and in a high spot I am in range of two sites with the same CC. Is there any way to know which I am hearing without figuring it out from the traffic I hear, or better still is there any way to enter them separately like you would with conventional systems that use different CTCSS or DCS? For sure the system radios know which one they are affiliated with, but how about monitoring by scanners... specfically my 396XT?

 

[UPMan]

Give each site a different alpha tag.

 

[KevinC]

Give each site a different alpha tag.

But he still can't tell which site he is actually hearing since they use the same frequency for their CC and no scanner takes advantage of the site # info broadcast on the CC.

Unless I misunderstood the original question.

 

[novascotian]

Right now I do have the sites alphatagged.... more specifically I have an alphatag for each set of CC's... So lets say Centerville and Maintown sites use the same CC... I have that CC and ACC programmed in separately from the other 15 and tag it as CTR/MAIN and that will apply to both. I could put this in twice, once tagged as CENTRVILLE and again as MAINTOWN but that wouldn't do any good as I would still receive both of them on both of those "channels". I am looking for some way, meaning tones or something like that, so that if I did in fact program them into the scanner separately I would only get Centerville or only get Maintown... So the basic question is this: is there in fact a way for a scanner to tell one site from another when they have the same CC frequency?

 

[UPMan]

There is no way to differentiate between simulcast sites. If you are within range of two, you could be receiving from either...it strictly depends on signal propogation to your location. The scanner does not tune to a site...it tunes to a frequency. Since simulcast sites operate on the same frequency, you cannot select between them.

Sorry, I missed in you OP that it was simulcast (I was replying as if it was two independent sites on the system).

 

[KevinC]

I don't believe it's simulcast. I "believe" it's 2 sites, geographically separated, that use the same control channel.

 

[novascotian]

You are correct KevinC, they are not simulcast. Yes there could be on occasion the same thing coming through both but that is only due to affiliations, so most of the time if there is traffic on one there isnt on the other, or two entirely different conversations.

I realize also that at any given time and given location I can actually only receive one of two site that have the same CC, as the capture effect will mean one of them "takes over the frequency" but it still remains that I would like to know which one I am receiving, or exclude one of the two. With conventional radio you can do that with tones if the transmitters have them but it sounds like for Motorola trunking that cannot be done with a scanner even if the actual system radios can diffferentiate between sites, at least I thnk so. In the hypothetical location I am speaking of, in range of two sites with the same CC I think I am right in saying that a system radio can easily display the site number or name of the site currently affiliated to and can be forced to change affiliations to another site that is in range (except in this case even it cannot go to another site that is on the same frequency because the stronger of the two has captured the frequency) I just thought that maybe there was a digital "tone" system that maybe a scanner could access to identify which site that is being received, and use as well to narrow reception down to just the one you want.

I think there is some way on the 396XT to display the system number however I have not mastered that feature, but I dont think it can show you the site number.

 

[GTR8000]

The problem is that the scanner doesn't know the difference between 860.1375 at the Morristown site, vs 860.1375 at the Barrington site, vs 860.1375 at the Maritime Centre site, etc. Nor should it, really, because it's only looking at the frequency of the active CC. So, if you travel across the province and have every site programmed in the scanner, it's simply going to stop on the first entry it finds with a matching CC. That means if it finds an active CC on 860.1375 while you're physically in Maritime Centre, it might stop on the Morristown system first, or vice versa.

So with all of that being said, the answer to your question is "no", there is no way for the scanner to know which site it's hearing, especially when you're receiving two sites at the same time that share a CC.

 

[novascotian]

Thanks Chauffeur6... I needed that answer even if it is not the one I wanted to hear! Also I am impressed by your use of the actual site names and frequencies from here in NS. You may know that this was one of the first wide area trunk systems, and has brought public safety agencies fed, provincial and municipal together for more than a decade. Here is a great map from Chris showing the site locations:

http://local.google.ca/maps/ms?ie=U...8164844284702764252.00045179812daf5676c30&z=7

 

[KE4ZNR]

And from a Radio System Engineer Point of View it would be foolish for
any smartzone system admin to "reuse" the same frequency for CCs in the same
geographic area. Heck, there are still times when ducting is just right that
CCs on opposite sides of the same state interfere with each other.
If the smartzone system is configured correctly you, monitoring with a scanner, should
never have to worry about your scanner having to pick between 2 CCs sharing the same frequency.
Marshall KE4ZNR

 

[GTR8000]

No problem, glad to help...even if I am the bearer of bad news.

Although this is probably not exactly what you're looking for, there is a way for you to figure out what site you are hearing whenever you're not certain. Program a custom search range for 800 MHz in C-Ch Only mode, and give it a SQK. You can probably limit it to 860-862 which looks like all the CC's for that system fall under. When you set that search range to C-Ch Only, the scanner will stop on active Motorola CC's and display the System ID and Site ID. You should be able to match that up to the database and determine what site you're receiving. Giving that search range a SQK allows you to turn it on/off like any other system.

 

[GTR8000]

And from a Radio System Engineer Point of View it would be foolish for
any smartzone system admin to "reuse" the same frequency for CCs in the same
geographic area. Heck, there are still times when ducting is just right that
CCs on opposite sides of the same state interfere with each other.
If the smartzone system is configured correctly you, monitoring with a scanner, should
never have to worry about your scanner having to pick between 2 CCs sharing the same frequency.
Marshall KE4ZNR

In a perfect world, maybe. But, when faced with a severely limited pool of frequencies to work with, and a system that requires a large number of sites due to geography/terrain...you do the best you can with what you have. :wink:

 

[novascotian]

Chauffeur6, thanks for the tip re identifying the sites... I didnt realize that it would show the site number.... I currently have a "bank" made up of the CC's set up as conventional, so I think that is basically equivalent to what you are suggesting as a search bank... I had been using this occasionally just to hear what CC's I was picking up but didnt realize I could see the system and site ID. Will give this try.

