fleetnet towers hit n miss

[petergriffin]

i was listening to the guelph west and the guelph main fleetnet towers a couple of days ago.
I noticed that there was a TG that was on both. NOW here is the kicker, on the guelph main tower i could only hear one person talking and one side of a convo that was it , now when i went over to the guelph west i could hear the same person but i could now also hear a reply BUT it was encrypted. as i further listened on both sites the ppl that were in the clear or "forgot " to hit the encryption switch i was able to hear. BUT when the encrypted party transmitted it would only register on guelph west. /guelph main NOTHING
can anyone explain this ?

 

[torontokris]

only a guess but maybe the encrypted person was in range of the Guelph west tower (but out of range for the Guelph tower), but the other parties were in a range between/in the middle of the 2 towers

 

[imcleish]

torontokris,

Your on to something...

petergriffin,

The issue you are having is common. It has to do with how the system and radios communicate. In your example there would have been more than 1 affiliated radio for the Talk Group you were monitoring on the Guelph West tower, and only a single radio affiliated to the same Talk Group on the Guelph Main tower.

As the system is designed to be most efficient and not over redundant, Fleetnet will only broadcast a Talk Group on a site where a radio on given Talk Group is Affiliated to the tower.

Essentially on Guelph Main with only the single radio affiliated, there is no need to repeat to another radio on that tower what is being said, where on Guelph West with more than 1 radio being affiliated, it is required for the other users on that tower to hear what is being said by that radio.

This is common on almost all Trunk Radio Systems, for more than 10 years. When I lived in the Town of Flamborough, at the 4th concession, we were Policed by the Hamilton Wentworth Regional Police (Now it is all City of Hamilton, way to go Queens Park). The Dundas/Flamborough/Moutain Dispatch (Main channel) was all on 1 talk group, although the talk group was very active, I would have periods of inactivity simply because there was No Affiliated Radio to the Local Simulcast/Repeater tower.

Hope this helps...

 

[petergriffin]

Hmm, see i thought about both of the scenarios, so that is why i hooked it up on uni trunker. and like i said. as time went on i could hear more ppl in the clear on the Guelph MAIN the same as Guelph West so that tells me the transmissions in the clear were affiliated to both towers. NOW confirming that, I actually saw the radio id's on unitrunker . for instance tower 02 Guelph main i would SEE for an example radio #1117 come up and i would HEAR it in the clear then i would go over to Guelph west i would SEE radio id #1119 but HEAR it encrypted ONLY on West but not Guelph main. then a few transmissions later i would SEE again #1119 on Guelph West but now i could HEAR it NOT encrypted on Guelph Main and Guelph West. Then within a matter of minutes #1119 would be encrypted AND only be able to HEAR/ SEE on Guelph West. There was no scenario of hearing transmissions in the clear on one tower and not the other (in other words: if i could hear it in the clear it was on both, if it was encrypted i could only hear the garble on Guelph west)

 

[mikewazowski]

This is common on almost all Trunk Radio Systems, for more than 10 years. When I lived in the Town of Flamborough, at the 4th concession, we were Policed by the Hamilton Wentworth Regional Police (Now it is all City of Hamilton, way to go Queens Park). The Dundas/Flamborough/Moutain Dispatch (Main channel) was all on 1 talk group, although the talk group was very active, I would have periods of inactivity simply because there was No Affiliated Radio to the Local Simulcast/Repeater tower.

This is incorrect. It's generally only very large systems covering a large geographic area that use Smartzone or similar technologies. Most single site or single city systems just use regular trunking.

When I lived in Hamilton, the regular system wasn't a Smartzone system and therefore, it couldn't behave in this way. Only Smartzone systems offer this type of behaviour.

As you've said, it was a simulcast system so even if a radio wasn't affiliated to your tower, you should still hear it from one of the other towers.

I was in the west end and then the downtown area for years and always heard the Dundas/Mountain police talkgroup and the Regional Fire talkgroups no problem even though it was very unlikely a vehicle was in the area.

All of Hamilton's sites broadcast the same control channel but the talkgroups were restricted to certain frequencies which were only broadcast at certain sites. From a distance, you could hear Hamilton's control channel quite easily but only the rural talkgroups were listenable as the City talkgroups were restricted to the sites within the City.

