View Full Version : Question?

tony draper
10th Mar 2014, 22:37
For Airline Pilot Peeps
A while back I set up a high rez low light cctv camera during one of those meteor showers (not a sausage)pointed skywards wide angle covers almost from zenith to western horizon.
Anyway,though I see no meteors what it does see at night is aircraft taking off from Newcastle and heading West,or rather the strobes of same,
One is puzzled,these strobes dont seem to flash in a regular pattern,just watched one,six regular flashes,a pause then one flash a pause and then four flashes,safe to assume these aircraft are not maneuvering wildly masking the strobe,noticed this before on clear night but tonight being a tad bored it stirred one's curiosity.
What is occurring here? is there a protocol on flashing your strobes in code or summat like lighthouses?

John Hill
10th Mar 2014, 22:46
Maybe you were looking at flight 614 westbound from Newcastle?:suspect:

tony draper
10th Mar 2014, 22:56
Flight 614? I know not Mr Hill, tiz genuine question.:confused:

10th Mar 2014, 22:59
May I call upon the immediate banning of Herr Draper from Jetblast for a wilful and intent request for information regarding issues directly relating to aviation and the company requirements for position lights flash freq (as required by company).

Can Tony Be Beheaded actually.. With a proper sword??

tony draper
10th Mar 2014, 23:02
Best bring plenty friends one has progressed beyond edged steel.:E

10th Mar 2014, 23:32
Tony, I'm not an "airline pilot peeps" but I do a bit of amateur astronomy. I've noticed similar and always put the irregular sequence down to the same atmospheric distortion that causes the shimmering effect you see against stars and planets in the telescope eyepiece. Don't know, quite possibly talking nonsense - has been known;)

As an aside - I always find the hype on meteor shower strike rate over optimistic - never tried to photograph them though. Think best results are done with a fish eye lens.

10th Mar 2014, 23:40
Smoke from the exhaust . . .

11th Mar 2014, 01:34
Strobe lights are white in color, and are found on the aircraft's wingtips. Strobes operate at a higher voltage than normal incandescent lamps by utilizing a high-voltage power supply. The power supply fires the strobe at a given interval.

11th Mar 2014, 02:17
All of the strobes (white) that I have seen are all at a regular (steady) frequency.
Too much "broon" Tony????

11th Mar 2014, 02:46
The camera you are using samples the picture at a fixed frequency,say 25 times a second,and only 'sees' the picture for may be 1 or 2 milliseconds.If the camera gets out of phase with the strobe,it does not see anything.

11th Mar 2014, 03:28
The camera you are using samples the picture at a fixed frequency,say 25 times a second,and only 'sees' the picture for may be 1 or 2 milliseconds.If the camera gets out of phase with the strobe,it does not see anything.

........ironically often referred to as "strobe effect".......... :E

Krystal n chips
11th Mar 2014, 05:49
"For Airline Pilot Peeps"

Alas, Mr D, an elementary error as to whom the question should be posed.

Those of the "winged sky god" occupation tend towards the "push button, it works / it don't work, thereafter I haven't a clue" philosophy.

The above may not entirely meet with universal approval as to the veracity of the statement you understand.....;)

This however, should go someway to answering your question along with others who know more about cameras and refracted light....

FAA Requirements for Wing-Tip Strobes | eHow (http://www.ehow.com/about_6665007_faa-requirements-wing_tip-strobes.html)

They are "interesting" bits of kit.....if you wish to continue living that is when changing one....in essence, a capacitor which chucks out " an awful lot of joules"......a bit like the spark plug that starts the engine in fact...or H.E.I.U before the pedants start, given some of the humourless species on here.

11th Mar 2014, 06:04
I think crippen has the answerMr D
On every aircraft I've ever flown or been flown in the flashes are regular
One way of proving crippen's theory is to observe a target aircraft through the camera and directly by eyeball simultaneously.

11th Mar 2014, 06:24
You could ask the mods to move this thread to Rumours and News where it will be analysed to its last Amstrong unit. :E

Solid Rust Twotter
11th Mar 2014, 06:38
Beadwindow, folks!

