Does your Unication work like a scanner? How is it different?
Erie County P25 System
- Thread starter MarkPalmer
- Start date
- Status
It is similar to a scanner. It will only scan one system or a list of up to 64 (I think) individual frequencies at a time. The Knob on top has 8 positions which can be used to select various combinations of the programmed data. For example all of site 1 or site 2, just the 1xx talkgroups for either site, the paging freqs. Prior to change over I ran a knob position for the analog frequencies. It is further sub divided into Zones. Each zone gives the Knob 8 different selections. Changing zones requires pushing a few buttons. Not sure how many zones it has, more than I need.
Drachen_Fire
Member
What would happen if you programmed the CCs for both sites as if it were one site?
Possibly a large mushroom shaped cloud. I don't really have any idea. I will have to try it, that is a good rainy day project.
Drachen_Fire
Member
Having seen some codeplugs that actual county shops have programmed on multisite trunks before, I have seen exactly this done in Motorola radios. It's not exactly optimal, but does seem to work
Actually, that is the optimal way to setup a codeplug. The radio periodically checks the RSSI of the control channel, and when it drops below a defined threshold, it will attempt to find an adjacent site control channel with a stronger RSSI. That's how the radios are able to seamlessly roam between sites or simulcast cells with no user intervention required.
The Unication does something similar, but it's not as intelligent. I believe it simply locks onto the first control channel it finds, and will remain on that until the RSSI drops below a very low threshold, then it looks for another control channel if programmed into the device.
Drachen_Fire
Member
I can see it being a problem, though, when you have statewide or wide-area systems, where there's more CC's than the CPS will actually let you input as a single site.
As for the Unication, I wonder if you can raise the RSSI threshold on those. I've never programmed a G4/G5, just G1.
As for the Unication, I wonder if you can raise the RSSI threshold on those. I've never programmed a G4/G5, just G1.
I can't speak for EJF or Harris, but Motorola APX allows for 250 unique control channel frequencies to be programmed per system. However keep in mind that with SmartZone, SmartZone OmniLink, Intra-WACN, or Inter-WACN coverage selected for a particular P25 system, the radio will do more than simply look at the frequencies in the codeplug. The radio will process the adjacent site messages coming over the control channel to determine which other control channels to sample first, before it starts to look at the list in the codeplug. As I said, the radios are intelligent, so every effort is made to streamline the process of affiliating with another site if the RSSI falls below the threshold.
On an actual radio under sites you can select most preferred and least preferred etc. There is like three or four settings in astro25 i remember. Now initially a county system that had two zones when the radios were programmed they just jammed all the trunk frequencies in. Lately i am now seeing site information and site preference based on which talkgroups are selected in the radio.
Yup exactly why neighboring sites are advertised via the cch.
I tried it this morning and just as GTR8000 surmised it locks on the first control channel it finds. In this case site 2 since that is the one I modified, adding the site 1 frequencies to it. I know it will seek a new control channel if one is lost since this system does switch control channels.
To add to what I said yesterday it has 64 zones available with 8 knob positions per zone for a total of 512 data configurations available.
Last edited:
Drachen_Fire
Member
The bias preferences on the new Butler addition to ICORRS comes to mind. I went to Pittsburgh Mills last night, which is solidly within the coverage area of the Westmoreland West site, and my radio did not affiliate, although my scanner was hearing Westmoreland traffic, no problem. Also it seems like the Armstrong zone will only affiliate Armstrong talkgroups to the Armstrong site, no Butler sites.
I guess this is the future now, where system admins are tweaking zoned systems to only affiliate with certain talkgroups and such. You know, pretty much rendering multisite trunks to operate like conventional coverage systems from the 70s.
Drachen_Fire
Member
I haven't had any experience programming or looking at codeplugs for the APX series. ASTRO25 family was the last I had the ability to look at, years ago. I think it was restricted to 20-25 CCs per site?
The control channels are entered at the system level in CPS, not the site level. ASTRO 25 CPS allows for 128 control channels per P25 system. It doesn't matter which sites those frequencies are used at, as the list of control channels in the codeplug applies to the entire system, not restricted per-site. If 460.550 is used at 5 sites across a state, you need only enter that frequency into the control channel list once.
Good discussion, but probably off topic here since Erie's system is not Motorola ASTRO 25 and I don't believe most of their subscriber radios are either?
Drachen_Fire
Member
My understanding is that it is 100% EFJ/Kenwood.
Not uncommon. In the Maryland statewide system, the counties that have migrated to the system will have their TGs limited to the sites (simulcast cells and / or multicast sites) that cover their geographical area, and usually the neighboring sites. As for state agency users, some TGs are regionalized (valid in multiple simulcast cells and ASRs), while others are statewide - valid in any site. What you do not see is traffic limited to only specific tower sites within a simulcast cell.
Just to let people know, I am having the best success with a telescoping antenna collapsed all the way, laying flat. Mine faces south. Paperclip works well too, but this antenna seems to outdo it. It now sounds like a normal system too - no distortion/garbling, and I think I'm getting all TG's. Using one on 3 scanners with good success. I previously tried attenuation, changing threshold levels, and moving scanners around. Nothing worked till I started using this antenna.
Good news, and makes sense. With P25 simulcast and a radio not optimised to receive it, you are at the mercy of your listening location. Detuning an antenna (by shortening it in your case,) can help to limit reception to one member tower of a simulcast site. It's also more elegant compared to a paper clip...
Anyone heard activity from EMA or Hazmat yet?
I think I did hear EMA a few days ago. Also hearing Erie Special Event 2 now and then.
- Status
Similar threads
