LCN to Frequency calculator for DMR TIII

thewraith2008

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Nov 22, 2016
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1,294
I have a CapMax network with many sites which all the CC and VC are calculated from the same base frequency with the exception of one CC.
If all possible CCs are programmed into radios with the frequency, then I would understand how radios find the neighbor CC.
I don't think this happens.
How real radios find this 'odd one out' control channel when needed is a mystery if a common base frequency is used.
I know the odd CC belongs to the network because it shares the same neighbor list (common CCs).

I have no way of knowing when this would be used in a network and therefore cannot program calculator for it.



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NOTE: Use 7zip or WinRAR to extract files from the .7z file and read the readme.txt file for usage.
 

Ubbe

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Sep 8, 2006
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Stockholm, Sweden
How real radios find this 'odd one out' control channel when needed is a mystery if a common base frequency is used.
If a radio looses reception completly it does a search over the whole frequency band. I had the same thing happening and to several sites in a system but I think it was just some error from the system managers as it was corrected after a few weeks.
Or they deliberately didn't want radios on the sites until they had done some work on it, maybe interference problems that needed to be fixed.

/Ubbe
 

zacaustin

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Joined
Nov 25, 2016
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Location
Sydney NSW Australia
If a radio looses reception completly it does a search over the whole frequency band.
Would that not cause confusion to the subscriber unit if it was operating in a RF dense area? All it would take is another TIII system using the same colour code and site numbers and it could end up on an entirely different network by mistake.

While in an ideal world you wouldn't have two systems operating like that with the same colour code, the first system engineer can't control if another system operates on the same colour code...
 

zacaustin

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Joined
Nov 25, 2016
Messages
5
Location
Sydney NSW Australia
I have a CapMax network with many sites which all the CC and VC are calculated from the same base frequency with the exception of one CC.
If all possible CCs are programmed into radios with the frequency, then I would understand how radios find the neighbor CC.
I don't think this happens.
How real radios find this 'odd one out' control channel when needed is a mystery if a common base frequency is used.
I know the odd CC belongs to the network because it shares the same neighbor list (common CCs).

I have no way of knowing when this would be used in a network and therefore cannot program calculator for it.



Download
NOTE: Use 7zip or WinRAR to extract files from the .7z file and read the readme.txt file for usage.
With some help from a few people on a local facebook group, they have explained why this occurs and how it works.

On a Motorola CapMax system, there is space for up to four different channel plans. These are called Fixed Channel Plans. The current version of the calculator can only use one plan at a time.

The subscriber units can become aware of these four channel plans over the air interface or during programming. During programming is the preferred method.

A single CapMax system can have anywhere from 1 to 4 different channel plans. Each plan has its own base frequency. With this in mind, I have gone across a bunch of the sites in my system and found 3 different base frequencies so far. If I enter those different base frequencies into the calculator and look for neighbour CC's it works correctly giving up to four possible results, only one of which is correct.

Perhaps support for these four different base frequencies could be added in the future? As you discover the up to four different bases you could enter them into the software. Then when you enter a new target, it displays the result in each of the four band plans as a new column on the table on the right. You could then test each result and identify the correct one.

Note that in addition to the four fixed plans, there are 'flexible' channels. These are 'one off' frequencies that are entered during programming. This is less ideal as subscriber units have to be reprogrammed each time a flexible channel is added, modified or removed.

Cheers
 

thewraith2008

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Joined
Nov 22, 2016
Messages
1,294
@Ubbe
I don't think it's a system configuration error as the odd CC (lcn) is active with voice and data.
When I use a different base frequency with it, the VCs are calculated and followed correctly.

Not that it bothers me that much because I don't need to hunt CCs like a real radio does. It's just curiosity why this is seen.

As I said, if a common base frequency is used and radio needs to switch to a new CC, the base frequency for odd CC is the wrong one to use to find a neighbor CC (from the neighbor list of lcns).



Download
NOTE: Use 7zip or WinRAR to extract files from the .7z file and read the readme.txt file for usage.
 

thewraith2008

Member
Joined
Nov 22, 2016
Messages
1,294
Perhaps support for these four different base frequencies could be added in the future? As you discover the up to four different bases you could enter them into the software. Then when you enter a new target, it displays the result in each of the four band plans as a new column on the table on the right. You could then test each result and identify the correct one.
The base frequency is an unknown until a correct Ref. Frequency/Ref. LxN/RF spacing is entered.
Calculating additional three other lists with different base frequencies is not possible this way.
You would need to enter the three additional different Ref. Frequency/Ref. LxN/RF spacing to also calculate.
It's easier just to do it individually for each one.

This calculator will never be fully automatic because it will always require a guess for the RF spacing used.
RF spacing (or Frequency Separation) is not sent over the air.



Download
NOTE: Use 7zip or WinRAR to extract files from the .7z file and read the readme.txt file for usage.
 
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