CrossMgr Impinj Tag Population - What effect does it have?

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Tim Mockford

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Jun 15, 2025, 8:34:07 AMJun 15
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Hi,
What effect does the tag population setting have on CrossMgr? Trying to get to the bottom of delayed read display issue.
Thanks!

Edward Sitarski

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Jun 15, 2025, 11:05:03 PMJun 15
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Hi Tim,

I don't think the tag population has anything to do with the delay.

The tag is always recorded at its RFID reader time, which comes from the reader.  Worst case, this is a UI update issue.

When CrossMgr processes a tag read, it does not update the display immediately.
Rather, it starts a timer for .1 seconds.  If an additional read comes within .1 seconds, it resets the timer to .2 seconds.
This continues up to 1 second, when an update is forced.

The purpose of this logic is that large RFID bunch reads can occur faster than CrossMgr can keep up if it refreshes after every single ead.
CrossMgr would appear to "hang" after a large number of reads, and it could sometimes take 10 or more seconds for it to become response again.

Hence the need for the refresh delays.  If multiple reads occur in quick succession, the update delays effectively "batch" them all together into one update.
This eliminates the "hang" at the expense of some delay in the update.

For 2 reads in quick succession, the delay should be max .2 seconds, and the max delay overall is capped at 1 second.
That doesn't sound like what you are seeing, or does it?

The other source of delay is when using CrossMgrImpinj and QuadReg.
Because QiadReg reads the tag multiple times and computes the time when it is closest, it wait for "silent" period after the last tag read before it assumes the tag is out of range of the antenna.  Then it does the signal processing on all the reads it has.
This adds a further delay.

However, there is no logic around "updating after the second read".  Everything is based on a timer.

Perhaps you could make a screen capture video and post it?  That way, I would be able to see exactly what is happening.
Thanks.

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Edward Sitarski

Tim Mockford

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Jun 16, 2025, 3:50:11 PMJun 16
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Hi,
Got a screenshot of the issue. Will be able to get a video next weekend as have four kids short track races to time.

In the screenshot bib/tag 10 has been the most recent past the reader. However the old read is still showing in recorded, the new read is not showing. Switching between chart and record updates the recorded pane.

Hope that helps! Will get a video next weekend.

Screenshot from 2025-06-16 20-38-43.png

Tim Mockford

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Jun 22, 2025, 3:55:55 PMJun 22
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Hi,
I can see you did some work on the latest release about this. Did happen today, but didn't feel as bad. See attached screenshots.

Interesting behaviour which may provide insight - for one reason or another the laptop disconnected from the wifi mid race, missed three riders before I got it reconnected, however afterwards the issue was much better. Then as the racing progressed it got worse again. I'm wondering if it might be router related.
crossmgr4.png
crossmgr1.png
crossmgr5.png
CrossMgr2.png
crossmgr3.png
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