JPH0320715B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a phased array sonar, and particularly to a phased array sonar that performs electronic real-time sector scanning and steers a beam to a wide angle of view over an extremely short range. It is intended to improve the wave data rate.
Such a phased array sonar can be widely applied for medical, industrial freshwater and saltwater applications.

(Prior Art) In conventional phased array sonar, the minimum requirement for the beamforming network (so-called beamformer) is to form only one transmission/reception line, and the hardware is Delay means sufficient to handle the desired maximum azimuth angle, such as LG ladder type delay-in (for receiving beamforming), variable length shift register, preset counter, combination of ROM and address scanner (both transmitting beamforming), etc. are available.

(Problem to be solved by the invention) However, these hardwares are utilized to their full potential only when the azimuth angle (steering angle) of the sound ray changes greatly; range), most sections of the delay line provided to create the reception delay map are not used. Although it is used as a signal path, it is not directly used to form a desired delay distribution.

Furthermore, since it is possible to receive the echo signal of only one sound ray at a time, and the method of focusing the wavefront on that sound ray (electronic focus) cannot be changed, real-time switching type reception dynamics is required. There was a problem in that the technique of focusing or receiving multi-beam forming (also referred to as multi-beam receiving) could not be implemented.

An object of the present invention is to provide a phased array sonar that solves these problems.

(Means for Solving the Problems) The present invention achieves the above object, and is configured to selectively apply a received echo signal to a delay line and to be able to use it separately in a sector scanning phased array sonar. a delay map, a plurality of delay lines which time-delay and output the echo signals given from this delay map, and the delay map and delay lines are used separately at a deflection angle smaller than approximately half of the maximum deflection angle in sector scanning. The present invention is characterized by comprising a control means for receiving echo signals at different azimuth angles or different focal points and controlling the echo signals to be edited into one image.

(Example) Examples of the present invention will be described in detail below using the drawings. FIG. 1 shows a phased array according to the present invention.
1 is a main part configuration diagram showing an example of a sonar. In the figure, 1 is a trigger generator that generates a wave transmission trigger, 2 is a wave transmission delay map, 3 is a wave transmission circuit group (so-called pulser), 4 is an array probe formed by arranging a plurality of transducers, 5 is a first stage amplifier group that receives the echo signal received by the probe 4, and 6 is a delay map that can be divided and used, for example, a cross point switch is used. Note that here, a case where the image is divided into two is shown. 7 ₁ and 7 ₂ are delay lines, and since this is an example of a two-division case, two sets are shown. When there are n divisions, there are n sets. 8 ₁ and 8 ₂ are the delay lines 7 ₁ and 7 ₂ respectively
This is a receiving amplifier consisting of a logarithmic amplifier or the like that receives the delay output of the 9 is digital scan
A converter (hereinafter referred to as DSC), 10 is a display device equipped with a CRT monitor, and 11 is a controller for controlling each part. 12 is a keyboard for inputting various necessary information, and 13 is a switch.

The operation in such a configuration will be explained next.
The pulser 3 consists of an individual pulser connected to each transducer(s) of the array probe 4, and each pulser receives an appropriately time-delayed trigger output trigger from a trigger generator via a transmission delay map. is given. The transmission delay map 2 is changed under the control of the controller 11, and the direction of the ultrasonic beam transmitted from the probe 4 can be swung in a fan shape (sector scanning) as shown in FIG.

The echo signal received by the probe 4 is guided to delay maps 6 ₁ and 6 ₂ via an initial amplifier group 5 consisting of a plurality of first-stage amplifiers provided in one-to-one correspondence with each transducer. It will be destroyed. Each output of the first stage amplifier group 5 is appropriately selected on delay maps 6 ₁ and 6 ₂ under the control of the controller 11 and sent to delay lines 7 ₁ and 7 ₂ , respectively. The output signal of the delay line ₇₁ (output signal on one output line) is passed through the switch 13 and the receiving amplifier ₈₁ ,
Further, the output signal of the delay line 7 ₂ is applied to the DSC 9 via the receiving amplifier 8 ₂ . The switch 13 switches between connecting the delay map 7 ₁ to the receiving amplifier 8 ₁ or to the delay line 7 ₂ depending on the mode described later.

The echo data taken into the DSC 9 is sent to the display device 10 under the control of the controller 11.
The image is displayed.

