LCN to Frequency calculator for DMR TIII

thewraith2008

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Nov 22, 2016
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The calculator appears to assume one base frequency and a step size of 12.5 kHz. The sites below do not follow those assumptions and give wrong answers from the calculator.
What was assumed is the frequency separation always been 6.25Khz.
Not the base frequency, it's calculated using a known LCN+frequency and 6.25Khz. Now if a different frequency separation is used then it will be wrong.
DSDPlus does not show the frequency separation value (5, 6.25, 10, 12.5, 15, 20, 25, 30, reserved) that I'm aware of. While easy enough to add to calculator, it add another unknown (x9) in to the mix.
 

kh6sz

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Here is another frequency and channel calculator I made a couple years ago. Don't know about using it on DT3 as I don't have any systems close, but it does work on DMR, NXDN, etc. It will work for standard and non-standard bandplans.


Let me know if it works for you.

P.S. It's an Excel spreadsheet format.
 

pro92b

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If the Vail-Beaver Creek site is entered into the calculator, the result is wrong. This is a site with 6.25 kHz spacing. The box for DSDPlus is unchecked since the inputs are LCN's. Your readme file is confusing me. My understanding is that DSDPlus displays logical slot numbers, showing a different number for each time slot for a frequency. Uniden scanners use logical channel numbers which display the frequency without considering the time slot. Uniden has one LCN per frequency and DSDPlus has two LSNs per frequency.

75894

Two of the three sites I posted earlier are examples of unusual spacing, 6.25 kHz and 25 kHz. The data for the sites came from the RadioReference database. Most of the sites in the database show 12.5 kHz spacing and only one base frequency. Most sites in the database list LCNs but there are exceptions. The calculator gives the expected result for 12.5 kHz spaced sites when the box is unchecked. The third example site, Broward County, has two base frequencies; the last two frequencies have a different base frequency than the others. The screen shots below are for Broward. The first one attempts to calculate the highest frequency in the site using the lowest frequency as the control. The result is incorrect because the site has two base frequencies and the calculation spans both base frequencies. The second screen shot calculates the second site frequency using the first frequency as the control. Here the result is correct but note the site step size or frequency spacing is 12.5 kHz, not 6.25 kHz.

75895 75896
 

thewraith2008

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Code:
Questar-Dominion Barton Peak Site (Sanpete County, Utah)
CH ID     Freq     Color    LCN
649     856.3375     0        324    Base: 848.2625
650     856.3375     0        324    Step: 0.025
729     857.3375     0        364    CH ID = LSN
730     857.3375     0        364
809     858.3375     0        404
810     858.3375     0        404
889     859.3375     0        444
890     859.3375     0        444
969     860.3375     0        484
970     860.3375     0        484
Code:
Vail-Beaver Creek Ski Resort Vail, Colorado
CH ID     Freq    Color
683     454.250     9        Base: 449.9875
699     454.350     9        Step: 0.00625
703     454.375     9        CH ID = LCN
719     454.475     9
Code:
Broward County Local Government Fort Lauderdale, Florida
CH ID     Freq     Color
51     451.625     1        Base: 451
190     453.3625     1        Step: 0.0125
210     453.6125     1        CH ID = LCN
212     453.6375     1
223     453.775     1
225     453.800     1
723     460.025     1
736     460.1875     1
748     460.3375     1
763     460.525     1
3929     472.850     1        Base: 423.75
3935     472.925     1        Step: 0.0125
I'm testing with the ability to change frequency spacing and you data is throwing odd results.

1st list:
CH ID and freq workout OK when 12.5 KHz spacing used, not 25 KHz.
The base frequency is calculating to be 848.225 MHz not 848.2625 MHZ (even at 25Khz it's 840.1125) (using LCN:649 and 856.3375)
Listed LCN seem out by -1

2nd list:
CH ID and freq workout OK with 6.25 KHz spacing as shown.
Base frequency is calculating to be 449.98125 MHz not 449.9875 MHz

3rd list:
CH ID and freq, some workout, some don't with 12.5 KHz spacing as shown.
Base frequency is calculating to be 450.9875 MHz not 451 MHz

190 = 453.350 (453.3625)
210 = 543.600 (453.6125)
212 = 453.625 (453.6375)
223 = 453.775
225 = 453.800
723 = 460.025
736 = 460.175 (460.1875)
748 = 460.325 (460.3375)
763 = 460.525

This 3rd list just seems jumbled.



If the Vail-Beaver Creek site is entered into the calculator, the result is wrong. This is a site with 6.25 kHz spacing. The box for DSDPlus is unchecked since the inputs are LCN's. Your readme file is confusing me. My understanding is that DSDPlus displays logical slot numbers, showing a different number for each time slot for a frequency. Uniden scanners use logical channel numbers which display the frequency without considering the time slot. Uniden has one LCN per frequency and DSDPlus has two LSNs per frequency.
Works fine when checked (for DSDPlus)
Nowhere in DSDPlus or it's documentation is LSN or Logical Slot Number used, LCN is mention in documentation.
LSN would make more sense to use, as that's what they are.

