KR101174546B1  Pass Band Reconfigurable Digital Filter Device  Google Patents
Pass Band Reconfigurable Digital Filter Device Download PDFInfo
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 KR101174546B1 KR101174546B1 KR1020100018219A KR20100018219A KR101174546B1 KR 101174546 B1 KR101174546 B1 KR 101174546B1 KR 1020100018219 A KR1020100018219 A KR 1020100018219A KR 20100018219 A KR20100018219 A KR 20100018219A KR 101174546 B1 KR101174546 B1 KR 101174546B1
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 H—ELECTRICITY
 H03—BASIC ELECTRONIC CIRCUITRY
 H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
 H03H17/00—Networks using digital techniques
 H03H17/02—Frequency selective networks

 H—ELECTRICITY
 H03—BASIC ELECTRONIC CIRCUITRY
 H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
 H03H17/00—Networks using digital techniques
 H03H17/02—Frequency selective networks
 H03H17/0223—Computation saving measures; Accelerating measures
 H03H17/0227—Measures concerning the coefficients

 H—ELECTRICITY
 H03—BASIC ELECTRONIC CIRCUITRY
 H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
 H03H17/00—Networks using digital techniques
 H03H17/02—Frequency selective networks
 H03H17/06—Nonrecursive filters
 H03H17/0621—Nonrecursive filters with inputsampling frequency and outputdelivery frequency which differ, e.g. extrapolation; Antialiasing
 H03H17/0635—Nonrecursive filters with inputsampling frequency and outputdelivery frequency which differ, e.g. extrapolation; Antialiasing characterized by the ratio between the inputsampling and outputdelivery frequencies
 H03H17/065—Nonrecursive filters with inputsampling frequency and outputdelivery frequency which differ, e.g. extrapolation; Antialiasing characterized by the ratio between the inputsampling and outputdelivery frequencies the ratio being integer
 H03H17/0657—Nonrecursive filters with inputsampling frequency and outputdelivery frequency which differ, e.g. extrapolation; Antialiasing characterized by the ratio between the inputsampling and outputdelivery frequencies the ratio being integer where the outputdelivery frequency is higher than the input sampling frequency, i.e. interpolation

 H—ELECTRICITY
 H03—BASIC ELECTRONIC CIRCUITRY
 H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
 H03H17/00—Networks using digital techniques
 H03H17/02—Frequency selective networks
 H03H17/06—Nonrecursive filters
 H03H17/0621—Nonrecursive filters with inputsampling frequency and outputdelivery frequency which differ, e.g. extrapolation; Antialiasing
 H03H17/0635—Nonrecursive filters with inputsampling frequency and outputdelivery frequency which differ, e.g. extrapolation; Antialiasing characterized by the ratio between the inputsampling and outputdelivery frequencies
 H03H17/065—Nonrecursive filters with inputsampling frequency and outputdelivery frequency which differ, e.g. extrapolation; Antialiasing characterized by the ratio between the inputsampling and outputdelivery frequencies the ratio being integer
 H03H17/0664—Nonrecursive filters with inputsampling frequency and outputdelivery frequency which differ, e.g. extrapolation; Antialiasing characterized by the ratio between the inputsampling and outputdelivery frequencies the ratio being integer where the outputdelivery frequency is lower than the input sampling frequency, i.e. decimation
Abstract
Description
The present invention relates to a digital filter, and more particularly, to a digital filter for passing a signal of a specific frequency band in a digital signal.
Digital filters have many advantages compared to analog filters because they can be integrated circuits and can be miniaturized, low cost, and high in reliability. In particular, as the communication speed, high speed, and the amount of communication increase, the field of application of the digital filter is increasing, and it is used in places such as the transmitting end and the receiving end of the baseband part of the mobile communication system.
Digital filters are generally divided into finite impulse response (FIR) filters and infinite impulse response (IIR) filters.
The finite impulse response filter uses the property that the impulse response will be of finite length when it is input to the filter because the finite impulse response filter does not use any feedback.
