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Most of the websites i have looked at, say that the frequency of middle C note is approximately 261.626 Hz. and that middle C on guitar is at the 5th string 3rd fret. but my tuner says the frequency at the 5th string 3rd fret is 130.81 Hz.
The frequency of a controller / receiver basically equates to the number of times the signal completes one wave a second. The higher the frequency, the more electromagnetic waves a second and the higher the energy of the signal. On R/C vehicles, the frequency is generally 25-75MHz or 2.4GHz - a higher energy frequency.