City Orangeburg PD/FD (Public Saftey)

[kg4ekc]

City has recently changed their radio system. I noticed I could not hear them on their frequency. They have Data units in there cars now and are using 460.1625 for some of the dispatches but I think this is a trunked system. I have been in the FCC data stuff and it is licensed for Trunked not conventional. I know they just put up repeaters through out the county in their (DPU) water towers. Now to figure out if trunked what type of system. I have not found data channels (this dispite signal stalker and search at home and close call and search in the office in the city). I know they have data channels I guess they could be using PALs 800 for these. They did have radios on PALS at one point but they did not work out well.

If anyone knows anything let me know. I have some contacts at the 911 center will find them if the next few days also

Thanks,

Greg

 

[brian]

When I was travelling through Orangeburg a few weeks ago, I had those UHF freqs programmed. They each had the tell-tale key-up every 5 seconds or so that tells me it is an LTR system. I didn't hear any traffic on it while I was listening.

Frequencies are 453.4375, 453.4875, 460.1625, 460.2875, 460.3875, 460.4625.

Brian

 

[kg4ekc]

Thanks, I have not messed with LTR at all. I will have to look it up. That makes sense though. I can hear most of the traffic on 460.1625. So, this gets programmed as an EDACS system in frequency order correct? I have to look up how to do this. I do not have alot of experience with LTR at all. Any hints would be greatly appreciated.

Thanks,

Greg

 

[INDY72]

You will need a LTR capable scanner, such as the PRO-96, PRO-97, or one of the Unidens. When you program the freqs in, you must put them in LCN order like an EDACS, but that is where the simularity ends. There is NO control chan on LTR, and TG's are different also. You may want to not only read up on LTR trunking in your scanner's owner's manual, but also do a lil reading in the LTR discussion threads on the forums here. And keep asking as we will gladly help ya out when we can. Enjoy!

 

[kg4ekc]

I have a BCT 246t and a PRO 2055. Let me ask a stupid question, LCN order is lowest frequency to highest frequency correct? Also can I program in and leave it open (RS) or search (BCT 246t) and pick up the TGs? I have just started to read this stuff when you posted. Thanks for your help.

Greg

 

[kg4ekc]

I have placed an LTR system in but I am sure I have the input LCN wrong. Any way to figure this out? I do think the home channel is the 460.1625 as above. Thanks,

Greg

 

[kg4ekc]

I have talked with one of tower climbers who is doing work for them and he is going to see what he can find out for us.

 

[INDY72]

LCN Order means the Logical Chan Numbering, which is the order they programmed them in sequence on the system... Not always in lowest to highest... If you have acess to a PRO-97, or its older twin the PRO-92 you can find the right LCN when monitoring the Repeater in manual mode.... The LCN method is the same way that EDACS systems are set up, but as I stated that is about the ONLY simularity between them.

 

[kg4ekc]

I talked with an officer this afternoon. They are using Motorola radio's. The shop in town here is a Moto shop. It is trunked for sure. I suspect it is a Motorola system. I have programmed my radio as such but no luck so far. Can Motorola radio's be programmed for LTR? I know the car radio's are Moto also. My friend is going to inquire with the radio shop for me and tell me the scoop but the mystery is killing me, LOL.

Greg

 

[Curfew]

Try these in order and let me know what you come up with-

1. 460.1625
2. 460.2875
3. 460.3875
4. 460.4625
5. 453.4375

or-

1. 460.1625
2. 460.2875
3. 460.3875
4. 460.4625
5. 453.4375
6. 453.4875
7. 460.3625
8. 465.1625
9. 465.2875
10. 465.3875 ( you may have to drop channel #'s 8, 9, and 10 out because it appears they are TX for 1, 2, and 3. It may be though where you have to keep them in this order for the whole system to work, i dunno. If i can get a fix on the frequencies from where i am i will see what i can come up with)


Curfew.

