Using DES/DVP with PL?

kb0nly · Post by **kb0nly** » Fri Feb 24, 2006 8:47 pm

Can anyone give me a definite answer about the use of PL with DES and DVP?

Some old posts on here had mentioned that while using DES or DVP the PL is disabled? I was hoping this was the case, it would make it nicer scanning the local PD channels to have the PL set on receive to block the DES and DVP transmissions. Nothing more annoying than a loud burst of static.

I have the correct tone set for two of the local counties, but whenever they go encrypted, i know for sure one uses DES-XL and the other reportedly uses DVP, and the monitor is turned off on my X9000, but i still have to listen to the encrypted transmissions, so i assume their systems still transmit the PL along with the DES and DVP otherwise my radio receiving it would stay muted.

Any way to make a receiver ignore DES and DVP so i just plain don't have to listen to the crap? I loved it on the Saber, i could dump in a random DES key and since it wasn't the correct key it would ignore any DES traffic and just stay muted. Would love to have that on the X9000, but it's too hard to find an internal securenet board and get it keyloaded to be worth it.

Microwave Mike · Post by **Microwave Mike** » Fri Feb 24, 2006 9:04 pm

The quick answer is NO.
When DES or DVP are used the signal must go to
DC levels of modulation. There is no room for a AC signal of PL frequencies.
When DES or DVP are used, there is a 1600 Hz end of message sent at the end
Of transmission. The entire digital signal of DES/DVP uses up all the modulation
Spectrum of the channel. The 1600 Hz EOM is used to squelch up the receiving radio.

mm

Post by Pj » Fri Feb 24, 2006 10:45 pm

When using securenet, the PL drops on PL enabled channels. Either your channels reverted back to CSQ on RX for some reason, or they are running something funky. Are you sure they are running true Moto encryption? There are aftermarket encyption modules out there that will sounds digital but are not DES/DVP. A fire department near me used some Transcrypt encyption that did this. I don't remember which one they had, will have to look it up. It was quite the annoyance.

kb0nly · Post by **kb0nly** » Sat Feb 25, 2006 7:41 am

Well, i know for sure that the county i live in uses DES, i have seen them keyload the radio in the new squad when they did the install, they used a T3011DX keyloader and the radio is an Astro Spectra, and i have been told that the neighboring county runs DVP. Heck, we even have one local county that uses the old speech inversion.

I know for a fact that the PL is being transmitted now. I have a Yaesu VX7R with tone scan, i monitored the main channel today and with the tone scan on it was grabbing the PL on every transmission including the secure ones.

Bummer... Would be nice to block it out somehow.

N9LLO · Post by **N9LLO** » Sat Feb 25, 2006 8:00 am

I'm not sure if it was made clear but the is NO PL on DVP/DES encrypted traffic. YES you can use PL decode to filter out encrypted traffic on your scanner if the unencrypted traffic uses PL.

Chris
N9LLO

kb0nly · Post by **kb0nly** » Sat Feb 25, 2006 8:24 am

Well, i hate to argue with you, but there is PL on the secure transmissions here.

I have a scanner and two X9000's and the VX7R set with PL on receive, they all open up when a secure transmission is made and the VX7R tone scan shows a PL being transmitted along with the DES.

RESCUE161 · Post by **RESCUE161** » Sat Feb 25, 2006 9:42 am

If you had a secure module in the X9000, you should be able to set it for unmute only on correct secure code, i.e. if you had the wrong key programmed in, then the radio would not unmute. I know the Spectras and Sabers are like this.

kb0nly · Post by **kb0nly** » Sat Feb 25, 2006 9:55 am

Yeah, i liked how the Saber would do that. Problem is finding the securenet internal option board, setting the radio for securenet, making a connection to load a key, etc etc... That is unless it could be put in there without a key loaded and it would still stay muted.

Even then it only helps with one of the two systems i listen to. When i had the secure saber it would stay muted on the local county channel but not on the neighboring counties frequency during secure transmissions, i assume because they were using DVP instead.

