| 摘要 |
<p>The present invention provides a digital transmission system for transmitting a transmission signal produced by superposing a sub-information signal on a main signal by a violation of a CMI coding rule. The sub-information signal consists of several different kinds of sub-information signals arranged in a frame. The system includes a circuit for separating the main signal which is pursuant to the CMI coding rule and a violation signal which violates the rule. A circuit is provided for generating an error pulse by detecting out of the violation signal a time slot of an error bit which appears in the transmission signal. A circuit is provided for detecting a time slot of the first sub-information signal out of the violation signal. The system also includes a circuit for generating a second sub-information signal by inserting a repeater's own sub-information signal in the time slot of the first sub-information signal. An error pulse position varying circuit compares the time slot of the error bit and the time slot of the second sub-information signal. If the two time slots are not coincident, the error pulse is generated and, if the two time slots are coincident, there is generated an error pulse which is delayed by a predetermined number of bits relative to the time slot of the second sub-information signal. There is provided a circuit for generating a violation indication signal by combining an error pulse signal outputted by the error pulse position varying circuit and the second sub-information signal. The violation indication signal is superposed on the main signal by a violation.</p> |