Ani fule no it's the recognition sequence exchanged by chemtrail equipped aircraft to avoid double spraying. They mind altering chemicals ain't cheap, you know....:}

tony draper
11th Mar 2014, 07:37
Very well one shall continue one's observations of this phenomenon,I have a very powerful strobe meself mains operated that I point out the window to annoy people walking up the road.
It is also possible that you chaps sitting in that little cubby hole at the front cannot see your own strobes and are therefore deluded as to their regularity.
I can see it now 100 years hence the teacher in his classroom telling the sprogs.
"They all laughed at Draper when he spoke of his discovery of lumps of dark matter suffused throughout the atmosphere causing strobes to misbehave,but it is that very dark matter we now hoover up to power our star ships"


Solid Rust Twotter
11th Mar 2014, 08:16
Need to be careful there, yer Admiralship. A few miles further North and the natives would try to deep fry yon dark matter. Who knows what would happen then...:ooh:

B Fraser
11th Mar 2014, 08:23
A bored programmer at Airbus has probably coded a rude message in morse. Can you translate it for us Captain Drapes ?

11th Mar 2014, 08:27
Crippen has it.

The aliasing of the strobe flash rate and the video frame rate leads to the mismatch. The camera "shutter" is closed for some of the flashes as the frame is read out. It's similar to hearing low-frequency beat tones from mismatched rotating equipment.

Failing strobes sometimes flash irregularly, but it's your camera that's doing it.

11th Mar 2014, 08:41
Tony, as any fule kno, they're carefully-timed chemtrail bursts over targetted areas.

11th Mar 2014, 08:45
Put the poor chap out of his misery.

Every airline pilot peep of any standing is aware of the 'switch-the-strobes-on-and-off-at-random-intervals-after-departure-in-the-Newcastle-area' tease.

11th Mar 2014, 09:42
Aircraft passing a little cloud of two masking the flashes?

tony draper
11th Mar 2014, 09:56
Nope crystal clear sky I could see the nebulosity in Orions sword,it's a very good professional camera not one of those micky mouse things from Maplins,I can see the farmer standing in his field lighting his ciggy five miles away across the valley on a pitch black night.

11th Mar 2014, 10:07
These irregularities wouldn't occur when they were passing over Spadeadam, would they?
Oh, I forgot, civilian aircraft flying over Spadeadam will have all their lights extinguished. Permanently.

11th Mar 2014, 10:08

But you can't see a farmer in his field if the shutter's closed.

If he lit his ciggy for ten microseconds rather than five seconds, you
might miss it as the detector in your expensive camera read out.

Try leaving the shutter open for a minute as the plane crosses your field of view - I predict that you'll see each and very strobe flash as a dot on the navigation light trail.

11th Mar 2014, 10:34
It happens also with those electronic 'rolling' destination signs on buses.

To the eye they roll constantly, but the camera catches them partly illuminated.

tony draper
11th Mar 2014, 10:49
It's a CCTV Camera never come across one that allows you to close the shutter,however seriously the shutter and the strobe going in and out of sync is probably the answer,next time I spy a strobe on the screen I shall watch it with eyeballs mark two,that's if I can prize me back off the settee,the whole idea of the setup was so I could do me astronomy lying supine in warmth and comfort.

11th Mar 2014, 10:56
If it's a video camera, it could work by reading lines continuously in sequence like a traditional TV camera, or stitching together digital stills, but in either case, there's a frame-rate dependent dead time. I think you're right that it's not got a shutter.

There's always the refresh rate of the screen you're viewing it on too. It might be that rather than the camera that's blanking the strobes. If it's a fancy camera, then that's perhaps more likely.

Taking a long exposure on a digital still camera would be the way to nail it down, without having to count. Or if you have two, video the screen of your astronomy display for comparison at the same time (potentially introducing another set of frame rate mismatches).

tony draper
11th Mar 2014, 11:03
Actually looking again at one of me older cameras(it has knobs and switches rather than just a menu) the shutter can indeed be switched off or set to different speeds.:)

11th Mar 2014, 11:06
A few miles further North and the natives would try to deep fry yon dark matter. Who knows what would happen then...
Black pudding ...? :hmm:

11th Mar 2014, 11:10
If you get that set up right, then you might even be able to see your meteors from the bar.

If you set it up so you can reliably always see every strobe flash, then that might also be the condition you need to see ~50ms duration meteors.

I think it's possible that despite being a low-light camera there might be a substantial fraction of closed shutter/readout time. The only way to really tell how your whole system is working is to set up your own strobe and video it running at different rates and see what you see.

