Steve Anderson wrote:Most of the designs on Chris's site will work at NBTV frequencies, the bandwidth was limited to about 300Hz-3kHz simply to get the best signal-to-noise ratio for telephone-quality speech. By opening the bandwidth up to say 10kHz you could expect the s/n ratio to worsen by 6-9db depending on the noise spectra.
But given a vastly shorter distance noise shouldn't be too much of a problem. I didn't have any problems with noise on my laser-link for NBTV up to 500 metres or so. What was a problem was atmospheric disturbances (scintillation) as I was using a laser-diode, not a LED/Luxeon as Chris did.
Steve A.
I was looking at your design as you know i tried the transmitter some time ago ,does the receiver just work on a Pwm signal ? its a very different design.
500 meters is pretty good range ,i did read on their site its better to use a luxeon ,i wonder if theres a point where ones better than the other sounds like the luxeon wins for long range .
I was thinking their light receivers must be better than our head amp versions due to its range ,i am curious as to what one of these would be like compared to our best head amp design .
The light sensor would be the heart of it ,i have tried my head amp with an LDR and solar cell the dome sensor which we now know is a photo diode and 3 photo transistors ,for me the photo transistor seems better it was a touch better than the dome sensor even with its larger surface area .
One thing i don't understand is why don't we use a bank of either photo diodes or what ever bit like in a nbtv monitor we want more light we use more than one luxeon .
May be its not as simple as just hooking up these together ? .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.