Why are the channels (78) in the channel subsets (13) using 6MHz spacing?

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    Question: Why are the channels (78) in the channel subsets (13) using 6MHz spacing?

     

    Answer:

    For the channel hopping algorithm to work, it is necesaary to have a prime number of channels. Because the bridge doesn't just go to the next channel in the subset, it skips 2-5 channels and by using a prime number of channels we guarantee that the entire channel subset will be covered no matter how many channels are skipped. It was found that 13 is a nice prime number of channels per subset, as the algorithm worked well with this number.