Finite impulse response filters that do not use feedback do not require a feedback loop to ensure stability. In particular, since the specification of the linear phase characteristic is satisfied, it is widely used for applications such as waveform transmission. However, when the finite impulse response filter tries to obtain the amplitude characteristic that is the same as that of the infinite impulse response filter, the order becomes larger, which causes more burden on hardware such as an adder and a multiplier.
When designing a finite impulse response filter, there are two design methods in the frequency domain and a design method in the time domain, and a window function method and a frequency sampling method are frequently used when designing in the frequency domain.
On the other hand, when designing in the time domain, the impulse response corresponds to the coefficients of the finite impulse response filter, which is simpler than the design in the frequency domain, and there are many known linear programming methods to approximate the transfer function. The optimal solution can be found.
In particular, the finite impulse response filter allows so that calculations whose finiteness of their outputs do not produce decimated outputs, or calculations with predictable values in interpolated outputs, are omitted, so called multirate. ) Is computationally efficient in applications, for example when interpolated or decimated to raise or lower the sampling rate of a signal.
The finite impulse response filter implemented in the form of hardware has a problem that it is very difficult to reconstruct the band pass characteristics when the number of taps and the filter coefficients are fixed and designed to have a specific pass band.
1 is a diagram illustrating an example of a filter for reconstructing a frequency by changing a conventional filter coefficient.
Referring to FIG. 1, a frequency reconstruction filter according to a conventional example includes a coefficient storage unit 100, a multiplexer 102, a multiplier 104, and an adder 106. The coefficient storage unit 100 of the conventional reconstruction filter stores coefficient information for a plurality of pass bands. By extracting the coefficient information according to the user's band selection and providing it to the multiplexer 102 so that the filter impulse response corresponding to the selected band can be generated, the generated filter impulse response is the input function (x [n]) The output signal y [n] is generated by filtering the input function.
Such a conventional method has a limitation in a band that can be reconstructed, and even if frequency reconstruction is performed, only the coefficients of the filter are changed, so that proper reconstruction is difficult to be achieved.
Various frequency reconstruction schemes have been proposed in addition to the abovedescribed methods, but there are many restrictions in reconfiguring frequencies without changing hardware, and in particular, frequency reconfiguration is very complicated due to too many parameters to be changed.
The present invention provides a digital filter device capable of simply changing the pass band by changing a simple parameter.
In addition, the present invention provides a digital filter device capable of reconstructing a pass band to have various band pass characteristics without changing hardware.
In addition, the present invention provides a digital filter device that allows a user to freely select a pass band while implementing good skirt characteristics with a small number of taps.
Other aspects of the present invention will be readily apparent to those skilled in the art through the following examples.
According to an aspect of the present invention, a plurality of complimentary images are provided in a frequency domain in which the first output and passbands corresponding to the plurality of multiimages are formed through interpolation based on a predetermined sampling constant and the multiimages are not formed. An upsampling unit configured to generate a second output forming a passband corresponding to the upsampling unit; An image number adjustment output unit configured to adjust the number of the multiimage included in the first output of the upsampling unit and the complementary image included in the second output; By subtracting the output of the image number control output part whose number has been adjusted up to the Lth image and the output of the image number control part whose number has been adjusted up to the (L1) th image, corresponding to each multiimage and multicomplementary image A second subtraction unit outputting a band pass signal; A register for storing a band pass signal of each of the multiimage and each of the multicomplementary images output from the second subtraction unit; There is provided a digital filter device capable of reconstructing a pass band including an adder for extracting and summing band pass signals of a multi image or a multicomplementary image corresponding to a designated pass band.
The upsampling unit includes a pass band including a first delay unit delaying an input signal based on the sampling constant to generate the first output and a filter unit filtering an output signal of the first delay unit to generate a first output. A digital filter device capable of reconstruction is provided.
