This is hik bullet camera with 12mm focus length
In this place I have two cameras, second hik too, but no flickering.
What to do? Is it broken camera?
Flickering night Image (link with video) DS-2CD2042WD-I 4MP 12mm
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This is hik bullet camera with 12mm focus length
In this place I have two cameras, second hik too, but no flickering.
What to do? Is it broken camera?
fenderman
Staff member
- Mar 9, 2014
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Thank you for answer fenderman,
I triedboth frequencies and problem exists.
Now i found workaround - flickering depends on number of Frame rate. 2fps - flickering slowlu. 6fps flickeriong medium 10fps - most no flickering. 20fps flickering very fast, 25fps - flickering proportionaly faster.
I chanded FPS to 10fps and it is better. But camera recognizes this flashing as "event" and generates alarm.
But still i dont understand the problem. The street has probably sodium light, but this place is in 4 cameras and only 1 is flickerig
I triedboth frequencies and problem exists.
Now i found workaround - flickering depends on number of Frame rate. 2fps - flickering slowlu. 6fps flickeriong medium 10fps - most no flickering. 20fps flickering very fast, 25fps - flickering proportionaly faster.
I chanded FPS to 10fps and it is better. But camera recognizes this flashing as "event" and generates alarm.
But still i dont understand the problem. The street has probably sodium light, but this place is in 4 cameras and only 1 is flickerig
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alastairstevenson
Staff member
These look like rolling bars that some LED streetlights can cause if their light has a strong mains-frequency-related variation in brightness.
Does the flickering camera have the same firmware version as the others?
Presumably the 2 cameras are pointing at different scenes?
J Sigmo
Known around here
- Feb 5, 2018
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Also, what shutter speeds do you have set on the two cameras? A slow shutter speed may well integrate the pulsations from a flickering street-light, while a higher shutter speed will often create bars with a pulsating light source. So it might pay to play with the camera's shutter speed settings, too.
Two cameras, not identical. Both bullet hik, one 3MP 6mm 2017y, second 4MP 12mm 2018y
They are mounted at opossite directions, making picture of the same spot.
Identical configuration, one is flickering second not
shutter 150/s
They are mounted at opossite directions, making picture of the same spot.
Identical configuration, one is flickering second not
shutter 150/s
I tried many shutters, but problem appears.
Need to have fast shootter (objects in traffic are fuzzy if shutter is 1/30s)
Need to have fast shootter (objects in traffic are fuzzy if shutter is 1/30s)
J Sigmo
Known around here
- Feb 5, 2018
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It seems like a beat-frequency between the readout rate for the camera sensor and the flicker of the street light. Often, LED lights will have a flicker rate that is quite fast. Far faster than (and unrelated to) the mains frequency. This is because the LEDs are driven by a constant current driver that starts with a DC voltage and switches it, using pulse width modulation, to achieve the average current that the designer wants for the LED array. This is better than simply driving the LED string through dropping resistors because it compensates for the variations in LED forward voltage drop over temperature, and also is more energy efficient than simply using a current-limiting resistor in series with the string.
So the upshot is that you can have LED lights flicker at very high frequencies. It just depends on the design. Higher frequencies have the advantage of keeping the size of inductors and capacitors smaller, thus lowering the size, weight, and cost of the power supply. Higher frequency drive also extends the life of the LEDs because at lower frequencies, the tiny die of the LED heats and cools, and you get physical expansion and contraction which can cause failures of the lead bonds as well as extra stress on the die itself. We were advised, years ago, by HP, to never run their LEDs below 100 Hz to avoid wearing them out rapidly. LED lamps that use the mains frequency to drive the LEDs are cheap to make, but will normally not last nearly as long as ones that properly drive the LEDs at a reasonably high frequency. We always set up our multiplexed LED arrays to drive at 1000Hz or better.
This also reduces the visible flicker that the human eye sees when moving your eye across the display, indicator, or light, or when viewing a moving object illuminated by a low-speed-driven LED lamp.
It may be that this particular street light is "tuned" just right to mess with the scan rate used to read the pixels out of that particular camera's sensor. Sort of like the "rolling shutter" effect often seen with most digital cameras (that don't employ a physical shutter).
Rolling shutter - Wikipedia
So the upshot is that you can have LED lights flicker at very high frequencies. It just depends on the design. Higher frequencies have the advantage of keeping the size of inductors and capacitors smaller, thus lowering the size, weight, and cost of the power supply. Higher frequency drive also extends the life of the LEDs because at lower frequencies, the tiny die of the LED heats and cools, and you get physical expansion and contraction which can cause failures of the lead bonds as well as extra stress on the die itself. We were advised, years ago, by HP, to never run their LEDs below 100 Hz to avoid wearing them out rapidly. LED lamps that use the mains frequency to drive the LEDs are cheap to make, but will normally not last nearly as long as ones that properly drive the LEDs at a reasonably high frequency. We always set up our multiplexed LED arrays to drive at 1000Hz or better.
This also reduces the visible flicker that the human eye sees when moving your eye across the display, indicator, or light, or when viewing a moving object illuminated by a low-speed-driven LED lamp.
It may be that this particular street light is "tuned" just right to mess with the scan rate used to read the pixels out of that particular camera's sensor. Sort of like the "rolling shutter" effect often seen with most digital cameras (that don't employ a physical shutter).
Rolling shutter - Wikipedia
Maybe the solution will be upgrade/downgrade software. Current version V5.5.0 built 170825 DS-2CD2042WD-I
and there is no setup to avoid flickering. During night camera generates about 30 alarms/60sec and alarm and events are unusable.
and there is no setup to avoid flickering. During night camera generates about 30 alarms/60sec and alarm and events are unusable.
SouthernYankee
IPCT Contributor
This really looks line a beat between different light sources.
Have you tried the flickering camera with the other camera turned off (NO IR) ?
Have your tried the flickering camera with the IR turned off ?
Have you tried the flickering camera with the other camera turned off (NO IR) ?
Have your tried the flickering camera with the IR turned off ?
thank you for reply.
In this place I have camera and additional IR lamp. I tried to disable IR from camera but not tried to disable additional source
In this place I have camera and additional IR lamp. I tried to disable IR from camera but not tried to disable additional source
fenderman
Staff member
- Mar 9, 2014
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you are joking right? would you not think that is the FIRST thing to mention when discussing the issue?
Doc, what do you think can be causing my splitting headache?
Could it be the axe sticking out of your skull?
Could it be the axe sticking out of your skull?
Today evening i will disable this small IR lamp. But if I remember, the camera flickered before I've installed this additional lamp.
Disabling additional IR lamp did not helped at all. There is no solution. Maybe there are sodium street lamps which are making camera to flick.
Problem not solved
Problem not solved
It looks like you are picking up a 60Hz AC component. Is this POE powered of do you use a 12VDC supply? If it is a separate supply try a new DC supply. If that doesn’t fix it, take the camera down and plug it directly into your computer with a different DC supply. If there are still rolling bars throw away the camera. If they go away and a new power supply at the camera location did not fix the problem, then it’s a wiring problem. Does the cable follow an AC supply?
Also are you using shielded cable you could have a ground loop. Need lots of details on cabling, how the cameras are powered. Cable lengths.
Also are you using shielded cable you could have a ground loop. Need lots of details on cabling, how the cameras are powered. Cable lengths.
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Thank you it is a good idea. Wiring in this camera is ugly becąuse it is about 20 meters of UTP 5cat. Two pairs are etheenet and two pairs is 12vcircuit