What's the lowest radio frequency one could usefully transmit phone quality speech/music upon? I am ashamed to admit I have entirely forgotten what little wireless theory I knew.
Well, I don't have any qualifications in physics but I do have a HNC in electronics, specialising in communications.
I can't actually remember anything as I've been doing software since I graduated, but I one thing I specifcally don't remember is any fudge factor for variance in the speed of light in wavelength calculations; the speed of propogation though air was assumed to be constant (at ground level).
(insert hazy memory may be talking bollocks disclaimer here)
The only problem I remember re variance in the speed of light was the fact that different frequencies propogate at different speeds[1]. Fourier shows us that a complex waveform is in fact made up of many sine waves of different frequencies. If all these frequencies are travelling at different speeds when it gets to the other end your waveform is going to be right mullered.
One of my first software jobs was doing some predictive modelling on this to see if it was possible to deduce from a badly distored wave what it should have been based on the known distortion factors. Sadly I don't get to do anything quite so interesting any more.
[1] My work was actually done with optical fibre, but I believe it's a problem with microwave transmission as well.
I can't actually remember anything as I've been doing software since I graduated, but I one thing I specifcally don't remember is any fudge factor for variance in the speed of light in wavelength calculations; the speed of propogation though air was assumed to be constant (at ground level).
(insert hazy memory may be talking bollocks disclaimer here)
The only problem I remember re variance in the speed of light was the fact that different frequencies propogate at different speeds[1]. Fourier shows us that a complex waveform is in fact made up of many sine waves of different frequencies. If all these frequencies are travelling at different speeds when it gets to the other end your waveform is going to be right mullered.
One of my first software jobs was doing some predictive modelling on this to see if it was possible to deduce from a badly distored wave what it should have been based on the known distortion factors. Sadly I don't get to do anything quite so interesting any more.
[1] My work was actually done with optical fibre, but I believe it's a problem with microwave transmission as well.
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