The Hamilton PS Intelligence system is Smartzone (as well as Peel's simulcast system) because a Smartzone controller is needed to support astro.

 

[Jammin_Jay]

I understand the affiliation with fleetnet towers. What i don't understand is the intermittantcy in the transmissions being encrypted for a particular tg. Why would it be encrypted on one tower, and not on another. Interesting? Unless the radio is programmed to be encrypted when transmitting to a certain tg, although if it is patched through to another radio that is not related to the same tg, it would be in the clear. Puzzling i must say. Just curious, which dept in Guelph is being encrypted partially.

 

[mikewazowski]

What i don't understand is the intermittantcy in the transmissions being encrypted for a particular tg.

It's usually just a case of somebody forgetting to switch the encryption on.

Why would it be encrypted on one tower, and not on another.

The radio on the one tower was transmitting encrypted and the radio on the other tower was not transmitting encrypted.

Unless the radio is programmed to be encrypted when transmitting to a certain tg

Fleetnet radios are not programmed that way. The user has the option of selecting encryption. In this case, one user forgot to select it.

although if it is patched through to another radio that is not related to the same tg, it would be in the clear.

I don't understand your comment. If they're both on the same talkgroup, there's no reason for a patch.

Puzzling i must say. Just curious, which dept in Guelph is being encrypted partially.

It would be a Government of Ontario agency not City of Guelph. Probably OPP Intelligence, MNR ESSU or a CISO radio.

The Guelph situation is interesting. Could be quite a few different reasons.

I don't buy the explanation that since there's only a single radio on the City of Guelph site there's no need to repeat the conversation. The input to the repeater is already tied up so there's no reason not to repeat the conversation. I'm also guessing that the local repeater would route the audio locally from the receiver rather then sending the audio out to the switch and back to the site again (but I could be wrong, Andy might have more info) for rebroadcast on the same repeater.

Could also be something to do with the fact that the City of Guelph site is usually reserved for City of Guelph radios only. I think it's very rare to find talkgroups other then the City of Guelph on the tower.

Another guess is that the City of Guelph site doesn't support encryption. It was the first site to be built and is only supposed to handle City of Guelph traffic. An improperly programmed radio could have affiliated to the tower and since it doesn't support encryption, the site didn't rebroadcast the encrypted comm's. Both radios involved in the conversation could have been on the Guelph West tower and a 3rd improperly programmed radio could have been on the City of Guelph site.

Hopefully Andy will chime in as he knows more about the inner workings of Smartzone then the rest of us.

 

[Jammin_Jay]

Mike i would agree on the assumption that one radio doesnot support encrpytion, so even if radio#2 did have encryption on it, since radio#1 cannot support encryption, the comms would be in the clear, so radio#2 could be heard. But it still doesnt explain why it flips back and forth clear, encrypted, clear, encrypted with the same tg on one tower as opposed to another. Yes hopefully Andy can explain it. Its peeked my curiousity

 

[mikewazowski]

Mike i would agree on the assumption that one radio doesnot support encrpytion, so even if radio#2 did have encryption on it, since radio#1 cannot support encryption, the comms would be in the clear, so radio#2 could be heard. But it still doesnt explain why it flips back and forth clear, encrypted, clear, encrypted with the same tg.

I never said anywhere that one of the radios didn't support encryption. I said the City of Guelph site might not support encryption.

What I also said was that one of the users forgot to switch his encryption on. Even with encryption turned off, he can still listen to encrypted signals as long as he has the correct encryption key. He can continue to transmit "in the clear" to the other radio and receive encrypted transmissions from the other radio.

Happens all the time on Fleetnet. Some users forgot to throw the encryption switch but that just means they are not transmitting encrypted signals.

 

[imcleish]

Always Happy to learn more...

Can anyone expand/clarify my thoughts on more than one radio required on that tower to carry both sides of the conversation from that radio?

I think it doesn't often happen that we know, but that there is likely something there....

Ian

 

[petergriffin]

Always Happy to learn more...

