JPH07254842A - Deemphasis device - Google Patents

Abstract

PURPOSE:To provide the deemphasis device whose characteristic is unchanged even when a sampling frequency is changed. CONSTITUTION:A selection means 304 selects a coefficient used to realize a deemphasis characteristic and stored in a 1st storage means 302 in the operation at a referenced sampling frequency and a coefficient is subject to interpolation arithmetic operation based on the coefficient stored in the 1st storage means 302 based on coefficient selection data corresponding to the sampling frequency measured by a frequency measurement means 306 and the obtained coefficient as the result of arithmetic operation is selected and the selected coefficient is fed to a product sum arithmetic means 305. The product sum arithmetic means 305 applies deemphasis arithmetic operation to input data based on a control signal outputted from a control means 301 depending on the received coefficient.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a de-emphasis device whose characteristics do not change even when the sampling frequency is changed in a digital system which can change the pitch of an input signal by changing the sampling frequency. .

[0002]

2. Description of the Related Art A conventional de-emphasis device can obtain a predetermined characteristic only at a reference sampling frequency.

The basic operation of a conventional de-emphasis device in a digital system will be described below with reference to the drawings. FIG. 5 is a block diagram of a conventional de-emphasis device. In FIG. 5, 501 is a control means, 502 is a storage means, and 503 is a product-sum calculation means. Storage means 502
Stores the coefficient for realizing the de-emphasis characteristic. The storage unit 502 gives the coefficient to the product-sum calculation unit 503 according to the control signal output from the control unit 501. The product-sum calculation means 503 performs de-emphasis calculation from the input data and the given coefficient, and outputs the calculation result.

FIG. 6 shows a filter configuration diagram for the de-emphasis operation. In FIG. 6, 601 is a first multiplication means,
602 is a second multiplication means, 603 is a third multiplication means, 6
04 is a first delay means for delaying one sample period,
Reference numeral 605 is a second delay unit that gives a delay of one sample period, and 606 is an addition unit. The output of the first delay means 604 holding the input data delayed by one sample period is multiplied by the coefficient b by the second multiplication means 602,
It is input to the adding means 606. Also, the second delay means 60 holding the output data delayed by one sample period.
The output of 5 is multiplied by the coefficient c by the third multiplication means 603 and added to the addition means 606. Further, the input I is multiplied by the coefficient a by the first multiplication means 601 and added to the addition means 606, and is also held in the first delay means 604. The output O, which is the above addition result, is taken out from the adding means 606, and the output O is held in the second delay means 605.

The transfer function in the filter configuration of FIG.
If the one-sample delay is expressed by Z ⁻¹ , it becomes (Equation 1).

[0006]

[Equation 1]

The coefficients a, b and c are as shown in (Equation 2) when de-emphasis having time constants of 15 usec and 50 usec is realized by a system having a sampling frequency of 96 kHz.

[0008]

[Equation 2]

Product-sum calculation means 50 for performing the above calculation
An example of the hardware configuration of No. 3 is shown in FIG.
In FIG. 7, 701 is selection means (SEL), 702 is multiplication means (MPY), 703 is accumulation means (ACC), 7
Reference numeral 04 is a delay means (RAM), and 705 is a data holding means (REG). The delay means 704 has input data IZ one sample period before corresponding to the data held in the first delay means 604 and one sample period before the sample data corresponding to the data held in the second delay means 605. Output data OZ is stored. The delay unit 704 first outputs the data IZ, and the selection unit 701 selects the output data of the delay unit 704. The multiplication means 702 multiplies the output of the selection means 701, that is, the data IZ and the coefficient b output from the storage means 502, inputs the result to the accumulation means 703, and then holds the data IZ in the delay means 704. The input data is stored in the memory location. Next, the delay means 704 outputs the data OZ,
Since the selection means 701 still selects the output of the delay means 704, the multiplication means 702 multiplies the data OZ by the coefficient c output from the storage means 502 and adds the output to the accumulation means 703. . Finally, the selection means 7
01 selects the input data I, then multiplies it by the coefficient a output from the storage means 502, and outputs the output by the accumulating means 7
Add to 03. After that, the output of the accumulating means 703 is stored in the data holding means 705 as the final result and output.
Further, the output of the accumulating means 703 is held in the memory location where the data OZ in the delay means 704 was held.
The above calculation is performed during one sampling period.

[0010]

However, in the conventional de-emphasis device, when the sampling frequency is changed to change the pitch of the output signal, the de-emphasis characteristic itself changes in proportion to the change of the sampling frequency. There was a problem that it did.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a de-emphasis device capable of maintaining a predetermined de-emphasis characteristic even when the sampling frequency is changed.

