JP2875118B2 - Ultrasonic detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic detecting device, and more particularly to an ultrasonic detecting device mounted on a high-speed ship.

[0002]

2. Description of the Related Art As is well known, an ultrasonic detection device is used to detect a fish school, an object floating near the sea surface or in the sea by mechanically or electronically changing a transmitting and receiving beam direction. Conventionally, as a type of ultrasonic detection device, for example, the one shown in FIG. 3 is known.

FIG. 3 mainly shows the configuration of a receiving system. The transmission signal transmitted by the transmission unit 1 is applied to the transmitter / receiver 3 via the transmission / reception switch 2. Thereby, an ultrasonic wave is transmitted, a reflected sound wave from near the sea surface or in the sea is received, and a reception signal converted into an electric signal is provided to the reception processing unit via the transmission / reception switch 2. The transmitter / receiver 3 in the illustrated example shows a type in which the direction of the transmitted / received beam is mechanically changed, and the direction of the transmitted / received beam is set to be a traveling direction of the ship and a direction substantially parallel to the sea surface. Indicates when

[0004] The reception processing unit is generally configured to perform alternate processing of band filtering and amplification in multiple stages. In the illustrated example, the band-pass filter 31, the amplifier 5, the band-pass filter 32, and the amplifier 7 perform alternate processing of band-pass filtering and amplification by two.
It shows the case of performing it twice.

[0005] Here, the passband of the bandpass filter (31, 32), as shown in FIG. 4, a bandwidth Δf of the output level is reduced 3dB with respect to the center frequency f _0, conventionally it is fixedly Was set.

[0006]

By the way [0007], in recent years, the boat speed is Ri tended to speed, enough to more than at most 10 knots
30 knots, or even more than 40 knots, from the speed of the ship
Faster to boat speed even that has been not rare, but the shift amount f _d of the frequency due to the Doppler effect as is well known, as shown in Equation 1, increased with faster boat speed, also the beam direction The effect is greatest when the ship is in the direction of travel and parallel to the sea surface. Note that in Equation 1, c
Is the speed of sound in water [m / s], V is the speed of the ship [m / s], f is the frequency [Hz], and θ is the angle between the transmitting beam direction and the sea surface [deg].
It is.

[0007]

F _d = (2Vf / c) · cos θ

In short, the pass speed of the band-pass filter is fixedly set at the time when the ship is stopped because the influence of the Doppler effect is small because the speed of the ship is low in the past. then, since the Doppler shift amount increases, then a frequency of the received echo (obtained by adding the Doppler shift amount f _d to the transmission frequency) is out of the bandwidth Delta] f, as high speed craft the result of a conventional ultrasound detection device However, there is a problem that the detection capability is reduced if the device is mounted on a vehicle.

[0009] Specifically, the higher the ship speed, the longer the traveling distance per unit time, until the ship can be stopped.
If the detection ability is shorter than the distance until the ship can be stopped, the detected target cannot be avoided,
If the target is a school of fish, the fish will pass through the area directly in Shanghai, and if the target is a floating object on the sea, it will collide with the target.

As a measure to cope with this, it is conceivable to set the pass band width of the band-pass filter wider than in the past, but if the reception band is widened, the reception noise component increases and the detection capability is rather lowered, which is not appropriate. In other words, since the conventional fixedly set passband width is a suitable value, it is not preferable to change it.

SUMMARY OF THE INVENTION The present invention has been made to meet such a demand, and an object thereof is to provide an ultrasonic wave capable of sufficiently maintaining a predetermined detection capability without changing the pass bandwidth of a band-pass filter even when the ship speed is increased. An object of the present invention is to provide a detection device.

[0012]

In order to achieve the above object, an ultrasonic detection apparatus according to the present invention has the following configuration. That is, ultrasound detection device of the present invention, there is provided an ultrasonic detection device for detecting the sea surface near or underwater object by transmitting and receiving ultrasonic waves are mounted on a ship moving at a high speed; the received signal Ship
A filter for performing a filtering process with a predetermined pass bandwidth at the time of stopping, wherein a center frequency is variably set without changing the predetermined pass bandwidth according to a control signal provided from the outside; A boat speed data generating section for detecting speed and generating and outputting boat speed data; a transmitting / receiving beam direction detecting section for detecting an angle between a transmitting / receiving beam direction and a sea surface; and a receiving signal based on the boat speed data and the angle. And calculating a Doppler shift amount and outputting the control signal for shifting the center frequency of the variable bandpass filter by the calculated and acquired Doppler shift amount.

