| 摘要 |
Disclosed is a digital transmission test signal generating circuit for generating a digital test signal applied to a digital signal transmission system having a scrambler, a transmission path, a gain control circuit, a phase locked loop, a descrambler, and a display supplied with the output of the descrambler. The digital transmission test signal generating circuit comprises a digital signal generator. The digital signal generator generates repeatedly specific data with a predetermined bit pattern. The timing of the digital test signals is controlled by digital signal generator in such a manner that the data will occur in the duration corresponding to a predetermined area of the display. The specific data generated constitute the worst-case state for the target transmission system to operate in. This provides easy, visual checks on the system to see on a monitor if it functions normally given the worst-case signals to work with. No specialized measuring instruments are required for the checks.
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