Back to the drawing board.

Post by Pj » Sat Feb 25, 2006 9:58 am

My x9000 does not unmute on secure rx without a board in there so... I don't know whats going on with your or the depts setup..

kb0nly · Post by **kb0nly** » Sat Feb 25, 2006 10:03 am

The problem is the tone being used 110.9 is present with the DES, i KNOW it is because all the radios unmute and the VX7R's tone scan shows it's receiving the PL 110.9 while i'm also hearing the secure transmission.

So for some reason they are transmitting the PL along with the DES, which i didn't think was possible because it would screw up the DES.

RESCUE161 · Post by **RESCUE161** » Sat Feb 25, 2006 10:18 am

They may be using an external PL encoder on the output of the repeater.

kb0nly · Post by **kb0nly** » Sat Feb 25, 2006 10:29 am

That's possible, but i wonder what the reason is for using it.

RESCUE161 · Post by **RESCUE161** » Sat Feb 25, 2006 10:36 am

To keep their units from hearing neighboring departments/intermod while they are in Secure mode.

kb0nly · Post by **kb0nly** » Sat Feb 25, 2006 11:16 am

Never thought about that. Well crap, i guess i'm stuck listening to it.

mancow · Post by **mancow** » Sat Feb 25, 2006 6:29 pm

How could an external pl encoder work?

I'm with the others on this. I just don't see how you can molest the signal with PL and expect it to pass DES. They are entirely two different things. It's almost like trying to run pl with Astro.

Is the 110.9 the same tone their regular analog transmissions use?

I just don't see how it could work but I can't say I've tried to force the two together to test it.

kb0nly · Post by **kb0nly** » Sat Feb 25, 2006 6:45 pm

Yes, they use a PL of 110.9 when just talking in analog voice, i have yet to ever hear them use digital. But then there HT's are not Astro, only a couple of the newest mobiles are because they were purchased later.

Let me rephrase that, some of their equipment is Astro but MOST is not. It just whatever the local dealer suckered them into buying on a vehicle by vehicle basis. Eventually they plan on getting everything upgraded, but they are still using a mix of MT1K's, Saber's, Spectras, Astro Spectra's, one vehicle even has an X9K in it yet.

As i mentioned, this is not a question of if they are using PL on the output with the DES, i KNOW they are, but i don't know why unless it's just to block other traffic. There is one county down south that uses the same frequency, if conditions are just right i hear both at once so i set PL on the receive of everything including a scanner.

If i tone scan the channel while they are transmitting in DES the tone is detected. So it's present at all times.

kb0nly · Post by **kb0nly** » Sat Feb 25, 2006 6:48 pm

Oh.. And before i forget, the neighboring county is using a PL with their DVP, so i have to listen to that as well.

mancow · Post by **mancow** » Sat Feb 25, 2006 6:56 pm

Man, you have some crazy stuff going on over there. The DES radios that will only talk to others they like and now PL with DES.

You got me. If you say so then I guess it's so but it seems technically impossible.

kb0nly · Post by **kb0nly** » Sat Feb 25, 2006 7:04 pm

The radios that were having the problems were a totally different system, a privately owned company and its communications. Which by the way was solved by the owner of the repeater that they lease. How, i don't know, they never told the guys i was trying to help and they won't talk to me. All i know is that they didn't have to make any changes to the Saber's and even refused to do anything to them if they needed it since they were not the ones that sold them the radios, yada yada...

Anyway, that worked out ok.

The DES that i am sick of listening to is the local county dispatch, same frequency for the Sheriff as well as the local PD's around here. The neighboring county uses DVP and it's the same issue. I couldn't make up a story this crazy, i'm not that creative. I'm just telling you what i know. Five different radios set with a PL on the receive, two of which are X9000's, a scanner, a Saber, and a Hamateur HT, and they all allow the DES and DVP through. And the VX7R tone scan is showing the correct tone being received on each encoded transmission.

