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  1. #1
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    Default NXDN Decoding Project

    Well, the new version of DSDPlus is seeing a NXDN48 control channel on 451.950. This is licensed to R.D.C. Communications and is almost certainly the site on Industrial Drive in Mashpee.

    The DSDPlus datastream shows as follows:

    Sync:-NXDN48 TB CCDATA

    I've heard no voice yet but I'm going to try to dig into that further if possible. I've known this signal has been present for quite a while but the older version of DSD didn't play nice with it.

    Let's see what we get....
    Scott - Scan New England Webmaster

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    Well I'm pleased to report that I have successfully decoded NXDN48 voice on 452.2125 which appears to belong to RDC Communications and may be from a site in Yarmouth. Voice decode was near perfect. Unfortunately there is not (or I'm not aware of) a "DMRDecode-like" software that will provide talkgroup information.
    Scott - Scan New England Webmaster

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    Thus far, and I will eventually start a Wiki page for this:

    451.950 NXDN48 Trunked Control Channel, very likely on Industrial Drive in Mashpee.
    451.7875 NXDN48 Trunked Control Channel, very likely on Whites Path in South Yarmouth (probably large tower adjacent to Route 6).
    452.2125 NXDN48 Voice Channel, very likely on Whites Path In South Yarmouth.

    This would appear to be the system: http://wireless2.fcc.gov/UlsApp/UlsS...licKey=1925098
    Scott - Scan New England Webmaster

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    452.650 is an active voice channel, license indicates that it is at the Whites Path site. Just confirmed voice traffic at about 1435.
    Scott - Scan New England Webmaster

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    Created Wiki Page. Link to it is under the New England section.

    http://scan-ne.net/wiki/index.php?ti...Listening_Area
    Scott - Scan New England Webmaster

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    Hello,

    Simmons College Police (WIL225) uses 6.25 KHz (4800 baud) conventional Nxdn on 483.8375. Voice is unencrypted.

    I also picked up encrypted 6.25 KHz conventional Nxdn on 461.6500 and 464.2875 that I suspect is WQMY404 Brewster Ambulance Service.

    I modified DSD so it can sync on more nxdn types, like control channels and trunked voice. There are two types of trunking defined. Kenwood uses Type-C that has a dedicated control channel and Icom uses Type-D that has bursts like LTR.

    470.3250 is a 6.25 KHz Type-C (4800 baud Kenwood) trunking control channel licensed to WQLB494 JR Holdings, LLC in Boston.

    A weird one is a 12.5 KHz Type-C (9600 baud Kenwood) trunking control channel on 470.2125 and on 470.2875 I hear analog voice transmissions with Nxdn digital in the background. It sounds like some sort of mixing at the site. Both are licensed to County Communications (WPMG276).

    73 Eric

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    That explains why I don't hear anything on the Brewster frequencies except and occasional morse code ID. I'll have to try the Simmons frequency to see if I can pick it up.

    Quote Originally Posted by wb1hbu View Post
    Hello,

    Simmons College Police (WIL225) uses 6.25 KHz (4800 baud) conventional Nxdn on 483.8375. Voice is unencrypted.

    I also picked up encrypted 6.25 KHz conventional Nxdn on 461.6500 and 464.2875 that I suspect is WQMY404 Brewster Ambulance Service.

    I modified DSD so it can sync on more nxdn types, like control channels and trunked voice. There are two types of trunking defined. Kenwood uses Type-C that has a dedicated control channel and Icom uses Type-D that has bursts like LTR.

    470.3250 is a 6.25 KHz Type-C (4800 baud Kenwood) trunking control channel licensed to WQLB494 JR Holdings, LLC in Boston.

    A weird one is a 12.5 KHz Type-C (9600 baud Kenwood) trunking control channel on 470.2125 and on 470.2875 I hear analog voice transmissions with Nxdn digital in the background. It sounds like some sort of mixing at the site. Both are licensed to County Communications (WPMG276).

    73 Eric
    We're peace loving people, we're not hunting trouble, but if trouble should find us, we'll stand up and fight.

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    I'm reanimating this thread from the dead. I've started work on figuring out NXDN Network 178. I'm able to receive the Fall River site pretty well. The data stream for NXDN is a bit more informative than MotoTrbo, but there is a lot that I need to understand before I take a try at updating the Wiki page.

    First, the data stream shows Aliases, so it's a lot easier to figure out who is using the system. For example TG1500 on this site has an Alias of "Amb Dispatch". That matches what's in the Wiki, so it's a good reference point for me from which to start.

    DSD+ also shows the Channel number for the channels. I know that those correspond to frequencies (like P25), but I don't have a reference handy.

    For Site 9 the channels are in this order

    231
    501
    514
    536
    556

    ETA: Using the formulas at this RR forum page, I'm getting some possible frequencies, but they don't match the Wiki here or the FCC license data for RDC Communications. I got audio on 452.875 that matched the Alias (Ambulance).

