JPH03239979A - Receiving equipment for detecting ultrasonic wave - Google Patents

Abstract

PURPOSE:To effectively execute the detection by executing amplification related to the pre-stage, based on a control signal in order to obstruct saturation of a supplied receiving signal, and thereafter, executing TVG amplification for correcting an attenuation characteristic by a TVG control signal. CONSTITUTION:In a transmitter/receiver 10, a reflected wave from a reflecting object is received, and a receiving signal Sf is led out. This signal Sf has an attenuation characteristic of a level corresponding to a distance to the reflecting object known in advance. Subsequently, the signal Sf is amplified by a variable amplifier 12. In this case, the amplification degree is set by a variable resistor VR so as not to be saturated in the maximum level of the signal Sf, that is, in the part of the signal Sf of a reflected wave in the nearest distance. In such a way, from the amplifier 12, an amplification signal Sg having the same characteristic curve as the signal Sf, and also, being free from saturation is led out. Subsequently, the signal Sg is supplied to a TVG amplifier 14, and a TVG control signal Si is supplied simultaneously. In such a way, control of amplification related to a distance (time) is executed, and an output signal So is led out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an ultrasonic detection receiving device used in alarm devices, fish finding devices, active sonar, and the like.

More specifically, first, the received signal is amplified based on the supplied control signal in order to prevent saturation of the received signal, which has an attenuation characteristic that depends on the distance between the receiver and the reflecting object. The amplified signal derived here is amplified based on the TVG control signal supplied to correct the attenuation characteristic, and the TVG amplified signal with the attenuation characteristic corrected is derived. The saturation is reduced and the attenuation characteristics related to subsequent TVG amplification are effectively corrected.

[Prior Art] Conventionally, alarm devices for intruders and systems that receive reflected waves from reflective objects such as underwater targets and record the state and distance of the reflective objects from the received signals as hard copies or C.
Detection devices such as so-called fish finders, active sonar, etc. that detect reflective objects by displaying images on RT or the like are widely used.

The ultrasonic detection receiving device in this type of detection device will be described below with reference to FIG. 8, which shows its outline, and FIGS. 9, 10, and 11, which show characteristics related to its operation.

First, a received signal Sa (see FIG. 9) from the transducer 2 that receives reflected waves from a reflecting object is supplied to the preamplifier 6 in the AGC amplifier 4, and an amplified signal sb is derived. Subsequently, the amplified signal sb is fed back via the feedback amplifier 8, so-called.
Well-known closed-loop control AGC is performed, and the amplified signal Sd is controlled by the AGC level Ca shown in FIG.
is derived. This amplified signal Sd is supplied to the TVG amplifier 9. Here, a TVG control signal S with a previously known characteristic that is line symmetrical to the received signal Sa is used.
(see figure), the attenuation characteristic (received signal Sa) related to the distance of the reflected wave is corrected, and an amplified output signal Se is derived.

In this way, a predetermined amplification of the received signal Sa, e.g.
When amplification by more than 100 dB is performed, first, in order to prevent saturation of the received signal Sa having a large level difference in the AGC amplifier 4, the amplitude is amplified to a constant value in the so-called AGC, and then,
The TVG amplifier 9 corrects the attenuation for the reflection distance and derives the output signal Se.

[Problems to be Solved by the Invention] However, in the ultrasonic detection receiver according to the above-mentioned conventional technology, as can be easily understood from FIG. 10, the level of the amplified signal Sd is not constant up to the distance T. be. Therefore, as shown in FIG. 11, the output signal Se of the TVG amplifier 9 temporarily increases in level up to the distance T by control corresponding to the temporal curve of the TVG control signal S, and after the distance T increases. It becomes a desired constant value.

In this way, the output signal Se within the distance T of the reflecting object is reduced, making subsequent signal processing difficult.

For example, when display processing is performed on a hard copy or CRT, etc., the output signal Se up to the distance T, especially,
It has drawbacks such as the beginning part being easily lost as an image.

The present invention has been made in view of these points, and its purpose is to reduce saturation in preamplification,
It is an object of the present invention to provide an ultrasonic detection receiving device that can effectively correct attenuation characteristics related to subsequent TVG amplification.