So, you got me. I guess there is no easy way to block it out so i don't have to listen to it. It's gotten really annoying lately, the local Sheriff is a total PITA and after getting in trouble over bad mouthing someone over the radio he won't say much of anything over the air unless its encrypted. Which is fine, i could care less, i just want to hear the local FD and PD activity but it happens to be on the same channel, everything shares one dispatch here. With the exception of the FD and Ambulance pages being sent on a seperate frequency all voice traffic is on the same channel.

mancow · Post by **mancow** » Sat Feb 25, 2006 7:19 pm

I dont' think you are making it up. It's just wierd and something I sure haven't heard of before.

I've seen DES false a PL search but that was all.

I wonder what the use would be. You would think they would want to be able to block the signal through PL squelch for the guys with the MT1000's etc...

kb0nly · Post by **kb0nly** » Sat Feb 25, 2006 7:26 pm

That's what i thought too, about the guys that have radios without DES. But i've heard one of the MT1K's with the DES coming over before while the local cops were sitting around chatting. Every time a DES transmission comes over you see them turning the radio down then back up.. LOL

I guess they didn't think about that, or the repeater is transmitting PL when it shouldn't.

N9LLO · Post by **N9LLO** » Mon Feb 27, 2006 3:35 am

OK, lets say you had a carrier access repeater that had PL encode so your portables/mobiles wouldn't unsquelch in the presence of noise. If you had some users running DES encryption simplex on the repeater input freq. you would hear the DES signal on the repeater output with the repeater generated PL tone. The DES signal would not be decodeable after being molested by the IF filters in the repeater but would sound OK to the naked ear. There could be a DES equipped base station in dispatch to decode the traffic.

There is no way you can encode DES and PL on the same carrier and decode the DES on the the other end. The only reason to let it pass through the repeater in this senario is to let other users know that the channel is busy. This is just too screwed up to think someone is actually doing it but you never know.

Chris
N9LLO

wb4bsd · Post by **wb4bsd** » Mon Feb 27, 2006 8:09 am

If PL is passed while using DES, then why cant i bring up a local police repeater that requires PL while i am encrypted?

I am having a hard time believing that PL is passed while operating in encrypted mode.

I think its impossible, but i am no RF engineer either.

N9LLO · Post by **N9LLO** » Mon Feb 27, 2006 8:46 am

PL will NOT be generated by a radio transmitting encrypted traffic under normal conditions. A carrier activated repeater will retransmit a DES signal as I stated above but the DES signal will not be recoverable after passing through the repeater. If the above repeater has a PL encoder it will also be present.

There is NO way to add PL to a DES signal and still be able to recover the audio on the recieving end.

Chris
N9LLO

kb0nly · Post by **kb0nly** » Mon Feb 27, 2006 9:24 am

Ok, that's understandable, but a few problems with your theory...

They do not change channels to operate DES. That means they never leave the primary channel to do so. I know how the radios are programmed, a friend of mine was the Chief here and i helped him with the squad and the radios whenever he couldn't figure something out.

I read the radios with RSS and have the codeplug to refer back to. There is the primary channel, seperate transmit and receive frequencies, and there is the PL set. So taking your example, they turn on the DES with the button on the head labeled as Ø and transmit on the repeater input to dispatch and then dispatch would probably transmit back on the repeater output frequency in DES bypassing the repeater to converse. However, there must be something still relaying the DES other than the dispatcher because they can talk car to car with DES from one end of the county to the other using what i had assumed was the repeater.

There is no way that they are talking back and forth in DES without some help using just simplex, you can barely hear the units on the input frequency with a base antenna of significant gain when they are up in the northern part of the county, and that's in analog. Unless you think that there is still some automatic relay of the DES going on at dispatch?

