SDS100/SDS200: Trouble programming a Tier III DMR system; LSN vs. LCN?

[W4KRR]

Mike, with regard to Tier III systems, some of the LCN information in the RR database follows the formula that you outlined in post #17 above, some doesn't. Which is obviously a problem. Some frequencies are using the divide by two method; some use the divide by two, minus one, method. Some don't seem to be using either of those methods.

How many people are using incorrect data based on the RR database and don't realize that their scanners aren't tracking properly?

I vaguely remember UP Man addressing LCN vs. LSN a long while back, but I can't find his posts with regard to this.

Ubbe: I always have all service types are enabled by default, to avoid problems like this. And color code set to search.

 

[mtindor]

Mike, with regard to Tier III systems, some of the LCN information in the RR database follows the formula that you outlined in post #17 above, some doesn't. Which is obviously a problem. Some frequencies are using the divide by two method; some use the divide by two, minus one, method. Some don't seem to be using either of those methods.

How many people are using incorrect data based on the RR database and don't realize that their scanners aren't tracking properly?

This was my fear as well. Although, it looks like just about every frequency that is noted as a CC has an LCN that doesn't match the "bandplan theory". I see you live in Coconut Creek. Presumably you could copy that site control channel yes? Can you get some DSDPlus information (and screenshots of the channel activity window showing LCNs) for any sites that you copy? I'd really like to know how much of the data in the RRDB was monitored directly versus how much of it was extrapolated using a particular bandplan calculation.

And the reason why the bandplan calculation concerns me is because no system (NXDN / DMR / IDAS) has to follow any bandplan for LCN<-->frequency pairing. A system maintainer could make those LCNs start at 1 and end 5 or anything like that. There is no guarantee that the system is adhering to a real bandplan, especially if the control channels (which presumably would be the ones with the most accurate LCN info) have LCNs that don't fit into the bandplan.

So i'm just suggesting that you might want to use DSDPlus to monitor the control channel of every site that you can pick up a control channel for, and then we can determine if a specific standard bandplan is in use or not.

Mike

 

[garys]

I made some corrections to the DSD+ file, plus I looked at my 436HP file. Wherein I found that I had transposed two numbers in the LCN for the control channel. Instead of 294, I had it entered as 249. Which explains why the 436HP wouldn't trunk track.

 

[b52hbuff]

Apologies for resurrecting a new thread, but it seemed the most closely related to what I wanted to ask.

I totally understand the LCN/LSN issue discussed in this thread.

My question concerns multiple bandplans. I remember there were certain 400MHz Moto TRS systems that required programming of multiple bandplans.

Do Tier III DMR systems support multiple band plans on a single site?

Or said another way, once I've verified the (LCN * offset) = Frequency, for most of the frequencies on a site, is it safe to assume that all frequencies for the site will also follow this formula?

 

[pro92b]

DMR Tier III

Calculate LCN from channel numbers provided by DSD+.

LCN = ((Upper DSD+ Ch) / 2) - 1

To calculate the step size, choose two system frequencies.
Then divide the difference in the frequencies by the
difference between the LCN's.
Example
Freq LCN
464.0500 1125
464.2875 1144

Step = (464.2875 - 464.0500) / (1144 - 1125)
= 0.2375 / 19 = 0.0125

Then calculate the base frequency using the formula below.
Base = Freq - (LCN - 1) * Step
Base = 464.0500 - (1125 - 1) * Step
= 464.0500 - 1124 * 0.0125
= 464.0500 - 14.05
= 450.0000

LCN = (Freq - Base) / Step + 1

Most systems use one base frequency and one step size. There are exceptions like the Broward County system.

Broward County Local Government Fort Lauderdale, Florida
CH ID     Frequency     Color Code
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