题目内容：
[阅读题,8.3分] The higher the frequency of the analogue signal, the more often it must be sampled. However, it is usually adequate to sample a signal at twice its highest frequency. Each binary digit used to show a binary bits used by the ADC. If the conversion is made using a four-bit ADC, only sixteen different binary values can be produced. The smallest value is 0000 and the largest is 1111. If an 8-bit ADC is used, then 256 different digital values can be produced. When a measurement of the analogue signal does not coincide with one of these binary values, it must be rounded up or down. 1) If the analogue signal is u=sin(200 t), then the adequate sampling frequency must be more than () A .50Hz. B.200 Hz C.100 Hz D.50 Hz 2) If the conversion is made using a ten-bit ADC, different binary values can be produced. () A. 1024 B.512 C. 256 D.10
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