Communications – electrical: acoustic wave systems and devices – Distance or direction finding
Patent
1987-09-04
1990-01-16
Tarcza, Thomas H.
Communications, electrical: acoustic wave systems and devices
Distance or direction finding
367127, 367 2, G01S 380
Patent
active
048948101
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method and a device for measuring a distance between two points by means of ultrasonic pulses.
It is well-known that the distance between two points can be measured in various ways. It is known to send an electromagnetic, acoustic or optical signal from a point of origin so that it is reflected back from a target point to the point of origin. The distance between the points is determined on the basis of the to-and-fro transmission time. In this way of measuring, a passive echo from the target point is not usually sufficient, but the target has to be provided with a reflector in order that the magnitude of the echo to be received would be sufficient.
Further, U.S. Pat. No. 4,254,478 discloses a method for the determination of a distance by means of ultrasonic pulses, in which method the target point is provided with a transmitter which sends the pulse back to its point of origin after a determined delay. The function of the delay is to eliminate possible disturbing echos from the surroundings.
A drawback of this known method for the determination of a distance by means of ultrasonic pulses is that the transmitting and the receiving means are separate, and they are designed to function according to whether they are positioned at the point of origin or at the target point of the measuring interval. Furthermore, the measuring result can be read only at one end of the measuring interval. On account of the rigid nature of the measuring methods, it is not easy to observe a varying distance between measuring points.
However, it would often be desirable that observers at different points would be able to easily follow the movements of each other and to control continuously the distance between the locations. This is necessary for, for example, policemen, divers, and in the field of land surveying and building.
The object of the invention is to eliminate the above drawbacks and to provide a method for the measurement of distances, which method enables a more flexible operation than known methods. This is achieved by means of the method disclosed in the prior art portion of claim 1 by means of the operational steps described in the characterizing portion of the claim.
Thus, the basic idea of the invention is to provide a method for measuring a distance in such a manner that devices positioned at different points interact with each other continuously and that the measuring result is visible in both devices.
On the other hand, the object of the invention is to provide a measuring device which is suitable for the measuring method and which ensures the simplest possible use. This is achieved in accordance with the characterizing portion of claim 4.
Since the devices positioned at the different points are identical, even a layman unfamiliar with the measuring techniques finds it easy to use them, and he does not need to know whether he should have with him a device intended for the point of origin or a device intended for the target point. The identical structure of the devices also makes them easier to realize and produce industrially.
In the following the invention will be described in more detail with reference to the attached drawing, wherein
FIG. 1 is a simplified view of transceiver units used in the method according to the invention and the interaction therebetween,
FIG. 2 illustrates on a time axis the significant events of the measuring procedure according to FIG. 1,
FIG. 3 is a block diagram of the structure of the transceiver unit used in the method according to the invention.
In FIG. 1, the transceiver (transmitter-receiver) units LVA and LVB are positioned at a determined distance from each other. The transceiver unit LVA comprises a transmitter L.sub.A and a receiver V.sub.A, and the transceiver unit LVB correspondingly a transmitter L.sub.B and a receiver V.sub.B. The measuring can be started at either end of the measuring interval. In the following example, the measuring is started by means of the device LVA by sending with the transmitter L.sub.A an ultrasonic pulse to the devic
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patent: 3895382 (1975-07-01), Litchford
patent: 4026654 (1977-05-01), Beaurain
patent: 4254478 (1981-03-01), Dumas
patent: 4376990 (1983-03-01), Metchev
Mikrovalmiste U.J. Pulkkanen Oy
Pihulic Daniel T.
Tarcza Thomas H.
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