[0012]

In order to achieve the above object, the de-emphasis device of the present invention comprises a first storage means for storing a coefficient for determining a de-emphasis characteristic at a normal time and a sampling frequency change time. Second to store the coefficient of
Storage means, selection means for selecting output data from any one of the first storage means and the second storage means,
A control means for outputting a control signal for performing a de-emphasis filter operation, and a product-sum operation means for performing a filter operation from the output data and the input data of the selecting means in accordance with the control output signal from the control means are usually provided. When the sampling frequency changes, the coefficient data stored in the first storage means is used, and when the sampling frequency changes, the coefficient data stored in the second storage means that is given from the outside is used to extract the output data from the product-sum calculation means. It is configured (first configuration).

Further, the de-emphasis device of the present invention is
Corresponding to the sampling frequency from the first storage means for storing the coefficient for determining the de-emphasis characteristic at the normal time and the coefficient data stored in the first storage means according to the coefficient selection data given from the outside when the sampling frequency changes. Interpolation means for obtaining the coefficient to be obtained by interpolation, selection means for selecting the output data of any one of the first storage means and the interpolation means, and control means for outputting a control signal for performing de-emphasis filter calculation. A sum-of-products calculating means for performing a filter operation from the output data and the input data of the selecting means according to the control output signal from the controlling means, and normally, the coefficient data stored in the first storing means is used, When the sampling frequency changes, output from the product-sum calculation means using the coefficient data obtained by the interpolation means Configured to retrieve over data are (second configuration).

Further, the de-emphasis device of the present invention is
First storage means for storing a coefficient for determining a de-emphasis characteristic at a normal time, frequency measurement means for measuring a sampling frequency, and coefficient stored in the first storage means according to output data of the frequency measurement means. Interpolation means for obtaining a coefficient corresponding to the sampling frequency from the data by interpolation, selection means for selecting output data of one of the first storage means and the interpolation means, and a control signal for performing de-emphasis filter calculation And a product-sum operation means for performing a filter operation from the output data and the input data of the selection means in accordance with a control output signal from the control means, and normally stored in the first storage means. The coefficient data obtained by the interpolating means is used when the sampling frequency changes, and the product sum is calculated. Constitutes a calculation means to retrieve output data (third configuration).

Further, the de-emphasis device of the present invention is
First storage means for storing a coefficient for determining the de-emphasis characteristic at the normal time, frequency change measuring means for measuring a change in coefficient selection data given from the outside when the sampling frequency changes, and output of the frequency change measuring means. According to the above, the coefficient corresponding to the sampling frequency is obtained by interpolation from the coefficient data stored in the first storage means,
Further, one of the interpolating means for obtaining a plurality of coefficients corresponding to frequencies before and after the current sampling frequency by interpolation in advance and outputting the coefficient corresponding to the current frequency, the first storage means and the interpolating means. Selection means for selecting the output data of the selection means, a control means for outputting a control signal for performing a de-emphasis filter operation, and a filter operation from the output data and the input data of the selection means according to the control output signal from the control means. An output data from the product-sum calculation means is provided by using the coefficient data stored in the first storage means in the normal time and using the coefficient data obtained by the interpolation means when the sampling frequency changes. It is configured to take out (fourth configuration).

[0016]

According to the above-described first configuration, a fixed coefficient stored in the first storage device is used when operating at the reference sampling frequency, and the sampling frequency of the sampling frequency is changed from the outside when the sampling frequency is changed. A coefficient corresponding to the change is given to the second storage means, and a sum of products operation is performed using the coefficient of the second storage means to give a predetermined de-emphasis characteristic to the input data and output it.

Further, according to the above-described second configuration, when the sampling frequency is operated at a standard, a fixed coefficient stored in the first storage device is used, and when the sampling frequency is changed, sampling is performed from the outside. Coefficient selection data corresponding to a change in frequency is given to the interpolating means, and the interpolating means obtains and obtains a coefficient corresponding to the sampling frequency changed from the plurality of fixed coefficients stored in the first storage means by interpolation according to the coefficient selection data. By performing the sum of products operation using the coefficient, a predetermined de-emphasis characteristic is given to the input data and output.

Further, according to the above-mentioned third structure, a fixed coefficient stored in the first storage device is used when operating at the reference sampling frequency, and a frequency measuring means when the sampling frequency is changed. A change in the sampling frequency is obtained by applying the coefficient selection data corresponding to the change to the interpolating means, and the interpolating means determines the coefficient corresponding to the sampling frequency changed from the plurality of fixed coefficients stored in the first storage means according to the coefficient selecting data. Is obtained by interpolation, and a product-sum operation is performed using the obtained coefficients to give a predetermined de-emphasis characteristic to the input data and output it.

