Well Neil, The Gilbert Police Dept. doesn't seem to have problems withtheir
alignment and scintillation......... They were able to ticket mewith a lasar
gun at 15 MPH over the limit on my Harley, in therain. However, I was actually
doing 5 MPH less than whatthe officer "clocked" me at sooooo. I'm for anything
that will add 5mph to my speed at Bonneville!
The problems with using a laser for free- space communications are:
1. Alignment-- a laser has an extremely narrow beam which makes
alignment difficult. This can be overcome by using a beam expander lens
but the laser power requirement goes up.
2. Scintillation-- over a long path, the heat refraction of the air
makes the optical signal unsteady, just like a "twinkling star";
overcoming this takes big mirrors or diversity receivers.
Regards, Neil Tucson, AZ
[mailto:email@example.com] On Behalf Of Jon Bishop
Sent: Friday, October 13, 2006 7:59 PM
Subject: Re: Timing light wires
What about a data link via a laser-beam? I realize that the distance
you're covering is enough that you will have to calculate for the
curvature of the earth, but if you had towers at either end you
should be able to aim a beam at a target and get the signal from the
timer at one end to the timing booth at the other end without having
to deal with wires. I don't know much about how the timing system
works now, but if you had something at either end with a beam that is
broken to signal the start/end of the course, those devices could
have a synchronized clock, and even if the signal is broken, the time
would be measured and stored for re-tmit when the link is
reconnected. Just a thought.