 

[INDY72]

Any of the Radio Companies can manufacture LTR capable equipment, though only EFJ makes the actual systems. For example, there is an Motorola UHF TRS, that is in use, that all the mobiles, and HT's are M/A-Com... go figure...

 

[kg4ekc]

Thanks for all of your help. I have been messing around a great deal trying different combinations to get it to work. I have even tried programming a moto system. I did see on my PRO 2055 some life last night. I have just programmed in the combination that Curfew suggested.

Again, thanks.

BTW, One of local FD Chiefs I know who works for DPU did not know what type of system they put in. He did know it was trunked but that of course did not help me. I will talk with the tower climber fella (fella Ham) hopefully he will know what the deal is.


Greg

 

[Curfew]

I drove to Orangeburg yesterday with the above info i gave you. I noticed with the grouping of the first 5 frequencies above i was getting strong signals on all 5 with some sort of keyed up signal as Brian described earlier, reminded me of a timed type signal and it was going on with all 5 at the same time. I beleive that this is what moves a keyed conversation to another frequency after they are finished talking with these systems.

I programmed in the second grouping of 10 frequencies and those 5 in the first grouping were for sure the strongest. I was getting a slight tick of this burst signal on one of the latter frequencies and i don't know if it has to be in the LCN order of this system.

I caught glimpses of chatter and when this would happen i tried hitting trunk and scan and it did not automatically follow to the next designated frequency. Then again i don't know if it was actually working because the system was not that busy with simultaneous calls. I only got one look at a ID number and after that nothing else appeared so this leads me to believe that some things were not quite right with how i programmed.

Since you saw some life last night this confirms that at least we have part of the nitty gritty.

All we can do is keep trying. Curfew.

 

[jeffmulter]

There are 7 frequencies to program for the system ... not 5 or 10. They might be in the system controller as LCN 1 through 7, although some systems have the frequencies spaced apart ... there are 20 potential LCN slots.

460.1625 460.2875 460.3875 460.4625 453.4375 453.4875 460.3625

The short burst of data at specific intervals is simply a status message to all radios who have that frequency assigned as their home channel. More than one talkgroup may share the same frequency. Several frequencies may serve as the home channel for their specific talkgroups.

Depending on the number of users on the system at any time, communications on a talkgroup will generally occur on the talkgroups's home channel, unless that frequency is in use. If the frequency is in use, the controller will assign the communications - and tell the radios on that talkgroup - to switch to a specific frequency not already in use.

So, on a system with low load, the frequencies might sound like conventional communications because the same talkgroups use the same frequencies most of the time ... police always use frequency A, fire always uses frequency B, etc. Only the telltale data burst gives it away that the communications are LTR.

Greg --- With the 2055, which is based on the Pro 97, you should have the ability to decode the LCN easily, since the Pro 97 had such a feature. See:

http://wiki.radioreference.com/index.php/Pro-97#Finding_LTR_LCN_order

For those who have a scanner that can do LTR, and does not use the Uniden Dynamic Memory structure, here's a workaround:

1 - Program a bank as LTR, and fill each of the memory slots 01 to 20 with just one frequency from the system ... in other words, all slots will have the same frequency.

2 - Keep track of which memory slot the scanner is stopping on when communications are heard. This should indicate what the LCN of that frequency in the system is. For instance, if the communications is mostly stopping on memory slot 07, 07 is likely the LCN of the frequency.

3 - If your scanner is capable, you can program multiple banks as described above ... each with a different system frequency ... to speed the process up.

Curfew --- The reason why you weren't receiving the same signal strength for all 7 frequencies was because 2 or the frequencies are at separate sites from the main site ... which is located near Cameron / Calhoun County.

One footnote to this system ... it is licensed for both analog and digital voice communications.

