TRX-1: Please NXDN Help

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kh6sz

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I've been doing a limit search on my trx-1 now for several weeks, and came upon 7 frequencies that are NXDN48 with some activity on each. I programmed the 7 frequencies in and wrote down all activity on those 7 frequencies. Here's the frequencies and their RAN's.

453.95 RAN6
460.125 RAN6
460.39375 RAN7
453.26875 RAN7
453.475 RAN5
453.775 RAN6
453.875 RAN5

I have been writing down all talkgroups and Unit ID's for each frequency for weeks now, and it seems that they are all part of the same network, sharing many talkgroups and ID's between all 7 frequencies.

Which comes to my question.....Can frequencies in the same system have different RAN numbers for each frequency? I was under the impression that the RANS needed to all be the same, and in the EZ-Scan program it seems to confirm that because it will only allow you to enter 1 RAN for the whole system.

This has really got me confused, I'm a newby with NXDN, but have programmed in several other systems in the area that work great, all with 1 RAN.

One other question....I've heard that NXDN works similar to EDAICS Provoice as a call is made on one frequency, and then it goes to another frequency for the reply, and cycles that way. I have no way of finding out.

Any help or information about the workings of NXDN would be appreciated! Thanks.
 

mmckenna

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Which comes to my question.....Can frequencies in the same system have different RAN numbers for each frequency?
Depends on what type of system they are running, but sure.


One other question....I've heard that NXDN works similar to EDAICS Provoice as a call is made on one frequency, and then it goes to another frequency for the reply, and cycles that way. I have no way of finding out. .[/QUOTE]

On trunking systems, yes, Depends if it's set up for message trunk or transmission trunked.
Message Trunk will hold the voice channel for a pre set amount of time to catch the reply.
Transmission trunk will release the channel right away. That might be what you are hearing/referring to. Transmission trunk allows the individual channels to be reused faster.
 

slicerwizard

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Here's the frequencies and their RAN's.

453.95 RAN6
460.125 RAN6
460.39375 RAN7
453.26875 RAN7
453.475 RAN5
453.775 RAN6
453.875 RAN5

I have been writing down all talkgroups and Unit ID's for each frequency for weeks now, and it seems that they are all part of the same network, sharing many talkgroups and ID's between all 7 frequencies.

Which comes to my question.....Can frequencies in the same system have different RAN numbers for each frequency? I was under the impression that the RANS needed to all be the same
Those frequencies likely belong to sites 5,6 and 7 of a network. If it's a NEXEDGE network, you should have no trouble finding the control channels, as they transmit 24/7, and that gives you the network ID and from there you can start building your programming file.
 

shajoe44

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I ordered a TRX-1 and have been reading up on its operation before it arrives Monday. I went to the above mentioned web site and typed in my county and search by frequency. It gave me about 12 railroad frequencies. I did not enter them but they look like the old conventional frequencies. So these frequencies listed are actually digital in format even though they are in the same band width as other railroad frequencies?
 

911lighting

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Even though they look like conventional freq they still can be nxdn alot of our old conventional frequicies were swapped over to digital when we moved to the nexedge system. The trx1 can auto decode the frequencies automatically

Sent from my SM-G955U using Tapatalk
 

troymail

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I ordered a TRX-1 and have been reading up on its operation before it arrives Monday. I went to the above mentioned web site and typed in my county and search by frequency. It gave me about 12 railroad frequencies. I did not enter them but they look like the old conventional frequencies. So these frequencies listed are actually digital in format even though they are in the same band width as other railroad frequencies?
DMR and NXDN can be conventional in addition to trunked.

If you're hearing analog on those frequencies in the area of the licensed NXDN, they haven't switched to NXDN.

The railroads have been updating licenses to include NXDN emissions all over the place but with some/few exceptions, it would seem these are simply for some updates/switch that will occur in the future. The only railroad NXDN I've detected is in the larger railyards. All road was still analog (but some have reported otherwise).

As far as license information, as an example, I see North Carolina adding P25 Phase 2 to their licenses but those in the know say NC VIPER won't be switching to Phase 2 anytime soon.

