Electromagnetic Spectrum Question

Not quite sure about your question, but modulated EM waves (information contained in modulation) move at the speed of light. The carrier wave needs to be several times higher in frequency than the modulating wave in order to recreate it at the receiving end.

Nowadays, good integrity is achieved by using digital encoding to transmit information, but the carrier still has to be several times higher than the rate of data transfer. e. g. If you desire to receive data via EM wave at 100 MHz, the the carrier wave needs to be around 700 MHz (minimum) for minimum integrity.

I would go into more detail, but, like I said, I'm not sure what you're asking.

In a word generally it isn't ....

Unless the data rate aproaches the frequency...or there is something about the particular frequency which means it is better or worse than some other frequency.

Some extremes like the very low frequencies used for communicating with submarines while underwater are a special case...but that's secret...so now I'll have to eat you.

Del

I agree with the above answers that they aren't strictly related, but in practice they are somewhat related. Not always but often with lower frequencies the bandwidth of the signal tends to be narrower due to how the spectrum is allocated and how the signals propagate. The narrower the bandwidth the slower the data rate of the information that can be sent.

Shannon rules here.

http://en.wikipedia.org/wiki/Bandwidth

http://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem

Lots of good answers here. The Shannon-Hartley Theorem pretty well defines it mathematically.

Basically, the higher the frequency, the higher the possible data rate.

In digital communications, bits are transmitted over the air by means of phase shift keying. PSK simply means that the phase of the signal is interrupted, or shifted, at certain points. Where the shift occurs determine the values transmitted. For example, in Binary Phase Shift Keying, the shifts occur at 180 degrees and 0 degrees (no shift). These are translated as 0 or 1. Since these occur in every cycle, the more cycles per second (frequency), the higher the potential data rate. This is essentially the explanation of Nyquist's rate.

In reality, there are a ton of other factors that affect the data rate as well -- principally signal quality as Bill pointed out in the first response and the protocol used -- or type of transmission technology: WiFi, GSM/EDGE, CDMA etc. These technologies use a variety of modulation techniques: Binary Phase Shift Keying, Quadrature Phase Shift Keying, 16-Quadrature Amplitude Modulation (QAM) and 64-QAM. They don't all use each modulation scheme; some only a few, some use them all.

If the question means "does the use of microwaves vs meter waves vs light (Angstrom wavelength) make a difference", then in a word, no. Much less technical answer than previous responses, mainly as a point of clarification...