Transmission and receiving apparatus and method having different sending and receiving clocks

A signal receiving apparatus operating in synchronization with a clock having a predetermined period to receive a transmission signal, comprising:

• a first level retaining part that retains a signal level of the transmission signal at a rising edge of the clock as well as at a falling edge of the clock;
• a first selecting part that selects and outputs one signal level changing first to a direction expected to be changed next out of two signal levels retained by the first level retaining part;
• a second level retaining part that retains an output of the first selecting part at a rising edge of the clock as well as at a falling edge of the clock;
• a second selecting part that selects and outputs one signal level changing first to a direction expected to be changed next out of two signal levels retained by the second level retaining part;
• a preceding level retaining part that retains an output of the second selecting part at a rising edge of the second clock;
• and
• an EXOR circuit part that inputs the output of the second selecting part and an output of the preceding level retaining part to generate and output a pulse signal from an exclusive logical sum of the two outputs.

A transmission method of transmitting a signal, comprising:

• using a transmission signal generating part to generate a transmission signal in synchronization with a first clock having a first period, the transmission signal having a signal level that is changed in response to an input of a first pulse signal;
• and
• using a second pulse generating part to generate a second pulse signal in synchronization with a second clock having a second period, the second pulse signal corresponding to the second period in response to changing of a signal level of the transmission signal;
• wherein the receiving step includes
• a relaying step of retaining the transmission signal based on a change in signal level at a signal level immediately after the change and outputting the signal level immediately after the change within a predetermined delay amount from the time of the change, and
• a third signal generating step of generating and outputting the second pulse signal corresponding to the second period from an output at the relaying step.

A signal receiving method performed by a signal receiving apparatus, the method being directed to receiving a transmission signal in synchronization with a clock having a predetermined period, comprising:

• utilizing a first level retaining part to perform a first level retaining step of retaining a signal level of the transmission signal at a rising edge of the clock as well as at a falling edge of the clock;
• utilizing a first selecting part to perform a first selecting step of selecting and outputting one signal level changing first to a direction expected to be changed next out of two signal levels retained at the first level retaining step;
• utilizing a second level retaining part to perform a second level retaining step of retaining an output at the first selecting step at a rising edge of the clock as well as at a falling edge of the clock;
• utilizing a second selecting part to perform a second selecting step of selecting and outputting one signal level changing first to a direction expected to be changed next out of two signal levels retained at the second level retaining step;
• utilizing a preceding level retaining part to perform a preceding level retaining step of retaining an output at the second selecting step at a rising edge of the second clock;
• and
• utilizing an EXOR circuit part to perform an EXOR step of inputting the output at the second selecting step and an output at the preceding level retaining step to generate and output a pulse signal from an exclusive logical sum of the two outputs.