I evaluated the efficiency of the ultrasonic range meter which was made this time.
I put the sound horn but when doing the long-range measurement, it has sometimes detected the reflection from the object nearby.
 Adjustment of the range meter
It adjusts the display of the range meter. Establishe the VR3 in the middle. If making the VR3 in the middle in case of the average measurement environment temperature, it is possible to revise the display near the temperature.
 Separate the range meter from the object by 1 m and adjust the VR2 for the display to become 1.00.
After that, the adjustment of the VR2 is unnecessary except for the case with the special temperature.
When turning the VR3 after doing above adjustment, the display changed as follows.
Condition
of VR3 | Display |
Temperature *1
which displays 1.00 |
When finishing
Counterclockwise | 0.97 | 3.0 °C |
| Middle | 1.00 | 20.0 °C |
When finishing
Clockwise | 1.04 | 42.7 °C |
*1:The maximum and the minimum are the value which was calculated from the display.
Measurement of the most short distance
When bringing the range meter close to gradually the object, display's change stopped at about 34 cm.
The circuit this time is using 0.1µF as the capacitor of the reception signal detector for the mis-detection prevention. At less than 34-cm distance, the reception pulse is guarded with the mis-detection prevention circuit too.
To measure the short distance more, making the sending-out time of the transmission pulse short, the value of the capacitor for the mis-detection prevention must be made small.
But, the energy of the ultrasonic becomes little when making the sending-out time of the transmission pulse short and it becomes not possible to do the long-range measurement.
Most long-range measurement
The long-range measurement is difficult a little. To measure the correct distance, following condition is necessary.
 | The object be perpendicular to the range meter. |
| The surface of the object be flat. |
| There is not object which reflects the ultrasonic around. |
When becoming the distance more than 10 m, the figure to 10 m isn't displayed because there is not an indicator. However, as for the 3 digits below, it displays the measurement result.
Because the transmission energy isn't big, about 10 m are the measurement limit of this range meter.
Attention in case of the measurement
When measuring, the range meter and the object must be right-angled.
When not right-angled, it sometimes measures the distance to the object of the destination that the ultrasonic was reflected, too.
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