In the present invention, the connection points on the delay maps 6 ₁ and 6 ₂ are changed depending on the mode, and the first stage amplifier group 5
Change the connection between the output and the delay line, and
Outputs A and B of receiving amplifiers 8 ₁ and 8 ₂ in DSC 9
Decide whether to use both or only one. For example, when the maximum deflection angle θ for sector scanning is set to ±45° as shown in Figure 2, when scanning starts from a deflection angle of +45° (or -45°), it reaches almost |θ|≧25°. day line 7 in the range of
A signal of the full width of the delay map 6 ₁ , 6 ₂ is applied to the full length of the delay map 6 ₁ , 6 ₂ so that it can be used. next,
In the range |θ|<25°, the mode is switched so that the two sections, the delay map and the delay line, are used independently. For example, as shown in FIG. 2, echo signals from a left receiving sound ray L and a right receiving sound ray R having slightly different azimuths with respect to the transmitting sound ray C are received by receiving amplifiers 8 ₁ and 8 ₂ . do.
The controller 11 controls such reception with different azimuth angles. In DSC9, the echo signal logarithmically amplified and detected by the receiving amplifier is A/
The data is converted into D and written into the prepared frame memory in a predetermined format.

FIG. 3 is a diagram showing another method according to the present invention. That is, this is an example of a two-stage dynamic focus, in which receiving beamforming is performed in which the solid line D for short distances and the dotted line E for long distances have the same azimuth but different focuses. These are edited in DSC9 and made into a single picture.

In the above description, the number of divisions of the delay map and delay line is two, but the present invention is not limited to this. Furthermore, the number of divisions may be changed depending on the deflection angle. Setting information such as the number of divisions, the range of division, and whether to use the multi-beam method or the dynamic focus method is input from the keyboard 12.

The above is for the receiving side, but the same idea holds true for the transmitting side in principle. However, wave transmission essentially cannot send two or more types of sound waves into the sound field at the same time, and pulsars and transmission delay map means essentially do not follow the law of weight, so they operate in a binary manner. I can only do it. Therefore, if you want to perform dynamic focusing of transmission waves, multi-beam formation, etc., extremely strict frequency division,
Or you have no choice but to take a time-sharing approach. When using time division, there is a drawback that the data rate cannot be improved. However, there are cases where it is necessary to set independent sound rays in two directions at the same time. This is the case when pulsed Doppler is intended to coexist with B-mode imaging. Whereas the former shifts the sound rays one by one (increasing or subtracting the sound ray number) each time a wave is transmitted or received,
The latter remains on a constant desired sound line. If this is done with one beamformer, the sound beam number or scanning data must be rewritten in a completely random access state. However, when two systems of beamformers (both transmitting and receiving) are used, the B beam only increases or decreases, and the Doppler beam does not need to be rewritten unless the desired sound ray changes. Such a procedure takes much less time than random access,
Possible due to procedural complexity and hardware.

FIG. 4 is a diagram showing the main parts of the configuration in such a case. In this figure, from the delay map 6 ₂ , the delay line 7 ₂ , and the receiving amplifier 8 ₂
The connections to the DSC 9 are the same as in FIG. A delay map 6 ₁ and a delay line 7 ₁ are used for Doppler, and the output of the delay line 7 ₁ is led to a Doppler processor 21 and processed. The output of the processor 21 is monitored by two speakers 22 and passed through a frequency analyzer (FFT etc.) 23.
Input to DSC9. For example, the scanning sequences for B mode and D mode are as shown in the following table. In this case, the repetition periods of the B trigger source and the DD trigger source do not necessarily have to be the same. However, they do need to be synchronized.

Transmission/reception process number Mode Sound beam number i B K i+1 D l i+2 B K+1 i+3 D l i+4 B K+2 i+5 D l i+6 B K+3 ・ ・ ・ (Effects of the invention) As described above, according to the present invention, beam forming For deflection angles smaller than approximately half of the maximum deflection angle in sector scanning, more homogeneous, well-focused, and high data rate images can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of a phased array sonar according to the present invention, FIGS. 2 and 3 are diagrams related to sound rays for explaining the operation of the present invention,
FIG. 4 is a block diagram for implementing another method of the present invention. 1...Trigger generator, 2...Transmission delay map, 3...Pulser, 4...Array probe, 5
...First stage amplifier group, 6 ₁ , 6 ₂ ... Delay map, 7 ₁ , 7 ₂ ... Delay line, 8 ₁ , 8 ₂ ...
Receiving amplifier, 9...DSC, 10...display device,
11...Controller, 12...Keyboard, 1
3...Switch.

Claims (1)

[Claims] 1. In a sector scanning phased array sonar, a delay map is configured to selectively apply received echo signals to a delay line and can be used separately, and a plurality of delay maps that output echo signals provided from this delay map with a time delay. For delay lines and deflection angles smaller than approximately half of the maximum deflection angle in sector scanning, the delay map and delay line are used separately to receive echo signals at different azimuths or different focal points and are edited into one image. A phased array sonar characterized in that it is equipped with a control means for controlling the sonar.