P25 Questions (some related to APX CPS)

[masstech]

I just got an APX 8000 I can call my own, and after a few hours of battling with the APX CPS and Unitrunker, I have a working no-affiliate trunk scanning setup now!

While I was initially setting this up, I ran into the problem of receiving the Control Channel and getting told the talkgroup - so my radio would see the talkgroup of interest - but I'd have no audio. I had origrinally put the voice channels into the Channel ID section of my trunking system page, but realized that didn't make sense, so threw Unitrunker at the system and noticed there was another section about Bandplan, and tried that in the order I saw it in (Lo)... Radio Reference ought to list this section in system pages as well!

So questions about bandplans and configurations:

- Does the order of Control Channels matter? The site I'm listening to of the system I'm interested in had the primary CC as the first one, so no problem there, but other sites have the primary CC listed after alternate CCs.
- The radio gets an idea of where to tune to from the Control Channel(s), right?
- So why is there a need for a "bandplan"? Is this because of rebanding/reconfiguration? This means that instead of going to a default channel that's calculated, the radio uses the Channel ID section as a lookup table? Why not have the site CC tell the radio that information?

Questions about multi-site systems (the system I'm currently listening to is https://www.radioreference.com/apps/db/?sid=7127):

- I currently have "Coverage Type" disabled. AIUI, as far as my radio is concerned, this is a one site trunking system. I'd love to figure out how to set up all the other sites. I tried doing this as "SmartZone & OmniLink" (since that was the only option that gave me the ability to edit the RFSS field in the "Site Alias" section, and I think the band plan/"Channel ID" is the same (per Unitrunker).
- Do I just need 1 trunking personality, or should I be setting up separate personalities for the talkgroups that only reside on one site and use "Preferred Sites"? I tried this, but from what I can tell I've been missing a call or two.
- Do I just clump all the control channels (primary and alternates) for all the sites in the Control Channels section? There's no way to label "these control channels are for this site"... This seems highly inefficient.

Questions about NAT scanning - after creating the trunking system and personality, having to:

- create a conventional personality
- set up 2x the channels in zone/channel assignments
- create a scan list
- tie the scan list back with the personality

for each and every single talk group, this is starting to get tiresome and painful. There can't be a better way, is there?

Honestly, if you work at MSP/BAPERN/etc. or on the "Commonwealth of Massachusetts P25 System"/"Metro Area Simulcast System", I'd love to work/intern for you. Spending these few hours futzing around in the APX CPS and watching the help videos have been completely enlightening.

 

[Outerdog]

Couple of thoughts, in order of your post...

- RR leaves the band plan off purposefully in most cases, particularly P25 trunking systems. No scanner user should ever need this.

- The order of the control channels does not matter.

- Why a band plan? Why anything? Why why? It's just the way it is. The band plan is required so the radio knows what the base frequency is in order to calculate the correct channel to go to when directed. Asking why doesn't do you any good. It is the way of things.

- In terms of sites and SZ and OL and all of that... SZ is designed for the affiliated subscriber. While the unaffiliated radio will try to roam when it can, it obviously can't pull your desired talk groups over to the next site (unless they are there already), so it is somewhat limiting. I prefer to set up each site as a separate system with its own talk groups. This way, if I am in one site and wish to hear another site that may have a weaker signal in my current location, I can FORCE the radio to the weaker site and hear the desired traffic by giving that Trunking System ONLY the control channels and site ID for the desired site.

You really have to look at your particular use-case and decide how to set up the radio... are you moving around or mostly stationary?

- Dumping control channels in - yes... that's how it works for subscribers. They take all the control channels from each site. There is no need to really know which site they belong to. The radio and controller takes care of that on a legitimate subscriber.

- What is NAT scanning? Do you mean no-affiliate scanning? Some people like to make 1:1 TG and scan list. I think that's stupid. Use scan lists with 5 or 6 members that are related somehow (regional PD and FD and SO, perhaps, whatever) and use Nuisance Delete to remove TGs that you currently do not wish to listen to.