The digital Frequency search link above looks at FCC license data. Given the examples above, that search tool is just that - a tool that gives you something to look for.

The FCC license data isn't anywhere near 100% accurate. Some licensees license and implement (in a relatively reasonable close timeframe), some implement but are slow (or never seem) to update their license, and others seem to update and never implement. And still others don't know what they want to do and you will find their license might indicate analog, DMR, and NXDN all on the same frequency.

The only TRUE indicator is seeing/hearing it on a radio... and in most cases, you have to be fairly close to hear these systems (conventional or trunked).
 

SCPD

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Im still waiting to hear NXDN here in New Jersey by New York City, haven't heard any railroad NXDN yet.
 

devicelab

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I've been doing a limit search on my trx-1 now for several weeks, and came upon 7 frequencies that are NXDN48 with some activity on each. I programmed the 7 frequencies in and wrote down all activity on those 7 frequencies. Here's the frequencies and their RAN's.

453.95 RAN6
460.125 RAN6
460.39375 RAN7
453.26875 RAN7
453.475 RAN5
453.775 RAN6
453.875 RAN5

I have been writing down all talkgroups and Unit ID's for each frequency for weeks now, and it seems that they are all part of the same network, sharing many talkgroups and ID's between all 7 frequencies.
Bill, just FYI, we have a commercial NXDN trunked system here in the Seattle area. The FCC license will show a frequency on the 12.5khz step but then offset by a freq below and above by 0.003125khz.

Example: 452.434375, 452.4375, 452.440625

So far, it seems the lower is the voice frequency and the upper is the control channel data.

So to program the TRX though, I simply just put in 452.4375 frequency only and the scanner seems to decode it fine. I'm not sure if it's actually using the control channel data or if it's just monitoring the voice channel traffic.

Anyway, for now, I'm just monitoring (2) sites and they have at least 3 frequencies each. Each site has a different RAN but all frequencies in that site use the same RAN.

FWIW, the audio quality from NXDN is far superior to DMR, IMHO.
 

Ubbe

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Example: 452.434375, 452.4375, 452.440625
It doesn't matter if you monitor 452.434375, 452.4375 or 452,440625 as there is only a 3.125KHz difference between channels and 6.25KHz from lowest to highest frequency and the most narrow filter in the scanner is something like 12KHz when you select NFM and 20KHz in FM.

If you enter those frequencies manually and listen you'll probably find that there is only one transmitter on air. There's no scanner or commercial radio I know of that have filters that handle transmitters 3.125KHz apart.

/Ubbe
 

devicelab

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It doesn't matter if you monitor 452.434375, 452.4375 or 452,440625 as there is only a 3.125KHz difference between channels and 6.25KHz from lowest to highest frequency and the most narrow filter in the scanner is something like 12KHz when you select NFM and 20KHz in FM.

If you enter those frequencies manually and listen you'll probably find that there is only one transmitter on air. There's no scanner or commercial radio I know of that have filters that handle transmitters 3.125KHz apart.

/Ubbe
Yep I get that. It was just confusing from the SDR perspective because I can see both clearly but wasn't sure what to program the scanner with...

Because NFM is so wide, does the TRX make use of the control channel data?

PS. I picked up my first NXDN direct convos today? The TRX software shows NDXN48-D... I take it this is a private call? The TGID was appended... 00-0<TGID> in the TGID column.

PPS. Does anyone know why sometimes I'm getting TGID 0 in the TRX? Is that a special call type?
 

troymail

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PS. I picked up my first NXDN direct convos today? The TRX software shows NDXN48-D... I take it this is a private call? The TGID was appended... 00-0<TGID> in the TGID column.

PPS. Does anyone know why sometimes I'm getting TGID 0 in the TRX? Is that a special call type?
The "-D" means the radio believes what is decoding is a Type D NXDN system (vs. a Type C). If I recall correctly, Type C talkgroup IDs are usually presented as simple decimal numbers like on this system:

https://www.radioreference.com/apps/db/?sid=8108

while Type C systems parse the value differently like on this system:

https://www.radioreference.com/apps/db/?sid=8005

However, I do see at times that the radio will indicate (probably incorrectly) that it thinks the system is Type D when it is not. For example, I'll get recordings of activity where 99% of the talkgroup IDs are Type C and a couple of stray Type D formatted talkgroup IDs for the same talkgroup(s).

