BCD436HP: Problems with N9600 conventional? NXDN

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jonwienke

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Multiple RAN codes involved might confirm that.
 

frazpo

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If you're seeing TGs on a conventional channel, program it as a OFT NXDN system.

It almost sounds like there is a OFT system and a conventional system on the same frequency.


One of the frequencies transmits bursts of pure data at random times. The same frequency is used for most of the depts traffic. When the traffic is on another frequency it will be repeated on this frequency also. I think there are a total 3-5 frequencies that you can find this depts traffic on. No CC though

I have better luck on a truly conventional N96 but it still misses too many transmissions comparing to the TRX. It’s like at times it doesn’t hear anything digital.
Once again N48 trunking works great.


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frazpo

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Mine uses only ran 20 too



While my p2 hears the analog, i tweak the squelch on the hp and it begins to parse the voice


Where’s your squelch at?


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Voyager

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Cb 9600 vhf
Crazy thing is, they have 2 xmtr towers within 10 miles of each other
I've worked on systems co-frequency with systems about 800 feet away (both properly licensed). 10 miles is a "blessing".
 

Voyager

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One of the frequencies transmits bursts of pure data at random times. The same frequency is used for most of the depts traffic. When the traffic is on another frequency it will be repeated on this frequency also. I think there are a total 3-5 frequencies that you can find this depts traffic on. No CC though

I have better luck on a truly conventional N96 but it still misses too many transmissions comparing to the TRX. It’s like at times it doesn’t hear anything digital.
Once again N48 trunking works great.
It sounds like a linked OFT system. Are you certain there is no databurst acting as a control channel? AFAIK only the IDAS flavor does that, but.... wait a minute, I wonder if this is a linked IDAS system. It will have occasional bursts on the control channel (not solid data) and carries voice traffic. But if DSD is reporting a RAN, I wonder if they mean AREA. I'll have to look at an IDAS system with DSD and see what it reports. Maybe this is an IDAS system.

What all does DSD say about it and what is the RR link to it?

Also, can you explain again when it uses TGs and when it doesn't?

Maybe they have multiple system types linked somehow.
 

vocoder

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Squelch 7 seems to be the best start for mine, if i go lower it gets worse

Nxdn simulcast? Like p25 conventional simulcast?
 

Voyager

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Not strictly simulcast, but perhaps psudo-simulcast by linking multiple transmitters on the same frequency together in the same area. The squelch should have no affect beyond being low enough to pass the signal.
 

jonwienke

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Multiple transmitters on the same frequency broadcasting the same signal is difficult to decode.

Multiple transmitters on the same frequency broadcasting different signals is much more difficult to handle.
 

vocoder

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That could be part of the trouble, if there is multiple data xmitting, the scanner becomes confused
 

Sanscanman

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I would start going with that theory. I am seeing more and more freqs with Multiple licensees and Many with mixed flavors. NX48 TB with Idas blipping on top of it. Or NX48 TB with NX96 CB chiming in and this morning at CC change where there should be a NX48 TB CC instead is a TIII DMR washing out the TB. This is all UHF btw.


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jhampton2000

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Ok, re-reading through the entire thread again, I suspect there are two things going on here:

The System:
1. The OP is listening to a system simply with an odd configuration. From what's been posted, it isn't trunked (DSD+ shows as CB96), it isn't simulcast (there appear to be multiple frequencies in use but I've seen no mention of multiple transmissions on the same frequency) and the odd data bursts might be due to something not yet understood (eg AVL etc). I think DSD+ would be the best tool to further investigate. So I don't believe the oddities of this NX96 system are the root cause of why the 436 isn't functioning as expected.

NX96 on a 436:
2. Several people are posting issues with missed NX96 transmissions. I have access to multiple 436's, a TRX1 and several NX48/NX96/DMR handhelds, so I've now spent a few hours running a number of side-by-side tests. All tests are on simplex Conventional channels, results are consistent across VHF and UHF, and between 436's. The 436's are both early models, both have self-mod C1 caps fitted, neither have had clock issues [yet !]. I've found:

a. Across all tests, FM works better than NFM (most noticeable on NX96, some improvement on DMR, little difference between NFM and FM on NX48)

b. I too can confirm AUTO Digital Threshold mode decode of NX96 is inconsistent.I too get the 'missed calls' behavior (it's like the NX96 signal doesn't exist, or the 436 is asleep). Frustratingly I can't pin point a set of circumstances where I can consistently replicate the problem. I have even seen several tests where two identically configured 436's behave differently on the same signal - one decodes, the other is asleep.

c. For me, Digital Threshold Mode Manual 10 gives best results for NX96. Others might (and have) find a different threshold works best. It rarely ever misses a call but will display higher ERR rates vs an AUTO setting (assuming the AUTO setting detects/decodes the signal in the first place). NFM seems to react slower than FM in this setting.

d. An incorrect Manual setting will render the 436 completely deaf to NX96, NX48 or DMR (eg setting Manual 12 vs 10 for NX96 consistently makes it deaf). Same issue for NX48 if the Manual setting is too far from the correct threshold.

e. For me, Auto Digital Threshold mode (noted working at 10) gives best results for NX48 and DMR. In contrast to the previous Firmware release, I used to have to run Manual 5 to have any chance of some simplex DMR decoding - even then it was hit and miss. Now I completely rely on an Auto Threshold setting, and DMR simplex is vastly improved as a result. I can even run repeatable tests where Manually setting one 436 to 10 won't work while the other 436 sat next to it is happily the decoding the same signal on Auto (showing 10).

3. So in conclusion:
a. I do believe there is a digital threshold related issue with NX96 decoding. It has similar traits to the DMR simplex problems when the DMR upgrade was first released. But fixing it might impact performance on DMR/NX48 (and possibly other formats).

b. FM is better than NFM all round. In theory that shouldn't be the case, but that's what I've found.

c. For NX48 and DMR Simplex I would recommend Auto Digital Threshold.

d. For NX96 I would INITIALLY recommend Auto Digital Threshold, then use FUNC+Volume to note the best threshold value, and then add this Manually to the System.

e. For Searching for mixed modes I would recommend Auto Digital Threshold, but be aware you might miss some NX96.

HTH

Jim
 

milf

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And is NO ONE doing this as NXDN OFT? Are you all just rolling with conventional and digital with NXDN?
 

jhampton2000

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And is NO ONE doing this as NXDN OFT? Are you all just rolling with conventional and digital with NXDN?
At the minute yes, until the software is released to make the programming easier (I have a lot of NXDN systems to program for, and the vast majority are conventional).
 

sibbley

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I am monitoring a 9600 system as NXDN Trunked. For reference this would be the system https://www.radioreference.com/apps/db/?sid=9209

I'm using Auto Threshold (Threshold Level 8), and Auto Modulation and it's working very well. I'm scanning two sites. Early on I had Modulation set as NFM, and things didn't seem to work as well. The 436 seemed to be missing things compared to the TRX-1. Once I switched to Auto they seemed to be fairly equal. I tried some different Manual Threshold settings and that also seemed to make things worse. Auto seems to work best for me.

I'm also scanning a conventional NXDN 4800 1 frequency as conventional since there is only 1 TGID. Auto Threshold (Threshold Level 8). Not much traffic, but decodes well. Once this 4800 frequency picks up in comms, I'll try it as OFT.

I have to say the TRX-1, even though it doesn't trunk, can keep up with the 436 on the trunked system. Only real difference is the 436 does not drop in the middle of a conversation where the TRX-1 still drops at times.

In my case, I think Uniden did a great job with this upgrade.
 
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