| 摘要 |
The speedometer is for use on a vehicle such as an automobile or train for providing a continuously updated digital reading of vehicle speed and a cumulative digital reading of total mileage traveled. By means of a front end transmitter-receiver antenna arrangement, a signal is provided, the frequency of which corresponds to velocity of the vehicle. This signal is coupled to a novel duty cycle detector which essentially rejects spurious noise signals and passes only signals of a predetermined duty cycle. A true signal is passed to a signal stabilization circuit which is responsive to the frequency of the signal for essentially replacing lost signal pulses. The pulse signal which is representative of vehicle speed is then coupled to both the odometer counter for ultimately providing a reading of mileage traveled and to the speedometer counter for ultimately providing a reading of vehicle speed.
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