Two of the three sites I posted earlier are examples of unusual spacing, 6.25 kHz and 25 kHz. The data for the sites came from the RadioReference database. Most of the sites in the database show 12.5 kHz spacing and only one base frequency. Most sites in the database list LCNs but there are exceptions. The calculator gives the expected result for 12.5 kHz spaced sites when the box is unchecked. The third example site, Broward County, has two base frequencies; the last two frequencies have a different base frequency than the others. The screen shots below are for Broward. The first one attempts to calculate the highest frequency in the site using the lowest frequency as the control. The result is incorrect because the site has two base frequencies and the calculation spans both base frequencies. The second screen shot calculates the second site frequency using the first frequency as the control. Here the result is correct but note the site step size or frequency spacing is 12.5 kHz, not 6.25 kHz.
Obviously the calculator is not going to work with anything but 6.25Khz for the DSDPlus option for now.
As I mentioned, I'm testing with ability to select frequency spacing.
I'm not sure the data you provided is 100%.
Can anyone else verify it.
 

pro92b

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Jun 27, 2002
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As I noted, the data for the sites all comes from the RadioReference database. The database is supposed to contain listings that are verified by local monitors. When I calculate the LCN - frequency correspondence by hand for the sites I listed, I find no inconsistencies. I don't really understand how you are getting your results and they do not agree with what I calculate by hand. I'm going to let it go at that since we just seem to disagree.
 

thewraith2008

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Nov 22, 2016
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Major re-write to fix (I really hope this time) the networks that use different RF spacings.



From the way I understand it:
LSN = Is a unique number for each slot on all frequencies used. (This term is made up and not in the standards)
LCN = Is a unique number for each frequency used. (This is used in the standards)

DSDPlus uses the term "LCN" through it's documentation.
It probably should use "LSN" like some people already do.

I'm told, scanners can use LCN or LSN as described.

Step or Channel spacing is the same as the DMR TIII parameter "Frequency Separation"
This value is the same weather LSN or LCN is used.
When we want the LSN value, we need to divide the 'Step' value by 2.
This comes about because the frequency for DMR is 12.5Khz (for RF bandwidth not step).
Each slot occupies 6.25 Khz of the 12.5 KHz RF bandwidth for a frequency used.
I think the 'Step' value should be this "Frequency Separation" value.
Any calculation will then factor in if LCN or LSN is to be calculated.
It would be handy if DSDPlus output this value somewhere to help us with working out LSN/LCNs

This 'Step' value seems to be a source of confusion because it can mean:
- for LSN it's an implied frequency spacing between each LSN value.
- for LCN it's the frequency spacing between LCN value.

e.g. for LCN with channel spacing of 25Khz
400.100 (slot1, slot2)
400.125 (slot1, slot2)
400.150 (slot1, slot2)

e.g. for LSN with channel spacing of 25Khz
400.100 (slot1)
-400.1125 (slot2) not really a used frequency
400.125 (slot1)
-400.1375 (slot2) not really a used frequency
400.150 (slot1)
-400.1625 (slot2) not really a used frequency


Anyway if people can give it a test run and see how it goes.

Testing with lists from pro92b seem to be OK now with the follow things noticed.

1. Questar-Dominion Barton Peak Site (Sanpete County, Utah)
This is OK, but the stated LCN values are out by -1.
The stated base frequency is not right. (should be 848.2125)

2. Vail-Beaver Creek Ski Resort Vail, Colorado
The values under 'CH ID' are said to be 'CH ID = LCN'. This is not the case, they are LSN.
When calculating as LSN, this is OK.
The stated base frequency is not right. (should be 449.975)
The stated value for 'Step' is 6.25 Khz. See above why I think this should be 12.5Khz.

3. Broward County Local Government Fort Lauderdale, Florida
This is OK.
The stated base frequency is not right. (should be 450.9875)
The last two (3929, 3935) are LSNs and use 25 KHz step and have a different base frequency (423.725)
- But these last two calculate OK as LSN when use '3929', '472.850' used as Ref. LSN and Frequency.



Code:
Changelog

v1.3.0
 
 Changed: Major re-write
 - Another value 'RF spacing' was need to correctly calculate LSN/LCNs.
 - UI changes - added 'RF spacing'
 - UI changes - added list (see below)
 
 Added: A list to show all calculated frequencies for a LSN or LCN.
 - Base frequency is shown on first line.
 - for LSN: shows Frequency - LSN - LCN
 - for LCN: shows Frequency - LCN - LSN for slot1 and slot 2


 Updated documentation to reflect changes.
As usual, please read any documentation supplied.
Any questions, ask away.
Hope it works for you.

