Why does the 536's RSSI drop out when site-holding to a 1-frequency site?

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wm8s

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I copied TxWARN Analog (RRDB SID 38) to an FL. I edited a site (League City, site 22, if it matters) to have just one frequency (the current control channel, 857.98750).

If I Site Hold on that site, the 536's RSSI blinks on and off at about 1 Hz while scanning. Why? What else could it possibly be looking at when the RSSI is off? Curiously, if I Channel Hold, it stops doing this, i.e., the RSSI stays on solid, as I would expect.

Is this responsible for my missing so much traffic? Some of the area departments patch their TGs to legacy conventional channels that I monitor on another receiver in the same room, and I hear much traffic on them that I completely miss on the 536 scanning the corresponding TGs, even in Department Hold with nothing else going on.

...R
 

wm8s

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FYI, this happens with System Hold Time set to 0. If I set it to a positive number of seconds, the RSSI drops out briefly after that many seconds. That would be expected IF there was something else the scanner would need to move on to. But I do not have priority or search with scan or anything else enabled, as verified by the fact that the display never budges from scanning that site on that system (and plus, in Site Hold, it shouldn't move on, anyway, I think).
 

kikito

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My guess is that after one whole cycle scan of the control channel stream, it drops it to look for something else enabled like close call or priority, etc. Even if you don't have anything else enabled, it'll still do it I guess to find out if anything else is enabled. I know, doesn't make much sense but neither do many other things. It'll be interesting to see what UPMan says.

In running this radio along older Unidens and GREs, I haven't noticed missed traffic. Even the GREs do it when I only have one site enabled without any traffic on it. You can see the 'T' blink off and on every second or so.
 

wm8s

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With the system hold time at 0 and locked on one site, the 536 appears (if the RSSI is any indication) to spend about 50% of its time not scanning. Specifically, the RSSI meter is high for about 500 ms and off for about 500 ms. That does not present especially good odds of catching a transmission.
 

whsbuss

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With the system hold time at 0 and locked on one site, the 536 appears (if the RSSI is any indication) to spend about 50% of its time not scanning. Specifically, the RSSI meter is high for about 500 ms and off for about 500 ms. That does not present especially good odds of catching a transmission.
Nice finding. If this is the case it could be the reason so many say they are missing traffic when another scanner sitting next to it does not.
 

Alliance01TX

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WM8S

Yep I see the same sorta thing on the HP1 and as prior post noted is a "housekeeping routine"....It appears to impact P25 much more ( may not be root-cause most likely) from my station than a TRS / Analog System and suspect that is related to the CC on P25 and other decode matters...

Niffy Test that might be done and reported::

So if you had say 3 exact models (same station/ location) same data base loaded up and one-antenna (power divider...) feeding all units with the same db loss aross all ports "measured" it would be an interesting Test to record and see the detla's between same if any.

Might be a zero-sum test, but at least the data (vs opinions) could tell us what it is or is-not really doing versus single source test arrangement which is my case this station....

Testers would have to video to validate the Test Set up (test gear used...etc...) and ensure Calabration is verified to get meaningful data vs conjecture....


Bill
 
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