| 摘要 |
For safety reasons, a redundant measurement of the duty factor of pulse-with-modulated signals 12 is performed in a vehicle control unit, such as in particular a brake control unit 10. Here, in the prior art, the duty factor of the pulse-width-modulated signal 12 is determined by way of a low-pass filter and an analogue-digital conversion and is compared with a value determined by way of a memory and comparison unit. According to the invention, a direct determination of the duty factor of the signal 12 is performed by way of periodic sampling. For this purpose, the durations of the states 18 and 20 of the signal 12 are determined with the aid of a clock signal 32. After one complete cycle, the duty factor can then be determined directly from the ratio of the durations of the states 18 and 20. |
