Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Having Fun With Through-the-Air Optical Communications Kerry Banke N6IZW [email protected] Updated 06/08/05 Basics of Common Amateur Equipment Audio communicators Wideband Laser Pointer link Non- line-of-sight communication Field Day Laser QSO Modulated Light Sources HeNe Lasers Chopped Using FAN for MCW Can be 10% AM Modulated Bragg Cell AM Modulator Laser Diodes & LEDs Pulse On/Off Linear AM Red and I/R Wavelengths Class 2A Visible Lasers (400 to 700 nm) Lasers emitting visible light not intended for viewing, and under normal operating conditions would not produce a injury to the eye if viewed directly for less than 1000 seconds.(i.e. bar code scanners) Class 3a Lasers that normally would not cause injury to the eye if viewed momentarily but would present a hazard if viewed using collecting optics (fibre optics loupe or telescope). Transmit Beamwidth Laser - Typically 1-2 milliRadian (.057-.114 deg) Spot Size > 100 Feet at 13 Miles LED (with optics) - 1.4 degrees Spot Size >1000 feet at 13 Miles Photo Detectors Photo Transistors Sensitive but slow & Noisey PIN Diodes - Fast But Lower Output Low Noise LEDs - High efficiency LEDS look similar to Pin Diode in Sensitivity Relative Speed & Noise Unknown Microphone Audio Amplifier Fresnel Lens 35 KHz VCO Power FET LED Transmitted Red Light Laser Pointer 145 MHz Oscillator 35 KHz Amplifier PIN Diode Photo Detector 2M FM Receiver 145.035 Mixer Optical Communicator Block Diagram Received Red Light W9FQN 35 KHz audio optical communicator schematic TV Camera CH3 RF Modulator Laser Pointer Amp 0 dB Video RF Mirror MIC. RF Amp Pin Photodiode Television on Ch 3 -45VDC Bias Reasonably flat frequency response to 500 MHz and Useable to 1300 MHz Basic TV Video/Audio modulated RF Laser pointer link - N6IZW - 05-16-05 Cloud Bounce Dust/pollution/moisture scatter NLOS Communication Paths Tx Laptop with PSK31 260 Hz Audio Laser Driver Interface 910 nm Laser Diode & Lens IR Tx Beam 4” optics Both Tx & Rx Rx Laptop with PSK31 260 Hz Audio Rx Lens Pin diode Preamp Maximum distanced tested so far is 15 miles NLOS communicator setup using PSK31 IR RX Beam 3 mile NLOS signal Displayed using Spectrum Lab Free softeware NLOS Reception equipment Basic K3PGP type optical receiver used for NLOS Experiments. So sensitive you can hear the light from stars scintillating which sounds like wind rushing over a microphone Simple Photo darlington photo detector for use with the soundcard in in a PC. Laser Rifle scope Positioner LED Tx Rx 35 KHz audio communicator Front View Scope Laser Rx unit LED Tx unit LED Transmitter Early LED Tx unit capable Of 4 miles with 35 KHz communicator Pin photodiode with preamp 35 KHz audio communicator Fresnel Lens cut from plastic reading Sheet lens Micrometer Az/El adjustment Moves scope & Laser only Where to Find More Information A Construction Article for the 35 KHz optical communicator Published in June-Aug Issues of 73 Magazine by Chuck WB6IGP Who is a Member of The San Diego Microwave Group and Writes the “Above & Beyond” Column for 73 Mag. Good Laser Web Site and Laser Email Reflector: http://www.qsl.net/wb9ajz/laser/laser.htm LED/Reflector Test Fixture Round reflector with LED in center which is modulated at 35 KHZ. Used to align Tx & Rx optics One end of 15 mile Field Day laser contact Laser pointer seen from 15 miles away Sun Relflected off mirror from Palomar Mt.