 

[INDY72]

Which would be potentially be the FIRST DIGITAL LTR system if they found a way to make it work.... hmmmmmmmmmmmmmm

 

[Curfew]

Jeff, thanks for kicking in. I looked at the FCC website on this station and noticed the site layouts but couldn't figure out what they had going on. I drove back down there yesterday and sat trying the different orders and arrangements in the records.

I did see the info on the 6.1 control station in that it had 7 frequencies ( TX freqs). I tried what was listed for this for the 7 RX freqs of the TX's and it did not track. I even tried the 7 as listed on the freq ID summary (channeling) to see if in fact what the channel numbers reported were possibly was the order, no go.

They do have the programming in the radios set up mixed up somehow in a non- low to high LCN order. I tried receiving the system from home but im out of range without getting closer to there.

I knew i had to be dead on with the order for my Uniden to track the system. Even if i had the order correct- For LTR with my Uniden, i have to program a repeater address of some sort for the system in which i don't know. May have been if i had the right order, my radio still wouldn't have followed without this info, or, programming at least two LTR ID's to start searching the system out. I assume it's the LTR ID of the system controller for the site for the repeater address, etc.

I can attest to what Jeff mentioned about this system sounding conventional because the majority of the comms were on one frequency (460.1625) and only moved occasionally, only when there was multiple calls. There was the another frequency i noticed that seemed this way.

Good thing that there is a way to figure the layout with a RS as mentioned above, there would be no other way besides sheer luck in getting the order right -or getting with the tech who programmed everything.


Thanks, Curfew.

 

[jeffmulter]

>> I drove back down there yesterday and sat trying the different orders and arrangements in the records.

Since there are 20 LCN slots, the number of combinations you could have would be (((((20x19) x18) x17) x16) x15) x14) ... or about 24 and a half million combinations.

It is certainly easier - and quicker - to fill seven banks with the system repeater frequencies.

>> Even if i had the order correct- For LTR with my Uniden, i have to program a repeater address of some sort for the system in which i don't know.

I've never had to program an "address" with any of my scanners that do LTR. Once you have the LCN correct, you just choose "search" or "scan." The latter option would require that you enter atleast one valid LTR talkgroup I-D to hear anything.

There are a couple of flavors of LTR, by the way, that might not be trackable.

 

[kg4ekc]

The system is a JPS ACU 1000. Article in the paper talking about lack of interoperablity with PAL 800 and county. It can interoperate with FD on VHF though. The city could not use PAL 800 due to several areas of no communication on 800. Especially in the Mall where a Cop was shot and killed few years ago. So that is why they dropped PAL 800. Not sure much else.

I will read everyones post as above. County says they can not scan it because they do not have a trunking scanner and are not sure if it is scanable? I know they are using data in the cars. I am told that DPU (Dept of Public Utilities, city's cash cow) who funded the system will be using this system also. Yes there is a repeater in Cameron, Bolentown, downtown and one more I forgot. This is to support DPU who will be using the system at some point also. Kind of hoping system name will help settle this. I will look at the above. I have been very busy this weekend and have not even had time to look at all your posts.

Greg

 

[kg4ekc]

Jeff, I have read the information on finding LCN order that you posted the link for. I was not successful in finding any LCN order but now and then I do see what I believe is a talk group. It flashes so fast I can not write it down. It does not occur with a transmission but out of the blue. I will keep trying to decpher this stuff.

Greg

 

[Curfew]

I saw that same very thing on mine, i got two different talkgroups that flashed quick. Too fast to write down.

Jeff, above you mention that you have to use a scanner that does not use "uniden dynamic memory structure". I was reading in the LTR forum where a fellow was using the 1-20 channel procedure with a 796 Uniden. Will a Uniden 296D or any LTR capable Uniden figure out the LCN with the single frequency only programmed in channels 1-20 of a bank?

I was thinking a uniden can't be used period from what you wrote about the dynamic memory structure. If it can't , i guess i need a RS LTR capable scanner.

Thanks, Curfew.