[Means for Solving the Problems] In order to solve the above problems, the ultrasonic detection receiving device of the present invention is provided with a receiving signal having an attenuation characteristic depending on the distance between the reflecting object and the receiver. , and an amplifying means for deriving an amplified signal whose saturation is prevented based on an input control signal; and an amplified signal to which the amplified signal is supplied and whose attenuation characteristics are corrected based on the supplied TVG control signal. TVG amplification means for deriving the.

Further, in the present invention, a received signal having an attenuation characteristic related to the distance between the reflecting object and the receiver is supplied to the amplifying section, and
AGC amplification means for deriving an amplified signal whose saturation is prevented based on an AGC control signal supplied to a feedback control section; TVG amplifying means for deriving a corrected amplified signal; and generating an AGC control signal having substantially the same characteristics as the TVG control signal;
AGC control signal generation means for supplying to the GC amplification means.

[Operation] In the above configuration, the amplification related to the previous stage is performed based on the supplied control signal in order to prevent saturation of the supplied received signal. Alternatively, an AGC control signal with substantially the same characteristics as the TVG control signal supplied to correct the attenuation characteristics of the received signal, for example, line-symmetrical, is generated, and this AGC control signal is used to amplify the preceding stage in order to prevent saturation. will be held. Then, after the previous stage amplification, TVG amplification is performed to correct the attenuation characteristics caused by the TVG control signal.

This effectively reduces saturation in the previous stage amplification,
Attenuation characteristics related to subsequent TVG amplification are effectively corrected.

[Example] Next, an example of the ultrasonic detection receiving device according to the present invention is as follows.
A detailed description will be given below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of the first embodiment, FIGS. 2 and 3 are characteristic diagrams for explaining the operation of the first embodiment, and FIG. 4 is the configuration of the second embodiment. A block diagram showing
FIG. 5 is a block diagram showing a specific configuration example of the second embodiment, FIG. 6 is a characteristic diagram used to explain the operation of the specific configuration example,
FIG. 7 is a block diagram showing another example of the specific configuration of the second embodiment.

First, a first embodiment will be explained using FIG.

In FIG. 1, in this example, a transducer 10 derives a received signal Sf having an attenuation characteristic depending on the distance to a reflecting object, and a variable amplifier 12 whose amplification degree is set by a connected variable resistor VR. and a TVG amplifier 14 which derives an output signal S○ whose attenuation characteristics related to the transducer 10 and the reflecting object are corrected based on the supplied TVG control signal Si.

Next, the operation in the above configuration will be explained.

The transducer 10 receives reflected waves from a reflecting object and derives a received signal Sf. As shown in FIG. 2, this received signal Sf has an attenuation characteristic with a level corresponding to a previously known distance to the reflecting object.

Further, this received signal Sf is amplified by a variable amplifier 12. In this case, the maximum level of the received signal Sf, that is,
The degree of amplification is set using the variable resistor VR so as not to saturate the part of the received signal Sf of the reflected wave at the closest distance. As a result, an amplified signal Sg having the same characteristic curve as the received signal Sf and without saturation is derived from the variable amplifier 12.

Subsequently, the amplified signal Sg is supplied to the TVG amplifier 14,
Here, the TVG control signal S1 shown in FIG. 2 is simultaneously supplied. As a result, amplification control related to distance (time) is performed, and the output signal SO shown in FIG. 3 is derived.

Next, a second embodiment will be described using FIG. 4.

In this example, AGC (closed loop control) is performed in the preceding stage of amplification.

In the example shown in FIG. 4, there is a transducer 10 that derives a received signal Sf, and an A that performs amplification control using a control signal Sp.
A TVG that derives an output signal S○ in which the attenuation characteristics related to the transducer 10 and the reflecting object are corrected by the GC amplifier 22, the AGC control circuit 23 that sends out the control signal Sp, and the supplied TVG control signal Si. It has an amplifier 14.

