KR102432813B1 - Noise canceller, method for canceling noise and apparatus for tracking laser - Google Patents

Abstract

The present invention relates to a noise remover, a noise removal method, and a laser search apparatus, and more particularly, to a noise remover, a noise removal method, and a laser search apparatus for removing noise included in a received signal.
The noise canceller according to an embodiment of the present invention is a noise canceller for removing a noise signal from a reception signal including a target signal and a noise signal, and includes a reception signal transmitted through a first path and a second path different from the first path. By calculating the difference of the noise signal transmitted to , the difference signal from which the noise signal is removed from the received signal is extracted.

Description

NOISE CANCELLER, METHOD FOR CANCELING NOISE AND APPARATUS FOR TRACKING LASER

The present invention relates to a noise remover, a noise removal method, and a laser search apparatus, and more particularly, to a noise remover, a noise removal method, and a laser search apparatus for removing noise included in a received signal.

The laser search apparatus irradiates laser light to detect a target, and uses a method such as light tracking to detect the target. When a laser beam is irradiated toward a target from an external device such as an aircraft or an indicator, the laser search device detects a laser signal reflected from the target and tracks the target.

The laser search apparatus includes a photo diode, a transimpedance amplifier (TIA), a limiting amplifier, a control circuit, and the like. Such a laser search device generates an output voltage from a laser signal, detects a target signal from a received signal transmitted as an output voltage in the system, and tracks the target.

As such, the received signal transmitted within the laser search apparatus includes a high-frequency noise signal and a low-frequency noise signal in addition to the target signal. Here, the high-frequency noise signal has a short wavelength, and is relatively easy to distinguish from the target signal compared to the low-frequency noise signal, so it is not a big problem in extracting the target signal. However, in the case of a low-frequency noise signal included in the received signal, it is generated by itself by the system and power supply of the laser search apparatus, and since it reduces the signal-to-noise ratio, it is a major cause of lowering the detection rate of the laser search apparatus. Accordingly, various studies are being conducted to remove the low-frequency noise signal from the received signal transmitted within the laser search apparatus.

US 10-2014-0054941 A

The present invention provides a noise remover, a noise removal method, and a laser search apparatus capable of effectively removing low-frequency noise included in a received signal.

A noise remover according to an embodiment of the present invention is a noise remover for removing a noise signal from a received signal including a target signal and a noise signal, comprising: a first path and a second path for transmitting the received signal; a noise signal extraction unit provided in the second path to extract a noise signal from the received signal; and a target signal extraction unit connected to the first path and the second path to remove a noise signal from a received signal using the extracted noise signal.

The target signal extractor may calculate a difference between the received signal transmitted through the first path and the noise signal transmitted through the second path to extract a difference signal from which the noise signal is removed from the received signal.

The noise signal extractor may include a low-pass filter.

The target signal extractor may include a fully differential amplifier having a first output terminal and a second output terminal.

The first output terminal subtracts a noise signal from the received signal, and outputs a first difference signal having a constant output value lower than that of the target signal in a section other than a section in which the target signal is present, and the second output section includes a noise signal. The received signal may be subtracted from the signal to output a second-order signal having a constant output value higher than that of the target signal in the remaining sections except for the section in which the target signal is present.

An analog-to-digital converter connected to the target signal extractor to convert the signal output from the target signal extractor into a digital signal; further comprising, wherein the analog-to-digital converter includes a second output terminal from the first output terminal and the second output terminal It may include a differential input analog-to-digital converter that receives the primary signal and the secondary signal as a differential signal.

A noise removal method according to an embodiment of the present invention is a noise removal method for removing a noise signal from a reception signal including a target signal and a noise signal, the method comprising: transmitting the reception signal through a first path and a second path; receiving a received signal transmitted through the first path; extracting a noise signal from the received signal transmitted through the second path; and removing the noise signal from the received signal by using the extracted noise signal.

The removing of the noise signal may include: calculating a difference between the received signal transmitted through the first path and the noise signal extracted from the second path, and extracting a difference signal from which the noise signal is removed from the received signal; may include

The noise signal includes a low-frequency noise signal, and in the process of extracting the noise signal, the low-frequency noise signal may be extracted by removing a target signal and a high-frequency noise signal from the received signal.