The upsampling unit delays the output signal of the first delay unit based on the number of taps of the filter unit and the sampling constant to generate the second output, and the second delay unit from the output signal of the filter unit. The apparatus may further include a first subtraction unit for subtracting the output signal.
Each of the plurality of multiimage and complementary images has the same shape as the baseband multiimage.
The multiimage and multicomplementary image have a predetermined period, which corresponds to the bandwidth of the baseband multiimage.
The sampling constant (
) May be set by the following equation.
In the above equation
Is the frequency of the passband Is the frequency of the stopband.The image number control output unit scales by a sampling constant and applies the first sampling kernel including the multiimage number as a variable to the first output of the upsampling unit to generate an output of adjusting the number of the multiimages.
The first sampling kernel including the multiimage number as a variable may be set as in the following equation.
In the above equation, L is the image number,
Is the sampling constant.The image number adjusting output unit is scaled by a sampling constant and adjusts the number of the multicomplementary images by applying a second sampling kernel including a multicomplementary image number as a variable to the second output of the upsampling unit. Produces one output.
The second sampling kernel including the multicomplementary image number as a variable may be set as in the following equation.
In the above equation, L is the multicomplementary image number
Is the sampling constant.The second delay unit in the z domain
Correspondingly delays the output signal of the first delay unit.The maximum value of the image number is set by a sampling constant, and the number from the adjusted output to the (L1) th image until the Lth image is changed until the image number L becomes the maximum while changing the image number L. Repeated subtraction of the adjusted output.
According to another aspect of the present invention, a plurality of complimentary images in a frequency domain in which the first output and passband corresponding to the plurality of multiimages are formed through interpolation based on a predetermined sampling constant and the multiimage is not formed. An upsampling unit configured to generate a second output forming a passband corresponding to the upsampling unit; An image number adjustment output unit configured to adjust the number of the multiimage included in the first output of the upsampling unit and the complementary image included in the second output; By subtracting the output of the image number control output part whose number has been adjusted up to the Lth image and the output of the image number control part whose number has been adjusted up to the (L1) th image, corresponding to each multiimage and multicomplementary image A second subtraction unit outputting a band pass signal; And a register for storing a band pass signal of each of the multiimage and each of the multicomplementary images output from the second subtraction unit, and outputting a bandpass signal of the multiimage or multicomplementary image corresponding to a specified pass band. Provided is a digital filter device capable of reconstructing a pass band including a.
According to another aspect of the present invention, a plurality of compliments in the first output to form a pass band corresponding to the plurality of multiimages through interpolation based on a predetermined sampling constant and in the frequency region where the multiimage is not formed An upsampling step (a) of generating a second output forming a passband corresponding to the image; (B) an image number adjustment output step of controlling and outputting the number of the multiimage included in the first output and the complementary image included in the second output; By subtracting the output of the step (b) in which the number is adjusted to the Lth image and the output of the step (b) in which the number is adjusted to the (L1) th image, each multiimage and multicomplementary image is subtracted. A subtraction step (c) of outputting a corresponding band pass signal; Storing and storing band pass signals of each multiimage and each multicomplementary image output in step (c), and outputting a band pass signal of a multiimage or a multicomplementary image corresponding to a predetermined pass band. Provided is a digital filtering method capable of reconstructing a pass band including the step (d).
According to the embodiment of the present invention, there is an advantage in that the pass band can be simply changed by simply changing the parameter.
In addition, according to an embodiment of the present invention, it is possible to reconfigure the pass band to have various band pass characteristics without changing hardware, and the user can freely select the pass band while implementing a good skirt characteristic with a small number of taps. have.
1 is a diagram showing an example of a filter for reconstructing a frequency by changing a conventional filter coefficient.
2 is a block diagram showing a module configuration of a digital filter device capable of reconstructing a pass band according to an embodiment of the present invention.
3 is a diagram illustrating an internal module configuration of a general filter.
4 illustrates a conceptual module of a filter for performing upsampling by a delay unit and a filter unit.
