WBMT.....What baffled me today

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Hopefully, someone with technical knowledge can answer this one.

Yesterday we stopped at a set of traffic lights...my wife was driving .. so I was able to look at the dash cam screen and I was intrigued by the very rapid pulsing of the red light. Looking at it (ie not on the dash cam screen) it was fine. So, when they changed I looked at the dashcam screen and the amber and the green did the same. We got to the next set and looking at the dashcam screen they were normal. Was the camera seeing something going on in the previous set that the naked eye couldn’t see ?
 

Tori_T

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LEDs tend to control brightness using pulse-width modulation (turning the power quickly off/on in various proportions) rather than varying the voltage. Human eyes tend not to be able to see the flickering, but a camera sensor will often pick up the off/on pattern if it's frequency is slightly out of sync with that of the LED.
You'll also likely see it with the rear lights on more modern cars.
 
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Was the first set led and the second conventional bulb by any chance?
Oh..I wouldn’t know that,Jon. The second set are only 6 months old,if that..on a multi-million pound city roads upgrade. The first set,the one with the issue, has been there ages So, I suppose thus old set will be using bulbs.
 
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LEDs tend to control brightness using pulse-width modulation (turning the power quickly off/on in various proportions) rather than varying the voltage. Human eyes tend not to be able to see the flickering, but a camera sensor will often pick up the off/on pattern if it's frequency is slightly out of sync with that of the LED.
You'll also likely see it with the rear lights on more modern cars.
Ok..thanks for that. Of course my next mission,now, will be to watch the rear lights of cars we are behind..

Could you have a go at this one too ? When a moving car (from stationary ) is filmed the spokes can be seen moving forwards...ie..clockwise but very soon,as the car accelerates they appear to turn anti-clockwise. It doesn’t happen looking at them,just when it’s on film.
 

Tori_T

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Film/video is made up of a series of still images, replayed at 25-30 frames/second. When the wheel is turning slowly, the frames catch the spokes a bit further round each time, so the wheel appears to be moving normally. If you have, say, a five-spoke wheel, when it gets to the point where it's rotating 60° between frames, the next spoke will be just behind where the previous spoke was in the last frame, so it will appear that spoke has moved "backwards" a bit. Faster still (72° ) and the wheel will have the next spoke in the same position in the next frame, so it'll look like it's not moving. 80° /frame, and it'll look like it's slowly moving forward again.
 
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Could you have a go at this one too ? When a moving car (from stationary ) is filmed the spokes can be seen moving forwards...ie..clockwise but very soon,as the car accelerates they appear to turn anti-clockwise. It doesn’t happen looking at them,just when it’s on film.

I’m not sure what the cause of the effect in your example is, but it sounds very much like the ‘Wagon Wheel Effect’ :

https://en.m.wikipedia.org/wiki/Wagon-wheel_effect

EDIT: Beaten to it by Tori !
 
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Film/video is made up of a series of still images, replayed at 25-30 frames/second. When the wheel is turning slowly, the frames catch the spokes a bit further round each time, so the wheel appears to be moving normally. If you have, say, a five-spoke wheel, when it gets to the point where it's rotating 60° between frames, the next spoke will be just behind where the previous spoke was in the last frame, so it will appear that spoke has moved "backwards" a bit. Faster still (72° ) and the wheel will have the next spoke in the same position in the next frame, so it'll look like it's not moving. 80° /frame, and it'll look like it's slowly moving forward again.
Much appreciated..thanks. I’m very impressed.(y)


I’m not sure what the cause of the effect in your example is, but it sounds very much like the ‘Wagon Wheel Effect’ :

https://en.m.wikipedia.org/wiki/Wagon-wheel_effect

EDIT: Beaten to it by Tori !

Thanks to you also,Danny A very good link. When I saw the plane prop photo I realised that it’s the same effect for footage of them too. I’ll read and re-read Tori’s explanation and your wiki link until it sinks in.(y)
 

nilagin

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According to someone on Facebook, in reply to a car magazine's post, my employer doesn't employ people in the UK anymore. I'd love to know how he knows this and I don't and when did this happen. I'd also like to know where my redundancy money is, although I have still been receiving regular weekly pay slips as well as money being deposited into my bank account on regular weekly intervals too. Should I bother to turn up for work in the morning. It's truly baffling. I have asked him for more details, but so far he hasn't replied.
I guess I shall just continue turning up until the money stops or someone tells me to stop. ;)
 
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I guess I shall just continue turning up until the money stops or someone tells me to stop. ;)
All part of the internatter phenomenon: "inaccuracy thy name is farcebook". :naughty:
 
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nilagin

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Well I turned up for work this morning and everything as normal. Not been told to stop and get escorted off the premises yet.
 

