Ultrasonic Distance Meter

Ultrasonic Distance Meter

Ultrasonic Distance Meters are terrific and affordable alternatives to a tape measure for distance measurements. They offer the convenience of being able to make measurements without a second person to hold the measuring tape. Easily measure hard-to-access areas, like high ceilings or depths such as an elevator shaft or well, without climbing a ladder.

Cable Height Meters
One notable application for ultrasonic distance meters is the measurement of cable height, cable sag and overhead clearance

General tips when using distance meters

• Choose a target that is flat, hard and smooth
• Use a piece of cardboard or similar material if the target size needs to be increased
• Always measure perpendicular to the target. Do not point at an angle
• Speed of sound increases with higher temperature and to a small extent speed increases at higher humidity. Ultrasonic distance meters compensate for temperature by including an ambient temperature sensor. Ultrasonics have a beam angle. Best analogy is a flashlight pointed at a wall. The cone increases and decreases as one moves away or comes closer. When using ultrasonics for long distances care must be taken not to have objects within the operating beam angle. Larger target sizes are needed at longer distances.

How does a distance meter work?
Distance meters operate on the principle of time of flight. Ultrasonic distance meters will excite a piezo crystal with high voltage low amperage to create a sound pulse in the kHz range. The time taken for the pulse to make a round trip to the target is measured. The speed of sound is known and so the distance can be calculated. Similarly laser distance meters send a pulse of light, however light pulses are much faster requiring high speed timers.