[HCARC] Are Engineers Trying To Make Non Engineers Feel Bad??

[H. Vordenbaum]

AAAhhhh, the infamous Westford Needles experiment.  It turned out that the
damned needles never did separate and spread out.  So the clumps remain in
orbit to this day making permanent orbital debris.  Wasn't there an AF lab
in Westford, MA?  Part of our section worked on orbital debris tracking
data.

Twinkling...
We did balloon borne UV telescope testing on the ground.  It had two star
trackers, inner loop and outer loop for guidance.  The star tracker signals
were incredibly noisy especially on a nice clear night.  Hazy was better,
but still bad.  At operational altitude >90K ft., they were nice and clean.
hv

-----Original Message-----
From: hcarc-bounces at mailman.qth.net [mailto:hcarc-bounces at mailman.qth.net]
On Behalf Of Kerry Sandstrom
Sent: Saturday, July 28, 2012 7:58 AM
To: Gary and Arlene Johnson; HCARC at mailman.qth.net
Subject: Re: [HCARC] Are Engineers Trying To Make Non Engineers Feel Bad??

Fred,

I saw this a couple days ago.  I'm not sure what they are really doing.  The

article I saw talked about experiments to use lasers to communicate from/to 
the earth to/from space.  LEDs flashing Morse code are not what the 
experiment is all about.  I really don't know what the point of the morse 
code is.

As far as using light as the carrier for digital signals, that is just not 
easy.  The stars twinkle becasue of multipath through the atmosphere.  I 
suspect that they will be using a fancy digital modulation scheme with a lot

of error correction coding on it to get a usable signal to the ground.  Of 
course,  tracking the light source isn't going to be easy either.  This gets

tried from time to time and the propagation problems always end up 
overwhelming the system.  There is no point in the system unless you can 
carry 100's of Mb/s over the link.  it will be interesting to see how this 
works.

The people who are worried about light polution I don't think will even 
notice!  several decades ago the AF tried to put a belt of X-band (I think0 
dipoles into orbit to reflect signals for communication.  Some people were 
concerned that it would blot out the sky.  I fact, the AF had a real problem

finding them even at X-band!  Never tried it again.  I think it was called 
Project Westford.

Kerry



______________________________________________________________
HCARC mailing list
Home: http://mailman.qth.net/mailman/listinfo/hcarc
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:HCARC at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html