The AGC amplifier section 22 includes a preamplifier 26 and a feedback amplifier 28 that sends a negative feedback signal Sm to the preamplifier 26 based on the supplied control signal sp.

Next, the operation in the above configuration will be explained.

The transducer 10 receives reflected waves from a reflecting object and derives a received signal Sf. This received signal Sf has an attenuation characteristic with a level corresponding to the distance of the reflecting object which is known in advance (see FIG. 2).

Furthermore, TVG with similar (line symmetrical) characteristics to this attenuation characteristic
The control signal Si (see FIG. 2) is connected to the TVG amplifier 14 and AG.
The signal is supplied to the C control circuit 23. Then, from the AGC control circuit 23, a control signal sp similar to the TVG control signal Si, for example, a control signal sp whose overall level is reduced, is derived.

The control signal Sp is supplied to the feedback amplifier 28, and the amplification of the preamplifier 26 is controlled by the negative feedback signal Sm derived here. In this case, the preamplifier 26 outputs the negative feedback signal Sm
Accordingly, AGC (closed loop control) is performed so as not to saturate at the maximum level of the received signal Sf, that is, the portion of the received signal Sf of the reflected wave at the closest distance. Therefore, the control signal Sp is set to a value at which AGC is performed so that saturation does not occur up to the distance T.

Through this AGC, an amplified signal Sg having the same characteristic curve as the received signal Sf and without saturation is derived from the preamplifier 26.

Subsequently, the amplified signal Sg is supplied to the TVG amplifier 14,
The amplification related to the attenuation characteristic is controlled by the TVG control signal Si (see FIG. 2) supplied at the same time. Then, an output signal So (see FIG. 3) is derived.

In this way, the received signal Sf is first amplified so as not to cause saturation. Next, the amplified signal Sg is amplified by the TVG amplifier 14 based on the value of the characteristic curve of the TVG control signal S1.

In this case, when the received signal Sf is amplified by a predetermined amount, for example, by a hundred and several tens of dB, saturation does not occur in the preceding stage amplifiers (variable amplifier 12, preamplifier 26). Therefore, the output signal SO derived from the TVG amplifier 14 thereafter is formed more flatly, that is, as shown in FIG. Attenuation characteristics related to the distance between the reflection object and the reflection object are effectively corrected.

A specific example of the configuration of the second embodiment will be described below with reference to FIG. 5.

In this example, the AGC control circuit 30 includes a buffer amplifier 32 to which the TVG control signal S1 is supplied, a voltage dividing adjustment circuit 34 including resistors R1, R2, a variable resistor VRb, etc., a negative feedback resistor Vt, and an operational amplifier. It has 36. Furthermore, a multiplier 38 is provided which sends out a negative feedback signal Sm for controlling the amplification of the preamplifier 26.

Here, the control signal sp is changed and derived by adjusting the variable resistor VRb, and as a result, the level of the amplified signal Sg is changed (K) and derived as shown in FIG.

In this case, when the level of the received signal Sf fluctuates depending on the distance between the transducer 10 and the reflecting object and is input, the variable resistor VRb can be manually adjusted. Detection corresponding to the observation situation of the target object (reflecting object) in the detection device to which this configuration example is applied, for example, the size of the target object, etc. can be performed more effectively.

Note that other operations and effects are the same as those of the second embodiment, and detailed explanation thereof will be omitted.

Furthermore, another example of the second specific configuration shown in FIG. 7 will be explained.

In this example, processing is performed using digital signals.

The AGC control circuit 40 includes an A/D converter 42 and a CPU 44.
and a ROM 46. Furthermore, corresponding to the feedback amplifier 28 in the basic configuration shown in FIG. 4, a switch control section 48 and switches 50a, 50b, 50c, -
50n and the resistors Ra%Rb and R connected in series with it.
c,...Rn. Furthermore, the preamplifier 26
An operational amplifier 52 is provided to control the amplification of the operational amplifier 52, and a negative feedback resistor Ra is connected in parallel to
It is set by %Rb, Rc,...Rn. Note that the resistor R is for determining gain.

