Patent ID: 8295334

Claim:
A signal transmission system including a receiving apparatus and a transmitting apparatus, comprising: the transmitting apparatus including: an A/D converter that converts an analog audio signal into a digital audio signal, and outputs the digital audio signal, a channel clock, and a bit clock; and a differential signal transmitting circuit that balanced-transmits the digital audio signal to the receiving apparatus via a pair of signal lines in a network cable, mixes the channel clock and the bit clock, and unbalanced-transmits the mixed channel clock and the mixed bit clock to the receiving apparatus via the pair of signal lines; and the receiving apparatus including: a first differential signal receiving circuit that receives the digital audio signal via the pair of signal lines; a second differential signal receiving circuit that receives the mixed channel clock and the mixed bit clock via the pair of signal lines; a first separation circuit that separates the channel clock from an output of the second differential signal receiving circuit; a second separation circuit that separates the bit clock from an output of the second differential signal receiving circuit; a first comparator that compares an output of the first differential signal receiving circuit with a reference electrical potential, and outputs an amplified digital audio signal depending on the result of the comparison; a second comparator that compares an output of the first separation circuit with a reference electrical potential, and outputs an amplified channel clock on the result of the comparison; a third comparator that compares an output of the second separation circuit with a reference electrical potential, and outputs an amplified bit clock on the result of the comparison; a correction circuit that corrects the reference electrical potential of the second comparator such that the reference electrical potential of the second comparator becomes half or approximately half of an amplitude of the channel clock depending on an electrical potential change of the output of the second differential signal receiving circuit; a PLL circuit that converts a frequency of the bit clock output from the third comparator to generate a system clock; and a D/A converter that converts the digital audio signal output from the first comparator into an analog audio signal based on the channel clock output from the second comparator, the bit clock output from the third comparator, and the system clock generated with the PLL circuit, and outputs the analog audio signal.