Where did the saying "five by five" originate from?

Question

meaning "it's all good"

Answer 1

Radio signal strength times clarity.

Five by five is a radio communications expression that means "loud and clear." The first number five represents the S units of reception strength (which could be read from a meter). The second five is a rating of the signal clarity (which was subjective).

I believe that Ham radio operators were the first to use this, but it was picked up by the military and even the F.C.C. as the amateurs became "professionals."

"Five by five" is a strong, clear signal.

Answer 2

It originally meant that there was the clearest, best broadcast signal that you could have on a two way, ship to ship to shore radio. One was the worst, five the best.
http://en.wikipedia.org/wiki/Five_by_five

Answer 3

It came from a song called Mr 5 By 5. It's an old jazz swing song. It means 5 foot tall and 5 foot wide.