JPH0413672B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ultrasonic transmitter/receiver comprising a plurality of identical transducers.

(Prior Art) For example, when performing underwater detection using a high frequency of 100 kHz or higher, propagation loss becomes a major problem. To deal with this, it is possible to increase the transmission power by increasing the diameter of the transducer, but the directivity will become narrower, resulting in detection omissions and making it impossible to provide an appropriate detection width for underwater detection. . For this reason, two methods can be considered: a method in which a plurality of identical vibrators are arranged to equivalently widen the directivity width, and a method similar to the above by using a plurality of vibrators with slightly different frequencies.

(Problems to be Solved by the Invention) However, in the case of , phase synthesis is required and the circuit for this becomes complicated and large, and in the case of , the frequencies of multiple oscillators are different, so the production price and the desired frequency of use of the main body There are problems such as being far removed from the original.

(Means for Solving the Problems) This invention has been made in view of the above, and includes a plurality of identical vibrators arranged so that the directivity directions of each vibrator are continuous, and an excitation circuit that excites at a frequency, a plurality of mixing circuits into which the signals received by each vibrator are sent and whose mixed output includes a constant frequency signal, and connected in series to each of the above mixing circuits, An ultrasonic transmitting/receiving device is provided that includes a plurality of filters that extract the constant frequency signal, a plurality of detection circuits that detect the outputs of the filters, and an addition circuit that adds the outputs of the detection circuits.

(Operation) According to the present invention, received signals at approximately the same frequency can be obtained by the individual vibrators directed in a wide range of directions. Then, each of these signals passes through a mixing circuit to produce a mixed output of the same frequency, and passes through the same filter and detection circuit to become a display signal.

(Example) FIG. 1 is a circuit diagram showing an example in which two vibrators are used.

In the figure, T _r1 and T _r2 are the same vibrator.
Oscillators are manufactured to match the frequency required for efficiency with the natural vibration frequency, but even if the frequency deviates slightly (about 1%), for example, as shown in Figure 3, it will hardly affect the gain due to its nature. Generally, this does not occur.

The vibrators T _r1 and T _r2 are used, for example, at frequencies f ₁ and f ₂ near the center frequency f _c . 1, 3 and 2, 4 constitute an excitation output circuit for that purpose;
Reference numeral 2 designates an oscillation circuit that sends out oscillation outputs of frequencies f ₁ and f ₂ , and 3 and 4 designate amplifier circuits that power amplify the outputs of the oscillation circuits 1 and 2 in order to obtain transmission power. 5
is a transmission trigger generation circuit that sends out a constant periodic pulse for operating the amplifier circuits 3 and 4 for a certain period of time. As a result, _the frequency f _{1 ,}
A high frequency ultrasonic pulse of _f2 is transmitted.

FIG. 2 is a diagram for explaining the relationship between the arrangement of the transducers T _r1 and T _r2 . Figure a shows the pointing width θ and the operating frequency f _c of one transducer T _r attached to the bottom of the ship (not shown), and the diagonally shaded circle at the bottom indicates the ultrasonic irradiation. It shows the face. Figure b shows two of the same transducers T _r1 and T _r2 as this transducer T _r .
This figure shows a state in which the beams are placed close to the bottom of a ship, etc., so that the directivity width is 2θ. Note that SB is the ocean floor.

Reference numerals 6 and 7 are trap circuits for switching signal paths during transmission and reception, 8 is an adder circuit for adding both received signals, and 9 is an amplifier circuit for amplifying the added output. 10 and 11 constitute a first mixing circuit;
is a local oscillator that transmits frequency f _c1 , and 11 is a mixer. Therefore, as the output of the mixer 11, f ₁ ±f _c1 ,
A frequency signal of f ₂ ±f _c1 is obtained. 12 is f ₀ (= f ₁ − f _c1
or f ₁ + f _c1 ) A filter that passes only the frequency signal,
13 is a detection circuit for detecting a signal. Also, 1
4 and 15 constitute a second mixing circuit, 14 is a local oscillator that sends out the frequency f _c2 , and 15 is a mixer. As the output of the mixer 15, frequency signals of f ₁ ±f _c2 and f ₂ ±f _c2 are obtained. 16 is f ₀ (= f ₂ − f _c2 or f ₂ + f _c2 )
A filter 17 which allows only frequency signals to pass is a detection circuit. Reference numeral 18 denotes an adder circuit that adds the output signals of the detection circuits 13 and 17. Since this method combines detected outputs, there is no need to consider complicated phase synthesis means. The added signal thus obtained is guided to a display (not shown) as a display signal. Also, each detection signal can be displayed individually.

(Effects of the Invention) As described above, according to the present invention, since the plurality of vibrators used are all the same, it is inexpensive and easy to install. Furthermore, since the frequency used is also in the immediate vicinity of the center frequency f _c , it can be regarded as detection based on the frequency f _c , and it can be said that the directivity width has been equivalently expanded.

Furthermore, mixers 11 and 15, filters 12 and 16
Also, since the detection circuits 13 and 17 can be the same, circuit design is also facilitated.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. FIG. 2 is a diagram for explaining the arrangement of vibrators. FIG. 3 shows a frequency-gain characteristic diagram of the vibrator. 1, 2...Oscillation circuit, T _r1 , T _r2 ...Resonator,
10,14...Local source, 11,15...Mixer, 1
2, 16...filter, 13, 17...detection circuit.

Claims (1)

[Claims] 1. A plurality of identical transducers arranged so that the detection directional ranges (directional angles) of each transducer are continuous; and a plurality of excitations that simultaneously excite each of the transducers at different frequencies. a circuit, an adding means for adding up the echo signals captured and sent out by each of the above-mentioned vibrators, and mixing the output signal sent out from the adding means and a plurality of local signals having different frequencies to generate a specific signal. A plurality of mixing circuits that each send out signals containing the same frequency, a plurality of filters that are connected in series to each of the mixing circuits and extract only the specific frequency signal, and a plurality of detection circuits that detect the outputs of the filters. An ultrasonic transmitting and receiving device.