I believe these "stray" incorrect values are due to poor reception / a weak signal or some other interference.

As for the TGID 0 -- this too sounds like possible weak signals/reception and/or intereference but it depends on where you are seeing it -- Talkgroup or Private Call? That depends on your configuration. I think the display and recordings should indicate for you one or the other.

Occasionally, when pulling recordings into EZ Scan, I see what looks like a field not being cleared/reset properly and a value seems to get carried into the record for the next recording (possibly). FWIW - I see similar things on the Uniden scanners as well where fields are not always cleared and you get false values for some fields.
 

AggieCon

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I've seen NXDN systems where different frequencies have different RAN values.

A lot of NXDN systems are a lot more complicated that other trunking systems. For instance, they might have a frequency or two that are only of data traffic and usually don't carry voice. Don't program those, it could foul up your scan speed.

As Troy said, the FCC data is marginal at best and the scanner recording information sheds only marginally more light into the system configuration. The Whistler scanners do NOT follow the control channels for either DMR or NXDN. There's an older thread were many of us debate how to best receive NXDN.

Also, keep in mind on distributed licensed frequencies, there could be more than one user/system on the frequency with multiple protocols utilized. In a perfect world where licensing is halfway correct, which is not ours, distributed systems (NXDN-D, DMR CapPlus, LTR, etc.) have a "6" in the station type (e.g. FB6, MO6) and centralized systems, which have control channels (e.g. P25, DMR ConPlus, NXDN-C) are licensed with an "8" (e.g. FB8). Here's a interesting one, which would lead me to think that the FB8 frequency is for a control channel (this is DMR): ULS License - Industrial/Business Pool, Trunked License - WQYP409 - AZLE COMMUNICATIONS SOLUTIONS, LP - Frequencies Summary

The point of all of this is to say that tools and references can help--heck of a lot better than doing a limit search on the entire spectrum, but it will take careful study of your local RF environment and the broadcasts you receive to determine system configurations.

I recommend programming your scanner liberally. You can always tighten things up later on if you receive unwanted broadcasts or interference.
 

devicelab

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As for the TGID 0 -- this too sounds like possible weak signals/reception and/or intereference but it depends on where you are seeing it -- Talkgroup or Private Call? That depends on your configuration. I think the display and recordings should indicate for you one or the other.
I'm just searching for wildcard TGIDs here... so no idea how to distinguish between private call or a regular group call. The audio recording doesn't provide any obvious info there...

I'm getting quite a few of these during each day of recording... signal sounds strong so no idea why this happens.

One thing that does seem common to these is that the ENCRYPTION busy signal will play for 1-2 secs and then normal voice comes thru. So perhaps the TRX is getting confused on the TGID due to the busy signal?
 

troymail

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I'm just searching for wildcard TGIDs here... so no idea how to distinguish between private call or a regular group call. The audio recording doesn't provide any obvious info there...

I'm getting quite a few of these during each day of recording... signal sounds strong so no idea why this happens.

One thing that does seem common to these is that the ENCRYPTION busy signal will play for 1-2 secs and then normal voice comes thru. So perhaps the TRX is getting confused on the TGID due to the busy signal?
It has been a while since I've played with PRVT calls -- but I used to see them alot in Maryland when I lived there. The display and recordings - if I recall correctly - will clearly indicate TGRP vs. PRVT if I am not mistaken. On the display, you may need to change the "Simple Display" option to see the additional information.

As far as the encryption sound at the start of the reception - this many times indicates weak/poor reception (as does other things like garbling of the talkgroup IDs, etc.). As mentioned earlier, you may need to get closer to the source of the signal - as in, sometimes - the parking lot of the facility where the radios are being used (no, I'm not kidding).
 
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