Range sensing system with shuttered receiver.

摘要

To sense the range of several objects energy such as light or radio wave or sound is radiated from the source toward the objects which in turn reflect some to the energy to be detected by the receiver. The source is activated and deactivated in a cyclic pattern at a particular frequency. A shield system blocks sensing of the reflected radiation from the objects and is activated and deactivated in a cyclic pattern at a frequency that is different from that of the source. The output signal of the receiver is compared with a reference signal to determine, from phase differences between the signals, a range value for a particular object from the receiver.