| 摘要 |
With an electrooptical distance meter a reference signal is timeshifted by means of an electronic phase shifter (20), until it has a given phase relation to the measurement signal. Both signals are compared in phase by a double balanced mixer (22), the output of which directs the electronic phase shifter (20) by a control loop (20, 22, 23). The phase shift is measured after frequency conversion by two additional double balanced mixers (24, 25). Thus handy precision distance meters with measurement frequencies about 500 MHz may be built, comprising control loops for laser diode transmitter (1), avalanche diode receiver (13), phase shifter (20) and intermediate frequency, as well as a processor (5, 29) control for automatic function of the instrument.
|
