JPS5822979A - Receiveng method of scanning sonar - Google Patents

Abstract

PURPOSE:To execute a faithful video display being in proportion to intensity of an echo without being subjected to influence of a switching noise, by dividing a receiving system into plural groups, and executing the gain control such as a time variable gain control, etc. in a prescribed time zone. CONSTITUTION:Transmitter and receiver elements TD- which have been arrayed in a circle are divided into plural groups, and when an echo group has arrived, each of them is amplified by a pre-amplifier PA group, and after that, its attenuation is controlled so as to be a suitable receiving level, by an attenuator ATT group. To these respective attenuator ATT groups, gain control voltage TVG/EA, TVG/EB- of a time variable gain control is applied in the time zone which has avoided a time zone using beam forming. Accordingly, a noise generated by switching a switch SW is separated from a picture, the gain after the switch SW can be raised, and even in case when an echo is intense, it is adjusted so that it is not saturated in the pre-amplifier, and it is possible to execute a faithful video display being in proportion to intensity of an echo.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning sonar reception method.

When detecting schools of fish with a scanning sonar, the strength of the echo from the reflector changes in proportion to the -2 to -4th power of the detection distance. In order to compare the strength of reflections, a time barrier gain control (commonly abbreviated as TVG) for proper distance compensation is required.

In particular, with fishing sonar, the range of the strength of the target echo itself is wide, that is, the strength of the echo itself, the size of the fish body, the bottom sediment and shape of the sea floor, the wake, and the strength difference is large, and the strength of each echo is also wide. Change.

Therefore, in order to faithfully display these many varied echoes on a cathode ray tube, the Guinants range of the cathode ray tube is not wide.
It is necessary to process using G.

Therefore, looking at the current situation, the reception system Fi is configured as shown in the program diagram of FIG. In the figure, TD two-circular array of transducer elements PA: Pre-preamplifier r'r: ycJ[t (for TVG) SW: Switch (for receiving beam scanning) Psi: Phase shifter (receiving beam scanning) PS2: t ATT2: Gain adjuster A2: Amplifier CRT display tube display TVG/E: TVG control voltage Voltage, 2...
...Sfi: Receiving system for channels l to n...
...#m: Receive beam changeover switch (high-speed changeover in the direction of arrow S), and its operation is as follows.

When a group of ECOs arrive at the transducers TD (s1 to φm) arranged in a circular manner, they are each amplified by the preamplifier PA group, and then each is amplified by the attenuation fiATT group so that the receiving level is adjusted to an appropriate reception level moment by moment. Attenuation is controlled to Figure 2 qualitatively shows the change in reception gain over time, that is, the TVG characteristics, where G□8 is the maximum gain, Gtn is the minimum gain, and 105 is the transmission time. It is. Next, regarding the circularly arranged transducer elements, a receiver formed by combining an appropriate number of adjacent elements (four in the figure) is a phase shifter PS1 and a phase shifter PS1.
2, the phase is corrected and a sharp receiving beam is formed. Then, the transducer elements are sequentially selected by the switch SW in the direction of the arrow S, and the receiving beam sequentially scans the search area. In this case, the receiving beam is scanned in synchronization with the spiral sweep angle (corresponding to the azimuth) of the cathode ray tube display CRT.

The signal on the azimuth side taken out by the switch SW is manually adjusted for the overall reception gain by the gain adjuster ATT2, and then amplified by the amplifier A2 and displayed on the cathode ray tube display CR.
TKPPI is displayed.

Figure 3 shows an example of switching the attenuator ATT in the previous stage.
Crosspiece, ... and R,1... are attenuation element resistances, TR1
゜T-... is the attenuation switching FET (field effect transistor), E,, E,... is the attenuation switching control voltage (first
(equivalent to TVG/E K in the figure) Teari, T, +, , T, +
, .

The interval between the points in time when the control voltage E, etc. is applied at
This is the same as the one-rotation scanning time of switch SW).

Therefore, the gain of the preamplifier PA is increased. Therefore, the strong echo saturates within the preamplifier PA, and a faithful image proportional to the intensity of the echo cannot be obtained on the cathode ray tube.

The present invention eliminates these drawbacks and will be described below based on an example of implementation.

Fig. 4 is a block diagram of the embodiment, and Fig. 5 is a diagram showing the time relationship between the 7 ohm beam and the operation of the TVG. In Fig. 4, the same units as in Fig. 1 are given the same reference numerals. The difference from Fig. 1 is that the attenuators ATT are organized by group (the figure shows ATT-A, ATT-B, and AT
(Example of three groups of T-C), and the control voltages TVG/Em to TVG/Eo of KTVG are applied to each group.

The group unit is the transducer T that makes up the group.
It may be determined by keeping in mind that a planned receiving beam will be formed by combining several D's. The example in the figure shows a case where one group is made up of six items.

In Figure 5, the part marked with a circle indicates the time period during which the beamform is activated for each group, and the mark indicates that the control voltage is applied to each group at 1 m, tl, and t□. This is the part where TVG is active, and as shown in the figure, TVG of each group is performed during the time when the beamform is not operating, so the noise caused by switching is separated from the video, so conventional Observed deficiencies are removed.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the sonar reception system. TD: Transducer/receiver element in a circular array PA: Preamplifier ATT: Attenuator SW: Switch PSt: Phase shifter PS2: # A2: Amplifier CRT Ni Braun tube display Figure 2 Example of FiTVG characteristics. FIG. 3 is an example of switching the ATT shown in FIG. 1. Bird......: Attenuation switching element Tls...
. . .: FET FIG. 4 is a block diagram of an embodiment of the present invention. FIG. 5 is an explanatory diagram of the operation. Patent applicant Kaiyo Denki Co., Ltd. Plan I Figure 2

Claims (1)

[Claims] A transducer is formed by arranging multiple ultrasonic transducers in a cylindrical shape, and simultaneously sends out ultrasonic waves over the entire range of detection directions.A sharp delivery beam is also created by combining any number of ultrasonic transducers. In a scanning sonar, the receiving system is divided into multiple groups, and the receiving system is divided into multiple groups. In addition, the configuration is such that gain control is performed in conjunction with TVG within each group. A reception method in a scanning sonar, characterized by controlling the gain of TVG, etc. for each group.