Same ID on a trunking smartzone system

SCPD · Jul 25, 2016

Seriously just out of curiosity because I have seen it happen by accident in the past,

If two radios are programmed with the same ID on a trunked smartzone system..what happens? Ive heard of "ghosting" where one radio ID will cause a second ID to transmit or turn to the channel that on the first ID's channel that is it on..

morganAL · Jul 25, 2016

A number of things. Radios can receive traffic from talkgroups they are not affiliated to, radios can miss calls because the system thinks the radio is on a different talkgroup or in multi-site it can also cause radios to miss traffic because it is sent to a different site. In the words of a Motorola Engineer when asked the same question: "Strange things happen."

SCPD · Jul 25, 2016

You answered your question.

SCPD · Jul 26, 2016

ActiveHat said:
You answered your question.

Negative, you answered by question by confirming my suspicions.

SCPD · Jul 26, 2016

A legit subscriber unit with a duplicate Id not only will do above but the admin or dispatch will call the unit to come in and then maybe turn off and on his radio. If nobody can be raised or it appears to be a ghost radio illegally on they will either stun one or both and have both users present themself in person with radio to the shop.

Project25_MASTR · Jul 26, 2016

It honestly depends on how the system is setup and how the multiple IDs are handled. On a single site , there most likely wouldn't be any downsides to multiple radios on the same ID as long as they remained on the same talk group (the watchdog may notice an excessive amount of affiliations for that radio and talk group but that's about it).

Get to multiple sites in which the same ID has affiliated and it's a different story. It can eat up capacity as well as present traffic and talk group errors/collisions. Most watchdogs will catch an ID affiliated to two sites simultaneously and notify a system admin.

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com501 · Jul 26, 2016

Most systems when presented with conflicting affiliations will automatically kill both radios. Most larger systems do this if they are smart. All mine do.

kv5e · Jul 26, 2016

How Stunning!

com501 said:
Most systems when presented with conflicting affiliations will automatically kill both radios. Most larger systems do this if they are smart. All mine do.

Best Practice!!!!

Stops the hacks who are monkeying around without ADMIN knowledge or explicit permission.

I have a stunned radio.....can you help me or...

Off to the DEPOT...........or the trash bin

MTS2000des · Jul 26, 2016

bwca44 said:
If two radios are programmed with the same ID on a trunked smartzone system..what happens? Ive heard of "ghosting" where one radio ID will cause a second ID to transmit or turn to the channel that on the first ID's channel that is it on..

On an Astro 25 7.xx system, that is exactly what happens and this is why it is a DANGEROUS potential LIFE SAFETY issue when cloned radios register.

The clone can cause the radio to affiliate on another talkgroup than the user has selected and transmissions by the legitimate subscriber to occur where they are not intended.

You do the math and see why this is a problem.

Jay911 · Jul 26, 2016

MTS2000des said:
On an Astro 25 7.xx system, that is exactly what happens and this is why it is a DANGEROUS potential LIFE SAFETY issue when cloned radios register.

The clone can cause the radio to affiliate on another talkgroup than the user has selected and transmissions by the legitimate subscriber to occur where they are not intended.

You do the math and see why this is a problem.

The one time I saw this happen on my local system, the "older" subscriber unit was deemed by the controller to be invalid and basically went "out of range" (probably "no comms" more likely) - I presume the controller said "Oh suddenly you're over on this tower instead of that one? Okay I guess". The "older" radio was for all intents and purposes dead until it was powercycled; at that point, the other one, since it was now "oldest" with the original one asking for an affiliation, did the same.

Thunderknight · Jul 26, 2016

com501 said:
Most systems when presented with conflicting affiliations will automatically kill both radios. Most larger systems do this if they are smart. All mine do.

That in itself can be a serious life safety issue. The innocent (real) user just had their radio killed for no apparent (to the user) reason. I wouldn't want to be searching a building or fighting a fire when my system kills my radio.
I agree that dupe IDs is bad, but this seems like throwing the baby out with the bath water. Get the "real" user into the shop ASAP, reprog with a new ID and then kill the rouge.

slicerwizard · Jul 26, 2016

com501 said:
Most systems when presented with conflicting affiliations will automatically kill both radios. Most larger systems do this if they are smart. All mine do.

Sounds like a great way to leave a first responder with a dead radio. So for my next bank job, gather up all the radio IDs used by the local PD division and kill en masse as I enter the bank. Wouldn't take much to generate affiliation ISWs with a laptop/phone/whatever and a TX-capable SDR...

SCPD · Jul 26, 2016

slicerwizard said:
Sounds like a great way to leave a first responder with a dead radio. So for my next bank job, gather up all the radio IDs used by the local PD division and kill en masse as I enter the bank. Wouldn't take much to generate affiliation ISWs with a laptop/phone/whatever and a TX-capable SDR...

Never thought about that!

com501 · Jul 26, 2016

This is why AES256 is used by smart people.

Thunderknight · Jul 26, 2016

com501 said:
This is why AES256 is used by smart people.

How does that help the affiliation issue?
Unless you are talking link layer authentication. Although that is not a 256 bit key.

com501 · Jul 27, 2016

Encryption stops people from even trying. Look at the stats for the California State Prison system for evidence.

Project25_MASTR · Jul 27, 2016

com501 said:
This is why AES256 is used by smart people.

My limited knowledge of encryption on phase 1 is making me curious as to how that would work. My understanding has always been Radio ID and TG are sent in the clear even when secured. So obtaining IDs would not be difficult. Now what it takes to stun/inhibit while secure is definitely not in my repertoire.

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Thunderknight · Jul 27, 2016

W5PKY said:
My limited knowledge of encryption on phase 1 is making me curious as to how that would work. My understanding has always been Radio ID and TG are sent in the clear even when secured. So obtaining IDs would not be difficult.

I think what com501 is saying is that if the traffic is encrypted, people won't bother with programming rogue radios because they still won't be able to listen.
(Vs the encryption creating a technical barrier).

radioman2001 · Jul 27, 2016

Something that popped into my mailbox this morning, about a request for more use of P25 in fire ground comms. I still don't agree, and it also deals with encrypting not only voice traffic but user ID's and the use of OTAR more as a viable use of encryption instead of having to reprogram each radio every time a new key is needed. I see that as happening very soon if the pirate radios don't stop affiliating.

http://www.project25.org/images/stories/ptig/IWCE_2015/IWCE_2015_P25_Foundations_Part_2_150308.pdf

Project25_MASTR · Jul 27, 2016

Nothing wrong with P25 and Fire ground. The issue in reliability is ensuring those in the fire ground know how to operate the equipment.

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