FIG. 5 is a graph showing an output of an impulse response of only the filter unit when the impulse function is input and an impulse response when the first delay unit and the filter unit operate integrally. FIG.
6 shows an example of a multiimage generated by the first output of the present invention and a multicomplementary image generated by the second output of the present invention.
FIG. 7 illustrates an example in which an image number is assigned to a multiimage of a first output of an upsampling unit according to an embodiment of the present invention. FIG.
8 illustrates an example in which an image number is assigned to a multicomplementary image of a second output of an upsampling unit according to an embodiment of the present invention.
9 illustrates a signal storage structure of a register according to an embodiment of the present invention.
FIG. 10 illustrates an example in which a filter response in which filtering is performed for multiple bands is configured according to an embodiment of the present invention. FIG.
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description with reference to the accompanying drawings, the same or corresponding components will be given the same reference numerals and redundant description thereof will be omitted.
2 is a block diagram showing a module configuration of a digital filter device capable of reconstructing a pass band according to an embodiment of the present invention.
Referring to FIG. 2, a digital filter device capable of reconstructing a pass band according to an embodiment of the present invention includes a first delay unit 200, a filter unit 202, a second delay unit 204, and a first subtraction unit. An upsampling unit 220 including an 206, an image number control output unit 208, a second subtraction unit 210, a register 212, and an adder 214 may be included.
The upsampling unit 220 performs upsampling on the filter response of the filter unit 202. The filter unit 202 included in the upsampling unit 220 may be implemented as a general filter chip, and has a fixed number of taps and a filter response.
The skirt characteristic of the filter portion 202 is determined by the number of taps of the filter. The higher the number of tabs of the filter, the better the skirt characteristic of the filter. However, in order to secure a large number of taps, the cost of the filter chip increases, and thus, the skirt characteristics of the filter are in a tradeoff relationship with the cost of the filter.
The upsampling unit 220 performs upsampling to have a better skirt characteristic than the number of taps of the filter unit 202. Such upsampling may be implemented by the first delay unit 200.
In addition, the filter response of the filter unit 202 is changed to have a plurality of pass bands as well as a base band pass band uniquely set in the filter unit 202 according to the upsampling in the upsampling unit 220.
The upsampling unit 220 outputs two signals, a first output and a second output. The upsampling unit 220 first describes the first output and then describes the second output. The first output is output through the first delay unit 200 and the filter unit 202.
The first delay unit 200 delays the input signal in correspondence with the sampling constant? Set for upsampling the input signal. Delaying the input signal corresponding to the sampling constant () in the first delay unit has the same effect as inserting 0 corresponding to the sampling constant in the middle of the input signal to perform interpolation.
Meanwhile, sampling constant
In setting, we can find the optimal sampling constant to have the optimal calculation amount. Equation 1 below is an example for obtaining an optimal sampling constant. Is the frequency of the passband Is the frequency of the stopband. The integer closest to the sampling constant obtained at this time is Determining and applying it can give the greatest efficiency in overall operation.
Of course sampling constant
May be set to other values to have the desired skirt characteristics without following the optimal equation above.The filter unit 202 performs filtering on the output signal of the first delay unit 200. The filter unit 102 includes a plurality of delayers and an adder like a general filter chip to perform a filtering operation on an input signal.
As described above, delaying an input signal corresponding to a sampling constant and performing filtering on the same may result in substantially the same result as performing interpolation, wherein the upsampled filter response h _{up} [n] May be expressed as Equation 2 below.
FIG. 3 is a diagram illustrating an internal module configuration of a general filter, and FIG. 4 is a diagram illustrating a conceptual module of a filter performing upsampling by a delay unit and a filter unit.
Referring to FIG. 3, a general filter includes a plurality of delay units z ^{−1} and a plurality of filter coefficients h0, h1, h2,...
