The knock sensor is there to help the ECU gauge fuel quality not actually to determine knock. If you're car begins to knock the ECU will switch to safety maps (and safety boost). You'd need very sophisticated equipment to actually analyze the signal coming from the knock sensor in order to determine anything useful from it.
"The 300ZX Turbo is a dance; it's a song; it's rolling, roaring automotive art. There is no color that doesn't suit it. There is no mood-lifting chemical substance it can't replace." - Automobile Magazine