Using TRX on TDHS District 7 NXDN

[theTastyCat]

I've been monitoring THP District 3 (Nashville) and the TDOT HELP trucks with some success....buuuuut....the HELP trucks are on Phase II, and are *so* much louder than all the other traffic on the scanner. I keep the volume all the way up in the truck just to make out what THP is saying, but the HELP trucks are super-loud in comparison - hope Whistler sorts this out!

 

[AggieCon]

I am not so sure about the accuracy of this system in the RR database. I recommending finding the closest site to you using FCC searches or my website and using those frequencies (yes, they might be on two separate licenses, one for Greer and one for the county).

 

[TomTN]

Springfield 020 has an error. The last "Channel" according to the database should have a frequency of 453.05000 but that is not in use on that site. The missing frequency is for channel number 531.

Channels in use are 164 194 215 528(CC) 529 530 531

 

[INDY72]

GUYS: Use the DB submission system to submit corrections and new data please. Posting info on the forums should be secondary to submitting the info in the correct method. TY

 

[KD4YGG]

And to re-iterate earlier postings regarding this system...

It is going to require an old style "boots on the ground" effort of searching, taking notes, researching various FCC records for a number of different licensee's, trial-and-error, etc.

This one's not coming to us delivered by a simple database download.

 

[AggieCon]

That's cute. Ask TastyCat about how he got his working.

Literally find the closest site. Put in all of the channels. Find and lockout the control channel. That's all it will take.

 

[bg_nashville]

Springfield 020 has an error. The last "Channel" according to the database should have a frequency of 453.05000 but that is not in use on that site. The missing frequency is for channel number 531.

Channels in use are 164 194 215 528(CC) 529 530 531

Site 20 is correct in the RRDB as is and 453.050 is active, because that is how I identified it as being a part of site 20.

 

[bg_nashville]

That's cute. Ask TastyCat about how he got his working.

Literally find the closest site. Put in all of the channels. Find and lockout the control channel. That's all it will take.

It is not as simple as that. When I searched your website and returned all NXDN frequencies in the state of TN, there are no frequencies in the 460-461 MHz range in the results, but in reality there is NXDN being used on frequencies in that range.

The frequencies for channels 529 and 530 for site 20, were not found by searching the RRDB, the FCC database, or any other DB, but was done by spending literally hours using the limit search on several scanners and most importantly watching the waterfall in SDR# and activity monitor in DSD+ for patterns. And there is occasionally voice traffic on the control channels.

 

[TomTN]

Perhaps they have changed something since then. I confirmed the seventh frequency today but apparently I'm not supposed to post it.

 

[AggieCon]

I'm not discounting your effort at all. I hope you realize that. I can certainly tell from looking at the webpage that you spent a substantial amount of time compiling all of that. And that's quite some task to do without information other than looking at the spectrum. You deserve major props for all of that.

I was just adding in that it was my experience that the site I programmed was not correct in the listing. My website pulled the correct frequencies.

By the way, if you are using my website to search, you have to search by both county and state. If you search by state only, it returns only those frequencies with a statewide area of operation. Searching by state does not return all of the frequencies in the state.

 

[KD4YGG]

Perhaps they have changed something since then. I confirmed the seventh frequency today but apparently I'm not supposed to post it.

By all means post it here or submit it per MILF's recommendation.

Only way this specific group effort can succeed if we all work TOGETHER.

 

[INDY72]

Post it.. but submit verified data first. Only a couple of admins ever read the forums unless there is an problem. The submission system is there for the express purpose of submitting data. These forums are not. The admins will get submissions. The only way they will get it here is if they read it, or someone reads it, and then submits it. Me and KD4YGG are 2 of the very few that bother digging into these forums on a regular basis. I again stress this: SUBMIT, then post. TY!

Not to mention that sometimes by the time an admin reads the thread, your post might be 2 pages buried! Where with an submission, it is in an list with date etc... And not buried under maybe 10, maybe 100 other posts that might be worthwhile data, or could be just arguements, spam, or other stuff.

 

[bg_nashville]

One of the challenges I have discovered in monitoring this system is the amount of interference on the frequencies in the 454-455 MHz range. The TRX appears to require an almost flawless signal to decode NXDN, but while monitoring the 454 MHz frequencies in analog mode on my 396XT and 436 I noticed some extreme interference, especially on the frequencies for site 20. I haven't found the source of the interference, but it does occur on all my radios and sdr dongles, even with the various antennas disconnected.

Most of the "missing conversations" are because the communication is on one of the frequencies that have interference. I also occasionally have interference on 460.325 from Bedford County, but at least I know the source of that one.

I haven't been able to determine with certainty if talkgroups have a "primary" site that carries all communications involving that talkgroup. For example, do all communications involving TG 57105 get transmitted on site 23 and then also on site 20 when needed or can the communication bounce back and forth between sites. I think it might be the latter of the two, which would explain why simply programming the site closest to my location doesn't work.

 

[vans113]

I'm not sure if NXDN has a "zone controller" if you will to turn on TG per site. I imagine they do with as many sites as they have , and traffic they would be keying up all kinds of sites. As for somebody also talking about interface , I do work for a shop here in the area , and we have had this system once interfere with life flight once for being on the same freq. everybody was on their correct freqs but the control channel was causing some at one point.

 

[bg_nashville]

I just sat my TRX-1 on the piece of sheet metal I use with my SDR mag mount antenna. The difference in reception blew my mind. I'm now able to hear the transmissions on the frequencies that suffer from interference. When using my Watson W-881 antenna, I'm no longer experiencing any noticeable gaps in conversations.

I also found another frequency, 454.55625, showing a RAN of 20. I'm not sure how that fits into site 20 given the channel map was determined.

 

[bg_nashville]

Here are the FCC licenses for the frequencies in the 454 MHz range in Robertson County. The frequencies are licensed to the City of Springfield in blocks under part 22 vhf/uhf paging licensing.

WPZG203 454.03750-454.06250
WPZG202 454.26250-454.28750
WPZG201 454.33750-454.36250
WPZG204 454.53750-454.56250

I will match them up to the sites and submit them to the database later tonight.

 

[theTastyCat]

Hey all - checking in again. I am absolutely struggling to get my TRX-2 to work correctly with this system. Granted, I'm in Joelton (Exit 31), which is not *that* close to any one repeater, but I've monitored Pleasant View and Ashland City and gotten decent signal.

The trouble is that it won't trunk for crap; LOTS of missing traffic and clipped transmissions. But, monitoring conventionally, while super-clunky and inconvenient, does much better. So it appears the radio *is* able to decode and deliver NXDN, but for some reason it doesn't want to when I ask it to monitor it as a trunked system.

Anybody else experienced this? Trying to narrow the issue down...if someone else can monitor the system (or maybe even the Pleasant View or Ashland City sites!!) on a TRX, then the problem is either my radio or the way it's idiot owner has programmed it

Thanks all!

 

[911lighting]

I have finally gotten humphreys county correct and all working in the trx1 scanner.

 

[buddrousa]

What changes did you make?

 

[911lighting]

Additional frequency to new johnsonville tower. I have noticed when you import them by city it adds a squelch to it and if you enter it manually it does not have that squelch. Not really sure of the difference but it is.