JPS59112715A - Amplitude and phase control type digital filter - Google Patents

Abstract

PURPOSE:To obtain a digital filter which controls a phase and an amplitude independently by cascading a phase controller and an amplitude controller. CONSTITUTION:The phase controller 20 which holds amplitude-frequency characteristics of a digital input signal linear and varies phase-frequency characteristics on the basis of specific phase information from a console panel 3 and the amplitude controller 30 composed of a real-time processing linear phase transversal filter 13 which holds the phase-frequency characteristics linear and varies the amplitude-frequency characteristics on the basis of the specific phase information from the console panel 3 are cascaded to constitute the amplitude and phase control type digital filter. Consequently, the amplitude and phase frequency characteristics of the digital input signal are varied independently and optionally.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a digital filter configured to independently control each frequency characteristic of the amplitude and phase of an input signal.

BACKGROUND ART Conventionally, there has been no single filter device that is configured to independently and variably control amplitude and phase.

In the field of analog signal processing, phase shifters are known that change the phase frequency and wave number characteristics by combining circuit grooves such as LG filters and RC filters, but the rotation angle of the phase is uniquely determined by the filter configuration. is,
It is not possible to change the phase rotation angle arbitrarily, and it is also impossible to control the phase and amplitude independently, so if you try to change the amplitude, the phase will change dependently. .

In addition, in the field of digital signal processing, the phase of a digital input signal is calculated over the entire band (from DC to 2 sampling frequencies).
A phase shifter (Hilbert transformer) that changes +90 degrees or 190 degrees over
However, this also had the drawback that the phase could not be changed arbitrarily.

DISCLOSURE OF THE INVENTION As mentioned above, an object of the present invention is to provide a digital filter that independently controls amplitude and phase, which has not been realized in the past.

In order to achieve the above object, the present invention provides a phase controller configured to linearly preserve the amplitude frequency characteristics of a digital signal and to variably control the phase frequency characteristics based on predetermined phase information. and a real-time processing linear phase transversal filter configured to store the phase frequency characteristic linearly based on predetermined amplitude information and to variably control the amplitude frequency characteristic. Configured filter.

With this configuration, even if each frequency characteristic of the amplitude and phase of the digital input signal is controlled independently based on predetermined information (amount of phase rotation and amplitude value to be changed), it will not affect other characteristics. It can be changed without any impact and is very easy to control.

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the structure of an embodiment of an amplitude/phase controlled digital filter of the present invention. In FIG. 1, 1 is an input terminal, 2 is an output terminal, and 3 is an operating wheel (console) for providing predetermined phase information and amplitude information (input information specifying a desired phase frequency and amplitude value).
, 4 is a first calculation means for calculating the real part response and the imaginary part response of the frequency response based on the phase information, and 5.6 is the real part response and the imaginary part response outputted by the calculation means 4, respectively. A second calculation means for calculating each time-series impulse response (for example, performs inverse Fourier transform), 8 is a Hilbert transformer which is a 90 degree phase shifter, 9 is a Hilbert transformer 8 with a predetermined filter coefficient. A memory (e.g. ROM>) for giving 10 uses the time-series impulse response calculated by the second calculation means 5 as a filter coefficient, and performs a convolution operation between this filter coefficient and the digital signal input from the input terminal 1. A real part filter 11 consisting of a real-time processing linear phase 1-rance versal filter uses the time-series impulse response calculated by the second calculation means 6 as a filter coefficient, and the filter coefficient and the digital output from the Hilbert transformer 8. This is an imaginary part filter consisting of a real-time processing linear phase transversal filter that performs convolution with a signal.In addition, in the Hilbert transformer 8, the digital signal input from the input terminal 1 and a predetermined filter given from the memory 9 are used. Performs convolution operation with coefficients.

Reference numeral 12 denotes an adder that adds the digital signals output from the real part filter 10 and the imaginary part filter 11, respectively. The arithmetic means 4.5.6, the Hilbert transformer 8, the memory 9, the real part filter 10, the imaginary part filter 11, and the adder 12 constitute a phase control B unit 20. The output from the adder 12 is a digital signal that has undergone the desired phase rotation. 14 is a third calculation means for calculating an amplitude frequency response based on the amplitude information; 7
13 is a fourth calculation means for calculating a time-series impulse response of the amplitude-frequency response calculated by the fourth calculation means 7, and 13 is a filter coefficient that is a time-series impulse response of the amplitude-frequency response calculated by the fourth calculation means 7. This is a real-time processing linear phase transversal filter that convolves the coefficients and the digital signal output from the adder 12, and its output is applied to the output terminal 2. And the above-mentioned calculation means 7゜14
The transversal filter 13 forms an amplitude controller 30, and this part is the part that performs amplitude control based on predetermined amplitude information.

