Metro Blue Line question

[Markb]

Hi All,

I have been checking out some of the NXDN rail comms and am hearing Blue Line on 160.4700. Shows in the DB as the input to 161.565 (Blue Line Ops), however, I am hearing all of the traffic on the supposed input and nothing on the output. Could this be an error in the DB? I am in north OC. Signal appears to be consistent in strength and not variable as one would suspect for a repeater input. Perhaps the input/output are flip-flopped?
If I can get confirmation, I will update the DB.

Thanks,
Mark

 

[kearthfan101]

What are you using to monitor?


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[Markb]

I am using a HackRF SDR and DSDPlus.

 

[LAflyer]

Much of the DB data is from when rail ops was using regular analog FM.
With move to NXDN its certainly possible some of the frequency configurations were changed around.

 

[kearthfan101]

I've searched thru every license Metro has for NXDN, in addition to all the frequencies once used for rail. When scanning all those together with my NXDN capable radio (i have them as their AAR aliases, 302-488) , multiple frequencies will actually come up with the same voice data. Frequencies that are not close to each other khz wise. Since NXDN is such a new thing, and I have no real source of official info of this set of frequencies or even if it is a trunked system, (MTA does have a trunked license in VHF) it's a trial & error deal, to figure out what is what, and the RAN used. (RAN is basically like a NAC for NXDN).


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[Markb]

I have not seen/heard any trunked traffic, but I don't monitor the Metro stuff very often.
Also, as I understand it, trunked systems are not monitorable with Kenwood gear unless you are logged onto the system. Do you have any information to the contrary?
As far as RAN's go, try RAN 20. Seems to be a common RAN from what I've seen so far.

 

[kearthfan101]

Sounds about right for trunked. Just monitor conventionally. And I've seen a couple other RAN's out there, but maybe your software lists it based on the freqs given?


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[karldotcom]

I doubt the MTA would trunk the rail lines. That is interesting about hearing the same audio on different frequencies though, like they are patched. Perhaps that is a cheaper solution that multiple towers and microwaves, etc.

MTA also has the bus and Freeway Service Patrol Trunked System.

 

[Markb]

That's why I was asking. I have heard that you cannot monitor a trunked NXDN system conventionally. I have a Kenwood NX-5700 on order, so I am hoping to be able to monitor some NXDN, but fom what I have read, trunking is out.
DSDPlus does list RAN by frequency. On 169.4700 the RAN is 20.
I am wondering if maybe some of the repeaters are linked, being that you hear the same thing on multiple channels?
I will have to look into it when this new radio arrives. With my current setup, my reception is limited from my loc.