NXDN Question

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n0vza

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I have a location I would like to try monitoring. On their FCC license I see the following:

Frequency 463.2625, 1 base, emissions 11K0F3E and 8K30F1E
Frequency 463.2625, 30 mobiles, emissions 11K0F3E and 8K30F1E

I tried monitoring the frequency on a BCD436HP as a single NFM but was unsuccessful (I don't recall the details, it was a few months ago).

I see the 8K30F1E emission is a 12.5khz voice NXDN. So I assume (with my limited knowledge/experience with NXDN) that the TRX-1 "might" work.

Before I rush out and buy a TRX-1, is there any chance that I can get this to work (on a TRX-1)?

Could there be more than one "group" operating on this single frequency?
 

troymail

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So....

Although the FCC license says they are using NXDN, it doesn't mean they actually are; many licences seem to get updated because someone planned to switch but haven't yet or changed plans. Other licensees are using digital modes that aren't listed on their license.

From all the literature I've read, vendors tout the ability to gradually migrate from analog to digital so all of the equipment doesn't need to be bought and/or put in service at the same time.

If they are analog, you should hear voice today on your 436. Additionally, you should hear digital noise on the 436 is they are using NXDN. If you're not hearing anything, you may be too far from the repeater, they aren't active on the frequency, or some one issues is at play (seen the UHF/noise cooper foil thread?).

Chances are pretty good that if they are using NXDN and you are in range of the repeater, the TRX will decode it and you'll hear voice (as long as they aren't using encryption).

Yes - there could be more than one talkgroup/group of users on any given frequency. In analog mode, they all just share the frequency and everyone hears the conversation. If digital mode, for example, the radios could be programmed with a supervisor talkgroup that only the supervisors can use.
 
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wbswetnam

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It is possible that they are using NXDN, but you're not hearing it because you have FM tone squelch enabled on that channel. Disable the tone squelch so that you receive it CSQ, then listen. If you hear something like a low ruh-ruh-ruh-ruh-ruh digital sound, that's NXDN.
 

n0vza

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Thanks for the replies, just what I needed to justify my want (not real need) to buy a TRX-1 and play. At least I will (hopefully) acquire more knowledge!

I may not have had the BCD436HP configured for the correct service type, which may explain why I didn't hear anything.

The radio system is at a large resort complex and I was staying on-site. Heading back there for Mother's Day weekend. I'll report back, what I discover.

The local two-way shop up there, appears to have a bunch of NXDN installs through-out the county, so I may try seeing if I can pick-up anything else. They may be trunked, but I read, just plug in the frequencies and see what happens.

Thanks again ....
 

wbswetnam

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So....

Although the FCC license says they are using NXDN, it doesn't mean they actually are; many licences seem to get updated because someone planned to switch but haven't yet or changed plans. Other licensees are using digital modes that aren't listed on their license.
This is very true. For example, a county just south of me got licensed to use DMR several years ago, but only recently did they actually purchase and install the new system. Also, a local volunteer fire department uses DMR for its communications, but their FCC license shows that they are licensed only for FM, and on a different frequency from what they are actually using.
 

troymail

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Thanks for the replies, just what I needed to justify my want (not real need) to buy a TRX-1 and play. At least I will (hopefully) acquire more knowledge!

I may not have had the BCD436HP configured for the correct service type, which may explain why I didn't hear anything.

The radio system is at a large resort complex and I was staying on-site. Heading back there for Mother's Day weekend. I'll report back, what I discover.

The local two-way shop up there, appears to have a bunch of NXDN installs through-out the county, so I may try seeing if I can pick-up anything else. They may be trunked, but I read, just plug in the frequencies and see what happens.

Thanks again ....
Service type would likely only be an issue if you imported the frequency data from the library/RRDB and that service was not enabled on your radio.

Try doing a custom search around the frequency and see if you hear anything. that should not be affected by service types.

BTW - here are samples of what NXDN sounds like when received in analog mode:

http://www.kb9ukd.com/digital/Nexedge478.6375control.wav

http://www.kb9ukd.com/digital/nxdn_raw_625.mp3
 
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