| 摘要 |
A method for performance monitoring of data transparent communication links, including a method wherein each symbol in an incoming data symbol stream is sampled at the center of each bit period to create a main line data bit stream, and concurrently sampled at a time instant displaced from the center of each bit period to create a second line data bit stream. During each bit period, the digital value of the second line data stream is compared with the digital value for the corresponding bit period in the main line. If the main line and second line digital values are the same, no error is indicated. If they are different, i.e. if, for example, the main line is bit "1" and the second line is bit zero, an error called a pseudo error is entered on a counter. The number of errors counted per number of bits or time is indicated as a pseudo error rate for each point of time displacement in the user-defined set. A pseudo error rate reference curve is independently, and previously determined and stored in a controller that indicates maximum allowable pseudo error rate data as a function of the time displacement from the center of the bit period. The values of the calculated pseudo error rate are compared with the corresponding points on the reference curve, and the deviation from the reference curve is quantified by a newly defined quantity termed a "transmission safety factor". If this factor is below a predetermined level, an alarm/notice is activated to indicate degraded performance.
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