Five by five is the best of 25 possible subjective responses used to describe the quality of communications, specifically the signal-to-noise ratio. As receiving stations move away from an analog radio transmitting site, the signal strength decreases gradually, causing the relative noise level to increase. The signal becomes increasingly difficult to understand until it can no longer be heard as anything other than static.:38 Five-by-five is the best possible Readability and Signal Strength Report previously used by some radio services. The term has its origins in the Q code used for commercial radiotelegraph communication, and later adopted by other radio services, especially amateur radio. The first number is the answer to the question "How do you receive me?" (Q code QRK), typically answered with "I am receiving (1–5)" where 1 is unreadable and 5 is perfect. The second number is the answer to the question "What is the strength of my signals?" (Q code QSA), typically answered with "The strength of your signals is ... (1 to 5).". "5 by 5" was the answer to the QRK/QSA questions to indicate the best quality signal. "5 by 5" being the best quality was applied to other things by analogy.