I am not sure why this system has 16 sets (pairs... CC and one ACC) of CC's for the nearly 70 sites. I guess that was all the spectrum avallable.. plus all the Voice frequencies of course. I would say that generally the same frequency CC's are like 50 miles or more apart and with hills in between, and in the areas where you can pick up both there are several other sites closer and stronger so I think it basically true that no system radio in range of them would be trying to affliate with the sites with the identical CC.

However there is one situation where two adjacent sites have the same frequencies... at least according to databases... This is not in my local area so havent really confirmed.. for anyone checking into it the two sites are Wharton and Amherst.. .yes there are hills between but they are neighboring sites so there would in this case be radios half way in between with two same frequency CC's to choose from. If this is the way it is, it has to be a mistake...but on the other hand it must work otherwise it would have been changed long ago..

Edit: I have re-read the directions re the 860 MHz search and see now that it is diffferent from me entering the CC's as conventional freqs, so for sure will try what you suggest. Thanks...

 

[novascotian]

I have re-read for a second time... and now not so clear on this.. If I put in a search range 860 to 862 in CC-onlymode and the scanner will stop on active CC's and then displays System and Site, how is this different from the way I have it with the 16 CC's each entered as a separate site... The scanner stops on any site for which it detects a CC and listens for activity on the TG's I have entered, so are you saying that I should be seeing the system and site when this happens? Or does it have to be a search rather than a straight scan of already entered CC frequencies?

 

[GTR8000]

Having them programmed as conventional frequencies will not display the System/Site info. If you setup a custom search for 860-862 with C-Ch Only enabled, whenever it detects a Motorola CC, it will lock onto it and will show you the System/Site ID.

For example, when it stops on the Maritime Centre CC 860.1375, the display will show:

SID:6939h-0038

6939 is the System ID and 038 is the Site #.

 

[KE4ZNR]

In a perfect world, maybe. But, when faced with a severely limited pool of frequencies to work with, and a system that requires a large number of sites due to geography/terrain...you do the best you can with what you have. :wink:

Indeed. VIPER is a perfect example of this and the
NCSHP has had their hands full over the years dealing
with issues like this with their 190+ sites statewide.
Marshall KE4ZNR

 

[novascotian]

I am realizing that I do not know how to program the 396XT to do a CC-only spectrum search. In fact I have not ever programmed any custom search. I use Freescan and have multiple systems in my radio but embarrassed to say I dont know how to set up this search, either on Freescan or manually.

 

[GTR8000]

You may not need to do that, upon further review. You said you have all of the possible CC's already programmed as systems/sites, correct? If so, then all you would need to do is press HOLD on the scanner when it's locked on a CC. You'll hear the CC noise and the scanner will display the System/Site ID.

I find the spectrum search to be a bit easier for finding activity and determining sites, but in this case where you already know all of the possible CC frequencies, you're probably be fine with using the HOLD method when locked on a site.

 

[novascotian]

Yes I do have them all in and have heard of this method from a local friend but I have found that if the scanner does not actually stop due to a programmed talk group being active there really is no way or shall I say time to press hold.....the scanner is too fast and that site just flies by in the scan.

If I am at some good reception spot and want to know what sites I am in range of (even if they are not active at the time... which is very common with our rural area sites) I am thinking that your CC search
method might be better, or did it also in practice require the scanner to stop on an active talk group? I was hoping in thet method it would stop on any CC it encounters and display the info, even if the site is completely idle at the time. I will be interested to hear your reply on that, and if it does stop on idle sites I will still need to find out how to set this up..

I have in the past just entered all the CC's as conventional frequencies and scan them so it stops on any in range and of course all you get is the data noise but no system and site information such as I am looking for... in many cases it is pretty clear which site you are hearing but like I had said at the start of this thread, there are times when there are two possibles for that frequency as I could be somewhere midway between sites with the same CC..

 

[GTR8000]

With a custom search in C-Ch Only mode, it will only stop on Motorola CC's, and does not require TG activity in order to stop. If it receives a signal, it pauses, checks to see if it's a Motorola CC, then displays the System and Site ID. It will hold on that frequency for as long as the signal is active (although it's good practice to hit HOLD yourself in case reception drops out before you get a chance to see the System and Site ID). It will mute the CC data noise, and when a TG is active it will open squelch for the TG audio and will display the TGID. If it detects a signal on a frequency that is not a Motorola CC, it will continue searching until it finds one.

To setup this custom search in Freescan, go to Scanner > Setup Scanner Options

On the Custom Search tab, first check the Show Advanced Options box

Now create a new custom search, something like this should do the trick:

Name: 800 CC
Low Limit: 860.000
Hi Limit: 862.000
Delay: 10
Lockout: Unchecked
Enabled: Checked
Hold Time: 0
Step: 12.5k
Att: Unchecked
Data Skip: Unchecked
C-Chan: Checked
Quick Key: 99 (or whatever you choose)
Startup Key: .
Modulation: FM
Num Tag: NONE
Analog AGC: Checked
Digital AGC: Checked
P25 Wait Time: 0
Rec Out: Checked