- Admitting on the internet that you've probably hacked around a bit or obtained unauthorized software to create system keys that allow you to program a TRS into a subscriber probably shouldn't be coupled with a unsolicited request for work/internship. Just saying... think things through.

 

[masstech]

Hi Outerdog, thanks for the reply!

- CC, bandplans: thanks. That all makes sense, including the "accept it's just the way it is" bit :^) I suppose the thing I'm interested in now is how a system controller (if that's the right term) wrangles radios as they move from site to site, but I can't investigate this without a system that I own. Well, time to start idly browsing ebay for used repeaters and controllers and thinking too hard about how licensing for this would look like :^)

- Indeed, monitoring another site confirms that some of the talkgroups I'm interested in listening in don't always appear, only usually when a subscribed unit says they're physically moving there. That totally makes sense, and so probably the best thing to do is make separate system/personality pairs for each site.

- Yes, no-affiliate scanning. Ah, Nuisance Delete is a good idea. Thanks!

- Hah, while I have heard about said software system key generator, I used BatLab's research on system keys to make my own by hand. Even my CPS is legal, purchased and downloaded from the /\/\othership.

 

[wardaddy]

A system key is just a software version of a metal key that opens a lock. Doesn't matter if you use a machine to cut it, file it by hand, or steal it off someone's desk; you still aren't allowed to use it to open the lock (without the owner's permission).

Personally, I don't think it's a big deal, but it would be wise not to talk about it.

 

[clbsquared]

Your CPS may be legitimate, but having the system key and admitting you found a way to create one, could land you in some hot water. System keys are not released into the wild for obvious reasons. Public safety radios are mission critical. System keys in the hands of anyone but the administrator of that system could pose a threat to the personal safety of LEO's and the like. Rogue radios floating around and programmed incorrectly could possibly tie up the system in question and cause some emergency traffic to not be received.

Just food for thought. Think about what you've said in your post. You've just admitted to creating a computer program to hack into a system that you're not allowed to be on.

Sent from my HTC One A9 using Tapatalk

 

[masstech]

Stop.

I'm not going to let this thread move away from the original topic at hand.

I haven't written any software or hacked anything. I'm not on a system, I haven't affiliated to it. Believe me, I know - I've been keeping this wired to an E4443A whenever I'm near one and making sure it doesn't transmit, regardless of the situation. An improperly configured radio is a sign of a bad engineer, let alone radio amateur.

If you are reading this thread and would like to "contribute", it will not be about system keys. Move along.

 

[wardaddy]

Welcome to RR, where mentioning system keys and NAT will bring about something akin to the Spanish Inquisition. Like I said, I don't think it's a big deal and refuse to argue the point with anyone that thinks otherwise. I just wanted to make sure you knew the legality of it, should anyone ever ask you questions about your setup.

Moving on to constructive conversation...

Yes, programming NAT via CPS is a tedious and time-consuming process (if you do it the right way, which it appears that you are). Even programming a legit subscriber unit to a system for the first time (with a fresh from scratch codeplug) is tedious and time-consuming.

As Outerdog explained, SmartZone is of limited use to an unaffiliated radio. I would second his recommendation on programming separate systems for each site, and switching to a zone tied to that site as you move around.

I have some other ideas, but I'm not going to post them publicly as I don't want to unnecessarily infuriate the radio police. As soon as you have enough posts to send a PM, get in contact

 

[masstech]

Heh - as a user of one of the talk groups on that system, my understanding (after chatting idly with a radio tech who was installing a new 8500 for my thing) was that in summary, "the maintainers will notice and care about radios that affiliate that they don't know about".

Indeed. Honestly, I feel like the CPS was written by some 13-year-old mashing on the keyboard, although I suppose the $385 is for the ability to program radios, not necessarily the UI...

Sounds good - will get in touch (what's the post limit here?)

 

[wardaddy]

(what's the post limit here?)

It's a secret (seriously).