1. Distance measurement

The commonly used distance measurement methods include tape measuring distance and photoelectric ranging. Measuring distance is measured with a tape ruler that can be rolled up/test large/along the ground, belonging to the direct measuring distance. Photoelectric ranging is to transmit and receive modulation light wave between two points with instruments, and determine the distance according to its propagation speed and time, for electronic physical ranging. Photoelectric ranging belongs to indirect ranging.

2. Measure the distance with a tape

Type of measuring tape and measuring distance Tool

Measuring tape the measuring tape can be 20m, 30m, or 50m in length.

3. Distance measurement

Generally, n whole foot section is measured first, marked on the ground with measuring brazing or marking, and finally measured the length, the total length is:

In order to prevent errors in measurement and improve measurement accuracy, round-trip measurement is required. The difference between the measured length and the measured length, divided by the approximate value of the length, into the numerator 1 fraction, known as the relative error, or relative accuracy. The relative accuracy of the gauge distance should not be less than 1/3000.

The standard length L is between the two endpoints of the scale field, which is measured with the authenticated steel ruler and obtained by temperature correction L ', (L-L ')/L is the number of corrections per meter. (4) length correction of steel measuring tape distance (1) when the length correction is greater than 1/10000 of the length of the ruler, the ruler length correction should be added;(2) when the temperature difference between the measurement distance and the standard temperature is plus or minus 10 degrees, the temperature should be added to correct; (3) If the ground slope measured along the ground is greater than 1.5%, the height difference should be added to correct.