Further, according to the above-mentioned fourth structure, a fixed coefficient stored in the first storage device is used when operating at the reference sampling frequency, and a frequency change measurement is performed when the sampling frequency is changed. The sampling frequency change is obtained by the means, the coefficient selection data corresponding to the change is given to the interpolation means, and the interpolation means corresponds to the sampling frequency changed from the plurality of fixed coefficients stored in the first storage means according to the coefficient selection data. A coefficient and a plurality of coefficients corresponding to sampling frequencies before and after the current sampling frequency are interpolated in advance, and a product-sum operation is performed using the coefficient corresponding to the current sampling frequency to obtain a predetermined data in the input data. Emphasis characteristics are given and output, and it also follows sudden changes in sampling frequency. That.

[0020]

Embodiments of the de-emphasis device of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a de-emphasis device according to the first embodiment of the present invention. In FIG. 1, 101 is a control means, 102 is a first storage means, 10
Reference numeral 3 is a second storage means, 104 is a selection means, and 105 is a product-sum calculation means. When the reference sampling frequency is, for example, 96 kHz, coefficients a, b, and c similar to those in the conventional example are stored in the first storage means 102, and these coefficients are selected by the selection means 104 and supplied to the product-sum calculation means 105. To do. When the pitch of the reference output signal is set to 1, in order to change the pitch to α (≠ 1), the sampling frequency may be changed to the current α times, but at this time, the reference de-emphasis characteristic is cut. A coefficient that realizes a characteristic when the off frequency is set to 1 / α is externally given to the second storage means 103, and the selection means 104 causes the second storage means 103.
Control to select the output of.

For example, the reference sampling frequency is 96
15usec and 50us when the sampling frequency during operation is + 12.5% of the standard at kHz.
The coefficient for realizing the de-emphasis characteristic having the time constant of ec is (Equation 3).

[0023]

[Equation 3]

The de-emphasis operation performed by the sum-of-products operation means 105 is the same as in the conventional example, and therefore a detailed description of the operation is omitted.

Next, a second embodiment of the de-emphasis device of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram of a de-emphasis device according to the second embodiment of the present invention. In FIG. 2, 201 is control means, 202 is first storage means, 20
Reference numeral 3 is an interpolating means, 204 is a selecting means, and 205 is a product-sum calculating means. The constituent elements with reference numerals 201, 204, 205 are 101, 104, 105 in the first embodiment.
Is the same as. The first storage means 202 stores a coefficient corresponding to a reference sampling frequency and a plurality of coefficients corresponding to sampling frequencies other than the reference.
By externally providing coefficient selection data according to the sampling frequency fs1 during operation, the first storage unit 20
From 2, the coefficient groups corresponding to the two sampling frequencies fs0 and fs2 that satisfy fs0 ≦ fs1 <fs2 are read out, and the sampling frequency fs1 is calculated by the interpolation means 203.
The coefficient corresponding to is calculated by interpolation. The coefficient obtained as described above is selected by the selection means 204, and the product-sum calculation means 2 is selected.
Supply to 05.

Now, 1 / for the standard sampling frequency
Coefficient groups a0, b0 corresponding to frequencies of α (α> 1) times,
Coefficient groups a2 and b corresponding to frequencies of c0 and β (> 1) times
2, c2 are stored in the first storage means 202, and the sampling frequency during operation is X (> 1) times the reference sampling frequency.

At this time, from the first storage means 202, coefficient groups a, b, c and + corresponding to the reference sampling frequency are added.
Coefficient group a2, b2, c2 corresponding to a frequency of 12.5%
Is read out, and the coefficient groups a1, b1,
To obtain c1, the interpolation calculation shown in (Equation 4) may be performed.

[0029]

[Equation 4]

The de-emphasis operation performed by the sum-of-products operation means 205 is the same as in the conventional example, so a detailed description of the operation will be omitted. In the second embodiment, linear interpolation is described as the interpolation calculation, but higher-order interpolation may be used.

Next, a third embodiment of the de-emphasis device of the present invention will be described with reference to the drawings.

FIG. 3 is a block diagram of a de-emphasis device according to the third embodiment of the present invention. In FIG. 3, 301 is control means, 302 is first storage means, 30
3 is an interpolating means, 304 is a selecting means, 305 is a product-sum calculating means, and 306 is a frequency measuring means. 301, 302,
The components with reference numerals 303, 304, 305 are 201, 202, 203, 204 in the second embodiment.
It is the same as 205. The frequency measuring means 306 obtains a sampling frequency during operation from a sampling clock and a reference clock given from the outside, and outputs the coefficient selection data described in the second embodiment. The operation of the other constituent elements is the same as that of the second embodiment, and the explanation thereof is omitted.

Next, a fourth embodiment of the de-emphasis device of the present invention will be described with reference to the drawings.

