METHOD AND A DEVICE FOR MEASURING THE CORRECTION FACTOR FOR THE VELOCITY OF ELECTROMAGNETIC WAVES IN AIR

摘要

1425745 Measuring pressure; temperature; electrically AGA AB 3 April 1973 [10 May 1972] 15797/73 Heading G1N A device for providing a measure of the correction factor for atmospheric pressure and temperature variations used in an apparatus for measuring the electromagnetic wave velocity in air comprises an aneroid barometer box 20 containing a given quantity of gas at approximately atmospheric pressure and with a wall 21 movable in response to variations of pressure, temperature to act on rod 22, link 23, axle 24 in support 25, pointer 26 on scale 27, circuit 28 including e.g. a variable capacitor, rotary potentiometer or oscillator and producing electrical signals which are passed to an instrument 30 utilizing light to measure distance and which is thus corrected automatically for variations in light velocity utilizing variations in volume of the box. The scale is calibrated in terms of the correction factor for the velocity of electromagnetic waves in air as a function of pressure and/or temperature and may also provide for humidity variations.