In the above configuration, first, the TVG control signal Si is converted into a digital signal. Then, it is converted using a data table in the ROM 46 corresponding to the characteristics of the TVG control signal Si,
Next, the switch control part 48, the switches 50a, 50b,
50c.

-50n switches resistors Ra, Rb, Rc, -Rn. As a result, the amplification degree of the operational amplifier 52 becomes TV
The characteristics of the G control signal Si are formed to be similar to the characteristics of the G control signal Si, and the initial part of the received signal Sf of the preamplifier 26 (the time in FIG.
AGC (closed loop control) is performed so as not to saturate at the distance (distance) up to T).

Furthermore, the program and setting section (
(not shown), it is possible to change the curve of the attenuation characteristic in response to multiple types of the transducer 10 and the reflecting object.

Thereby, for example, the detection of a target by a detection device to which another example of the specific configuration of serious condition 2 is applied is made more effective as in the first specific configuration example.

Note that the other operations and effects are the same as the basic configuration described above, and detailed explanation thereof will be omitted.

[Effects of the Invention] As can be understood from the above description, in the ultrasonic detection receiving device of the present invention, in order to prevent saturation of the received signal, the received signal is amplified in the previous stage based on the supplied control signal, or , T supplied to correct the attenuation characteristics of the received signal
An AGC control signal having substantially the same characteristics as the VG control signal is generated, and amplification is performed based on the AGC in the previous stage to prevent saturation with this AGC control signal. It is characterized in that TVG amplification is performed to correct the attenuation characteristics caused by the TVG control signal.

This has the advantage that the saturation in the previous stage amplification is effectively reduced, and the attenuation characteristics related to the subsequent TVG amplification are effectively corrected. , in addition, the TV you can get here
Hard copy or C using the output signal related to G amplification
When display processing such as RT is performed, for example, there is an advantage that effective detection is possible without image loss at the beginning of the curve of the attenuation characteristic of the derived TVG amplified signal.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of the ultrasonic detection receiving device according to the present invention, and FIGS. 2 and 3 are explanations of the operation of the first embodiment shown in FIG. FIG. 4 is a block diagram showing the configuration of the second embodiment of the ultrasonic detection receiving device according to the present invention, and FIG. 5 is a specific diagram of the second embodiment shown in FIG. 4. 6 is a characteristic diagram for explaining the operation of the specific configuration example shown in FIG. 5. FIG. 7 is a block diagram showing a specific example of the second embodiment shown in FIG. 4. A block diagram showing another example of the configuration; FIG. 8 is a block diagram showing the configuration of a conventional ultrasonic detection receiving device; FIGS. 9, 10, and 11 are shown in FIG. FIG. 2 is a characteristic diagram used to explain the operation of the configuration of a conventional ultrasonic detection receiving device. 10... Transmitter/receiver 12... Variable amplifier 14... TVG amplifier 22... AGC amplifier section 23... AGC control circuit 26... Preamplifier 28... Feedback amplifier Sf... Received signal Sg...Amplified signal Si...TVG control signal SO...Output signal Sp...Control signal Sm...Negative feedback signal■ FIG, 2 "Korokubi (Between β1) FIG, 5 Distance (Time) - 1in FIG8 FIG, 9 Distance (time) →

Claims (2)

[Claims] (1) Amplifying means for deriving an amplified signal to which a received signal having an attenuation characteristic related to the distance between the reflecting object and the receiver is supplied and whose saturation is prevented based on an input control signal; A receiving device for ultrasonic detection, comprising: a TVG amplifying means to which a signal is supplied and for deriving an amplified signal with the attenuation characteristic corrected based on the supplied TVG control signal. (2) A received signal having an attenuation characteristic related to the distance between the reflecting object and the receiver is supplied to the amplification section, and an amplified signal whose saturation is prevented based on the AGC control signal supplied to the feedback control section. AGC amplifying means for deriving the amplified signal, and TVG amplifying means for deriving the amplified signal with the attenuation characteristic corrected based on the TVG control signal supplied with the amplified signal; AGC control signals having the same characteristics are generated to
An ultrasonic detection receiving device comprising: AGC control signal generation means for supplying a GC control signal to a GC amplification means.