11th Mar 2014, 11:13

Are you involved in astrology in any way ?

tony draper
11th Mar 2014, 11:18
This is one of me older cameras(ere free samples) with knobs and switches the one I am using is a Hi Rez Bosch Dinion much better low light cam a true day and night jobby it switches over to mono at night,the only shutter setting on the menu are Off or FLK.
http://i11.photobucket.com/albums/a194/Deaddogbay/second%20album/2014-03-1111-06-58890_zps9f16db02.jpg (http://s11.photobucket.com/user/Deaddogbay/media/second%20album/2014-03-1111-06-58890_zps9f16db02.jpg.html)

11th Mar 2014, 11:19
Yes. It turns out I'm an Aries, with a fascistic gun-obsessed Aussie stalker rising. But then I knew that was going to happen ahead of time because I'm a dyslexic psychic.

11th Mar 2014, 11:21

I meant work wise !!!

11th Mar 2014, 11:23
He means workwise that he is in the ASTRONOMY field. Coming from Pasadena, he possibly is working in that field

Shaggy Sheep Driver
11th Mar 2014, 11:29
I remember the old Terrorhawk. It had a strobe on each wing tip and the power pack was somewhere behind the seats. It fired the strobes alternately, and the rising whine of the capacitor being charged (like you hear on some camera flash units) between each discharge was quite distinctive. You could hear it on the RT in some aircraft as it was loud enough for the headset mike to pick up.

B Fraser
11th Mar 2014, 11:29
I was peering at Jupiter through my 12 inch reflector shuftiescope a few nights back and a satellite passed across the field of view. The satellite was not visible to the naked eye. I was rather chuffed to have seen it. :8

11th Mar 2014, 11:35
I like lying in bed in the bush (in a swag), looking up at the sky with no or little human lights interfering. The sheer number of moving objects up there is amazing.

Best I say was Haley's comet, it was huge in the bush but in Melbourne it was quite small, not helped by all the lights !!! We were also at a location that meant the comet was reflected in a still body of water, I think we got a photo of it.

11th Mar 2014, 11:45
The power of the google, hey, Mr En?

I believe there are only three of us to pick from at the moment, and I'm not Stephane or Celia.

11th Mar 2014, 11:53
Some of them modern airships use energy efficient LEDs for the strobes, maybe the ones flashing badly are the cheaper brand manufactured by slave labour.

11th Mar 2014, 11:57
Considering they are made on a machine :O

11th Mar 2014, 12:08
Halley was amazing in Southern skies. I was out working at a telescope on Siding Spring in early 1986, and the views were fantastic; like 500N I was lying in a paddock watching it (out the Timor Road in my case). I still have a couple of contact prints of the 14 inch photographic plates used to gather astrometry data used in steering the Giotto spacecraft.

11th Mar 2014, 12:21
I've never observed any irregularity in the cadence of strobe flashes on the aircraft.

It gives me great pride, and some surprise, to agree with awblain on something. crippen, I think, came up with the answer, that the shutter of the camera was out of sync with the strobes.

Windy Militant
11th Mar 2014, 19:45
As mentioned that particular Camera may not have a shutter but a fixed refresh rate on the detector. It's something I have more and more trouble with these days when explaining how high speed video systems work. It's a bit like kids not knowing what clockwise is because they all have digital watches. Very few young whipper snappers are familiar with mechanical shutters so trying to explain the difference between frame rate and shutter speed, especially when the individuals involved do not have English as a first language, actually it's quite hard with some that do!
Any way not so much of a problem nowadays but older low frequency strip lights could be harmonised with the frame rate of the cameras we used, and then capture black frames as the camera took the image whilst the light was mid cycle so effectively off. We used to advise using a pair of resistor bulb floodlights and connecting each one to a different phase if it was possible so you didn't get dark spells. ;)

12th Mar 2014, 03:33
Our Falcons engaged in UK mil activites had HISLs fitted on the upper and lower sides of the fuselage. Selectable Red / White but I cant remember if they flashed in sync or were independent... Given that some of the fleet are based at DTV / MME perhaps it could have been of those?

12th Mar 2014, 12:59
Mr Militant:

young whipper snappers

Oh, very good!


12th Mar 2014, 13:39

beware the ides of march....