RadioReference on Facebook   RadioReference on Twitter   RadioReference Blog
 

Go Back   The RadioReference.com Forums > Scanners, Receivers and Related Equipment Forums > Uniden Forums > Uniden Thread Archives


Uniden Thread Archives - A depository of archived threads from the original Uniden forum.

 
 
LinkBack Thread Tools Search this Thread Display Modes
  #1 (permalink)  
Old 10-01-2013, 3:12 PM
Member
   
Join Date: Dec 2004
Posts: 235
Default P25 Garbled in first few seconds

I tried finding a few threads that answered this directly, but found some indirect comments instead.

While on vacation I had the opportunity to monitor the Coast Guard channels using P25 on my BCD396XT.

I heard several transmissions on CG108 and CG112 that were quite clear.

I received a few transmissions that stopped on these channels that the first few seconds were garbled and the radio did not indicate ENC. After the garbled sounds no decoded audio could be heard for the rest of the transmission. The signal level was high according to the signal strength meter.

Was this actually an Encrypted transmission, or one with a different NAC?

I don't have many opportunities to monitor P25 so I lack some experience. I do receive the Blue Ridge Parkway channels at times when I am up that way.

Last edited by KD4UXQ; 10-01-2013 at 3:23 PM..
Sponsored links
  #2 (permalink)  
Old 10-01-2013, 4:16 PM
ChrisP's Avatar
Member
  Premium Subscriber
Premium Subscriber
 
Join Date: May 2002
Location: Portland, OR
Posts: 1,009
Default

The Coast Guard often uses encryption on the P25 VHF frequencies. These would normally be muted by the 396XT radio, with a brief burst of what sounds like garbled voice at the beginning.

The ENC indicator on my 396XT does not always seem to appear, even with encrypted transmissions. I'm not sure why, but it is not consistent.

The Coast Guard has almost always used the default NAC of $293, but if you are in doubt, set the radio to search for the NAC, rather than programming a NAC in the channel.

It sounds to me like your radio is behaving normally with an encrypted P25 transmission.

- Chris
__________________
Chris Parris
Federal Wavelengths Columnist, The Spectrum Monitor Magazine, www.thespectrummonitor.com
chrisparris@thefedfilesDOTcom
http://mt-fedfiles.blogspot.com/ @TheFedFiles on Twitter
  #3 (permalink)  
Old 10-01-2013, 5:06 PM
Member
   
Join Date: Sep 2013
Posts: 25
Default

I don't have a lot of monitoring experience but I have a BCD996T and when I monitor the Border Patrol [ENC P25 System] it behaves exactly the same as Chris and the OP describe. Sometimes it shows "ENC" and sometimes it does not.
  #4 (permalink)  
Old 10-02-2013, 5:23 PM
tampabaynews's Avatar
Member
  Premium Subscriber
Premium Subscriber
Amateur Radio Operator
Amateur Radio
 
Join Date: Jan 2007
Location: Tampa, FL
Posts: 1,168
Default

I also concur, ENC does not always show for me.

It is also normal that you may be hearing P25 in the clear on the same channel. More than likely some mobiles are not transmitting with encryption.
__________________
Ryan
XG-25P, P7200, P7100, NX-5300, NX-300, IC-F4161DT, IC-F4161DS, IC-F4011, BCD996P2, BCD325P2, BCD996XT, RH-96
  #5 (permalink)  
Old 10-02-2013, 6:28 PM
Member
  Premium Subscriber
Premium Subscriber
 
Join Date: Nov 2007
Location: St. Louis County, MO
Posts: 2,299
Default

Quote:
Originally Posted by tampabaynews View Post
I also concur, ENC does not always show for me.

It is also normal that you may be hearing P25 in the clear on the same channel. More than likely some mobiles are not transmitting with encryption.
What I've found on the 396 or 996XT's is that if you are in Scan or Search mode, the scanner will often not show ENC. It will usually just skip right past the channel and keep on scanning. If you are sitting on a channel that had some in the clear chatter while in the Scan or Search mode and a user comes on that is encrypted, I do see it light up ENC for a very brief time before moving on.

If you Hold on the channel or talkgroup in a trunked system, then mine have always shown ENC when an encrypted user is talking but again, I must be held or holding on that channel in a conventional system or holding on a talkgroup in a trunked system. If I'm scanning or searching either type of system, ENC usually never displays as the radio knows to keep scanning or searching so it never has a chance to display ENC.
Sometimes during a scan or search, if you are using remote software such as Pro96com or any of the others that allow remote operation, you can catch it display ENC but only in the software display as it is slower than the radios display. ENC may also not display at all if older forms of encryption are being used. Usually the radios will also stop on those types of encrypted channels though.

I should also add that I monitor the STL City P25 system here in Missouri. They don't have any fully encrypted TG's but do have several users that use encrypted radios. When monitoring that system with a Uniden, the Uniden never stops or anything when one of the encrypted users is talking. The only way I can tell is to turn on a GRE 500 or 600 and actually hear the encryption sound or place a Uniden into Hold mode on the talkgroup that the encrypted user is on. On the GRE, you hear the horrible sound of encryption while on the Uniden's, all you see is the word ENC on the held display but no audio is passed to the speaker. The GRE PSR800 is an exception to the rule. That model can be set to pure silence or a tone of your choice when it encounters encryption or you can make it pass the encrypted audio to the speaker just as the 500 and 600 do. The only drawback to that method is the PSR800 will stay on that channel or talkgroup until the signal has dropped where the Uniden's will continue scanning for in the clear talk instead of tying up the radio on an encrypted signal or channel. I don't recall how they do it on the Home Patrol but I think it simply skips encrypted audio much like the 396 or 996 do but without any screen indication that a signal is encrypted.
I own an HP1 so I guess I should try the hold mode and see what it says when encryption comes on the air.