Meanwhile, sampling constant
In the present invention, which performs upsampling by inserting a zero corresponding to, the filter response is substantially operated as shown in Equation 2 by delaying corresponding to.When such an upsampling method is used, it is possible to ensure better skirt characteristics compared to the number of taps of the filter used in the filter portion. For example, even if the number of taps of the filter is fixed to N, according to the present invention,
The same skirt characteristics as in the case where N or more tabs are used can be ensured.FIG. 5 is a graph illustrating an output of an impulse response of only the filter unit when the impulse function is input and an impulse response when the first delay unit and the filter unit operate integrally.
In FIG. 5, the graph of (a) is an impulse response of the filter unit only, and the graph of (b) is an impulse response when the first delay unit 200 and the filter unit 202 of the present invention operate together. It is a graph.
As shown in Figure 5, when the upsampling according to the present invention it can be seen that the skirt characteristics of the filter is significantly improved compared to the case of using only the filter unit by a general filter chip. In this case, the skirt characteristic is a sampling constant
Improved in proportion toMeanwhile, referring to FIG. 5, when upsampling according to the present invention is performed, it can be seen that a passband is formed in a plurality of bands as well as a baseband, which is an additional result of upsampling. In this embodiment, each of a plurality of pass bands formed in the frequency domain by upsampling according to the present invention will be referred to as an "image". Such multiimages occur additionally when upsampling as in the present invention is performed.
In other words, when upsampling according to the present invention is performed, a plurality of multiimages are generated in addition to the baseband. After all, when the input is an impulse function, the first output improves the skirt characteristic of the filter part well, but forms a plurality of pass bands in not only the base band but also other bands.
The multiple images formed form the same shape as the baseband image. For example, if a baseband image has a bandwidth of W, a skirt property of C, and a size of A, a plurality of formed multiimages also have the same property of having a bandwidth of W, a skirt property of C, and a size of A.
In addition, a plurality of multiimages generated by upsampling based on the baseband image have a certain period, where the period is related to the bandwidth of the baseband image.
For example, when a baseband image has a bandwidth of 2W from W to W, many multiimages generated by upsampling are repeatedly formed in the same form as the baseband image with a period of 2W. Will be.
Thus, when there is a baseband image with a bandwidth of 2W from W to W, upsampling produces a second multiimage in the 3W to 5W band and forms a third multiimage in the 7W to 9W band. . In this case, the number of formed multiimages may vary according to a sampling constant. As such, a plurality of multiimages generated through upsampling may be used to reconstruct a passband to a passband desired by a user.
In the above, the principle of the first output in which a pass band corresponding to a plurality of multiimages is formed by upsampling has been described. Hereinafter, the second output will be described.
The multiple images formed by the first output are formed discretely with a predetermined period. If the passband desired by the user is a frequency domain in which the multiimage is not formed, the multiimage alone cannot cover all the passband desired by the user. Therefore, it is necessary to generate images even in a frequency region where no multiimage is formed, and the second output is an output in which a plurality of images are formed in the frequency region where the multiimage is not formed. In the present embodiment, a plurality of images formed in a frequency region in which the multiimage is not formed at the second output will be referred to as a multicomplementary image.
6 is a diagram showing an example of a multiimage generated by the first output of the present invention and a multicomplementary image generated by the second output of the present invention.
Referring to FIG. 6, the multiimage generated by the first output and the multicomplementary image generated by the second output are formed in opposite frequency regions.
Multicomplementary images also have the same shape as baseband images of multiimages. That is, it has the same bandwidth, skirt characteristics, and size as the baseband image of the multiimage.
In addition, the plurality of multicomplementary images also have a certain period, where the period corresponds to the bandwidth of each image.
The second output is output through the first delay unit 200, the filter unit 202, the second delay unit 204, and the first subtraction unit 206.
