(meteorobs) OT-Possible single station determinationofmeteordistance.

Swift, Wesley R. (MSFC-NNM05AB50C)[RAYTHEON] Wesley.Swift at nasa.gov
Fri Dec 19 12:04:42 EST 2008


Just a couple of notes.

1) Some cameras can be easily synchronised with an external video input.
2) In order to make the angle in your diagram reasonable the camera
seperation is in miles.
3) If instead of a "streetlight" at 10 miles one uses the fixed stars,
one is back to two station observation. 

Wes


-----Original Message-----
From: meteorobs-bounces at meteorobs.org
[mailto:meteorobs-bounces at meteorobs.org] On Behalf Of stange
Sent: Wednesday, December 17, 2008 5:12 PM
To: Global Meteor Observing Forum
Subject: Re: (meteorobs) OT-Possible single station
determinationofmeteordistance.

I was reviewing M&M + light speed for "ideas" of how to EASILY make a 
ranging device that was cheap and simple. I ruled out split image and 
mirrors as being totally impractical and could not find any sound idea
using 
that material for what I wanted.

At present the only concept that I think is workable & easier, is 
investigation into reverse autoranging using two cameras. The idea seems

sound, but whether it can be made practicle and can stand alone in
operation 
is the difficulty.

It can be done with a memo-scopes or a dual trace trigger and other ways
but 
stand alone multiple triggering with hard drive storage is key functions

needed all night long to be realistic.

My tests this afternoon on reversing the splitter determined two
identicle 
cameras nearly synched in a lock-on but repeated out of phases would
cause 
thousands of false triggers with a capture program. So that is the
problem. 
"HOW" to get automatic overlays or two image captures AND storage of
stable 
events without 2 computers running independantly with split capture and
at 
no cost to the user like having to double up on capture cards & having a
two 
processor computer. A hardware Engineer is needed here or someone to
follow 
up on anything with what little merit I have given.

Basic dwg. illustrating the simple principles without ccd diagonal
measure 
correction.....
http://www.geocities.com/stange34@sbcglobal.net/Distance

YCSentinel
(Area 51 is being disinfected)


----- Original Message ----- 
From: "Chris Peterson" <clp at alumni.caltech.edu>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: 2008/12/17 10:52
Subject: Re: (meteorobs) OT-Possible single station determination 
ofmeteordistance.


>I can't really figure out from your description what the actual setup
is, 
>or
> how this would work. I do have a few observations that might prove 
> helpful:
>
> 1) If your intent is somehow based on interferometry (as in M-M), you 
> can't
> achieve this by combining the video signals of two cameras.
>
> 2) If you are depending on critical timing, keep in mind that the
video
> cameras will be running asynchronously of each other, so you can't
depend 
> on
> timing to better than 1 frame time. That is, each camera will be
seeing 
> the
> fireball at different times.
>
> 3) Video signals are not RF, and can't be combined with a passive 
> splitter.
> You would need some kind of delay-and-lock circuit (since the frames
are 
> not
> in sync), or a pair of frame grabbers.
>
> 4) Your camera with a 4mm lens has a pixel scale of about 260
arcseconds.
> The angular deviation of a fireball 10 miles away, with cameras 6 feet
> apart, is 23 arcseconds. The latter is about the best precision you
could
> expect for a centroid calculation; it's probably far too small to use
> parallax to reliably get a distance.
>
> 5) If you're going to invest in two camera systems, why not just put
the
> other one 20 miles away? It's easy to find people willing to host
cameras.
> That will allow you to get much better data on the meteor, including
its
> velocity and the absolute position of any terminal explosion. It will
also
> allow you to get data on many more meteors, since the distance you can
get
> good data is now pushed to several hundred miles.
>
> Chris
>
> *****************************************
> Chris L Peterson
> Cloudbait Observatory
> http://www.cloudbait.com
>
>
> ----- Original Message ----- 
> From: "stange" <stange34 at sbcglobal.net>
> To: <meteorobs at meteorobs.org>
> Sent: Wednesday, December 17, 2008 1:48 AM
> Subject: (meteorobs) OT-Possible single station determination of
> meteordistance.
>
>
>> Tossing this bit of thought out....after re-reading Michaelson-Morley
>> interferometer stuff.
>>
>> If two cameras with square CCD's and identicle 4mm lenses were
mounted on
>> a
>> common platform about 6 feet apart and UNLIKE a range finder which
you
>> could
>> not adjust in time for a fireball explosion.... those cameras were
>> pre-aimed
>> at a small terrestrial light source about 10 miles out and the
platform
>> with
>> the mounted cameras unchanged were to have their individual composite
>> signals combined into a single point of light by inputting into a 
>> reversed
>> RF-splitter with the output going into a computer frame grabber and
>> detection software with the light spot centered in the monitor or the
>> software, one could expect detection of a fireball explosion and the
>> DISTANCE to that explosion could be measured by the actual
displacement
>> between the two images in seconds of a degree. The monitor centering
is
>> only
>> to make room for the different azimuths and elevations the fireball
might
>> occur. Those spot images can be anywhere on the screen.
>>
>> Magnification of the "split" image may be necessary to resolve a
second 
>> of
>> a
>> degree. Some correction might be needed for elevations because CCD
>> cross-sections are greater than the length or width of a square CCD.
>>
>> If the fireball occurs ten miles distant... there will be no
displacement
>> between the spots.
>> Beyond ten miles the displacement grows proportionally. The cameras
and
>> platform would need aiming skyward after the "collimation" or
calibration
>> of
>> the two spot images into one.
>>
>> YCSentinel
>
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