FIG. 4 is a block diagram of a de-emphasis device according to the fourth embodiment of the present invention. In FIG. 4, 401 is a control means, 402 is a first storage means, 40
3 is an interpolating means, 404 is a selecting means, 405 is a product-sum calculating means, and 406 is a frequency change measuring means. 401, 40
The components with reference numerals 2, 404 and 405 are the same as 201, 202, 204 and 205 in the second embodiment. The frequency measuring means 406 obtains the change of the sampling frequency during operation from the sampling clock and the reference clock given from the outside, and measures the present sampling frequency and the change of the sampling frequency. The interpolating means 403 outputs the frequency change measuring means 406,
The coefficient corresponding to the current sampling frequency is obtained by the method as described in the third embodiment, and a plurality of coefficients corresponding to the sampling frequencies before and after the current sampling frequency are obtained in advance, and the current sampling frequency is set. Output the corresponding coefficient. If the sampling frequency changes abruptly, the coefficient obtained beforehand is used to realize a smooth change. The operation of the other constituent elements is the same as that of the second embodiment, and the explanation thereof is omitted.

[0035]

As described in detail above, the de-emphasis device of the present invention can be used even if the sampling frequency is changed.
It is possible to maintain a predetermined de-emphasis characteristic.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a de-emphasis device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a de-emphasis device according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a de-emphasis device according to a third embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a de-emphasis device according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a conventional de-emphasis device.

FIG. 6 is a block diagram showing a filter configuration of a conventional de-emphasis operation.

7 is a block diagram showing a configuration of a product-sum calculation means 503 in FIG.

[Explanation of symbols]

 101, 201, 301, 401 Control means 102, 202, 302, 402 First storage means 103 Second storage means 104, 204, 304, 404 Selection means 105, 205, 305, 405 Sum of products operation means 203, 303 , 403 Interpolating means 306 Frequency measuring means 406 Frequency change measuring means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location H03H 17/02 P 8842-5J (72) Inventor Hideaki Hatanaka, 1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric Sangyo Co., Ltd.

Claims (4)

[Claims] 1. A first storage means for storing a coefficient for determining a normal de-emphasis characteristic, a second storage means for storing a coefficient when a sampling frequency changes, the first storage means and the first storage means. Selecting means for selecting the output data of one of the two storage means, control means for outputting a control signal for performing de-emphasis filter operation, and output data of the selecting means according to the control output signal from the control means And a sum-of-products calculating means for performing a filter operation from the input data, the coefficient data stored in the first storing means is normally used, and the second storing means is supplied from the outside when the sampling frequency changes. A de-emphasis device for extracting output data from the product-sum calculation means by using the coefficient data stored in. 2. A first storage means for storing a coefficient for determining a de-emphasis characteristic at a normal time, and coefficient data stored in the first storage means in accordance with coefficient selection data given from the outside when a sampling frequency changes. An interpolation means for obtaining a coefficient corresponding to the sampling frequency by interpolation, a selection means for selecting the output data of one of the first storage means and the interpolation means, and a control signal for performing a de-emphasis filter operation. The control means for outputting, and the product-sum operation means for performing a filter operation from the output data and the input data of the selection means in accordance with the control output signal from the control means, are normally stored in the first storage means. The coefficient data obtained by the interpolation means is used when the sampling frequency changes. De-emphasis apparatus, characterized in that retrieving the output data from the product-sum operation unit. 3. A first storage means for storing a coefficient for determining a de-emphasis characteristic at a normal time, a frequency measurement means for measuring a sampling frequency, and the first storage means according to output data of the frequency measurement means. Interpolating means for obtaining a coefficient corresponding to the sampling frequency from the coefficient data stored in the table by means of interpolation, selecting means for selecting output data from either the first storing means or the interpolating means, and a de-emphasis filter operation. And a sum-of-products calculating means for performing a filter operation from the output data and the input data of the selecting means in accordance with the control output signal from the controlling means. The coefficient data stored in the storage means No. 1 is used, and is calculated by the interpolation means when the sampling frequency changes. A de-emphasis device for extracting output data from the product-sum calculation means using coefficient data. 4. A first storage means for storing a coefficient for determining a de-emphasis characteristic at a normal time, a frequency change measuring means for measuring a change in coefficient selection data given from the outside when a sampling frequency changes, and the frequency. According to the output of the change measuring means, a coefficient corresponding to the sampling frequency is obtained by interpolation from the coefficient data stored in the first storage means, and a plurality of coefficients corresponding to frequencies before and after the current sampling frequency are obtained by interpolation in advance. An interpolating means for outputting a coefficient corresponding to the current frequency, a selecting means for selecting the output data of one of the first storing means and the interpolating means, and a control signal for performing a de-emphasis filter operation And a control means for outputting the output data of the selecting means according to a control output signal from the control means. And a sum-of-products calculation means for performing a filter calculation from the input data. Normally, the coefficient data stored in the first storage means is used, and when the sampling frequency changes, the coefficient data obtained by the interpolation means is used. A de-emphasis device characterized in that output data is taken out from the product-sum operation means by using the de-emphasis device.