Re:High frequency EMR? (Score 1)

it is to do the emmisitivity and reflectivity, mostly reflectivity but emisitivity is related) of objects to specific frequencies.

shine white light on to a red house brick, the red bits are reflected, the reflectivity of photons in the red part of the spectrum is higher. and the brick heats up, other frequencies are obsorbed in to the object, increasing to a degree the kenetic energy, which then results in radiated heat (Ingra Red)

the frequency of the EM radiation you use has little effect on the amount of interference you recieve. the more important factor is the amount of noise in that band. eg a system that tries to transmit information by infra red is not the best choice for a coms system. IR is readily radiated by objects in our environment which means that bespite a wave length of about 800nm we can only transmit at a few bits/s or at most half a dozen megabit/s

there is a famious theorem in regards to the amount of information you can transmit in a specified chanel at a particular level of noise, it's called the Shannon Information Capacity Theorem.

C = B log(1+SNR)

C is the maximum capacity of the channel (bits per second), B is the bandwidth of the channel, usualy near enough to some percentage of the carrier, and SNR is the signal to noise ratio.