All i know is what i'm telling you. By the way, the DES can be decoded on the output frequency with the PL present. If one radio with DES capability is listening on the output and another without DES is, at the same time, you will hear decoded traffic from the radio that is capable and just the burst of data from the other radio because it will unsquelch due to the tone being present. So if there was a seperate transmitter being used rather than the repeater to send the DES then why is the PL still present to open the radio without DES capability??

wb4bsd · Post by **wb4bsd** » Mon Feb 27, 2006 11:50 am

They are probably using a repeater with a DES board in it to pass the encrypted signal or a transparent repeater. In either case, the repeater would be set up to unmute if it hears DES or PL.

kb0nly · Post by **kb0nly** » Mon Feb 27, 2006 12:11 pm

That's what i am thinking, the repeater is made to pass the DES, but i don't know why they would also have the PL on the output if everyone says it would cause decode problems.

Nickb · Post by **Nickb** » Wed Mar 01, 2006 10:10 am

The way this might be working is if:

- the PL deviation is fairly low
- the PL frequency is fairly low (and it is)
- the DES radios can track the wavering transmit frequency

There may be some DES data errors but not enough to cause serious trouble, but with PL added, the range will be reduced in weak-signal areas.

I suspect if it were DPL, then that would really wreak havoc.
PL being tone, might just be tolerable with strong signals.

I don't see how any Motorola radio would be allowing PL in encrypted transmit. Unless it is an add-on external PL tone.

Nick

RADIOMAN2002 · Post by **RADIOMAN2002** » Fri Mar 03, 2006 7:26 am

When a DES or DVP or DVI with or without XL format is transmitted, the PL transmit is disabled. It would distort the 6k waveform if used. If you program your scanner for the proper PL for that channel, you shouldn't hear it at all. What I suspect is happening, is the secure repeater is not dropping the PL when rebroadcasting the secure transmissions. Do you know what kind or repeater they are using? Also if this is true, they are probably exceeding their allowable bandwidth and could recieve a citation from the FCC. DES or any other of the analog encryption formats use between 3.75kc and 4.25kc of deviation, and when the EOM signal goes out it is at 6k audio at 5kc deviation, basically a turnoff code so you don't get a squelch tail. Now if you add the PL of 750hz, they could realisticly be overdeviating their channel.

kb0nly · Post by **kb0nly** » Fri Mar 03, 2006 11:17 am

No idea what the repeater is, or what the other equipment in service at the LAC is.

Knowing the local Motorola dealer that they work with it's probably just not setup correctly. They don't know their a-hole from a gopher hole.

network · Post by **network** » Sun Mar 05, 2006 3:00 pm

kb0nly
Hi, i made the rib that has the link on the button of this page.

I am trying to program the radio with versions R 03.00.08 and R08.01.00, but the software say me " Radio not respond " about 4 times and then " Codeplug version not supported by this RSS "

The radio info is this:
Model NO: M08KHE4AA2AN
TYPE NO: MD334BA
TANAPA: EUD4844B
SERIAL NO: 821IXL4283

Can you help me with this problem? I made the rib from this link:

http://www.ham.dmz.ro/motorola/gm300-rib-ivg.php

I don´t know if i did somethig wrong or i have not the required software. I am new on this...

Thanks everybody.

kb0nly · Post by **kb0nly** » Sun Mar 05, 2006 4:07 pm

Sounds like a RIB or Cable problem if your not getting a response. I would suggest you start a new thread with your question so that others will notice it as well. Tagging a question on to an existing thread, hijacking as its also known, isn't the best way to get help. No offense, just trying to be helpful!

Post by **wavetar** » Mon Mar 06, 2006 1:54 pm

Yes, please Network, start your own thread about your problem instead of hijacking other posts. We have split this exact same post 3 times from other threads today, and PM'd you about it. Seeing as how kb0nly answered you in this one, I'm leaving it be here, but take the advice given & post problems in your own threads. Thanks,

Todd

Using DES/DVP with PL?

Using DES/DVP with PL?

DES-PL-DVP

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