RadioReference on Facebook   RadioReference on Twitter   RadioReference Blog
 

Go Back   The RadioReference.com Forums > Computer Aided Monitoring and Programming > Voice/Control Channel Decoding Software


Voice/Control Channel Decoding Software - For discussion of software applications which decode digital voice formats and trunking control channels. Please use the HF Digital Signals forum for anything below 30MHz.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #61 (permalink)  
Old 07-22-2017, 2:13 PM
troymail's Avatar
Silent Key
  Premium Subscriber
Premium Subscriber
 
Join Date: Dec 2002
Location: Supply (Lockwood Inlet area), NC
Posts: 9,977
Default

Quote:
Originally Posted by garys View Post
I'm monitoring a NXDN trunk system which is part of a network in eastern MA. One site seems to operating as a single frequency trunk as the control channel data is also a voice channel.

Has anyone else seen that sort of activity?
Yes - there is a site on a system in Maryland where when I last looked, only the control channel frequency was active and when the only user talked, they took over that frequency. The CC returned when they were done talking.

Not the same thing but I've monitored another system that used the control channel frequency as a voice overflow when all other frequencies on the system were in use.
__________________
Unication G5(UHF)
TRX-2,TRX-1,WS1098,1088x2,1095,1080, PSR1080,PSR500,PRO96
BCD536,436,396T,BC296D,245XLT,600XLT,IV,VX-8R,MD-390
Reply With Quote
Sponsored links
  #62 (permalink)  
Old 07-22-2017, 2:47 PM
mmckenna's Avatar
Member
   
Join Date: Jul 2005
Location: WTVLCA01DS0
Posts: 9,326
Default

Quote:
Originally Posted by troymail View Post
Yes - there is a site on a system in Maryland where when I last looked, only the control channel frequency was active and when the only user talked, they took over that frequency. The CC returned when they were done talking.

Not the same thing but I've monitored another system that used the control channel frequency as a voice overflow when all other frequencies on the system were in use.
In Kenwood NexEdge terminology this is known as a "Non-dedicated Control Channel".

It can be used in a single channel trunking system. The channel will function as a control channel until a call is made, then it becomes a traffic channel. Useful for very low traffic sites. As you can guess, when the channel switches from a Control Channel to a Traffic Channel, other radios on that system are not able to hear the control channel signal.

It can also be used on a multi-channel site. If all the traffic channels are in use, you can allow the system to utilize the control channel for traffic.
Reply With Quote
  #63 (permalink)  
Old 07-22-2017, 3:47 PM
garys's Avatar
Member
   
Join Date: Jun 2002
Location: Eastern MA
Posts: 4,289
Default

Thank you. That's very helpful information.

Quote:
Originally Posted by mmckenna View Post
In Kenwood NexEdge terminology this is known as a "Non-dedicated Control Channel".

It can be used in a single channel trunking system. The channel will function as a control channel until a call is made, then it becomes a traffic channel. Useful for very low traffic sites. As you can guess, when the channel switches from a Control Channel to a Traffic Channel, other radios on that system are not able to hear the control channel signal.

It can also be used on a multi-channel site. If all the traffic channels are in use, you can allow the system to utilize the control channel for traffic.
Reply With Quote
  #64 (permalink)  
Old 07-22-2017, 5:59 PM
garys's Avatar
Member
   
Join Date: Jun 2002
Location: Eastern MA
Posts: 4,289
Default

Another question. The Channel numbers seem to go in an ascending order. 201 is lower than 202, which is lower than 203, etc...

Does this necessarily hold for channel numbers above 800? Does 801 have to be a lower frequency than 802? Or are all bets off?
Reply With Quote
  #65 (permalink)  
Old 07-22-2017, 6:25 PM
Member
  RadioReference Database Admininstrator
Database Admin
Amateur Radio Operator
Amateur Radio
 
Join Date: Nov 2002
Location: Boston, Ma
Posts: 2,186
Default

Quote:
Originally Posted by garys View Post
Another question. The Channel numbers seem to go in an ascending order. 201 is lower than 202, which is lower than 203, etc...

Does this necessarily hold for channel numbers above 800? Does 801 have to be a lower frequency than 802? Or are all bets off?
Hello,

If it is a standard UHF map, then any channel above 800 is a custom channel and can be anything.

73 Eric
Reply With Quote
Sponsored links
  #66 (permalink)  
Old 07-22-2017, 7:56 PM
mmckenna's Avatar
Member
   
Join Date: Jul 2005
Location: WTVLCA01DS0
Posts: 9,326
Default

Quote:
Originally Posted by mmckenna View Post
As you can guess, when the channel switches from a Control Channel to a Traffic Channel, other radios on that system are not able to hear the control channel signal
This should have said "other radio on that SITE are not able to hear the control channel signal since it's been stopped so the channel can become a traffic channel. Usually the radios will throw an "out of range" message on the screen and beep, if set up that way.
Reply With Quote
  #67 (permalink)  
Old 07-22-2017, 11:18 PM
garys's Avatar
Member
   
Join Date: Jun 2002
Location: Eastern MA
Posts: 4,289
Default

Thanks. That gave me a good hint and I found the voice channel. It's Network 178, which you're familiar with. I have the frequency and Channel number matched.