The second delay unit 204 is in the z domain
Correspondingly delays the output signal of the first delay unit 200. Here, N means the number of taps of the filter unit 202. The output signal of the second delay unit 204 is input to the first subtraction unit 206, and the output signal of the filter unit 202 which is the first output is also input to the first subtraction unit 206.The first subtraction unit 206 subtracts the output signal of the second delay unit 204 from the output signal of the filter unit 202. The output signal of the first subtraction unit 206 is a second output signal and the second output corresponds to a plurality of multicomplementary images as shown in FIG. 6 to form a pass band.
The first and second outputs output from the upsampling unit 220 are input to the image number adjustment output unit 208. The image number adjustment output unit 208 adjusts and outputs the number of the plurality of multiimages and the plurality of complimentary images included in the first and second outputs.
For example, when four multiimages are included in the first output, the image number adjustment output unit 208 provides an output in which the number of the multiimages is adjusted from one to four.
An image number may be assigned to each of the multiimages of the first output, and FIG. 7 is a diagram illustrating an example in which an image number is assigned to the multiimage of the first output of the upsampling unit according to an embodiment of the present invention. FIG. 1 is a diagram illustrating an example in which an image number is assigned to a multicomplementary image of a second output of an upsampling unit according to an embodiment of the present invention.
Referring to FIG. 7, image numbers L of 0, 1, 2, and 3 are assigned to each of the multiimages.
The image number adjustment output unit 208 provides the second subtraction unit 210 with an output in which the number of images is adjusted up to the Lth image and an output in which the number is adjusted up to the (L1) th image. For example, the second subtraction unit 210 may provide the second subtraction unit 210 with an output provided with multiple images up to image number 2 (three multi images) and an output with multiple images up to image number 1 (two multi images). This output operation is repeated until L reaches its maximum value.
That is, when L = 1 is set, the output when L is 1 and 0 is provided primarily, and when L = 2, the output when L is 2 and 1 is provided as secondary, and L is at the maximum value. It is repeatedly provided until this is done.
The response for generating the multiimage up to the image number L in the image number adjustment output unit 208 may be set as in Equation 3 below.
In Equation 3 above,
Is the sampling kernel and h [k] is the first output. That is, the image number control output unit 208 is an impulse response of the first output and the image number control output unit. It is possible to generate a desired multiimage up to a desired image number L through a convolution operation with. As seen from Equation 3 above, the sampling kernel is a sampling constant. Is scaled by.Various functions may be applied as the sampling kernel. However, when the Sinc function is applied, the sampling kernel may be expressed as Equation 4 below.
In addition, various functions may be applied to the sampling kernel as well as the Sinc function as the sampling kernel, and an example thereof is given by Equation 5 below.
In Equation 5 above, the first equation is a raisedcosine, where R is a rolloff constant and is a criterion for determining the bandwidth of the filter. In Equation 5 above, the second equation is Kaiser, and the third equation is DolphChebychev. This adaptive window function has the advantage that the passband has a flat characteristic, so it does not affect the specification of the final filter passband designed by applying it.
In the above, the operation of outputting the image number adjustment output unit 208 by adjusting the number of the multiimages for the first output of the upsampling unit 220 has been described. The image number adjustment output unit 208 adjusts and outputs the number of multicomplementary images in the same manner with respect to the multicomplementary image of the second output.
That is, the image number adjustment output unit 208 outputs an image in which the number of images is adjusted up to the Lth multicomplementary image for the second output and an output in which the number is adjusted to the (L1) th multicomplementary image. Is provided to the second subtraction unit 210. For example, the second subtraction unit 210 may provide the second subtraction unit 210 with an output provided with multiple images up to image number 2 (three multi images) and an output with multiple images up to image number 1 (two multi images). This output operation is repeated until L reaches its maximum value.
The response for adjusting and outputting the number of multicomplementary images in the image number adjustment output unit 208 is shown in Equation 6 below.
An example of is as shown in Equation 7 below.
In Equation 6 above,
Denotes a filter response for generating a complementary image.As confirmed from Equations 6 and 7 above, the variable applied to the sampling kernel is changed from (2L + 1) to 2L. That is, there is a slight difference between the sampling kernel applied to adjust the number of multiimages of the first output and the sampling kernel applied to adjust the number of multicomplementary images of the second output.
