6 May 2012

AM lightbeaming down the street

With my wife manning the TX this afternoon and pointing it out of the landing window we managed a daylight speech test today with 100mm optics at both ends at 0.3km using the v.simple AM lightbeam TX described in the previous post. The LED was run with an 80mA standing current. Biggest problem was aligning the TX beam and the lack of talkback, but I managed to get 59+ copy of my wife saying, "I'm bored with this. Come home and have some tea" when I was aligned on the TX beam.

There is no doubt the simple circuit can be refined to improve audio quality when clipping, but it works. The RX is far more sensitive at night too.  I am now finding a way of replacing the XYL for these tests by using another source of speech such as a radio receiver or MP3 player. She is good at cooking and other things, but not at doing optical tests!

Later this week I'll begin experiments with a simple single LED AM 481THz transceiver.


Eldon R. Brown SR said...


Long ago, I did some optic experiments with reflected light using a simple Homebrew three-cornered mirror.

The three-cornered mirror was created using three cheap (1 foot) tile mirrors, the three-way alignment was a little tricky, but very doable with a simple flashlight on a dark evening, and/or looking at the mirror from a distance.

Once setup, the large capture area and the optics of a corner mirror is tolerant enough to do some fun things.

One interesting thing to do was view the HB corner mirror with binoculars, alignment (or lack of) is very obvious.

With a well placed corner mirror you can transmit and receive from the home QTH, and drink fresh tea at the appropriate time.

73 Eldon - WA0UWH - http://WA0UWH.blogspot.com

Bert, PA1B said...

Hello Roger, Sometimes my wife assisted me with putting up an antenna on holiday.
I read this post and later that evening I told my wife what your wife had said. She replayed: Sensible woman. hi
From my own experience I know that the radio is an excellent idea.
73, Bert