Cobra

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Talking of Farce book.
A guy phoned the supervisor Sunday night to say he was unwell and wouldn't be in today.
The supervisor checked the guys FB page and just half an hour before the call, he was out ferreting...
Twatt!

And that is why everyone I work with is blocked from my FB.
It baffles me every day, how stupid some people can be!
 
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It baffles me every day, how stupid some people can be!
Long before the internet I worked on a local London newspaper. A bloke in the distribution department called in sick one Friday morning (which was publishing day). He found himself in an awkward situation after the sports desk bought in a picture of the winning goal in a game between the local team and another on the other side of town on the day he was "ill". There he was, sharp as a needle, sitting in the front row behind his team's goalie... :sulk:
 

nilagin

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We had a bloke that had got his wife to call in for him as he had a bad cold, sore throat and lost his voice. There was a radio on at work which one of our managers heard as he walked by. The idiot who had pulled a Dickie had phoned up the radio station to enter a competition. He was duly sacked when he returned to work.
 
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Many years ago I remember my father (shop floor machine operator) struggling to get to work through the snow, it was so bad he couldn't drive so he walked the 3 miles to work & arrived 5 minutes late. He was docked pay for being late, imagine how annoyed he was to discover office staff who didn't turn up for work at all that day were paid in full.

When he became a union official, his biggest achievement was to negotiate equal rights for shop floor and admin staff.
 

Marc

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Many years ago I remember my father (shop floor machine operator) struggling to get to work through the snow, it was so bad he couldn't drive so he walked the 3 miles to work & arrived 5 minutes late. He was docked pay for being late, imagine how annoyed he was to discover office staff who didn't turn up for work at all that day were paid in full.

When he became a union official, his biggest achievement was to negotiate equal rights for shop floor and admin staff.
On a similar note. A number of years ago, we had some very heavy snow but there was a clear corridor where there was no snow between where I lived (Leighton Buzzard) and work (Hemel Hempstead, 15 miles) so I was able to get in easily. I had to make a phone call to my contact in another company who happened to be just down the road. When someone answered his phone and I asked to speak to him, I was told he couldn't get in because of the snow. When I asked where he was trying to get in from, he said Leighton Buzzard! :oops: :$
 

Gremlin

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Seems I have a warrant for arrest about to issued by HM Revenue and Customs for fraudulent use of my name to make a claim and not hitting the 1 button on my phone

Odd that as I don't think I have ever given them my mobile number:thinking:
Oh well I'll just wait for the knock on the door :D
 
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Seems I have a warrant for arrest about to issued by HM Revenue and Customs for fraudulent use of my name to make a claim and not hitting the 1 button on my phone
I wouldn't worry to much there must be quite a backlog as I had a similar call 2-3 months ago and I'm still waiting, I'll give you a heads-up when they come for me.
 

Gremlin

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I wouldn't worry to much there must be quite a backlog as I had a similar call 2-3 months ago and I'm still waiting, I'll give you a heads-up when they come for me.
Damn I thought a nice easy christmas with everything done would be good :confused:
You can see how some people might get scared and lose money. I'm just sorry I never got to the real person it was an
automated message
 

Marc

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Travelling home from work this evening, oncoming traffic at a standstill. As I'm going along, I spot movement in the middle of the road coming towards me. As it got closer, I realise it's a motorbike. No lights on or any hi-vis!
 
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Travelling home from work this evening, oncoming traffic at a standstill. As I'm going along, I spot movement in the middle of the road coming towards me. As it got closer, I realise it's a motorbike. No lights on or any hi-vis!
A recipe for a (fatal?) accident :(

PS Once past you, did you see any 'his' rear light in your mirror?
 
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Ah!!! this is one main reason I lament the low numbers of traffic patrol cars and so few bobbies on the beat................there is oh so much reliance of ANPR to catch specific legal infractions and not the misaligned/missing lamps etc (NB I wonder if there are any statistics about the Police stopping such non ANPR detected motoring offences?)
 

Marc

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Ah!!! this is one main reason I lament the low numbers of traffic patrol cars and so few bobbies on the beat................there is oh so much reliance of ANPR to catch specific legal infractions and not the misaligned/missing lamps etc (NB I wonder if there are any statistics about the Police stopping such non ANPR detected motoring offences?)
TBF, if there were more traffic patrol cars, they would just add to the gridlock! Traffic was horrendous this evening, got stuck myself just 50 yards on! Was even worse yesterday, took 45 minutes to travel less than a mile!!
 

Nod

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Not to mention horses out after full dark with absolutely no hi-viz or lights.

ETA ridden!
 
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