In summary, the image number adjusting output unit 208 repeatedly provides the outputs up to the Lth image and the outputs up to the (L1) th image until L reaches the maximum value for the multiimage of the first output. In the same manner, the number of images is adjusted to provide a multicomplementary image of the second output.
The second subtraction unit 210 outputs a band pass signal corresponding to each of the individual multiimage and the individual multicomplementary image by using the signal output from the image number control output unit.
For example, in the multiimage of the first output, the band pass signal corresponding to the image number 2 is adjusted so that the multiimage is output only to the image number 1 so that the multiimage is output to the image number 2 only. The output can be obtained by subtracting the output from the second subtraction unit.
The second subtraction unit 210 outputs a band pass signal corresponding to each of the multiimage and the multicomplementary image through a subtraction operation in the manner described above.
The register 212 stores a band pass signal corresponding to each of the multiimage and the multicomplementary image output from the second subtractor.
9 illustrates a signal storage structure of a register according to an embodiment of the present invention.
Referring to FIG. 9, a band pass signal corresponding to each multiimage and each multicomplementary image is stored.
The adder 214 sums and outputs signals corresponding to a pass band set by a user among the signals stored in the register.
For example, when the user sets a band corresponding to a multiimage of L = 2 and a multicomplementary image of L = 1 as a pass band, the adder 214 corresponds to the multiimage number 2 in the register. The stored signal and the signal stored in the register corresponding to multicomplementary image number 1 are summed to provide the final output.
As such, a method of setting a pass band by designating an image number corresponding to a required band may be usefully applied when implementing a multiband filter.
FIG. 10 is a diagram illustrating an example of configuring a filter response for filtering in multiple bands according to an embodiment of the present invention.
In FIG. 10, (a) is a first output of an upsampling unit composed of multiple images when the input function is an impulse function, and (b) is a second output of an upsampling unit composed of a multicomplementary image when the input function is an impulse function. .
At this time, when the user selects a band corresponding to the multiimage number 3 and the complimentary image number 1, the adder 212 is the output of the multiimage number 3 stored in the register and the multicomplementary image number 0 By multiplying the outputs, a multiband filter such as (c) can be implemented.
As described above, the present invention enables reconfiguration of various pass bands by designating a pass band desired by a user, that is, a multi image or a multicomplementary image number. That is, the user can reconfigure and use the filter used as the low pass filter as a band pass filter or a multi band band pass filter by changing the L value, and does not require a separate hardware change or complicated operation.
In addition, it will be understood by those skilled in the art that the bandwidth of each multiimage or complementary image can be adjusted by adjusting the sampling constant so that a free pass band reconstruction is possible.
Although the above has been described with reference to embodiments of the present invention, those skilled in the art may variously modify the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. And can be changed.
