DAT/LNK flashing while idle 536HP

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RFI-EMI-GUY

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I am monitoring the City of Oviedo FloridaPD talkgroups as a sole favorite list activated from the Seminole County P2 simulcast system.

I think I am missing traffic and I constantly see the DAT/LNK icon flashing while apparently idle, The P25 icon appears while there is voice.

Shouldn't the icon remain steady on DAT while monitoring the CC????
 

jonwienke

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Not if data is being transmitted.
 

RFI-EMI-GUY

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Not if data is being transmitted.
So if data is being transmitted, like to an MDC, the LNK will flash? Can it be any MDC on the system? I kind of doubt there is much P25 packet data being used as that is pretty restrictive. Can you elaborate?
 
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ofd8001

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No. When you see DAT when monitoring a trunked system, that means the scanner is receiving control channel data.

LNK means data is being receiving on a Voice channel in Receive/Hold modes. It's that brief time between the end of a voice transmission and the scanner returns to monitoring the control channel. Sort of like that unmodulated "hang time" of a conventional repeater.

So if you think of the scanner progression being Monitoring the control channel for channel grants, switching to a voice channel when there is a grant, that "hang time" and lastly return to the control channel, you'll see DAT, then P25, then LNK, then back to DAT.
 

RFI-EMI-GUY

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Why then if the radio is on, even at a very late hour, when the talk groups apparently are inactive, the icon is constantly toggling between those two states?

Sent from my SM-T350 using Tapatalk
 

troymail

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Why then if the radio is on, even at a very late hour, when the talk groups apparently are inactive, the icon is constantly toggling between those two states?

Sent from my SM-T350 using Tapatalk
(Likely) because the radio isn't processing the CC and/or voice signal properly -- Regardless of what you've heard or been told, the x36 can/does miss alot of traffic - particularly on simulcast systems. Sometimes, it doesn't receive anything unless you move the radio to a different location.

The only way users know this is happening (mostly) is to put another radio nearby and watch one radio receive while the other does not..... It is also typically noticeable to users who listen primarily to a single system.

Users who are scanning alot of stuff probably don't notice either -- some people apparently just don't care - as long as they are hearing "something"...
 

jonwienke

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If simulcast is the problem, then you'll have garbled audio, not just flashing DAT/LNK. My county P25 system is simulcast, so I've experienced issues, but not to the degree others have.

I've monitored systems where the scanner behaved similarly, and when I checked the same system with DSD+, it turned out that the system was sending a lot of data transmissions. It was a school system, so it wasn't MDT-style data, more likely vehicle telemetry. There was actually slightly more of it than voice traffic on some days. Anyway, I wasn't missing nearly as much voice traffic as I thought I was.

Simulcast can cause reception problems, but there are other factors that can cause odd scanner behavior, and failing to investigate every aspect of the problem before jumping to a confusion is unwise.
 

troymail

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If simulcast is the problem, then you'll have garbled audio, not just flashing DAT/LNK. My county P25 system is simulcast, so I've experienced issues, but not to the degree others have.
I routinely see the x36 actually stop on talkgroups and hear nothing while other radios are exhibiting voice on the same talkgroup. Other times, the x36 just "scans right by" active talkgroups that other radios are receiving. Don't get me wrong - my other radios (even the Unication G4) appear to miss traffic (the latter most likely because of the known issue where they only pay attention to initial channel grants).

Every situation is going to be different and none of us can say for sure what is happening unless you are there and have other tools (like another receiver of the same system/site CC) to know for sure what is happening.
 

RFI-EMI-GUY

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I am getting garbled messages from time to time. Other times I think I am missing stuff. If I had another radio , a "proper one" I wouldn't require the 536. Anyway I am just trying to verify that the toggling DAT/LNK isn't normal operation.

I have moved my antenna a bit to try and stabilize the DAT icon and the reception is good at the moment. Yes I am in a simulcast overlap, because when this system was analog, I could hear the phasing at times. So it will be more critical in digital.

My Denon FM receiver has a multipath scope output. We need that feature in these receivers. I would like to find a reliable "sweet spot" in my office for the 536 instead of having to wire a yagi to it.

Here is what Uniden should add in next firmware:

McIntosh Laboratory Part 1
 

ofd8001

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Just taking a guess without knowing how your scanner is programmed and what system you are monitoring. . .

If you are monitoring a simulcast system, that toggling between DAT and LNK may mean the scanner is detecting a simulcast transmission. However due to simulcast distortion issues, your scanner isn't decoding the audio so it can be heard clearly.

Tweaking a simulcast system on a scanner is challenging. As you seen, just a slight change in antenna positioning makes a difference. Other things to try are setting site attenuation On, setting Digital Threshold Mode to Manual and using a different Digital Threshold Level might also give different results. You may have to experiment with different combinations.

I agree it would be nice if scanners could have the same amount of pristine audio as "regular" system radios due. I suspect that scanners having to deal with a lot of different things (AM, FM, different trunked formats and Digital etc.) have something to do with this. Kind of the "jack of all trades but master of none" situation.
 

phask

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FWIW - Ohio MARCS seems to tranmit a station ID VERY frequently... No sure if that shows as SAT or not. PErsonall - I just don't worry about it.
 

RFI-EMI-GUY

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Just taking a guess without knowing how your scanner is programmed and what system you are monitoring. . .

If you are monitoring a simulcast system, that toggling between DAT and LNK may mean the scanner is detecting a simulcast transmission. However due to simulcast distortion issues, your scanner isn't decoding the audio so it can be heard clearly.

Tweaking a simulcast system on a scanner is challenging. As you seen, just a slight change in antenna positioning makes a difference. Other things to try are setting site attenuation On, setting Digital Threshold Mode to Manual and using a different Digital Threshold Level might also give different results. You may have to experiment with different combinations.

I agree it would be nice if scanners could have the same amount of pristine audio as "regular" system radios due. I suspect that scanners having to deal with a lot of different things (AM, FM, different trunked formats and Digital etc.) have something to do with this. Kind of the "jack of all trades but master of none" situation.
Yeah; I have tweaked the thresholds, The receiver needs some sort of real time BER feature. The tools they provide are slow and clunky. Yes I know you have to accumulate a certain numbers of good bits to reflect a BER rate, but if there were a direct indication of bad bits, one could walk the antenna around. Listening isn't the best way.
 
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