Experimental Study of Horn Influence on Sound Ranger Sensitivity

The tasks where it is necessary to measure the exact distance between objects are considered. Ultrasonic rangefinders have been found to be the most effective for distance measurement due to their non-contact operation, high accuracy, wide measurement range and ability to function in various conditions. The use of a horn in ultrasonic rangefinders is a fairly common practice, as they allow to significantly increase their sensitivity. It is known that there are many different types of horn that differ in shape, size and materials. However, the most common of them are conical horns, which do not require complexity in manufacturing and have a fairly low cost. Six variants of experimental horns with lengths ranging from 10 mm to 60 mm were designed and manufactured using 3D printing. An experimental stand with a rotating platform has been developed, which has a receiver and a transmitter between which the distance and sound pressure directional diagrams are measured. Experimental studies were carried out at distances from one to three meters with an interval of half a meter. All measurement results were processed and directional diagrams were constructed for all cases using one of the manufactured horns. Directional diagrams are presented for the minimum and maximum distances of the selected range. The study showed that the use of a horn with a length of 50 or 60 mm resulted in an increase in sound pressure level by 10 dB compared to measurements without a horn. But when the length of the horn is reduced to less than 40 mm, there is a decrease in the efficiency of sound emission. This is explained by the violation of optimal conditions for the formation of a sound wave, which leads to energy losses and expansion of the directional pattern. The most rational length of the horn, at which there is no drop in the efficiency of the emission of sound waves, is substantiated.