The low-frequency noise signal may have a frequency of 100 kHz or less.

The extracting of the difference signal may include: subtracting a noise signal from a received signal to extract a first difference signal having a constant output value lower than that of the target signal in a section other than a section in which the target signal is present; and subtracting the received signal from the noise signal to extract a second-order signal having a constant output value higher than that of the target signal in the remaining sections except for the section in which the target signal is present.

The method may further include converting the extracted difference signal into a digital signal, wherein the converting to the digital signal may include receiving a first difference signal and a second difference signal as a differential signal and converting it into a digital signal.

In addition, a laser search apparatus according to an embodiment of the present invention includes: a photodetector for receiving a laser signal reflected from a target and outputting a photocurrent; an amplifier coupled to the photodetector to generate an output voltage from the photocurrent; and a noise remover connected to the amplifier to remove a noise signal from the received signal transmitted to the output voltage, wherein the noise remover includes any one of the noise removers described above.

The photodetector divides a laser signal receiving area into a plurality of regions, and outputs a photocurrent from a laser signal input to the divided receiving area, respectively, and the amplifier and the noise canceller each receive an output voltage from the photocurrent outputted from the photodetector. , and may be provided in plurality in order to remove the noise signal.

According to the noise remover, the noise removal method, and the laser search apparatus according to an embodiment of the present invention, the circuit structure can be simplified and noise can be effectively removed by removing the noise signal from the received signal using the noise signal extracted from the received signal. .

In addition, in calculating the difference signal from which the noise signal is removed from the received signal, conversion into a digital signal can be facilitated and the dynamic range can be improved by using a fully differential amplifier having a plurality of output stages.

1 is a view schematically showing a noise canceller according to an embodiment of the present invention.
FIG. 2 is a diagram showing the state of a signal at point A of FIG. 1; FIG.
FIG. 3 is a diagram showing the state of a signal at point B of FIG. 1 .
FIG. 4 is a diagram showing the state of a signal at point C of FIG. 1; FIG.
FIG. 5 is a diagram showing the state of a signal at point D of FIG. 1; FIG.
6 is a diagram illustrating a state in which a low-frequency noise signal is removed by a noise canceller according to an embodiment of the present invention;
7 is a diagram schematically illustrating a noise removal method according to an embodiment of the present invention.
8 is a view schematically showing a laser search apparatus according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the embodiments of the present invention allow the disclosure of the present invention to be complete, and the scope of the invention to those of ordinary skill in the art It is provided to fully inform In order to explain the invention in detail, the drawings may be exaggerated, and like reference numerals refer to like elements in the drawings.

1 is a diagram schematically illustrating a noise canceller according to an embodiment of the present invention.

Referring to FIG. 1 , a noise remover according to an embodiment of the present invention is a noise remover for removing a noise signal from a reception signal including a target signal T and a noise signal, and a first path ( 110 ), a second path 120 , a noise signal extraction unit 130 provided in the second path 120 to extract a noise signal from a received signal, and the first path 110 and the second path 120 . ) and includes a target signal extraction unit 140 for removing the noise signal from the received signal by using the extracted noise signal.

The received signal is a signal input to the noise canceller, and includes a target signal T and a noise signal. Here, the target signal T has a frequency exceeding 100 kHz, and the noise signal may include a low-frequency noise signal L having a frequency of 100 kHz or less. In this way, the received signal including the target signal T and the noise signal is transmitted to the target signal extraction unit 140 to be described later via the first path 110 and the second path 120 , respectively.

The first path 110 forms a main path for transmitting a received signal. Here, the first path 110 may connect the input terminal to which the received signal is input and the target signal extractor 140 . Here, the target signal extraction unit 140 may include an operational amplifier having a positive (+) input terminal and a negative (−) input terminal, and the first path 110 includes an input terminal and the target signal extraction unit 140 . You can connect the positive (+) input terminals of

The second path 120 is branched from the first path 110 to form a bypass path for transmitting a received signal to a path different from that of the first path 110 . Here, the second path 120 connects the input terminal to which the received signal is input and the target signal extraction unit 140 via a noise signal extraction unit 130 to be described later, or the first path 110 and the target signal extraction unit 140 . The unit 140 may be connected via the noise signal extraction unit 130 . As described above, the target signal extraction unit 140 may include an operational amplifier having a positive (+) input terminal and a negative (-) input terminal, and the second path 120 is an input terminal or a first path ( 110 ) and a negative (-) input terminal of the target signal extraction unit 140 may be connected to each other.

The noise signal extraction unit 130 is provided in the second path 120 to extract a noise signal from the received signal. That is, the noise signal extraction unit 130 is located on the second path 120 and removes the target signal T and the high frequency noise signal H from the received signal transmitted through the second path 120 . Here, as described above, the received signal may include a target signal T having a frequency exceeding 100 kHz and a low-frequency noise signal L having a frequency of 100 kHz or less. In addition, the reception signal may further include a high frequency noise signal H having a frequency exceeding 100 kHz in addition to the target signal T and the low frequency noise signal L. In this case, the noise signal extraction unit 130 may extract the low frequency noise signal L by removing the target signal T and the high frequency noise signal H having a frequency exceeding 100 kHz from the received signal.

FIG. 2 is a diagram illustrating the appearance of a signal at point A of FIG. 1 , and FIG. 3 is a diagram illustrating the appearance of a signal at point B of FIG. 1 .

The received signal transmitted through the first path 110 is a target signal (T), a low-frequency noise signal (L), and a high-frequency noise signal (H) as shown in FIG. 2 on a graph representing the output voltage of the signal over time. ) will be included. Here, the received signal as shown in FIG. 2 is also transmitted to the noise signal extraction unit 130 through the second path 120 . At this time, the noise signal extraction unit 130 removes the target signal T and the high frequency noise signal H from the received signal including the target signal T, the low frequency noise signal L, and the high frequency noise signal H. . At this time, the noise signal transmitted from the noise signal extraction unit 130 is a low frequency in which the target signal T and the high frequency noise signal H are removed as shown in FIG. 3 on a graph representing the output voltage of the signal over time. Only the noise signal L is included.

To this end, the noise signal extraction unit 130 may include a low pass filter (LPF) that passes a signal of a low frequency band and removes a signal of a high frequency band. It is important that the low-pass filter minimizes the distortion of the low-frequency signal and completely removes the high-frequency signal. Here, the low-pass filter is designed to have a 100 kHz reference phase change within 15° to minimize the phase change of the low-frequency band, and as the phase change is smaller, the low-frequency noise at points A and B in FIG. 1 is reduced by the target signal extraction unit 140 can be completely eliminated. The low-pass filter includes a resistor, a capacitor, and an amplifier, and has two feedback paths as shown in FIG. 1 to pass only a low-frequency band signal, and a detailed description of the filter structure and operation principle will be omitted.

In the target signal extraction unit 140 , a first input terminal 141 is connected to the first path 110 , and a second input terminal 143 is connected to the second path 120 , and the second path 120 . ), the noise signal is removed from the received signal using the extracted noise signal. Here, the target signal extractor 140 may calculate a difference between the received signal at point A and the noise signal at point B of FIG. 1 to extract a difference signal from which the noise signal is removed from the received signal. Meanwhile, the first input terminal 141 of the target signal extraction unit 140 may be a positive (+) input terminal, and the second input terminal 143 may be a negative (-) input terminal.

The target signal extraction unit 140 includes a first input terminal 141 and a second input terminal 143 , and a difference between a received signal inputted from the first input terminal 141 and a noise signal inputted from the second input terminal 143 . Various types of differential amplifiers for extracting a difference signal by calculating ? may be used, but may include a fully differential amplifier having a first output terminal 147 and a second output terminal 149 . Here, the fully differential amplifier has two output stages consisting of a first output stage 147 and a second output stage 149 . In this case, the first output terminal 147 may be a positive (+) output terminal, and the second output terminal 149 may be a negative (-) output terminal. In the fully differential amplifier, the first output terminal 147 outputs a first difference signal obtained by subtracting the noise signal transmitted from the noise signal extraction unit 130 from the received signal transmitted through the first path 110 , and the second output terminal Reference numeral 149 may output a second-order signal obtained by subtracting the received signal transmitted through the first path 110 from the noise signal transmitted from the noise signal extraction unit 130 .

FIG. 4 is a diagram illustrating the state of a signal at point C of FIG. 1 , and FIG. 5 is a diagram illustrating a state of a signal at point D of FIG. 1 .

The first difference signal output from the first output terminal 147 is shown in the form shown in FIG. 4 on a graph representing the output voltage of the signal according to time. That is, it can be seen that the first signal has a constant voltage value according to time, but has an increased voltage value in a section in which the target signal T is present. Here, when the noise signal transmitted from the noise signal extraction unit 130 is simply subtracted from the received signal transmitted through the first path 110 , the first primary signal has a constant voltage value of, for example, 0V and then the target signal It will appear to have a positive voltage value in the section where (T) exists, but apply the reference voltage Vref to the second path 120 and apply the common mode voltage Vcm to the fully differential amplifier. 4 , the first primary signal has a constant voltage value over time as shown in FIG. 4 , and then has an increased voltage value in a section in which the target signal T is present. That is, the first difference signal output from the first output terminal 147 has a constant output value lower than the target signal in the remaining sections except for the section in which the target signal T is present.

On the other hand, the secondary signal output from the second output terminal 149 is shown in the form shown in FIG. 5 on a graph representing the output voltage of the signal according to time. That is, it can be seen that the secondary signal has a constant voltage value with time, and then has a reduced voltage value in a section in which the target signal T is present. Here, when the received signal transmitted through the first path 110 is simply subtracted from the noise signal transmitted from the noise signal extraction unit 130, the secondary signal has, for example, a constant voltage value of 0V and then the target signal It will appear to have a negative voltage value in the section where (T) exists, but apply the reference voltage Vref to the second path 120 and apply the common mode voltage Vcm to the fully differential amplifier. As shown in FIG. 5 , the secondary signal has a constant voltage value over time and has a reduced voltage value in a section in which the target signal T is present. That is, the second difference signal output from the second output terminal 149 has a constant output value higher than the target signal in the remaining sections except for the section in which the target signal T is present.

As such, the difference signal extracted from the target signal extraction unit 140 has characteristics of the signal from which the low-frequency noise signal L is removed from the received signal including the target signal T and the noise signal, as shown in FIG. 6 . have In FIG. 6 , (a) shows a signal input to the target signal extractor 140 , and (b) shows a signal output from the target signal extractor 140 . As shown in FIG. 6 , it can be seen that the low-frequency noise signal L is effectively removed from the signal output from the target signal extraction unit 140, whereby the target signal T can be easily distinguished from the noise signal. be able to

On the other hand, the noise canceller according to an embodiment of the present invention is connected to the target signal extraction unit 140, the analog-to-digital conversion unit 150 for converting the signal output from the target signal extraction unit 140 to a digital signal. may include more. Here, as described above, the target signal extracting unit 140 may include a fully differential amplifier having a first output terminal 147 and a second output terminal 149 , and the analog-to-digital converter 150 is a first A differential input analog-to-digital converter for receiving differential signals from the two output terminals including an output terminal 147 and a second output terminal 149 may be included. The differential input analog-to-digital converter receives the first and second signals respectively and generates a digital signal.

Hereinafter, a noise removal method according to an embodiment of the present invention will be described. Since the noise removing method according to an embodiment of the present invention can be performed by the above-described noise canceller, a description overlapping with the above-described content will be omitted.

7 is a diagram schematically illustrating a noise removal method according to an embodiment of the present invention.

Referring to FIG. 7 , the noise removing method according to an embodiment of the present invention is a noise removing method for removing a noise signal from a received signal including a target signal T and a noise signal, and includes a first path 110 and a second path 110 . 2 The process of transmitting the received signal through the path 120 (S100), the process of receiving the received signal transmitted through the first path 110 (S200), and the noise from the received signal transmitted through the second path (120) A difference in which the noise signal is removed from the received signal by calculating the difference between the signal extraction process ( S300 ) and the received signal transmitted to the first path 110 and the noise signal extracted from the second path 120 . A process of extracting a signal (S400) is included.

In the process of transmitting the received signal ( S100 ), the received signal is transmitted to the first path 110 and the second path 120 , respectively. Here, the first path 110 forms a main path for transmitting the received signal. In this case, the first path 110 may connect the input terminal to which the received signal is input and the target signal extractor 140 . The target signal extraction unit 140 may include an operational amplifier having a positive (+) input terminal and a negative (−) input terminal, and the first path 110 includes an input terminal and a positive input terminal of the target signal extraction unit 140 . The (+) input terminals can be connected to each other.

The second path 120 is branched from the first path 110 to form a bypass path for transmitting a received signal to a path different from that of the first path 110 . Here, the second path 120 may connect an input terminal to which a received signal is input or the first path 110 and a target signal extractor 140 to be described later. As described above, the target signal extraction unit 140 may include an operational amplifier having a positive (+) input terminal and a negative (-) input terminal, and the second path 120 is an input terminal or a first path ( 110 ) and a negative (-) input terminal of the target signal extraction unit 140 may be connected to each other.

In the process of receiving the reception signal ( S200 ), the reception signal including the target signal T and the noise signal is received. Here, the target signal T has a frequency exceeding 100 kHz, and the noise signal may include a low-frequency noise signal L having a frequency of 100 kHz or less and a high-frequency noise signal H having a frequency exceeding 100 kHz. In addition, the received signal including the target signal T and the noise signal is transmitted to the target signal extraction unit 140 via the first path 110 and the second path 120 , respectively.

In the process of extracting the noise signal ( S300 ), the noise signal is extracted from the received signal including the target signal T and the noise signal. The process of extracting the noise signal ( S200 ) is performed by the aforementioned noise signal extraction unit 130 , which is provided in the second path 120 and extracts the noise signal from the received signal. That is, the noise signal extracting unit 130 is located on the second path 120 and from the received signal transmitted through the second path 120 , the target signal T and the high-frequency noise signal having a frequency exceeding 100 kHz ( H) is removed. Here, as described above, the received signal includes a target signal (T) having a frequency exceeding 100 kHz, a low-frequency noise signal (L) having a frequency of 100 kHz or less, and a high-frequency noise signal (H) having a frequency exceeding 100 kHz can do. At this time, the noise signal extraction unit 130 removes the target signal (T) and the high-frequency noise signal (H) having a frequency exceeding 100 kHz from the received signal to extract the low-frequency noise signal (L) having a frequency of 100 kHz or less. can

In the process of extracting the difference signal ( S400 ), the difference signal is extracted by calculating the difference between the received signal input through the first path 110 and the noise signal extracted from the noise signal extraction unit 130 . The process of extracting the difference signal ( S400 ) is performed by the above-described target signal extraction unit 140 , wherein the target signal extraction unit 140 has a first input terminal 141 connected to the first path 110 , A second input terminal 143 is connected to the second path 120 to calculate a difference signal between the received signal transmitted to the first path 110 and the noise signal transmitted from the noise signal extractor 130 . . Here, the first input terminal 141 may be a positive (+) input terminal, and the second input terminal 143 may be a negative (-) input terminal.

The target signal extraction unit 140 includes a first input terminal 141 and a second input terminal 143 , and a difference between a received signal inputted from the first input terminal 141 and a noise signal inputted from the second input terminal 143 . Various types of differential amplifiers for calculating signals may be used, but may include a fully differential amplifier having a first output terminal 147 and a second output terminal 149 . Here, the fully differential amplifier has two output stages consisting of a first output stage 147 and a second output stage 149 . In this case, the first output terminal 147 may be a positive (+) output terminal, and the second output terminal 149 may be a negative (-) output terminal. In the fully differential amplifier, the first output terminal 147 outputs a first difference signal obtained by subtracting the noise signal transmitted from the noise signal extraction unit 130 from the received signal transmitted through the first path 110, and the second output terminal ( 149 may output a second difference signal obtained by subtracting the received signal transmitted through the first path 110 from the noise signal transmitted from the noise signal extraction unit 130 .

The noise removal method according to an embodiment of the present invention may further include converting the calculated difference signal into a digital signal. In this case, in the process of converting the digital signal, a signal obtained by subtracting the second signal from the first signal may be converted into a digital signal.

That is, the process of converting the difference signal into a digital signal is performed by the analog-to-digital converter 150 , and as described above, the target signal extractor 140 connects the first output terminal 147 and the second output terminal 149 to each other. and a fully differential amplifier including It may include a digital converter. The differential input analog-to-digital converter receives the first and second signals respectively and generates a digital signal.

Hereinafter, a laser search apparatus according to an embodiment of the present invention will be described. The laser search apparatus according to an embodiment of the present invention includes the noise remover described above, and the above-described contents are equally applied with respect to the noise remover included in the laser search apparatus according to the embodiment of the present invention. A detailed description will be omitted.

8 is a diagram schematically illustrating a laser search apparatus according to an embodiment of the present invention.

Referring to FIG. 8 , a laser search apparatus according to an embodiment of the present invention receives a laser signal reflected from a target and outputs a photocurrent, and is connected to the photodetector 20 and the photocurrent and an amplifier 40 generating an output voltage from the amplifier 40 and a noise canceller 10 connected to the amplifier 40 to remove a noise signal from a received signal transferred to the output voltage. In this case, the noise remover includes the noise remover according to the above-described embodiment of the present invention.

The laser searcher according to an embodiment of the present invention includes a plurality of photodetectors 20 that are respectively input by dividing a laser signal reflected from a target into a plurality of optical signals. Here, when the laser search apparatus irradiates a laser light toward a target from an external device such as an aircraft or an indicator, the laser light reflected from the target is detected and the target is tracked.

Here, the laser signal is divided into a plurality of optical signals according to the reception area, and the photodetector 20 included in the laser search apparatus is disposed in each reception area to receive the optical signal and track the target.

A laser signal received by the laser search apparatus is divided into a plurality of pieces according to a reception area. That is, the laser signal received by the laser searcher is divided into a plurality of optical signals according to a reception area, and the plurality of optical signals are, for example, an optical signal input through the first quadrant (A) and the second quadrant (B). It may include an optical signal input through , an optical signal input through the third quadrant (C), and an optical signal input through the fourth quadrant (D). Here, the photodetector 20 is disposed on each quadrant, detects light input through each quadrant, and controls the direction based on the coordinate value accordingly to track the target.

A coordinate value according to light detected on each quadrant may be obtained as in Equation 1 below.

Here, ΔX means the coordinate deviation in the X-axis direction, and ΔY means the coordinate deviation in the Y-axis direction. In addition, A, B, C, and D denote electrical signal magnitudes of light detected from the first to fourth quadrants.

Accordingly, the laser search apparatus checks the coordinate deviation using the ΔX value and the ΔY value, and tracks the target by controlling the direction so that a spot of the received laser signal is located at the center of the entire reception area. Here, the photodetector 20 is disposed on each quadrant to detect light input through each quadrant, and since the description is the same with respect to each photodetector device, a redundant description thereof will be omitted. decide to do

The laser tracking device according to an embodiment of the present invention may further include a saturation preventer 130 connected to the output terminal of the photodetector 20 to remove the direct current component of the photocurrent output from the photodetector 20 . have. The photocurrent output from the photodetector 20 has a direct current component (DC) and an alternating current component (AC) by combining a laser signal and a solar light signal. In this case, the saturation preventer is connected to the output terminal of the photodetector 20 to remove the direct current component of the photocurrent output from the photodetector 20 . At this time, the saturation preventer 130 may be composed of a transistor, an inductor, etc., and the configuration for removing the DC component using the same may be variously modified and applied, so a detailed description thereof will be omitted.

The amplifier 40 of FIG. 8 is connected to the photodetector 20 to generate an output voltage from the photocurrent. The amplifier 40 is connected to the output terminal of the photodetector 20 to generate a first output voltage from the photocurrent inputted from the output terminal. That is, the amplifier 40 is connected to the anode side of the photodetector 20 to receive a photocurrent from the output terminal of the photodetector 20 . Such an amplifier 40 may include a transimpedance amplifier 40 (TIA: TransImpedance Amplifier). The amplifier 40 has an inverting terminal (-) and a non-inverting terminal (+), the inverting terminal (-) is connected to the output terminal of the photodetector 20, and the non-inverting terminal (+) receives and outputs the reference voltage Adjusts the DC level. An output terminal of the amplifier 40 may be connected to a noise canceller.

As described above, according to the noise remover, the noise removal method, and the laser search apparatus according to an embodiment of the present invention, the noise signal is removed from the received signal by calculating the difference signal between the received signal and the noise signal, thereby simplifying the circuit structure and effectively reducing the noise. can be removed.

In addition, by using a fully differential amplifier having a plurality of output stages in calculating the difference signal, it is possible to facilitate conversion to a digital signal and improve the dynamic range.

In the above, preferred embodiments of the present invention have been described and illustrated using specific terms, but such terms are only for clearly describing the present invention, and the embodiments and described terms of the present invention are the spirit of the following claims. And it is obvious that various changes and changes can be made without departing from the scope. Such modified embodiments should not be individually understood from the spirit and scope of the present invention, but should be said to fall within the scope of the claims of the present invention.

10: noise canceller 20: photodetector
30: saturation preventer 40: amplifier
110: first path 120: second path
130: noise signal extraction unit 140: target signal extraction unit
150: analog-to-digital conversion unit

Claims (14)

A noise canceller for removing a noise signal from a received signal including a target signal and a noise signal, comprising:
a first path and a second path for transmitting a received signal;
a noise signal extraction unit provided in the second path to extract a noise signal from the received signal; and
a target signal extraction unit connected to the first path and the second path to remove a noise signal from a received signal using the extracted noise signal; and
The target signal extraction unit includes a fully differential amplifier (Fully Differential Amplifier) having a first output stage and a second output stage,
A reference voltage is applied to the second path, a common mode voltage is applied to the fully differential amplifier, and the first output stage subtracts a noise signal from a received signal, so that the target signal is present in the remaining section except for the section in which the target signal is present. Outputs a first difference signal having a lower constant positive (+) voltage value, and the second output terminal subtracts the received signal from the noise signal, so that in the remaining section except for the section in which the target signal is present, a constant higher than the target signal Outputs a secondary signal having a positive (+) voltage value,
Further comprising; an analog-to-digital converter connected to the target signal extraction unit to convert the signal output from the target signal extraction unit into a digital signal;
and the analog-to-digital converter includes a differential input analog-to-digital converter that receives a first difference signal and a second difference signal from the first output terminal and the second output terminal as differential signals.
The method according to claim 1,
The target signal extraction unit,
A noise canceller for extracting a difference signal from which the noise signal is removed from the received signal by calculating a difference between the received signal transmitted through the first path and the noise signal transmitted through the second path.
The method according to claim 1,
The noise signal extractor includes a low-pass filter.
delete delete delete A noise removal method for removing a noise signal from a received signal including a target signal and a noise signal, the method comprising:
transmitting a received signal through a first path and a second path;
receiving a received signal transmitted through the first path;
extracting a noise signal from the received signal transmitted through the second path;
extracting a difference signal from which the noise signal is removed from the received signal by calculating a difference between the received signal transmitted through the first path and the noise signal extracted from the second path; and
The process of converting the extracted difference signal into a digital signal; including,
The process of extracting the difference signal is
By subtracting the noise signal from the received signal using a Fully Differential Amplifier, the first signal having a constant positive voltage value lower than the target signal in the remaining section except for the section where the target signal is present. Subtracting the received signal from the extraction process and the noise signal, and extracting the secondary signal having a constant positive (+) voltage value higher than the target signal in the remaining sections except for the section in which the target signal is present,
The process of converting the digital signal is,
A noise removal method in which a differential input analog-to-digital converter receives the first and second signals as differential signals and converts them into digital signals.
delete 8. The method of claim 7,
The noise signal includes a low-frequency noise signal,
The step of extracting the noise signal is a noise removal method of extracting a low-frequency noise signal by removing a target signal and a high-frequency noise signal from a received signal.
10. The method of claim 9,
The low-frequency noise signal is a noise removal method having a frequency of 100 kHz or less.
delete delete a photodetector receiving a laser signal reflected from a target and outputting a photocurrent;
an amplifier coupled to the photodetector to generate an output voltage from the photocurrent; and
and a noise canceller connected to the amplifier to remove a noise signal from the received signal transferred to the output voltage;
The noise eliminator is a laser search apparatus including the noise eliminator according to any one of claims 1 to 3.
14. The method of claim 13,
The photodetector divides a laser signal receiving area into a plurality and outputs a photocurrent from the laser signal input to the divided receiving area,
The amplifier and the noise canceller are provided in plurality to respectively generate an output voltage from the photocurrent output from the photodetector and to remove the noise signal.

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