    Which brings up another question. Does NEXEDGE use one data and one voice channel on the control channel and two voice channels on the other frequencies?



    RAN is 9 for this site. NL is 1,2,3,4, 5,10.

    I'm also not seeing any activity on FMP-VC at all. With MotoTrbo, even if the channel order isn't correct, FMP24-VC will try to generate a frequency. I'm guessing that I need more information in the DSD+.frequencies file, but again, I don't know what.

    The neighbor list shows the follow
    Site 1 CC =178
    Site 2 CC =157
    Site 3 CC =109
    Site 4 CC =802
    Site 5 CC =805
    Site 10 CC =812

    I have a lot of learning to do before I can start updating the Wiki.

    Scott and anyone else with the Whistler NXDN capable scanners, is there anything like the Uniden discovery or analyze feature with those scanners?
    Last edited by garys; 12-17-2016 at 14:51.
    We're peace loving people, we're not hunting trouble, but if trouble should find us, we'll stand up and fight.

  9. #9
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    Hello,

    Here is some information I have on 178 and 51. The same map is used for all the sites so copying the control channel of several sites can help. NXDN is not TDMA, so Type-C repeaters are mostly either Control Channel or Voice. There are single repeater sites where the control channel switches to Voice and back again.

    Standard UHF map used by Local System 178
    1 = 450.000 Step 0.0125
    401 = 460.000 Step 0.0125
    800 = 464.9875
    801 = Custom Frequency because of T-Band 470.3250
    805 = Custom Frequency because of 6.25KHz step 464.78125

    Local System 178 RDC Communications in SE MA
    Site 1
    Adj Sites: 2, 3, 6, 7, 8
    451.7875 (144)
    452.2125 (178)
    452.6500 (213)
    461.2000 (497)
    461.4625 (518)

    Site 2
    451.9500 (157)

    Site 3 WQQK694 RDC Communications Plymouth MA
    Adj Sites: 1, 2, 4, 5, 7, 8, 6
    462.1500 (573)
    462.3500 (589)
    464.7375 (780)

    Site 4 WQLB494 JR Holdings Boston MA
    470.3250 (801)
    471.2250 (802)

    Site 5 WQQK694 RDC Communications Cumberland RI
    Adj Sites: 2, 3, 4, 1, 6, 7, 5
    464.78125 (805)

    Site 6
    451.9125 (154)

    Site 7
    452.3375 (188)

    Site 8
    461.4125 (514)

    Local System 51 Radiophone in RI
    Site 1
    Adj Sites : 2, 3
    451.9875 (160)

    Site 2
    451.7875 (144)
    461.1750 (495)

    Site 3
    Adj Sites: 1, 2
    452.2625 (182)

    73 Eric

  10. #10
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    Gary, at this time DSD+ is FAR more useful for NXDN exploring than the Whistler scanner is. I wouldn't even bother trying to analyze anything with it. I don't think it even actually "trunk tracks", I think it's just looking for signals and throwing up talkgroup information because I have a wild card programmed. Stick with DSD+.
    Scott - Scan New England Webmaster

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    ETA a couple of updates to my post. First, I figured out why I was having trouble with the formula. It was a simple math error. Once I realized it and correct, the formula seems to work as it should.
    Second, from looking at control channel data in DSD+, it seems that several sites share frequencies and thus channels. For example Sites 3, 9, 10 all use 501, 536, 556. At least if the information that DSD+ is reporting is correct.

    I don't know how that sharing works. Are those used as surge/overflow channels if a site gets busy? Are the prioritized? I have no idea, so I'm throwing that out there for discussion.

    Based on the channel data, I've filled in site information in DSDPlus.frequencies. I'll hold off for a few days on updating the Wiki further until I have a better grasp of the situation.

    Here is what I have so far,

    NXDN Network 178 Site 3 Plymouth

    NEXEDGE48, 178, 3, 109, 451.3500, 0.0, 0
    NEXEDGE48, 178, 3, 501 461.2500, 0.0, 0
    NEXEDGE48, 178, 3, 514, 461.4125, 0.0, 0
    NEXEDGE48, 178, 3, 536, 461.6875, 0.0, 0
    NEXEDGE48, 178, 3, 556, 461.9375, 0.0, 0
    NEXEDGE48, 178, 3, 573, 462.1500, 0.0, 0
    NEXEDGE48, 178, 3, 589, 462.3500, 0.0, 0
    NEXEDGE48, 178, 3, 780, 464.7375, 0.0, 0


    ; NXDN Network 178 Site 9 Fall River

    NEXEDGE48, 178, 9, 231, 452.87500, 0.0, 0
    NEXEDGE48, 178, 9, 501, 461.25000, 0.0, 0
    NEXEDGE48, 178, 9, 536, 461.68750, 0.0, 0
    NEXEDGE48, 178, 9, 556, 461.93750, 0.0, 0
    NEXEDGE48, 178, 9, 622, 462.76250, 0.0, 0


    ; NXDN NETWORK 178 SITE 10 BROCKTON

    NEXEDGE48, 178, 10, 109, 451.35000, 0.0, 0
    NEXEDGE48, 178, 10, 536, 461.68750, 0.0, 0
    NEXEDGE48, 178, 10, 556, 461.93750, 0.0, 0
    NEXEDGE48, 178, 10, 514, 461.41250, 0.0, 0
    NEXEDGE48, 178, 10, 812, 462.53125, 0.0, 0

    Please let me know if you see any glaring errors.



