[Laser] NLOS update - IR Laser test at 15 miles

[Kerry Banke]

Last evening I set up my 910 nm 1 W Laser with 4"  beam expander to see if 
the beam was detectable at W6OYJ's home some 15 miles away over the edge of 
a hill.  The Laser was carefully  pointed about 2 degrees above the visible 
horizon in the direction of Ed's home.  The beam modulated at 259 Hz was 
just barely  audible with no filtering.  We set up the laptop running 
Spectrum Lab which showed the signal to be about 25 dB above the noise in a 
1 Hz bandwidth. This is compared to the previous experiment at 3 miles 
where we saw about 35 dB.  The received signal was detectable for maybe 10 
degrees above the horizon.  The weather condition was high clouds with some 
drizzle and the signal was quite stable. I have a JPEG screen capture of 
the signal if anyone is interested.  Setup time on the laser end was about 
an hour to confirm pointing off a landmark tree maybe 1/2 mile away using a 
CCD camera with telephoto lens after dark.  On the receive end, we had a 
signal in a few minutes.
  - Kerry N6IZW -