Can anyone expand/clarify my thoughts on more than one radio required on that tower to carry both sides of the conversation from that radio?

I think it doesn't often happen that we know, but that there is likely something there....

Ian

Hey Ian

I don't think you understand what my original post was about.. basically . When a radio was encrypted it would be ONLY heard( garbled) on the guelph WEST and when the radios were in the CLEAR they would be heard on BOTH Guelph West and Guelph MAIN. AND to clarify i used UNItrunker and i could see the RADIO ID's and #1119 would be encrypted and only be seen on guelph west . then it would come in the clear like an hour later (but VERY poor audio) and then i could HEAR/See it on both sites. and there was ONE radio that stayed ENCRYPTED the ENTIRE time like #1125 and i could only see it/ hear it on guelph west.


Also i have heard some Guelph police tg ie 336 and 384 that were encrypted(20% and 85%of the time, respectively)(i could hear the garble) on the GUELPH MAIN site and other times they are in the clear. when i do see Ciso on guelph Main it is 95% of the time ENcrypted

Also guelph TG 320 main ops is now transmitting on both GUELPH MAIN AND GUELPH WEST. i use to only hear SOME radios of the 320 TG on west but now they are all associated.. i dunno, maybe because of the growth of Guelph? i have never heard fire or any other GPS TG on the west site.

And MIKE_OXLONG could you explain the repeater thing with the Guelph main site? i never new fleet net used repeaters. Although, i have heard their dispatch say "units on the road ,repeaters are on"( only when they have switched to back up power. i.e storm, power out etc.)

 

[mikewazowski]

And MIKE_OXLONG could you explain the repeater thing with the Guelph main site? i never new fleet net used repeaters.

Every channel on the Fleetnet system uses a repeater. That's just how it works.

There's also the mobile repeaters installed in the vehicles.

 

[Jay911]

I know I'm not in the area nor a recognized authority on the subject, but I support the idea that the tower you're not hearing the encrypted comms on is simply not capable (or configured) to support encryption. You wouldn't get into a situation where you would hear only one side of a conversation on a given tower, just because only that user is affiliated to that tower. By nature of the way Smartzone works, and trunking in general, you'd have to have "both sides of the conversation" on all towers with affiliated radios.

The most likely situation is that the conversation is actually taking place on Guelph West, and either Guelph Main is configured to broadcast that talkgroup regardless of whether or not there are any radios affiliated to that group on the tower (which is a configuration option), or there is a radio affiliated to that TG sitting on Guelph Main.

Having said that, I suppose that the in-the-clear user could be on Guelph Main, and that's the reason the TG is carried there. However, the ultimate answer to why you're not hearing the encrypted traffic on Main is, as Mike said, because that tower is most likely not set up to carry it.

Smartzone trunking is a unique beast with some configuration options which defy what many scanner listeners "know" about trunking. You can say that some towers broadcast all talkgroups, or you can say that a tower will only broadcast a given TG when a radio on that tower is affiliated. You can also say that talkgroups ONLY function on a specific tower (or multiple specific towers). We have this last one in our system so that if/when the hardline links between towers fail, communications will be forced to function on the main site or a designated backup site. And, as Mike said, talkgroups CAN be set to automatically encrypt all transmissions, but in most cases, like on Fleetnet and on the system I work on, radio users can turn encryption on or off at will. Also as Mike said, a user who is ABLE to run encryption but chooses NOT to, will hear the conversation on his radio in exactly the same way as his encrypted colleague will. Only looking at the radio to see the encrypt switch is in the wrong position - or, listening on a scanner - will he learn of his error.

As for the question of repeaters, again, Mike has it right. All trunking systems use repeaters. On 800MHz systems, the splits are 45MHz down ... meaning that if I'm listening to a conversation on 866.5625, the user is transmitting on 821.5625 into the repeater/trunk site. On VHF systems like Fleetnet, I don't know if there's any hard and fast rule on splits, as there aren't (as far as I know) any default splits for VHF conventional either. Every channel you listen to on a trunk system - even the control channel - has an input frequency. On a Smartzone system where the person transmitting into the system might be on another tower site, the input for whatever frequency's being used on this tower will be silent for the moment.