    Quote Originally Posted by Scott SNE Webmaster View Post
    Gary, at this time DSD+ is FAR more useful for NXDN exploring than the Whistler scanner is. I wouldn't even bother trying to analyze anything with it. I don't think it even actually "trunk tracks", I think it's just looking for signals and throwing up talkgroup information because I have a wild card programmed. Stick with DSD+.
    Thanks. i wasn't planning to buy a Whistler. I was curious as to whether those that have them found that useful. Since I have 3 x36HP scanners, I'll wait and see what Uniden comes up with.

    Quote Originally Posted by wb1hbu View Post
    Hello,

    Here is some information I have on 178 and 51. The same map is used for all the sites so copying the control channel of several sites can help. NXDN is not TDMA, so Type-C repeaters are mostly either Control Channel or Voice. There are single repeater sites where the control channel switches to Voice and back again.
    Thanks. Watching closely this morning, Site 9 is working as a single channel repeater. So far, I've only heard one user, a private ambulance service. It's the weekend of course, so that might be just because it's not busy. Control channel data does show five channel numbers, tomorrow that site might get busier. I'm still trying to figure out how to use the formulas you've shown here and on Radio Reference. I'll keep hacking away at it. I'll probably also try the Plymouth site, if I can here it.
    Last edited by garys; 12-18-2016 at 16:59.
    We're peace loving people, we're not hunting trouble, but if trouble should find us, we'll stand up and fight.

  12. #12
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    Site 4 control channel data shows 801, 802, 803 as active channels. Also, the 501,514,536,556 channels show up, but again with no activity. I have tried to calculate the frequency for 803, but to no avail. I think I have the base frequency wrong. Can anyone confirm 803?
    We're peace loving people, we're not hunting trouble, but if trouble should find us, we'll stand up and fight.

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    I just started a system at RR for network 178 based on data in the Wiki. I only added sites 1, 2, and 3 as they're currently the only ones I can confirm.

    http://www.radioreference.com/apps/db/?sid=9129

    If we can shore up the remainder of the data I'll continue to add it. This benefits people coming into the area from other locations that may wish to have a listen.
    Scott - Scan New England Webmaster

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    I've been working on the Wiki page here. Most of site 4 is confirmed, except as I mentioned Channel 803. I'm going to work on that later today if I get time. After doing some more reading and experimentation, it seems that the formula for calculating channels up to 800 does not work above that. I'd expect that 803 is in the upper 471 or somewhere in 472.

    I'm very confident that the 2100 series is Coastal Medical Transportation out of Yarmouth. They appear to be non emergency ambulance, chair car, and handicapped transportation.

    Quote Originally Posted by Scott SNE Webmaster View Post
    I just started a system at RR for network 178 based on data in the Wiki. I only added sites 1, 2, and 3 as they're currently the only ones I can confirm.

    http://www.radioreference.com/apps/db/?sid=9129

    If we can shore up the remainder of the data I'll continue to add it. This benefits people coming into the area from other locations that may wish to have a listen.
    We're peace loving people, we're not hunting trouble, but if trouble should find us, we'll stand up and fight.

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    This is a little confusing to me. I've found a NEXEDGE96 system with a control channel of 464.6000. There is a system licensed to New England Baptist Hospital in Boston with an emissions type of 8K30F1E, which is NXDN. That all makes sense. What doesn't make sense is that the system identifies as L90-1. That's the same system ID as County Communications NXDN trunk network.

    Does that seem right? Are NXDN systems different from Motorola systems in that a unique system ID is not assigned?
    We're peace loving people, we're not hunting trouble, but if trouble should find us, we'll stand up and fight.

  16. #16
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    Default Formulas for figuring out NEXEDGE systems.

    At this thread over at RR Eric posted the formulas for figuring out the frequencies for the Channel Numbers used in NEXEDGE trunking systems.
    I used those formulas today to try to figure out a NEXEDGE96 system. As it turned out, the system is the County Communications trunking site in Georgetown.
    The problem I ran into is that when I used the formulas, the frequency I arrived at was exactly 1 Mhz below what it should have been.

    For example 450+((23-1) * 0.0125 = 462.5625. The correct frequency is 463.5625. I ended up using 451 as the base for frequencies below 460 and 461 for frequencies above 460. Doing that, I got a match to what Eric posted here.

    I'm at a loss to understand this, so if someone can explain to me if I am actually doing something wrong, I'd really appreciate it.

    Gary
    We're peace loving people, we're not hunting trouble, but if trouble should find us, we'll stand up and fight.

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