Abstract: A nonsynchronous communication controller for an AV system is disclosed including a first collision detector for detecting a first collision signal and a noise of an impulse component; a noise removing portion for detecting the first collision signal without noise; a 1/2 window signal generator for producing a 1/2 Tm window signal; a delay compensator for compensating for time base delay; a first collision compensator for comparing and mixing a compensation signal of the delay compensator and the 1/2 Tm window signal of the 1/2 window signal generator; a second collision detector for comparing and mixing the first compensated signal of the first collision compensator and the 1/2 Tm window signal of the 1/2 window signal generator; a window signal generator for changing the second collision signal of the second collision detector to a window signal, and interrupting data transmission to a microcomputer; a transmission determining portion for comparing and mixing the window signal of the window signal generator