Download

HASH: 92174eca213b3679e13fd0b1439aa56c
 

jets1961

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Jan 21, 2002
Messages
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In Canada I think the first channel in VHF Hi is 138.000 MHz and the LCN is zero or is it one, anyone know?
 

thewraith2008

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Nov 22, 2016
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In Canada I think the first channel in VHF Hi is 138.000 MHz and the LCN is zero or is it one, anyone know?
The standards TS102-361-04 'C.1.1.2 Fixed Channel Plan' 'Table C.5: Logical Channel Numbers' show the following ranges:


So zero is not used and 4095 from the standards is mentioned under '6.7.1.3 Vote now advice'
Code:
..... If the value of the Channel Number is 4095 the Channel Number defines a multi-block MBC where 
the absolute transmitter and receiver frequency is defined in a second block concatenated to this block (defined in 
clause 7.2.19.3.1).
 

thewraith2008

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Nov 22, 2016
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Just small fix

Code:
Changelog

v1.3.1

 Fixed: Labels for 'Target LxN' and 'Target LxN frequency' and 'Calc LxN frequency' where incorrect at start.
 - Switching via 'Calculate LxN' would correct this.

As usual, please read any documentation supplied.
Any questions, ask away.
Hope it works for you.

Download

HASH: 97cc98290cebac47f40a86a36d5f6580
 

thewraith2008

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Nov 22, 2016
Messages
1,289
Just another small update

Code:
Changelog

v1.3.2 - minor

 Changed: UI 'RF spacing' text colour to bold green for 12.5 and 25 KHz to highlight the most
           commonly used values.

 Updated: Documentation.

As usual, please read any documentation supplied.
Any questions, ask away.
Hope it works for you.

Download

HASH: eededc55c2010c7a0c385d5b7eefa11c
 

Annunaki

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Oct 5, 2014
Messages
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Thanks for this tool it helps a bunch!

Would you consider sharing the "updated" DSD+ 2.212 plugin for SDR# that you mentioned in a previous thread?
 

thewraith2008

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Nov 22, 2016
Messages
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Thanks for this tool it helps a bunch!

Would you consider sharing the "updated" DSD+ 2.212 plugin for SDR# that you mentioned in a previous thread?
I need to contact Vasili (TSSDR) to see if he is OK with me doing that.
Other email's I sent to him have gone unanswered.
He tends to fall of the face of the planet for a few months at a time.
 

DRL-XM43

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Durham Region
Thanks for this tool it helps a bunch!

Would you consider sharing the "updated" DSD+ 2.212 plugin for SDR# that you mentioned in a previous thread?
In the meantime (this works for me)

In SDR# set audio to VBCable (I have it this way full time.)

Start an instance of DSD+ FL with something like DSDPlus.exe -m1 -fa -e -g0 -OM NUL -_3

The -m1 passes clear AM/FM to the speakers so it is the same as the audio being pointed to speakers anyway.

If you tune to digital then of course DSD+ kicks into decode.

For convenience you can start both sdr# and the DSD+ bat with a single bat.

- OR

Try SDRConsole V3 which has DSD+ trunk following with 2 dongles built right in - it works very well and is an easy set up.

The only thing it won't decode is P25 phase II - phase1 it will.
 

slicerwizard

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Are these downloads still usable?

 

rumcajs_tr

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Sorry I was loking for wrong version. The one I am looking for is DSD+ TCP plugin for DSD-Fastlane. Not the audio plugin. The TCP plugin does not require virtual audio cable. But works only with last public release.
 

thewraith2008

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Nov 22, 2016
Messages
1,289
I have some questions for those that use a scanner to monitor DMR TIII.

Do you have to use a base frequency so LCN frequencies can be calculated or do you have to enter all the known LCN frequencies manually like you have too for DSDPlus?
If using a base frequency for scanner, is it LCN 0 frequency or is it the same as the LCN 1 frequency?
449.975000 - LCN 0 - Is this base frequency?
449.987500 - LCN 1 - Or is this base frequency?
...
450.050000 - LCN 6

Reason I ask is currently the calculator shows LCN 0 as base frequency and was wondering if this needed to be changed to be LCN 1 (if that is used) so it's useful for scanner users.
Using the base base frequency is not really used for DSDPlus as user just adds all the LSN (not LCN) in manually as seen.

The calculation for LCN seems more logical when : Base_Frequency + (LCN + Frequency Separation) [ 449.975000 + (6 * 0.0125) = 465.400000]
 

slicerwizard

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Toronto, Ontario
Calculations would be based on RF channels, not DSD+ LSNs. Step size would be 12.5 kHz (RF channels are 12.5 kHz apart)

Some scanners don't trunk track DMR, so they need no LCNs, just frequencies.
 
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