The Hilbert transformer 8 is also a linear phase transversal filter (L 1near p 11ase typ.
e Transversal F 1lter
; Abbreviated as L p TF. >, and all including the calculation means 4 to 7.14 can be constructed of high-speed calculation processors.

As is clear from FIG. 1, the present invention stores amplitude-frequency characteristics linearly based on predetermined phase information from the console 3,
A phase controller 20 realizes a desired phase frequency characteristic in a band selective manner, and an amplitude controller configured to linearly store the phase frequency characteristic based on predetermined amplitude information from the console 3 and to variably control the amplitude frequency characteristic. The controller 30 is connected in series. Although the first and third calculation means are separate processors in this embodiment, they can be combined into the same processor.

The operation will be explained below with reference to the frequency response of each part shown in FIG.

If the transfer function of the digital phase controller 20 of the present invention described above is H(ω)=Cp(ω)+jSp(ω), then the response of the real part filter 10 is Cp(ω).
The response Sp(ω) of the imaginary part filter 11 is as shown in FIGS. 2(A) and 2(B), respectively.

The two filter characteristics of the real part filter 110 and the imaginary part filter 11 have amplitude frequency characteristics such that the sum of their squares is 1. The bottom of the groove is adjusted so that IH(ω)12=cp2(ω)+SI)'(ω)=1. Also, the phase frequency characteristic ξ(ω
) is ξ (ω ) = tan ' (sp (ω
) /CFI (ω) ), and information on H(ω) and ξ(ω) determined by these two equations is input from the console 3. Therefore, in the response of the digital phase controller 20, as shown in FIG. 2(C), the amplitude characteristic is constant and only the phase characteristic can be arbitrarily changed.

On the other hand, if the transfer function of the amplitude controller 30 is G(ω)=CA(ω)+jSA(ω), its real part response C(ω) and imaginary part response SA(ω) are its − Examples are shown in Figure 2 (
D) and (E). That is, S.A.
Bottom the groove so that (ω) becomes 0. Therefore, the amplitude controller 3
0 amplitude response IG(ω)12 and phase response ζ(ω) [maIG(ω')l'=cA2 (ω)+SA
2 (ω)=CA 2 (ω) ζ(ω) =tan −' (SA (ω)/Cx,
(ω))−〇, and the response is as shown in FIG. 2(F). These responses can be achieved by inputting predetermined information from the console 3.

Therefore, the overall transfer function of the digital filter of the present invention is as follows, where A(ω) is the overall amplitude response and θ(ω) is the overall phase response. cA 2 (ω) θ(ω)−ξ(ω)+ζ(ω) =tan −' (Sp (ω)10p (ω))
Therefore, it becomes as shown in Fig. 2<G). This second figure (
The characteristic of G) corresponds to the information given from the operation console 3, as well as the amplitude information and phase information, and a digital filter whose amplitude and phase can be controlled independently has been realized. Two and (Konaru.

As explained above, by applying J' to the digital filter of the present invention, each frequency characteristic of the amplitude and phase of the digital input signal can be independently (and arbitrarily variably controlled).・1
The practical effect of the 4'L-bye using one line equalizer or the like is very large.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the groove bottom of an embodiment of the present invention, and Fig. 2 (A to (G) are characteristic diagrams showing the frequency response of each part.4... ...First calculation means, 5.6...Second calculation means, 14...Third calculation means, 7...Fourth calculation means, 8 ...Hilbert transformer, 9...Memory, 10...Real part filter, 11...Imaginary part filter, 12...Adder , 13...Transpanal filter for imaging width controller, 20...Phase controller, 30...Amplitude controller. Applicant: ShinNippon Electric Co., Ltd. Agent, Patent Attorney Takeo Masuda

Claims (1)

[Claims] 1. A first calculation means that calculates a real part response and an imaginary part response of a frequency response based on predetermined phase information, and 16
a real part filter consisting of a real-time processing linear phase 1~rance versal filter using the calculated time series impulse responses as filter coefficients; It has an imaginary part filter and a Hilbert transformer continuously connected to the imaginary part filter, and the real part filter, the Hilbert transformer, and the imaginary part filter connected in cascade thereto are connected in parallel to convert the digital signal. a phase controller configured to linearly store the amplitude frequency characteristic and to variably control the phase frequency characteristic; a third calculating means for calculating the amplitude frequency response based on predetermined amplitude information; A fourth calculation means for calculating a time-series impulse response of the response, and an amplitude control configured to use the calculated time-series impulse response as a filter coefficient, store the phase frequency characteristic linearly, and variable control the amplitude frequency characteristic. 1. An amplitude/phase control type digital filter comprising: an amplitude controller comprising a dexterous real-time processing linear phase transversal filter; and the phase controller and the amplitude controller are connected in cascade.