JPS58201416A - Digital filter - Google Patents

Abstract

PURPOSE:To simplify the constitution, by providing a digital filter having a strong resonance characteristic for a post-stage of another digital filter having a certain resonance characteristic and making a connection so as to reduce the gain of the two digital filters to a value smaller than a prescribed value. CONSTITUTION:A voice coder 1 starts a control circuit 3 according to an instruction inputted from an outputted instruction input terminal 2 and initiates the synthesizing processing. The control circuit 3 performs the address designation of a coefficient of filter inputted to digital filters 6-9 and the address designation of sound source information inputted to a sound source generating circuit 4 to a synthesized information storage circuit 5. In the synthesized information storage circuit 5, when the digital filters 6-9 have inputs, the gain by the filters 6, 7 and 8, 9 is smaller than a prescribed value and the filter coefficients having the strong resonance characteristics are stored in order at the post-stage of the filter coefficients having the weak resonance characteristics. Further, in the control circuit 3, the strength of the resonance characteristics of the two digital filters and the gain in case of cascade connection are detected, and the inputted address of the filter coefficients is changed, allowing to obtain an effect equivalent to that of a conventional scaler.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital filter, and particularly to a configuration method thereof.

Conventionally, when a filter group is formed by connecting digital filters #Ea, a scaler is used for each input/output of each stage of the digital filter as a means to realize the calculation word length of each digital filter with different gain. However, it is known to provide l! which constitutes the filter group. If there are a plurality of 1IIk2 digital filters, it is mandatory to provide at least the same number of scalers as the number of digital filters forming the film group t#1.
, 4111a in the digital filter group has the disadvantage that it becomes (L).

An object of the present invention is to improve the resonance characteristic Qs in a digital filter group in which a plurality of digital filters are connected in cascade.
A digital filter having a resonance characteristic Q that is stronger than Ql is provided at the downstream stage of the digital filter having a resonance characteristic Q, and has at least one set of filters connected so that the gain of the two digital filters is smaller than a predetermined value. This invention solves the above-mentioned drawbacks by applying 5tffC to 5tffC, and provides a simple configuration of a digital filter that is stable even when integrated into short calculations @-&. In a group of cascade-connected digital filters, Q is placed after the digital filter having common characteristics Q, t-.

A digital filter having a strong resonance characteristic of -3 is provided, and the two digital filters are connected so that the gain is smaller than a predetermined value to form the following filter configuration:
It must be configured to have at least one set of palms with a diameter of 1 cm.

According to this invention, in a digital filter group in which a plurality of digital filters t'' are cascaded, strong resonance %
A digital filter having a weak resonance characteristic is provided in III& of the digital filter having a characteristic, and -0 self 2
By configuring the filters connected so that the gain of the two digital filters is 4 times smaller than the predetermined value, the output of the two digital filters can be suppressed, and an effect similar to that of a conventional scaler can be obtained. It will be done.

Embodiments of the present invention are shown below with reference to the drawings. This will be explained in more detail.

Figure 1 shows the configuration of the device applied to X-ray light. In the same figure, VC is shown, 1 is a speech synthesizer, 2 is an output 66
Command input terminal 3 is a control circuit, 4Fi sound source generation circuit, 5 is a synthesis 1#@memory circuit, 6, 7, 8.9 are digital filters, and 10 is a digital filter group formed by 6.7, 8, and 9. , 11 is a D/human tear evacuator 12 is an analog output terminal. Further, the digital filters 6.7 and 8.9 have the configuration shown in FIG. 2, for example. In FIG. 2, 13.
14 is a unit delay element, 15! -j input terminal, 16 is an output terminal, 17.18 is a multiplier, and 19 is an adder, whose resonance is custom-made by filter coefficients A and H set in multiplier i7.18, for example, as shown in Fig. 3. It comes to show. Third
In the figure, Q indicates the resonance strength of the filter, F is the sum of the resonance frequencies of the filter, and the filter coefficients A and B are respectively
determined by.

The operation based on this configuration will be explained using arrows.

First, the speech synthesizer 1 activates the wIll-circuit 3 in accordance with a command input from the output command input terminal 2 to start a synthesis session. The control circuit 3 specifies the addresses of the filter coefficients to be input to the digital filter 6.7.8° 9 and the input f to the sound source generation circuit 4 to the synthetic information storage circuit 5.
Addresses the original information. The synthesis/distribution circuit 5 includes filter coefficients that, when input to the digital signals 6.7 and 8.9, have a gain smaller than a predetermined value and a weak resonance characteristic by the filters 6.7 and 8.9. The filter coefficients having all the strong resonance characteristics are stored in an ordered manner in the subsequent stage. The control circuit 3 first reads out the t original information from the combined RFI and information storage circuit 5, and sequentially reads out the filter coefficients that are input to the zero-order digital filter 6°7.8.9 that is input to the f-image generation circuit 4. Input to filters 6.7 and 8.9. Thereafter, until it is time to change the coefficients of the digital filter group, the filter group 1 (1) is driven according to the sound source output from the sound source generation circuit 4, inputted to each output t-D/AK unit 11, and subjected to D/A conversion. Thereafter, it is output to the analog output terminal 12.The control circuit 3 detects the synthesis output stop information stored in the synthesis information storage circuit 5 and completely stops the synthesis operation.

In this embodiment, the control circuit 3 controls the digital filters 6.7.8 configured in the digital filter group 10.
．． The filter coefficients to be stored in the synthesis information storage circuit 5 are assigned in advance to each digital filter 6, 9 in the filter group 1O.
7, 8.9 are stored in association with each other, in the side repair circuit 3, the strengths and weaknesses of both fi%a of the two digital filters and the gain when connected in cascade are detected, and the cutting edge of the filter coefficient is detected. The effect of co-workers can be obtained by changing the relationship,
Vertical MtWl for digital filters other than the speech synthesizer!
It is clear that the same effect can be obtained even in devices used in conjunction with one another.

[Brief explanation of the drawing]

Figure 1 is a circuit block configuration diagram showing an embodiment of the present invention, Figure 2 is a block diagram of a digital filter used in the embodiment of Figure 1, and Figure 3 is a characteristic diagram of the filter. In addition, in the figure, ]...Speech synthesis i&so, 2.
... Output command input terminal, 3 ... Part # (b) path, 4 ... Sound source generation circuit, 5 ... Synthesis information recording circuit, 6. 7.8゜9...Digital filter, lO...Digital filter group,
ll...D/A converter, 12...analog output terminal. Part I Zuka 2 Closed 3rd Close

Claims (1)

[Claims] In a digital filter in which a plurality of digital filters are arranged vertically #R, a digital filter having a resonance characteristic Qs t- is followed by a digital filter having a resonance characteristic Qs stronger than Qt, and 1. A digital filter comprising at least one set of filters connected so that the gain is smaller than a predetermined value.