RR database vs FCC database - Questions about starting from nothing

[Facsimile]

I found a trunked system in my county that has essentially zero information about it in the database. I figured I could contribute to it and learn at the same time. This has led me down a rabbit hole but I think I will learn from it. For context I will be using WPMQ666 as the trunked system in question.

When looking at the sites frequencies HERE #1, there are only 7 frequencies listed compared to HERE #2 which list 10. The 10 listed are also identical to the FCC listing.

1. Why is there a difference? Should they be the same? Why does each list (see attachment) contain frequencies that the other does not?
2. Assuming the 7 frequencies from the RR listing is correct, how does one determine correct frequencies outside of the licensed frequencies for that site?
3. If I were starting from scratch without the help of the RR database, would I put all 10 frequencies associated with this specific license as one "site?" What other information from the FCC license search would be useful?
4. Will a control frequency always be transmitting? Or can there be intermittent pauses? It would appear that 452.150 is the control frequency as it never ceases that digital rumbling sound.
5. I can't seem to grasp the concept of LCNs - when you need them all vs when you don't. How do I determine if I do or not when starting from scratch?
6. Initially when I had the site programmed with the 7 original frequencies, the LCN search feature on my SDS200 found them all within minutes. I tried the same thing with the list of 10 frequencies and it took significantly longer aka did not finish after 24 hours. Will the LCNs found on the list of 7, be usable/equivalent on the list of 10 if the frequencies are on both lists? Or do LCNs change based on the full list of frequencies for a site?

If you've made it this far, thanks. I've found for me that finding random systems that aren't documented on RR is really fun. I imagine contributing discoveries is even better!

 

[nd5y]

The frequencies on the FCC license page with a station class code that starts with FB are the repeater outputs. Those are the ones you program in your scanner. The others that start with MO and FX are the input frequencies. 99.9% of the time those are useless for scanning and can be ignored.

The extra frequencies that are in the rrdb but not on the license could be several things.
1. It could be an error. There is no guarantee that anything in the rrdb is accurate. People can submit whatever they want and most of the time the admins have no way to verify what was submitted.
2. It could be a valid frequency on another license. Click on the FRN on the license data page and see if there are other licenses with that frequency at the same location or near it.
3. They could be illegally using a frequency they aren't licensed to use.

 

[dave3825]

Why is there a difference? Should they be the same?

What's listed in the rr db is what's known to be in use. What's listed on the FCC license is all freqs licensed under that call sign.

The license associated with the system in the database, WPMQ666, lists 5 freqs
452.100
452.150
452.400
452.800
461.075


That system in the db lists 7 freqs,
452.100
452.150
452.400
452.800
461.075
461.275
463.6625

The 2 extra freqs are on 2 other licenses. Whoever made the submission did not include them.

461.275 is on KQH203
463.6625 is on WPEH911

If you want to, you can submit the additional 2 licenses to the database.

If I were starting from scratch without the help of the RR database, would I put all 10 frequencies associated with this specific license as one "site?" What other information from the FCC license search would be useful?

You don't mention if your using scanner or sdr. When I do a Nxdn system, I use sdr and park one dongle on the control channel. I watch the data screen for indication of conversation on another freq. Take note of channel id and what freq. Usually have the rest of the freqs running in another sdr instance. If I start to see ch id and freqs that were not on the license, it usually means there is more than one license involved. That's a good time to start looking on the license for "Assoc.Call Signs" or running the FRN to see all licenses associated with the said user.

Busy systems can be done pretty quick. Slow systems can take a long time.

Will a control frequency always be transmitting? Or can there be intermittent pauses? It would appear that 452.150 is the control frequency as it never ceases that digital rumbling sound.

Depends on the flavor. Some are constant, some are not. Some are data bursts and some (minimal amount) do not use a control channel at all.

 

[Facsimile]

The frequencies on the FCC license page with a station class code that starts with FB are the repeater outputs. Those are the ones you program in your scanner. The others that start with MO and FX are the input frequencies. 99.9% of the time those are useless for scanning and can be ignored.

That is good to know, I had no idea. If a frequency on a license is only MO and no other class, is it safe to assume that the frequency would be simplex only? Or does simplex not exist on trunked systems?

You don't mention if your using scanner or sdr. When I do a Nxdn system, I use sdr and park one dongle on the control channel. I watch the data screen for indication of conversation on another freq. Take note of channel id and what freq. Usually have the rest of the freqs running in another sdr instance. If I start to see ch id and freqs that were not on the license, it usually means there is more than one license involved. That's a good time to start looking on the license for "Assoc.Call Signs" or running the FRN to see all licenses associated with the said user.

I am using a scanner. But you have me interested now in sdr! With sdr, can you use one dongle and have multiple instances? Or do you need a dongle for each instance?

The 2 extra freqs are on 2 other licenses. Whoever made the submission did not include them.

461.275 is on KQH203
463.6625 is on WPEH911

If you want to, you can submit the additional 2 licenses to the database.

I think I will once I gather a bit more data. Now how would these two licenses affect the "site?" Would they be their own site or lumped together with the existing one? This concept is really hard for me to grasp.

 

[nd5y]

It's impossible to have a simplex trunked system.
If a license only has mobiles then you need to look at the radio service code and actually listen to figure out how the frequencies are used.

 

[Facsimile]

It's impossible to have a simplex trunked system.
If a license only has mobiles then you need to look at the radio service code and actually listen to figure out how the frequencies are used.

Well this is embarrassing. I was so tired when I asked the question, I didn't even realize I was looking at a completely different DMR system and not the NXDN one in question. My bad.

 

[dave3825]

I am using a scanner. But you have me interested now in sdr! With sdr, can you use one dongle and have multiple instances?

If you had one sdr and ran that on the control channel, the remaining freqs could be run on a scanner quite easily.

I think I will once I gather a bit more data. Now how would these two licenses affect the "site?" Would they be their own site or lumped together with the existing one?

Licences are just that and have nothing to do with how a system is set up. I have seen some systems use up to 4 different licenses on the same system.

 

[AB4BF]

I use Antenna Search ( AntennaSearch - Search for Cell Towers & Antennas ) and look up the antennas mounted on the towers. Most of the time there will be frequencies associated with each antenna. Most of the time there will be more frequencies listed than what RR has in the database. I just enter all those frequencies into the 996P2 and viola! I hear a little extra!
However, your mileage may vary...

 

[dlwtrunked]

The frequencies on the FCC license page with a station class code that starts with FB are the repeater outputs. Those are the ones you program in your scanner. The others that start with MO and FX are the input frequencies. 99.9% of the time those are useless for scanning and can be ignored.

The extra frequencies that are in the rrdb but not on the license could be several things.
1. It could be an error. There is no guarantee that anything in the rrdb is accurate. People can submit whatever they want and most of the time the admins have no way to verify what was submitted.
2. It could be a valid frequency on another license. Click on the FRN on the license data page and see if there are other licenses with that frequency at the same location or near it.
3. They could be illegally using a frequency they aren't licensed to use.

"The others that start with MO and FX are the input frequencies. 99.9% of the time those are useless for scanning and can be ignored."

Not true. Some are mobile only and even ones that are repeater inputs are useful if one wants to only scan when a mobile is close. In the case of encrypted comms, the inputs can tell you a unit is close even though you do not know what was said.