[0013]

Next, the operation of the ultrasonic detecting apparatus according to the present invention having the above-described structure will be described. According to the present invention, the band filter is of a type capable of changing the center frequency, and the shift amount calculation unit calculates the angle between the ship speed data (output of the ship speed data generation unit), the transmission / reception beam direction, and the sea surface (the transmission / reception Output from the beam direction detector) to calculate the Doppler shift amount,
The center frequency of the bandpass filter is shifted by the calculated Doppler shift amount.

Therefore, even if the ship speed is increased and the Doppler shift amount is increased, the reception processing can always be performed with a suitable bandwidth.
The detection ability does not decrease and can be maintained at a predetermined level.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an ultrasonic detection device according to one embodiment of the present invention. In FIG. 1, the receiving system has a two-stage configuration as in the conventional system (FIG. 3). However, variable band filters (4, 6) are provided in place of the band filters (31, 32), and the ship speed data is provided. A generator 8, a transmitted / received beam direction detector 9, and a shift amount calculator 10 are provided. Hereinafter, a description will be given mainly of a portion according to the present invention.

The variable bandpass filters (4, 6) have a pass band width Δf (bandwidth when stopped) as in the prior art, and only the center frequency changes in accordance with the control signal from the shift amount calculation unit 10.

The ship speed data generator 8 detects the ship speed V by, for example, an electromagnetic log and outputs ship speed data.

The transmission / reception beam direction detecting unit 9 includes the transmission / reception
Is a type that mechanically changes the direction of the transmitted / received beam as in the prior art, so that the rotation angle of the transducer 3 is detected. That is, in the illustrated example, the wave transmitting / receiving device 3 has a wave transmitting / receiving direction which is a traveling direction of the ship in a plane including the longitudinal direction of the hull and is substantially parallel to the sea surface (θ = 0 °) and directly below the ship. (Θ = 90
°). This corresponds to the degree of influence of the Doppler effect.

From the above equation (1), when the transmitting and receiving beam direction is the traveling direction of the ship and is substantially parallel to the sea surface,
Since θ = 0, cos θ = 1 and the Doppler shift amount becomes the maximum. However, as θ increases, that is, as the transmitted / received beam is directed toward the seabed, cos θ approaches 0, and the influence of the Doppler effect is reduced. Because it becomes.

The shift amount calculating unit 10 calculates the Doppler shift amount f _d at the ship speed by substituting the ship speed data and the angle θ into the above equation 1, and converts the control signal for changing the center frequency into a variable bandpass filter ( 4, 6).

As a result, as shown in FIG. 2, the receiving band has a bandwidth Δf similar to the conventional one, but the center frequency is f ₀₁ , f ₀₂ ,..., F _0n according to the ship speed V. And the filtering process can be optimally performed on the Doppler shifted received signal.

[0022]

As described above, according to the ultrasonic detection apparatus of the present invention, the bandpass filter is of a type that can change the center frequency, and the center frequency is shifted by the Doppler shift amount. However, even if the speed is increased and the Doppler shift amount increases, reception processing can always be performed with a suitable bandwidth, and the detection capability can be maintained at a predetermined value without lowering. Therefore, it is possible to provide an ultrasonic detection device suitable for mounting on a high-speed ship.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of an ultrasonic detection device according to an embodiment of the present invention.

FIG. 2 is a control mode diagram of a variable bandpass filter.

FIG. 3 is a configuration block diagram of a conventional ultrasonic detection device.

FIG. 4 is a band characteristic diagram of a conventional band filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmission part 2 Transmission / reception switch 3 Transceiver 4 Variable band filter 5 Amplifier 6 Variable band filter 7 Amplifier 8 Ship speed data generation part 9 Transmission and reception beam direction detection part 10 Shift amount calculation part

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01S 7/52-7/64 G01S 15/00-15/96

Claims (1)

(57) [Claims] <br/> predetermined pass band at the stop for the received signal Ship; 1. A high speed is mounted on a moving ship ultrasound in ultrasound detection device to detect the sea level near or underwater object by transmitting and receiving waves of A variable bandpass filter for performing a filtering process with a width, wherein a center frequency is variably set without changing the predetermined passband width in accordance with a control signal provided from the outside; A ship speed data generation unit for generating and outputting; a transmission / reception beam direction detection unit for detecting an angle between the transmission / reception beam direction and the sea surface;
A shift amount calculating unit that calculates the Doppler shift amount of the received signal based on the boat speed data and the angle, and outputs the control signal that shifts the center frequency of the variable bandpass filter by the calculated and acquired Doppler shift amount. An ultrasonic detection device, characterized in that: