KR101421987B1 - Spectrum analyzer and method for processing a measured signal - Google Patents

Abstract

The present invention relates to a spectrum analyzer and, more particularly, to a method for processing measured signals for removing discontinuity at the time of overlap-adding the measured signals and a spectrum analyzer employing the method. The method comprises: a step for measuring signals by repetitively moving center frequencies (f_c) in the frequency band of signals to be measured; a step for respectively obtaining signals of sections having no DC in the signals positioned at the right and left sides of the moved center frequencies in each signal measured by repetitively moving the center frequencies (f_c); a step for multiplying the signals of each of the obtained signal sections by a pulse shaping function in order to remove discontinuity points; and an original signal recovering step for overlap-adding each of the obtained signals which have been multiplied by the pulse shaping function in the multiplying step in order to obtain original signals to be measured.

Description

TECHNICAL FIELD [0001] The present invention relates to a frequency analyzer and a frequency analyzer,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectrum analyzer, and more particularly, to a measurement signal processing method for eliminating discontinuity when combining measurement signals and a frequency analyzer employing the method.

In a general wireless communication system, a signal transmission / reception method generates and transmits a low frequency baseband signal using a high frequency carrier wave. A spectrum analyzer measures and verifies and analyzes these signals.

DC offset is generated according to the structure and configuration chip of the frequency analyzer and the RF module. If a DC offset occurs, there is a problem in correct analysis of the low frequency baseband signal. Therefore, the generated DC offset must be removed properly or suppressed beforehand.

A method of eliminating and preventing DC offset is to set a threshold and lower or eliminate the DC offset. There is a method of shifting the center frequency to measure in multiple stages (only the left or right spectrum at the measured center frequency) .

A method of lowering or removing a DC offset (hereinafter referred to as DC) by setting a threshold value may cause signal distortion. One example of such a distortion is to set the size to be erased incorrectly even if the DC component is correctly judged, or to erroneously distinguish the DC from the original signal and not to remove the original signal or remove the DC.

Another example of how to shift the center frequency and measure it in multiple steps is to move the center frequency three times within the measurable maximum span of the frequency analyzer. Since this method avoids the frequency at which the DC exists, it is not influenced by DC. However, since the center frequency is shifted three times, the measurement time is delayed and troublesome, and furthermore, The coupling discontinuity 20 exists as shown in FIG. 1 (d).

For reference, FIG. 1 shows a discontinuity in the case of combining measurement signals obtained by measuring a signal while shifting the center frequency. In FIG. 1, (a) shows a case in which the LPF, which is one component of the frequency analyzer, The present example illustrates the presence of the DC 10 at the center frequency. (b) shows a signal measured by adjusting a frequency higher by a at the original center frequency to the center frequency, and (c) shows a signal measured by adjusting a frequency lower by a at the original center frequency to the center frequency will be. Thus, DC 10 can be avoided by measuring the signal while shifting the center frequency. On the other hand, when signal sections 2 and 4 and 1 and 3 to be obtained in the measurement signal sections shown in FIGS. 1B and 1C are extracted and combined, DC is not generated as shown in FIG. A discontinuity 20 is generated between the coupled signals 1, 2, 3, and 4, and signal distortion occurs.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a method and apparatus for measuring a signal while moving a center frequency in order to avoid DC, And to provide a measurement signal processing method.

Still another object of the present invention is to measure the signal while shifting the center frequency within the measurable maximum span of the frequency analyzer, while avoiding DC while decreasing the signal measurement time, And a frequency analyzer that employs the method of processing the measured signal.

According to an aspect of the present invention, there is provided a method of processing a signal to be measured through a filter, the method comprising: receiving a signal of a desired frequency bandwidth (BW)

)를 반복 이동하여 신호 측정하는 a) 단계와;The center frequency of the frequency band of the signal to be measured

) Repeatedly to measure a signal;

)를 반복 이동하여 측정되는 각각의 신호에서 그 이동된 중심 주파수 좌, 우측에 위치하는 신호에서 DC를 포함하지 않는 구간의 신호를 각각 획득하는 b) 단계와;The center frequency (

B) obtaining a signal of a section not including DC in a signal located on the left and right sides of the shifted center frequency, respectively;

C) multiplying the signal of each acquired signal interval by a pulse shaping function for discontinuous point removal;

And d) combining the acquired signals multiplied by the pulse shaping function in the multiplication step to obtain the original signal to be measured and restoring the original signal.

)의 이동범위는 상기 필터의 대역폭(BW)에 따라 결정되되, DC의 영향을 회피하기 위해 이동 가능한 중심 주파수(

)의 범위는 최대 BW/4 이고, 상기 중심 주파수의 반복 이동 횟수는 2회임을 특징으로 한다.Further, in the measurement signal processing method,

) Is determined according to the bandwidth (BW) of the filter, and the moving range of the movable center frequency (

) Is the maximum BW / 4, and the number of repeated movements of the center frequency is two.

)가

와

로 이동한 경우, 그 각각의 중심 주파수(

,

)의 좌측과 우측에 각각 위치하는 신호구간 중 대역폭이 BW/4인 신호를 획득하는 방식으로 총 4구간의 신호를 획득하여 펄스 정형함수를 승산함을 특징으로 하며,Further, in the measurement signal processing method,

)end

Wow

, The respective center frequencies (

,

And a signal having a bandwidth of BW / 4 is acquired from the signal sections located on the left and right sides of the input signal, respectively. In this way, signals of four sections are obtained and multiplied by the pulse shaping function.

는 BW/8의 값을 가짐을 특징으로 한다.In order to equally combine the obtained signals,

Is characterized by having a value of BW / 8.

와

값을 가짐을 특징으로 한다.In addition, the pulse shaping function is a raised cosine function, and the function multiplied according to the coupled part is

Wow

Value. ≪ / RTI >

According to another aspect of the present invention, there is provided a frequency analyzer comprising:

A low pass filter for obtaining a signal of a desired frequency bandwidth (BW) with respect to a received signal to be measured;

A sampler for sampling and outputting a measurement signal output through the filter according to a sampling rate;

An ADC for digitally converting the sampler output;

An FFT for Fourier transforming the digitally converted measurement signal;

)를 상기 주파수 대역폭 내에서 반복 이동하되, 그 반복 이동된 각각의 중심 주파수 좌, 우측에 위치하는 신호에서 DC를 포함하지 않는 좌, 우측 구간의 신호를 각각 획득하고, 이동된 중심 주파수 각각에 대해 획득된 좌, 우측 구간의 신호에 펄스 정형함수를 승산한 후 결합하여 원 신호 복원하는 신호처리부;를 포함함을 특징으로 한다.The center frequency of the Fourier transformed measurement signal (

) Are repeatedly shifted within the frequency bandwidth, signals of left and right sections that do not include DC are obtained from the signals located on the left and right sides of the repeatedly shifted center frequencies, respectively, And a signal processing unit for multiplying the obtained signals of the left and right sections by a pulse shaping function, and combining and restoring the original signal.

According to an embodiment of the present invention, a signal is measured while shifting the center frequency to avoid DC, and a discontinuity that may occur when the signals measured in the two measurement steps are combined is measured using a pulse shaping function So that it can be effectively removed.

In addition, the present invention measures a signal while moving a center frequency within a measurable maximum width (Span) of a frequency analyzer, and does not move the center frequency three times as before, It is possible to reduce the signal measurement time, and furthermore, there is an advantage that the distortion of the signal can be reduced by eliminating the discontinuity that may occur when combining the measurement signals.

FIG. 1 is an example of a spectrum for showing a discontinuity in the case of combining signals obtained by measuring a signal while shifting the center frequency. FIG.
2 is a block diagram of a frequency analyzer according to an embodiment of the present invention;
3 is a diagram for explaining a measurement signal processing method executable in the frequency analyzer shown in Fig. 2; Fig.
FIG. 4 and FIG. 5 are exemplary spectrums for illustrating the signal processed by the method of measuring signal processing according to an embodiment of the present invention and the discontinuity of the signal removed when combining them. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In the following, a spectrum analyzer of Fast Fourier Transform (FFT) method will be described as an example of an apparatus for acquiring and processing a signal of a desired frequency bandwidth with respect to a signal to be measured through a filter.

FIG. 2 illustrates a block diagram of a frequency analyzer according to an exemplary embodiment of the present invention. Referring to FIG.

)의 이동범위는 LPF(50)의 대역폭에 따라 정해지며, 측정 가능한 신호의 대역폭은 하기 수학식 1과 같이 나타낼 수 있다. 이에 DC의 영향을 피하기 위해 이동 가능한 중심 주파수(

)의 범위는 최대 BW/4가 된다. 그리고 중심 주파수

는 측정하고자 하는 주파수 대역의 중심 주파수인 것으로 가정한다.Referring to FIG. 2, a frequency analyzer according to an embodiment of the present invention includes a low pass filter (LPF) for obtaining a desired band width (BW) Filter 50 as shown in FIG. For reference, the center frequency (

) Is determined according to the bandwidth of the LPF 50, and the bandwidth of the measurable signal can be expressed by the following equation (1). In order to avoid the influence of DC, a movable center frequency (

) Is the maximum BW / 4. And the center frequency

Is the center frequency of the frequency band to be measured.

)에 따라 샘플링 출력한다. 참고적으로 FFT 방식의 주파수 분석기에서는 FFT후 각 포인트들의 간격은 샘플링 레이트(

)와 FFT의 수에 따라 정해지며 하기 수학식 2와 같은

의 값을 갖는다.Meanwhile, the sampler 60 samples the measurement signal output through the LPF 50 at a sampling rate

). For reference, in an FFT frequency analyzer, the interval of each point after the FFT is the sampling rate

) And the number of FFTs, and is expressed by the following Equation 2

Lt; / RTI >

는 샘플러(60)의 샘플링 레이트,

는 FFT 포인트 수

The sampling rate of the sampler 60,

The number of FFT points

An ADC (Analog-to-Digital Converter) 70 converts the sampler 60 output to a digital signal, and the FFT 80 performs a Fourier transform on the measurement signal output from the ADC 70.

)를 LPF(50)의 주파수 대역폭 내에서 반복 이동(본 발명의 실시예에서는 2회 이동)하되, 그 반복 이동된 각각의 중심 주파수 좌, 우측에 위치하는 신호에서 DC를 포함하지 않는 좌, 우측 구간의 신호를 각각 획득하고, 이동된 중심 주파수 각각에 대해 획득된 좌, 우측 구간의 신호에 펄스 정형함수, 예를 들면 올림 코사인(raised cosine) 함수를 승산한 후 이들을 결합하여 원 신호 복원하여 후단의 표시부(100)로 출력한다. 이러한 신호처리부(90)의 상세 동작 설명은 도 3에서 설명될 측정신호 처리방법에서 보다 구체적으로 설명하기로 한다.The signal processing unit 90 measures the center frequency of the Fourier transformed measurement signal (

) In the frequency band of the LPF 50 (two movements in the embodiment of the present invention) within the frequency band of the LPF 50, The signals of the left and right sections obtained for each of the shifted center frequencies are multiplied by a pulse shaping function, for example, a raised cosine function, and then the signals are combined to restore the original signal, To the display unit 100 of FIG. The detailed operation of the signal processing unit 90 will be described in more detail in the measurement signal processing method described with reference to FIG.

FIG. 3 is a view for explaining a measurement signal processing method that can be executed in the FFT type frequency analyzer shown in FIG. 2, and FIGS. 4 and 5 are diagrams for explaining a method of processing a measurement signal according to an embodiment of the present invention And the spectra to show that the signal to be processed and the discontinuity of the signal are removed when combining them.

Hereinafter, the operation of the signal processing unit 90 and the method of processing a measurement signal according to the embodiment of the present invention will be described with reference to FIGS. 3 to 5. FIG.

First, in the frequency analyzer of the FFT method, as described above, the interval of each point after the FFT is determined according to the sampling rate and the number of FFTs and has a value of DELTA f defined as Equation (2).

라 가정하면 본 발명의 실시예에서는 중심 주파수를 2번 이동하여 측정하기 때문에, 이동하는 중심 주파수는

와

가 된다. 이 두 신호에서 원 신호를 복원하기 위해 특정 부분(각 신호에서 DC를 포함하지 않는 부분)을 가지고 결합하되, 불연속점을 제거하기 위해 펄스 정형함수의 하나인 올림 코산인(raised cosine) 함수를 승산하여 결합(overlap add)하면, 불연속성이 제거된 원 신호를 복원할 수 있다.If the center frequency of the frequency band to be measured is

In the embodiment of the present invention, since the center frequency is measured by moving twice, the moving center frequency is

Wow

. In order to recover the original signal from these two signals, we combine the specific part (the part not including DC in each signal) to recover the original signal, and multiply the raised cosine function, which is one of the pulse shaping functions, If the signal is overlapped, the original signal from which the discontinuity is removed can be restored.

)를 이동하는 범위는 언급한 바와 같이 LPF(50)에 따라 정해지며 측정 가능한 신호의 대역폭은 상기 수학식 1과 같다. DC의 영향을 피하기 위해 이동 가능한 중심 주파수의 범위는 최대 BW/4 가 된다. 즉,

가 된다. 이에 중심 주파수

보다 a*△f 만큼 높고 낮은 신호의 중심 주파수는 각각

와

가 되며, 이 두 신호의 시작과 끝 주파수 즉, LPF(50)를 통과한 두 신호의 영역은 하기와 같다.On the other hand,

) Is determined according to the LPF 50 as mentioned above, and the bandwidth of the measurable signal is expressed by Equation (1). To avoid the effects of DC, the range of movable center frequencies is at most BW / 4. In other words,

. Therefore,

The center frequencies of the signals, which are higher and lower by a * Δf than

Wow

And the start and end frequencies of the two signals, that is, the areas of the two signals passing through the LPF 50, are as follows.

를 중심 주파수로 갖는 신호의 측정 가능 최대 주파수

는

보다 커야 하고,

를 중심 주파수로 갖는 신호의 측정 가능 최소 주파수

는

보다 작아야 한다. 이는 다음과 같이 나타낼 수 있다.

Of the signal having the center frequency as the maximum measurable frequency

The

≪ / RTI >

The minimum measurable frequency of the signal having the center frequency

The

. This can be expressed as follows.

That is, in order to avoid the influence of DC, the range of the movable center frequency becomes maximum BW / 4.

는 BW/8 가 된다.On the other hand, when using the overlap add multiplied by the carry cosine function, the frequency shift should be smaller than BW / 4 in order to avoid the influence of the DC of the two signals measured twice. In order to uniformly apply the overlap add, the frequency can be measured by moving the frequency by BW / 8,

Becomes BW / 8.

)를 우측으로 a*△f 만큼 이동하여 측정한 신호(b)와 좌측으로 -a*△f 만큼 이동하여 측정한 신호 (c)를 결합한 것을 도시한 것이다. 중심 주파수를 두 번 이동하여 각각 측정된 신호에서 각 중심 주파수의 좌측과 우측에 위치하는 2개의 음영처리구간(2와 4, 1과 3)을 획득하여 결합하면 도 1의 (d)와 같은 신호가 얻어진다. 이는 LPF(50)의 대역인 BW를 4등분한 것이므로, 4개의 각 구간의 대역폭은 BW/4 가 된다.For reference, FIG. 1 (d) shows the center frequency (

) To the right by a * [Delta] f and the signal (c) measured by shifting to the left by- a * [Delta] f . When the center frequency is moved twice and the two shading sections (2 and 4, 1 and 3) positioned on the left and right sides of each center frequency are acquired and combined in the measured signals, the signal as shown in FIG. 1 (d) Is obtained. Since the bandwidth BW of the LPF 50 is divided into four equal parts, the bandwidth of each of the four sections is BW / 4.

주파수에서 DC(10)가 포함되어 있으므로 사용할 수 없다. 이와 같은 기준으로 도 1의 (c)에서도 (b)의 4번 구간과 2번 구간은 사용할 수 없으므로 나머지 구간인 1과 3 구간의 신호만을 획득하여 결합시 이용한다. 이때 각 구간의 대역폭은 앞서 설명한 바와 같이 BW/4 가 된다. 그리고 각 측정 신호에서 컷오프 주파수와 DC가 존재하는 구간을 제외한 구간을 주파수와 FFT 포인트로 나타내면 하기와 같다.The reference for obtaining the shaded sections 2 and 4, 1 and 3 shown in FIG. 1 is that the section corresponding to the section 1 in FIGS. 1B to 1C is the cutoff frequency section of the LPF 50 (B) to (c) in the section corresponding to section 3,

It can not be used because DC (10) is included in frequency. In this case, only the signals of the first and third sections, that is, the sections 4 and 2 of FIG. 1 (c), can be used. At this time, the bandwidth of each section becomes BW / 4 as described above. The frequency and the FFT point represent the cutoff frequency and the interval excluding the interval where the DC exists in each measurement signal as follows.

- Section 1

- Section 2

- Section 3

- Section 4

On the other hand, when the signals obtained from the signals measured in FIGS. 1 (b) and (c) are combined, a discontinuity 20 such as (d) may appear in the coupling portion. When the discontinuity 20 is multiplied by the raised cosine function and the overlap add is used, the discontinuity as shown in FIG. 5 (a) can be removed as shown in (b).

와

의 값을 가진다.However, in order to use the overlap add, the bandwidth (BW / 4) of the signals (1 to 4 intervals) obtained in (b) and (c) of FIG. Each of the obtained intervals should have a bandwidth of BW / 2, and the signals of the obtained intervals should be multiplied by an up cosine function and then combined. The raised cosine function, which is multiplied by the combined part,

Wow

Lt; / RTI >

이므로 결과적으로 중심 주파수를 달리하여 획득된 신호에 올림 코산인 함수를 곱하여 오버랩 애드를 하면 신호의 변화가 없게 된다. 즉, 원 신호 복원이 가능하게 되는 것이다.

As a result, if the signal obtained by varying the center frequency is multiplied by the adder cosine function and overlapped add is performed, there is no signal change. That is, the original signal can be restored.

)를 나타낸 것으로 가정한다. 그리고 도 4에 도시된 참조번호 1,2,3,4는 중심 주파수를 이동하여 측정한 신호에서 획득해야 하는 구간의 신호를 나타낸 것이다.A method of processing a measurement signal that can be executed by the signal processing unit 90 shown in FIG. 2 based on the above-described contents will be described in detail with reference to FIGS. 3 and 4. FIG. In the following description, BW shown in FIG. 4 represents the frequency bandwidth of the LPF 50, and reference numeral 10 denotes a center frequency at which DC exists

). Reference numerals 1, 2, 3, and 4 shown in FIG. 4 represent signals of a section that should be acquired from a signal measured by moving the center frequency.

를 도 4의 (b)에 도시한 바와 같이 기설정된 제1중심 주파수

로 이동하고, 그 이동된 중심 주파수에서 신호를 측정(S12단계)한다.First, in step S10, the signal processing unit 90 of FIG. 3 calculates the center frequency (hereinafter referred to as " center frequency "

As shown in Fig. 4 (b)

And measures the signal at the moved center frequency (step S12).

의 좌, 우측에 위치하는 신호에서 DC를 포함하지 않는 구간, 즉 2와 4구간의 신호를 획득(S14단계)한다. 도 4의 (b)에서 2 구간과 4구간의 주파수와 FFT 포인트는 앞서 설명한 바와 같다. 획득된 구간의 신호는 내부 메모리에 일시 저장한다.In the signal measuring step, the signal processing unit 90 measures the shifted center frequency of the signal measured as shown in FIG. 4 (b)

The signals in the second and fourth sections, which do not include DC, are obtained in the signals located on the left and right sides of the signal (step S14). In FIG. 4 (b), the frequency and FFT points of the two and four sections are as described above. The acquired signal of the section is temporarily stored in the internal memory.

로 이동(S16단계)하고, 그 이동된 중심 주파수에서 신호를 재 측정(S18단계)한다.The signal processing unit 90, which obtains the signal of the desired section by measuring the signal by moving the center frequency once, again transmits the center frequency to the second center frequency

(Step S16), and re-measures the signal at the shifted center frequency (step S18).

의 좌, 우측에 위치하는 신호에서 DC를 포함하지 않는 구간, 즉 1번과 3번 구간의 신호를 획득(S20단계)한다. 이와 같이 2번의 중심 주파수 이동으로 소망하는 구간의 신호들을 획득한 신호처리부(90)는 불연속점 제거를 위해 획득된 각 신호 구간의 신호에 올림 코사인 함수를 하기 수학식 3과 같이 승산(S22단계)하고, 원 신호 복원을 위해 올림 코사인 함수가 곱해진 획득 신호들을 결합(가산)(S24단계)한다.In the signal measurement step, the signal processing unit 90 calculates the center frequency of the shifted center frequency

(S20), that is, the signals of the first and third sections, which do not include DC, in the signals located on the left and right sides of the signal line. The signal processor 90, which obtains the signals of the desired interval with the center frequency shift of 2 times, multiplies the signal of each signal section obtained for discontinuous point removal by the multiplication (S22) as shown in Equation (3) (Sum) the acquired signals multiplied by the raised cosine function to restore the original signal (step S24).

는 약 BW/8의 값을 가짐으로 BW/4를 나타내기 위해서는 2a 개수 만큼의 포인트가 필요하게 된다. 따라서 2번 구간의 신호와 3번 구간의 신호 결합은 상기 수학식 3과 같이 나타낼 수 있는 것이다.Referring to FIG. 4, in the combination of the second and third sections, the maximum frequency region (right portion) of the second section and the BW / 4 region of the third minimum frequency region (left portion) overlap each other.

Has a value of about BW / 8, so that it requires 2a points to indicate BW / 4. Therefore, the signal combination of the signal of the second interval and the interval of the third interval can be expressed as Equation (3).

In Equation (3), the left term is the signal of the second interval, and the right term is the third interval signal. The combination of the signal region of the first interval and the signal region of the second interval (overlap add), and the combination of the signal region of the third interval and the signal interval of the fourth interval may be combined in the same manner as in Equation (3).

When the signals obtained from the measurement signals shown in FIGS. 4B and 4C are combined by the method of Equation 3, the original signal as shown in FIG. 4D is restored, And outputs the restored signal to the display unit 100 for display (step S26). Comparing FIG. 4 (d) with FIG. 1 (d), it can be seen that the discontinuity that was present in the coupled interval has been removed.

Therefore, the present invention can effectively remove the discontinuity that may occur when combining the signals measured in each measurement step by using the pulse shaping function while measuring the signal while shifting the center frequency to avoid DC.

In addition, the present invention measures a signal while moving a center frequency within a measurable maximum width (Span) of a frequency analyzer, and does not move the center frequency three times as before, It is possible to reduce the signal measurement time, and furthermore, it is a useful invention that can reduce the distortion of the signal by eliminating the discontinuity that may occur when combining the measurement signals.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. For example, in FIG. 3 illustrating the embodiment of the present invention, the signal measurement and signal acquisition steps are repeated by shifting the center frequency. However, after the signal measurement and signal acquisition are performed after the center frequency shift, And then the center frequency is shifted again to perform signal measurement and signal acquisition. Then, the signal is multiplied by an up cosine function, and then the up-sampled signal obtained by multiplying the up-sampled cosine function stored in the previous step is multiplied by the up- The measurement signal may be processed in such a manner that the measurement signal is processed. Accordingly, the true scope of the present invention should be determined only by the appended claims.

Claims (12)

delete A method of processing a measurement signal that is executable in an apparatus for acquiring and processing a signal of a desired frequency bandwidth with respect to a signal to be measured through a filter,
In the frequency band of the signal to be measured,

) Repeatedly to measure a signal;
The center frequency (

B) obtaining a signal of a section not including DC in a signal located on the left and right sides of the shifted center frequency, respectively;
C) multiplying the signal of each acquired signal interval by a pulse shaping function for discontinuous point removal;
And d) combining the acquired signals multiplied by the pulse shaping function in the multiplication step to obtain the original signal to be measured, thereby restoring the original signal,
The center frequency (

) Is determined according to the bandwidth (BW) of the filter, and the moving range of the movable center frequency (

) Is a maximum BW / 4, and the number of repeated movements of the center frequency is two or more times. The method of claim 2, further comprising:

)

Wow

Wherein the measurement signal processing method comprises the steps of:

,

The sampling rate of the sampler,

Is the interval frequency of each point after the FFT 4. The method of claim 3,

)end

Wow

, The respective center frequencies (

,

A signal having a bandwidth of BW / 4 is acquired from a signal section located on the left and right sides of the input signal, and a signal of a total of four sections is acquired and multiplied by a pulse shaping function. 5. The method of claim 4, further comprising:

Has a value of BW / 8. The pulse shaping function according to claim 2 or 4, wherein the pulse shaping function is an up cosine function, and the function multiplied by the coupled part is

Wow

Value of the measured signal. delete A low pass filter for obtaining a signal of a desired frequency bandwidth (BW) with respect to a received signal to be measured;
A sampler for sampling and outputting a measurement signal output through the filter according to a sampling rate;
An ADC for digitally converting the sampler output;
An FFT for Fourier transforming the digitally converted measurement signal;
The center frequency of the Fourier transformed measurement signal (

) Are repeatedly shifted within the frequency bandwidth, signals of left and right sections that do not include DC are obtained from the signals located on the left and right sides of the repeatedly shifted center frequencies, respectively, And a signal processing unit for multiplying the obtained signals of the left and right sections by a pulse shaping function, and combining and restoring the original signal,
The center frequency (

) Is determined according to the bandwidth (BW) of the filter, and the moving range of the movable center frequency (

) Is a maximum BW / 4, and the number of repeated movements of the center frequency is two or more times. 9. The method of claim 8, further comprising:

)

Wow

.

,

The sampling rate of the sampler,

Is the interval frequency of each point after the FFT The method of claim 9,

)end

Wow

, The respective center frequencies (

,

A signal having a bandwidth of BW / 4 is acquired from a signal section located on the left and right sides of the frequency domain, respectively, and a signal of a total of four sections is obtained and multiplied by a pulse shaping function. 11. The method of claim 10, further comprising:

Has a value of BW / 8. The pulse shaping function according to claim 8 or 10, wherein the pulse shaping function is an up cosine function, and the function multiplied by the coupled part is

Wow

And a frequency analyzer.

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