| 摘要 |
<p>The suitability of a transmission path (16 or 18) for transmission of digital data is monitored by transmitting a test signal over the transmission path. The test signal is composed of a succession of video signal lines each including a horizontal sync pulse and a pattern of digital 1's and 0's at a predetermined frequency and occurring on each line at the same data position relative to the horizontal sync pulse. The patterns comprise a reference pattern of alternating 1 's and 0's and test pattern of 1's and 0's at random or in a sequence known to be disruptive to the transmission path. The test signal is received and is displayed on a waveform monitor (28) with the reference pattern and the test pattern interleaved with the complement of the reference pattern and complement of the test pattern, so that the four patterns are superimposed and enclose a generally eye-shaped area.</p> |
