Cmi-code coding method, cmi-code decoding method, cmi coding circuit, and cmi decoding circuit

A CMI decoding method for regenerating a first signal (511) and a second signal (512) from a CMI code (521) in which the second signal is superposed on the first signal, comprising the steps of:

• converting the CMI code to the first signal while, when a first code (115) coded by a CMI coding rule different from that for the CMI code is detected, outputting (522) a signal indicating the detection of the first code;
• and
• converting a second code (130), disposed in the time slot after a time slot where the first code is disposed, to an output (523) of two binary bits of the first signal according to the different CMI coding rule

A CMI coding circuit (100, 100′) for converting a first signal (511) and a second signal (512) to a CMI code (517, 817), comprising:

• a sampling circuit (515) for sampling the second signal at a predetermined period;
• a coder (516, 516′) for converting a received signal to a CMI code,
• wherein the coder converts the first signal to a CMI code by using the first clock, converts the first signal in a certain time slot (110) to a first code by a CMI coding rule different from that for the CMI code according to a sampling result of the second signal by using the second clock, converts two bits of the first signal originally disposed in the time slot where the first code is to be disposed and the next time slot (120) thereof, to a second code (130) by the different CMI coding rule, and places the second code in the next time slot.

A CMI decoding circuit (101, 101′) for regenerating a first signal and a second signal from a CMI code (521) in which the second signal is superposed on the first signal, comprising:

• a decoder (522) for converting a received CMI code to the original signal;
• a low speed signal regenerator (525, 526, 527, 528, 821, 822, 824, 825) for regenerating a signal (529, 529′) from the output of the decoder (522) according to a predetermined rule,
• wherein the decoder converts the received CMI code to the first signal, detects a first code coded according to a CMI coding rule different from that used for the CMI code, and converts a second code disposed in the time slot after a time slot where the first code is disposed to two binary bits of the first signal (523) according to the different CMI coding rule, and the low speed signal regenerator regenerates the second signal, which has been superposed on the first signal at a transmission side, from the decoder (522) output according to a predetermined rule.