JPH07101834B2 - Digital signal processor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal processing device used in digital audio equipment.

2. Description of the Related Art In recent years, digital devices such as compact disc players and satellite broadcast receivers have become widespread. Also, a digital audio tape recorder will be put into practical use. Against the background of such enrichment of digital sources, digital control amplifiers capable of processing digital signals as they are have been developed. The digital control amplifier is composed of a digital signal processing device and an analog signal processing device.

A conventional digital signal processing device will be described below with reference to the drawings.

FIG. 2 shows the configuration of a conventional digital signal processing device. In FIG. 2, 8 is a digital signal input terminal for inputting any one of several kinds of digital signals having different sampling frequencies, and 9 is a digital signal processor (hereinafter referred to as a DSP) for inputting the digital signal.
The first sampling rate converter (hereinafter abbreviated as SRC) that converts into a digital signal with a sampling frequency of (abbreviated) and 10) receives the output signal of the first SRC9 and follows a predetermined program. DSP that performs digital signal processing and outputs the result, 1
1 is a digital-to-analog converter (hereinafter abbreviated as DAC) that inputs the digital signal output from the DSP 10 and converts the digital signal to an analog signal for output; 12 is an analog signal output terminal that outputs the analog signal; 13 is the DSP 10
Input the digital signal from and change it to the digital signal of the sampling frequency of the equipment connected in the second stage.
SRCs and 14 are digital signal output terminals for outputting the signal from the second SRC 13.

The operation of the digital signal processing device configured as described above will be described below.

First, a digital signal is input to the digital signal input terminal 8. The sampling frequency of this input signal is, for example, 32 KHz, 44.1 KHz, 48 KHz, etc., but is converted by the first SRC 9 into a digital signal of the sampling frequency of the DSP 10 in the subsequent stage and output. The output signal of the first SRC9 is DSP1
It is input to 0, and is subjected to digital signal processing such as tone control and reverberation according to a predetermined program, and then output. The digital output signal of the DSP 10 is input to the DAC 11, converted into an analog signal, and output from the analog signal output terminal 12. Also, DS
The digital output signal of P10 is input to the second SRC 13, converted into a digital signal of the sampling frequency of the device connected in the subsequent stage, and output from the digital signal output terminal 14.

Problems to be Solved by the Invention However, the above-mentioned configuration has a problem that the digital signal is distorted because it passes through the first SRC 5. That is, the influence of the theoretical error of the algorithm itself generated for calculating the signal at the time when it is not originally in the input signal and the error due to the calculation accuracy is considered.

In view of the above problems, the present invention provides a digital signal processing device capable of eliminating distortion due to SRC.

Means for Solving the Problems In order to achieve this object, a digital signal processing device according to the present invention includes a digital signal input terminal and a sampling frequency for detecting a sampling frequency of a digital signal input to the digital signal input terminal. A DSP for inputting the digital input signal and having a plurality of programs corresponding to a plurality of sampling frequencies, selecting a program corresponding to the sampling frequency detected by the sampling frequency detector, and performing signal processing to output the DSP. When,
A DAC for inputting a digital signal from the DSP and converting it into an analog signal, an analog signal output terminal for outputting the analog signal, and converting the digital signal from the DSP into a digital signal having a sampling frequency of a device connected in a subsequent stage. SRC and a digital signal output terminal for outputting a digital signal from the SRC.

Operation With this configuration, the SRC in the preceding stage of the DSP can be omitted, and the distortion of the analog output signal due to the SRC can be eliminated.

Embodiment One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a digital signal processing apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a digital signal input terminal, 2 is a sampling frequency detector for detecting the sampling frequency of the input digital signal, 3
Is a DSP that inputs a digital input signal, performs signal processing by a program according to the sampling frequency detected by the sampling frequency detector 2 and outputs the signal, 4 is a DAC that converts the digital signal from the DSP 3 into an analog signal, and 5 is a DAC
An analog signal output terminal that outputs the analog signal from 4, 6 is an SR that converts the digital signal from DSP3 to the digital signal of the sampling frequency of the device connected in the subsequent stage
C and 7 are digital signal output terminals for outputting the digital signal from SRC6.

The operation of the digital signal processing device configured as described above will be described below.

First, a digital signal is input to the digital signal input terminal 1 from a device preceding the digital signal processing device. The sampling frequency of the input digital signal is detected by the sampling frequency detector 2. The digital input signal is also input to DSP3. DSP3 is a processing program for each sampling frequency so that it can handle multiple sampling frequencies (any number of steps less than the maximum number of steps that can be processed at that sampling frequency, processing steps within one sampling cycle due to conditional branching, etc.) The number may be changed), a program corresponding to the sampling frequency detected by the sampling frequency detector 2 is selected, and signal processing is performed according to the program. The digital signal processed by the DSP 3 is converted into an analog signal by the DAC 4 and output from the analog signal output terminal 5. When input to another digital device, the digital signal processed by the DSP3 is converted by the SRC6 into a digital signal having the sampling frequency of the connected device and output from the digital signal output terminal 7.

As described above, according to the present embodiment, by making the DSP 3 compatible with digital signals having a plurality of sampling frequencies, the SRC in the preceding stage of the DSP 3 can be omitted and the distortion due to the SRC can be eliminated. At the same time, the number of parts can be reduced by omitting the SRC.

EFFECTS OF THE INVENTION The present invention makes a DSP that performs digital signal processing compatible with a plurality of sampling frequencies, thereby providing an SRC in the preceding stage of the DSP.
Therefore, it is possible to eliminate the distortion due to SRC, and at the same time, it is possible to realize an excellent digital signal processing device that can reduce the number of parts.

[Brief description of drawings]

FIG. 1 is a block diagram of a digital signal processing device according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional digital signal processing device. 1 ... Digital signal input terminal, 2 ... Sampling frequency detector, 3 ... Digital signal processing device, 4 ... Digital-analog converter, 5 ... Analog signal output terminal, 6 ... Sampling rate converter, 7 ... Digital Signal output terminal.

Claims (4)

[Claims] 1. A sampling frequency detector for detecting a sampling frequency of a digital signal, and a program corresponding to each of the plurality of detected sampling frequencies, and the sampling frequency detector detects from the plurality of programs. A digital signal processor that selects a program corresponding to the selected sampling frequency and processes the digital signal using the selected program; and a digital-analog converter that converts the digital signal output by the digital signal processor into an analog signal, A digital signal processing device comprising: a sampling rate converter for converting a sampling frequency of a digital signal output from the digital signal processor. 2. A sampling frequency detector for detecting a sampling frequency of a digital signal and a program corresponding to each of the plurality of detected sampling frequencies, and the sampling frequency detector detects from among the plurality of programs. A digital signal processor for selecting a program corresponding to the selected sampling frequency and processing the digital signal using the selected program. 3. A sampling frequency detector for detecting a sampling frequency of a digital signal and a program corresponding to each of the plurality of detected sampling frequencies, and the sampling frequency detector detects from the plurality of programs. A digital signal processor that selects a program corresponding to the selected sampling frequency, processes the digital signal using the selected program, and a digital-analog converter that converts the digital signal output by the digital signal processor into an analog signal. A digital signal processing device provided. 4. A sampling frequency detector for detecting a sampling frequency of a digital signal, and a program corresponding to each of the plurality of detected sampling frequencies, and the sampling frequency detector detects from the plurality of programs. A digital signal processor that selects a program corresponding to the selected sampling frequency, processes the digital signal using the selected program, and a sampling rate converter that converts the sampling frequency of the digital signal output by the digital signal processor. A digital signal processing device provided.