On both models, you can tune the control channel and use Pro96com and it will indicate if a talkgroup is encrypted or not regardless if the audio is pumped to the speaker. It will display (Enc) in realtime when it detects an encrypted signal.
I'd guess that Unitrunker can also display that info but I don't use Unitrunker that often so I'm not sure.

edit: The HP1 does not seem to indicate it is hearing an encrypted signal even when held on a talkgroup.
It just mutes the audio when held or keeps on scanning when encryption is detected. I also did not see it indicate the RID when it was held on a TG with encrypted audio. It would only display the RID when it was an in the clear transmission.

Last edited by kruser; 10-02-2013 at 7:03 PM..
Sponsored links
  #6 (permalink)  
Old 10-03-2013, 4:41 PM
Member
   
Join Date: Dec 2004
Posts: 235
Default Encryption sounds likely

Thanks for the responses. I suspected it may have been Encryption, but I wasn't sure. It's also logical from the behavior. I'm not sure when I'll be able to monitor them again, but it helps to have some idea what to expect. I had not experienced this before as so far all the other P25 channels I have monitored had not done this. Apparently because none were encrypted.
  #7 (permalink)  
Old 10-03-2013, 4:41 PM
Member
   
Join Date: Dec 2004
Posts: 235
Default

Quote:
Originally Posted by kruser View Post
What I've found on the 396 or 996XT's is that if you are in Scan or Search mode, the scanner will often not show ENC. It will usually just skip right past the channel and keep on scanning. If you are sitting on a channel that had some in the clear chatter while in the Scan or Search mode and a user comes on that is encrypted, I do see it light up ENC for a very brief time before moving on.

If you Hold on the channel or talkgroup in a trunked system, then mine have always shown ENC when an encrypted user is talking but again, I must be held or holding on that channel in a conventional system or holding on a talkgroup in a trunked system. If I'm scanning or searching either type of system, ENC usually never displays as the radio knows to keep scanning or searching so it never has a chance to display ENC.
Sometimes during a scan or search, if you are using remote software such as Pro96com or any of the others that allow remote operation, you can catch it display ENC but only in the software display as it is slower than the radios display. ENC may also not display at all if older forms of encryption are being used. Usually the radios will also stop on those types of encrypted channels though.

I should also add that I monitor the STL City P25 system here in Missouri. They don't have any fully encrypted TG's but do have several users that use encrypted radios. When monitoring that system with a Uniden, the Uniden never stops or anything when one of the encrypted users is talking. The only way I can tell is to turn on a GRE 500 or 600 and actually hear the encryption sound or place a Uniden into Hold mode on the talkgroup that the encrypted user is on. On the GRE, you hear the horrible sound of encryption while on the Uniden's, all you see is the word ENC on the held display but no audio is passed to the speaker. The GRE PSR800 is an exception to the rule. That model can be set to pure silence or a tone of your choice when it encounters encryption or you can make it pass the encrypted audio to the speaker just as the 500 and 600 do. The only drawback to that method is the PSR800 will stay on that channel or talkgroup until the signal has dropped where the Uniden's will continue scanning for in the clear talk instead of tying up the radio on an encrypted signal or channel. I don't recall how they do it on the Home Patrol but I think it simply skips encrypted audio much like the 396 or 996 do but without any screen indication that a signal is encrypted.
I own an HP1 so I guess I should try the hold mode and see what it says when encryption comes on the air.

On both models, you can tune the control channel and use Pro96com and it will indicate if a talkgroup is encrypted or not regardless if the audio is pumped to the speaker. It will display (Enc) in realtime when it detects an encrypted signal.
I'd guess that Unitrunker can also display that info but I don't use Unitrunker that often so I'm not sure.

edit: The HP1 does not seem to indicate it is hearing an encrypted signal even when held on a talkgroup.
It just mutes the audio when held or keeps on scanning when encryption is detected. I also did not see it indicate the RID when it was held on a TG with encrypted audio. It would only display the RID when it was an in the clear transmission.
Thanks much for the detailed tips!
  #8 (permalink)  
Old 10-03-2013, 5:47 PM
lep's Avatar
lep lep is offline
Member
   
Join Date: Jan 2002
Posts: 948
Default

I have the known ENC channels entered into my HP-1 Favorite List as, for example: "PD (ENC)" with the appropriate Talk Group. I wanted to make certain the channel would HOLD so I could more easily ID them with the Trunk Analyzer features of the EE version, maybe I did not have to do it this way but it doesn't seem to hurt anything. Even an ENC channel still needs a channel grant on trunking system and you can still log the UID of the units using the ENC channels.
 

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 10:49 AM.


Powered by vBulletin® Version 3.8.2
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
All information here is Copyright 2012 by RadioReference.com LLC and Lindsay C. Blanton III.Ad Management by RedTyger
Copyright 2015 by RadioReference.com LLC Privacy Policy  |  Terms and Conditions