Claims (14)
 Interpolating based on a predetermined sampling constant to form a pass band corresponding to a plurality of complimentary images in a frequency domain in which the first output forms a pass band corresponding to a plurality of multi images and a frequency region in which the multi image is not formed. An upsampling unit generating a second output;
An image number adjustment output unit configured to adjust the number of the multiimage included in the first output of the upsampling unit and the complementary image included in the second output;
By subtracting the output of the image number control output part whose number has been adjusted up to the Lth image and the output of the image number control part whose number has been adjusted up to the (L1) th image, corresponding to each multiimage and multicomplementary image A second subtraction unit outputting a band pass signal;
A register for storing a band pass signal of each of the multiimage and each of the multicomplementary images output from the second subtraction unit;
And a summation unit for extracting and summing band pass signals of a multi image or a multicomplementary image corresponding to a designated pass band from the register.  The method of claim 1,
The upsampling unit includes a first delay unit for delaying an input signal based on the sampling constant to generate the first output, and a filter unit for filtering the output signal of the first delay unit to generate a first output. A digital filter device capable of reconstructing a pass band.  The method of claim 2,
The upsampling unit delays the output signal of the first delay unit based on the number of taps of the filter unit and the sampling constant to generate the second output, and the second delay unit from the output signal of the filter unit. And a first subtraction unit for subtracting an output signal.  The method of claim 1,
And the plurality of multiimages and the complementary images each have the same shape as a baseband multiimage.  The method of claim 4, wherein
The multiimage and the multicomplementary image has a predetermined period, the predetermined period corresponding to the bandwidth of the multiimage of the baseband, the digital band passband reconfigurable device.  The method of claim 1,
The image number control output unit scales by a sampling constant and generates an output of adjusting the number of the multiimages by applying a first sampling kernel including a multiimage number as a variable to the first output of the upsampling unit. A digital filter device capable of reconstructing a pass band.  The method of claim 1,
The image number adjusting output unit is scaled by a sampling constant and adjusts the number of the multicomplementary images by applying a second sampling kernel including a multicomplementary image number as a variable to the second output of the upsampling unit. A reconfigurable digital filter device, characterized in that for generating one output.  The method of claim 1,
The maximum value of the image number is set by a sampling constant, and the number from the adjusted output to the (L1) th image until the Lth image is changed until the image number L becomes the maximum while changing the image number L. A digital filter device capable of reconstructing a pass band, characterized by repeatedly performing a subtraction of the adjusted output.  Interpolating based on a predetermined sampling constant to form a pass band corresponding to a plurality of complimentary images in a frequency domain in which the first output forms a pass band corresponding to a plurality of multi images and a frequency region in which the multi image is not formed. An upsampling unit generating a second output;
An image number adjustment output unit configured to adjust the number of the multiimage included in the first output of the upsampling unit and the complementary image included in the second output;
By subtracting the output of the image number control output part whose number has been adjusted up to the Lth image and the output of the image number control part whose number has been adjusted up to the (L1) th image, corresponding to each multiimage and multicomplementary image A second subtraction unit outputting a band pass signal; And
A register for storing a band pass signal of each of the multiimage and each of the multicomplementary images output from the second subtractor and outputting a bandpass signal of the multiimage or multicomplementary image corresponding to a specified passband Digital filter device capable of reconstructing the pass band comprising a.  Interpolating based on a predetermined sampling constant to form a pass band corresponding to a plurality of complimentary images in a frequency domain in which the first output forms a pass band corresponding to a plurality of multi images and a frequency region in which the multi image is not formed. An upsampling step (a) of generating a second output;
(B) an image number adjustment output step of controlling and outputting the number of the multiimage included in the first output and the complementary image included in the second output;
By subtracting the output of the step (b) in which the number is adjusted to the Lth image and the output of the step (b) in which the number is adjusted to the (L1) th image, each multiimage and multicomplementary image A subtraction step (c) of outputting a corresponding band pass signal;
Storing and storing band pass signals of each multiimage and each multicomplementary image output in step (c), and outputting a band pass signal of a multiimage or a multicomplementary image corresponding to a predetermined pass band. And (d) performing a reconstruction of a pass band.
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PCT/KR2011/001407 WO2011105879A2 (en)  20100226  20110228  Frequency reconfigurable digital filter and equalizer using the same 
US13/580,133 US9099989B2 (en)  20100226  20110228  Frequency reconfigurable digital filter and equalizer using the same 
PCT/KR2011/001408 WO2011105880A2 (en)  20100226  20110228  Digital filter having improved attenuation characteristics 
CN2011800111988A CN102812637A (en)  20100226  20110228  Frequency reconfigurable digital filter and equalizer using the same 
EP11747769.5A EP2540000B1 (en)  20100226  20110228  Frequency reconfigurable digital filter and equalizer using the same 
JP2012554949A JP5882917B2 (en)  20100226  20110228  Digital filter capable of frequency reconstruction, filtering method, equalizer using the same, and design method thereof 
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