Intrusion/line crossing at dusk and dawn? Possible answer...

[fullboogie]

About eight months ago I installed a Hikvision I-series NVR with eight 2355/2385 cams. I've always had three cams that set alarms on either intrusion or line crossing at both dawn and dusk each day. Those three cams are oriented the same direction, west, which is different than the remaining 5 cams. I've done all the tweaking I can think of to eliminate the false alerts to no avail. The false alerts have followed the changing times of dawn and dusk throughout the year. Reviewing recordings the alarms always came immediately after the cams switched from day to night, color to b/w, and IR kicking in.

So after digging around, I realized that on my cams the "video tampering" feature was automatically enabled. After disabling that feature on those three cams, I have not had an alert at dusk/dawn for 5 days. If you ever see video of the dusk/dawn changeover it's a large "blink" that momentarily blanks out the feed when it switches over. I think the "video tampering" setting being "on" sees that as an alert and sets it off. Since turning that feature off it's been good so far. Crossing fingers...

 

[John Williamson]

About eight months ago I installed a Hikvision I-series NVR with eight 2355/2385 cams. I've always had three cams that set alarms on either intrusion or line crossing at both dawn and dusk each day. Those three cams are oriented the same direction, west, which is different than the remaining 5 cams. I've done all the tweaking I can think of to eliminate the false alerts to no avail. The false alerts have followed the changing times of dawn and dusk throughout the year. Reviewing recordings the alarms always came immediately after the cams switched from day to night, color to b/w, and IR kicking in.

So after digging around, I realized that on my cams the "video tampering" feature was automatically enabled. After disabling that feature on those three cams, I have not had an alert at dusk/dawn for 5 days. If you ever see video of the dusk/dawn changeover it's a large "blink" that momentarily blanks out the feed when it switches over. I think the "video tampering" setting being "on" sees that as an alert and sets it off. Since turning that feature off it's been good so far. Crossing fingers...

Yes the IR cut filter moving in at dawn/out at dusk may trigger that. I have some low cameras that I need the "scene change" detection on in case anyone messes with them and I found them to be triggering at dusk/dawn. I just dropped the sensitivity down by 5 points each day until it stopped. I found that a sensitivity of 30 -35 works well without false alerts.

 

[alastairstevenson]

Yes the IR cut filter moving in at dawn/out at dusk may trigger that.

The later firmware specifically doesn't generate events on the day/night switch over.
It was mentioned in a release note - though I'm not sure what version of firmware was referenced.

 

[fullboogie]

Not sure what to say, Alastair. Mine are US legit cams from B&H with the most recent firmware. They've done this since February when I installed the system and have gone through 2 or 3 firmware upgrades over time. Since unticking the "video tampering" box I've not had one single alert at dusk or dawn. So I'm happy!

 

[alastairstevenson]

They've done this since February when I installed the system and have gone through 2 or 3 firmware upgrades over time. Since unticking the "video tampering" box I've not had one single alert at dusk or dawn. So I'm happy!

Yes, what you described is a clear cause & effect.
Though I have to say I don't recall seeing 'Video tampering' defaulting to on. Possibly this varies with the model.

This is what I remembered, from the 5.5.0 firmware.

 The filtering time of Day/Night switch is increased from 5s to 10s.
Note: During Day/Night switch filtering time, no events would be triggered to avoid false alarms.

 

[fullboogie]

There may be some way to make it work, but I tried many combinations of sensitivity and shorter/longer filtering times with no luck. I wish I could make it work, as the extra protection against tampering would be nice. Thanks for the input, sir.