JPS5947826A - Multichannel digital filter - Google Patents

Abstract

PURPOSE:To make delay characteristics between channels uniform, by providing a delay circuit to each digital filter channel, in a multichannel digital filter having plural filter channels of different pass frequency bands. CONSTITUTION:Data A/D-converted at a sampling frequency is inputted to a filter arithmetic section 9 from an input terminal 1. The arithmetic of a polynomial expressing the attenuation and phase frequency characteristics of the filter in terms of the Z transformation of the transfer function is performed at the arithmetic section 9. A control parameter is inputted to a control section 10 from an input terminal 2. A control section 10 transfers a control signal relating to a filter coefficient and the degree to the operating section 9 and a control signal relating to the delay amount to a delay section 11. Further, the operating timing of the arithmetic section 9 and the delay section 11 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital filter widely used in fields such as communications and audio signal processing, and more particularly to a multi-nayer digital filter having an initial number of filter channels each having a different pass frequency band.

In the communication field, conventionally, each frequency band of the initial filter channel is used to send information.
I am getting information from. In addition, in field 111 of the audio signal processing section, the received audio signal is frequency-divided and encoded in each frequency band.

7) At each frequency band! t+re/ko11'1
When collecting information and decoding it as comprehensive data/(Line'1), if there is a synchronization difference between frequency bands, 1'II
(Reading error or d: causes an encoding error. There are two possible causes of such a reading error:

(1) The filter characteristics of each frequency band are different, so the delay characteristics of each frequency band are different.Rumor 1: Passing frequency band of the filter is realized using a digital filter. Me to change
If a method is adopted in which the timing of time discretization of the signal, that is, the sampling period is changed, the sampling period time includes dead time t6, so the delay characteristics of each frequency band are different.

Usually, as a filter used for signal extraction of each frequency band of multiple filter channels, 1rj, pass frequency band,
Attenuation/Phase 1'fil'' Blue - There are many cases where it is easy to use the filter freely, so a digital filter is suitable.
At this time, the same 1s 1s -re's c;
My 2 items are not taken into consideration.

- The present invention describes a multi-channel tee/multi-channel system having a pass frequency band of 5゛ (57 seconds) filter channels, each with a passing frequency band of 5゛ (57 seconds).
By providing each digital noise tab circuit and four delay circuits in the digital filter, the delay between the channels of the digital filter can be reduced by 1, ! 4Jj"fJ' is a multi-channel digital inverter with uniform characteristics.
The purpose is to

Another object of the present invention is to provide a multi-channel digital filter that can freely control the dead time by controlling the sampling group jυ to the t+J function.

The loss of the present invention shown in the drawings below, correction 1 for IJ111 example
．． 11.

In Figure 1, 1.5 is the digital data input terminal, 2
, 6-digit filter parameter input terminal, 3.7H: There are first and second digital filter channels, indicating that two digital filter channels are arranged. Circuit configuration of the first and second filter channels 3 and 7 1d<;l=J,'. The circuit configuration is shown in FIG.

In FIG. 2, one piece of data that has been A/D converted at a sampling frequency set by an external device (not shown) is input to a data input terminal 1 through a filter output 'r,! p: Personnel will be assigned to Department 9. In this filter operation section 9, the attenuation and phase frequency 'PJ of the filter are expressed by Z transformation of the transfer function, and a polynomial is calculated. The data of the filter coefficient and the filter order delay ht calculated by the external arithmetic device are input to the control unit 10 from the filter parameter input terminal 2 as control parameters. Control over order'
The IA signal is transferred to the filter calculation section 9, and a control signal regarding the amount of delay is transferred to the delay section 11, and the operation timings of the filter calculation section 9 and the delay section 11 are further controlled. The delay unit 11 may be a random access memory circuit that can shift the read address and write address by an arbitrary number corresponding to the delay 4; It may be a shiftable 7-nt register, or it may be possible to use a tapped delay line once a month.

Next, let's talk about how to set the delay amount. Now, let's talk about how to set the delay amount. Now, what is the noise frequency 1 set for the noise r sound μ9 of the 11 digital filter channel? The amount of delay caused by l is 500 μs x the sampling group of the first digital filter channel + U+], 0 0 /1s
shall be. In addition, the amount of delay caused by the filter frequency bands set in the filter calculation section of the second gain filter circuit is set to 600 μs, and the sampling J.I. 'J Jsu] is set to 200 μS. Then, the total delay of the first digital filter channel is 600 μs, and the delay of the second digital filter channel is: 1:', (':j: 8
0011 SE'- becomes. Therefore, the delay amount of the delay unit 11 of the first digital channel is set to 200 μs (7,
Unless the delay part of the second digital filter channel has a delay amount, the total delay of both filter channels is: 1;
are the same. Furthermore, when using a large number of digital filter channels, set the delay amount of the delay section of the digital filter channel to 5 to match the delay amount of the f'R digital filter channel with the maximum delay amount. The amounts can be the same.

As described above, according to the present invention, delay sections between a plurality of digital filter channels having different pass frequency bands can be created by simply providing a simple delay circuit in each digital filter channel.

This makes it possible to easily eliminate or reduce the synchronization difference in the data demodulation or encoding process of the signal output from each digital filter channel, thus ensuring accurate decoding and encoding. can be achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a block circuit diagram showing details of the digital filter channel shown in FIG. 1. ■, 5...Digital data input/Rui-r-129,
6.--Filter parameter input/terminal 13゛・fj,
, 3. $41 Digital filter channel 4...Digital data output terminal 17...Second digital filter channel 8)/Digital data output terminal 2 9...Filter calculation section 10...Control section 11...Delay section

Claims (1)

[Claims] (1) In a multi-channel digital filter having a plurality of digital filter channels with mutually different passbands, each digital filter channel receives a digital signal and executes a predetermined polynomial operation. A filter calculation unit and the filter calculation 1111
′:f\, which is calculated by
A control signal 7g regarding delay, daughter, and sound V to be delayed by the intersection, coefficient data of the polynomial used in the calculation, and the degree of the polynomial is sent to the filter operation section 4, and a control signal regarding the delay amount is sent to the extension section. and control the operation and timing of the first filter calculation section and the delay section (i+l
By appropriately adjusting the filter characteristics and slow 4L characteristics respectively determined by the filter calculation section and the delay section, the difference in delay characteristics between the channels of the multi-channel digital filter can be corrected. l+l!
A multi-channel digital filter characterized by the ability to erase i'. (2. In claim 1, the previous DL, "'
[Mold] [Multi-channel digital filter 3 whose crystal feature is that the section is a random access memory circuit, (3) In claim 1, the front M+-: , N 44
[A multi-channel digital filter whose characteristic is that the section is a ζ, seat register. (4) In claim 1, the iY extension portion is a tapped delay line! A multi-channel digital filter with 41f characteristics.