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Trunking Control Channel Decoding For discussion of installation, setup, configuration, and use of the Trunker / Unitrunker digital decoding utilities (for decoding Trunking control channels)

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Old 05-15-2010, 6:37 PM
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Default LCN to frequency conversion

It's been a long time since I've had a question for this group. I've been (slowly) plugging away at my own pet project to decode Motorola control channels.

Right now, one of my announces is the fact that I am only displaying LCN, not the frequency. I think I've found at least two different ways to convert LCN to frequency. One is SlicerWizard's table (http://home.ica.net/~phoenix/wap/TRU...%20Numbers.txt). The other seems to be calculating frequency based on an algorithm (Custom Band Plans - UtahRadio).

QUESTION 1:
Are there any systems that use a band plan that doesn't fit into SlicerWizard's frequency chart?

I found that band plan algorithm and noticed it seems the GRE scanners have you entering LCN, not frequency. The Uniden scanners are opposit. I also noticed that the plan chart for rebanding is quite different between the two sites above. All this leads me to believe that having the user (OK, me) type in the band plan could be quite hard.

QUESTION 2:
What is the proper method for converting LCN to frequency?
1) have user pick standard, rebanded, splinter, 900 and use SlicerWizards tables to look to frequency
2) have user enter band plan (ala Unitrunker) and calculate frequency
3) some other method I have yet to discover

Thanks,
Frank

Last edited by fpo701; 05-15-2010 at 6:38 PM.. Reason: typos
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Old 05-15-2010, 8:50 PM
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Normally, at least for Uniden/Radio Shack scanners, the only time you need LCN is for EDACS systems.... and there is no algorithym for deciding what LCN is what frequency, since EDACS LCN's are assigned by the system programmer, however they like, when the specific system is designed.

EDACS can use, or skip, any LCN, and they may be in frequency order, reverse order, or random, whatever the system programmer dreamed up while drunk.

Motorola systems go by algorythm, using whatever bandplan is appropriate to their system, though some systems may be using unique bandplans. That's relatively common on federal 400 MHz Motorola trunk systems, for instance. They may use 12.5 KHz channels, 25 KHz channels or combinations, and have multiple table entries for various frequency ranges in the band.
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Old 05-15-2010, 9:27 PM
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<editted out original reply>

I'm not trying to decode EDACS. Just Motorola. I understand the radios don't know about LCNs, but when monitoring control channels that is the only information you get.

That being said, are there systems that don't fit SlicerWizard's table?

Last edited by fpo701; 05-15-2010 at 9:33 PM..
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Old 05-16-2010, 2:43 PM
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Quote:
Originally Posted by fpo701 View Post
<editted out original reply>

I'm not trying to decode EDACS. Just Motorola. I understand the radios don't know about LCNs, but when monitoring control channels that is the only information you get.

That being said, are there systems that don't fit SlicerWizard's table?
Assuming you are only talking about 800 MHz Motorola systems, it would appear that SlicerWizard's table is correct. Now a point to be made. Radios (including scanners) only know about LCN's (as you point out). They must use an algorithm to calculate the frequency based on a starting point (base frequency), channel separation (spacing), and an offset (the LCN). The problem is that scanner folks assume that Motorola systems don't use LCNs because the operation is hidden from them by already preprogrammed tables/algorithms (at least for 800 & 900 MHz systems); however, with the advent of rebanding, one would have thought that even that false assumption would have been erased.

If you look at the RS, GRE and Uniden forums, you will see that all are using the same algorithm for following rebanded systems, although the information added to the band plans are slightly different in format only. As for your query of will these work for all systems, and again assuming 800 MHz systems, the answer is a qualified yes. The qualification is that Motorola is now offering a scrambled LCN; however, this appears to be a marketing point only as it appears the only systems known to use this are merely reversed LCN order. More discussion of this new twist exists in the Uniden forum at the least and perhaps elsewhere.
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Old 05-16-2010, 7:04 PM
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Thanks for the great reply!!!

I just want to reiterate something.

TRUE OR FALSE. There are no custom band plans being used by existing systems.

I believe that is TRUE based on your response, excluding that new LCN functionality.
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Old 05-16-2010, 10:16 PM
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Quote:
Originally Posted by fpo701 View Post
TRUE OR FALSE. There are no custom band plans being used by existing systems.
The only 800 mhz plans I know are: Standard, Splinter, Australia, Red Deer, and Rebanded.
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Old 05-17-2010, 8:34 PM
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Quote:
Originally Posted by Unitrunker View Post
The only 800 mhz plans I know are: Standard, Splinter, Australia, Red Deer, and Rebanded.
And shuffle.
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Old 05-22-2010, 10:33 AM
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Thanks Wayne and Unitrunker.

Do either of you have the LCN to frequency list for Australia, Red Deer, and Shuffle?

I've used SlicerWizard's to start with, but would love to have the others.

Frank
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Old 05-22-2010, 12:20 PM
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The Red Deer plan being talked about comes from this system: Red Deer Public Safety & Public Works Trunking System, Red Deer, Alberta - Scanner Frequencies

Essentially it appears that frequencies are shifted 0.0125 up or down from the "normal" band plan's "LCNs" - I forget which.
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Old 05-23-2010, 4:39 AM
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Quote:
Originally Posted by fpo701 View Post
Thanks Wayne and Unitrunker.

Do either of you have the LCN to frequency list for Australia, Red Deer, and Shuffle?

I've used SlicerWizard's to start with, but would love to have the others.

Frank
The Australian 800 MHz Band runs from:-

865.0125 MHz - LCN 560 (Dec) / 230 (Hex), to 869.9875 MHz - LCN 759 (Dec) / 2F7 (Hex)

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Old 05-25-2010, 7:56 PM
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Quote:
Originally Posted by fpo701 View Post
Do either of you have the LCN to frequency list for Australia, Red Deer, and Shuffle?
Shuffle info: Shuffle Band Plan
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