Quote:
Originally Posted by EricCottrell View Post
Hello,

If it is a standard UHF map, then any channel above 800 is a custom channel and can be anything.

73 Eric
Reply With Quote
  #68 (permalink)  
Old 05-02-2018, 2:47 PM
Dispatcher308's Avatar
Member
  Premium Subscriber
Premium Subscriber
 
Join Date: Jun 2003
Location: Hon Land!!!!!
Posts: 743
Default

Quote:
Originally Posted by EricCottrell View Post
Hello,

Some more information to help in figuring out the Channel Map.

Standard UHF Map Formulas
For Channels 1 to 400:
Freq = 450 + (( Ch - 1 ) * 0.0125

For Channels 401 to 800:
Freq = 460 + (( Ch - 401 ) * 0.0125

For Channels 801 to 1023
Custom frequency, i.e. T-Band or on a 6.25 KHz step.

What is the frequency for Ch 511?
Freq = 460 + (( 511 - 401 ) * 0.0125 ) = 461.3750

Otherwise each system implements their own channel map. After getting a few frequencies on the system, you can try the same techniques used to get the frequency mapping of a Motorola Analog VHF/UHF system. For example, the frequencies for these three channels where figured out.
472.350 MHz = Ch 377
471.600 MHz = Ch 257
471.350 MHz = Ch 217

Figure out the step size
( 471.600 - 471.350 ) / ( 257 - 217 ) = 0.00625 KHz (reasonable step size).

Find the base
Base (Ch 1) = 471.350 - (( 217 - 1 ) * 0.00625) = 470.000

See if the other frequencies fit, they do.
471.6000 = 470.000 + (( 257 - 1 ) * 0.00625)
472.3500 = 470.000 + (( 377 - 1 ) * 0.00625)

So the system has a Base (Ch 1) of 470.000 MHz with a 6.25 KHz step size. I do not know if the mapping is always divided into three parts (1 - 400, 401 - 800, 801 - 1023).

73 Eric
This formula makes no sense to me and I do pretty well in math, what gives?
__________________
Nathan

Every cloud has a silver lining!!! Except for the mushroom shaped ones, which have a lining of Iridium & Strontium 90.
Reply With Quote
  #69 (permalink)  
Old 05-02-2018, 3:09 PM
u2brent's Avatar
Member
  Premium Subscriber
Premium Subscriber
 
Join Date: Jul 2010
Location: KRWDPAXKRS1
Posts: 779
Default

They do not work for every system.

What do you not understand? It's basic algebra.

Standard UHF Map Formulas
For Channels 1 to 400:
Freq = 450 + (( Ch - 1 ) * 0.0125)

For Channels 401 to 800:
Freq = 460 + (( Ch - 401 ) * 0.0125)

For Channels 801 to 1023
Custom frequency, i.e. T-Band or on a 6.25 KHz step

You just need to perform the calculations in () first.
__________________
Uniden SDS100/ (2) BCD436HP/ BC450A/ ICOM IC-7600/ IC-R20/ IC-R3/ Sony ICF-2010
Radio Shack (2) PRO-651/ (2) PRO-164/ PRO-97/ PRO-404/ PRO-2026
SDR: NooElec NESDR Mini 2+/ NESDR XTR+/ RTL-SDR Blog
Reply With Quote
  #70 (permalink)  
Old 05-02-2018, 3:22 PM
troymail's Avatar
Silent Key
  Premium Subscriber
Premium Subscriber
 
Join Date: Dec 2002
Location: Supply (Lockwood Inlet area), NC
Posts: 9,977
Default

Quote:
Originally Posted by Dispatcher308 View Post
This formula makes no sense to me and I do pretty well in math, what gives?
See also: https://forums.radioreference.com/ge...ulator-v3.html

Seeing in in writing like this could help....
__________________
Unication G5(UHF)
TRX-2,TRX-1,WS1098,1088x2,1095,1080, PSR1080,PSR500,PRO96
BCD536,436,396T,BC296D,245XLT,600XLT,IV,VX-8R,MD-390
Reply With Quote
  #71 (permalink)  
Old 05-03-2018, 7:45 PM
Dispatcher308's Avatar
Member
  Premium Subscriber
Premium Subscriber
 
Join Date: Jun 2003
Location: Hon Land!!!!!
Posts: 743
Default

Quote:
Originally Posted by troymail View Post
See also: https://forums.radioreference.com/ge...ulator-v3.html

Seeing in in writing like this could help....

Thanks Troy!
__________________
Nathan

Every cloud has a silver lining!!! Except for the mushroom shaped ones, which have a lining of Iridium & Strontium 90.
Reply With Quote
Reply

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 4:42 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