JPH0536997U - Audio amplifier - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an audio amplifier capable of significantly reducing the amount of data required for processing in a digital signal processor. In an audio amplifier including a digital signal processor 13 to which digital signals sampled at different sampling frequencies are input, the input digital signal is converted into a signal having a unified sampling frequency, and the output digital signal is converted into a digital signal processor 1.
The sampling frequency converter 19 for supplying to the No. 3 is provided.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to an audio amplifier having a digital signal processor and receiving input digital signals sampled at different sampling frequencies.

[0002]

[Prior Art]

 A conventional audio amplifier equipped with a digital signal processor to which digital signals sampled at different sampling frequencies are input is configured as shown in FIG.

As shown in FIG. 3, the audio amplifier outputs a digital signal obtained by converting left and right channel audio signals by an A / D converter 11 and an output digital signal from a digital audio interface receiver (hereinafter referred to as DIR) 12, respectively. It is sent to the digital signal processor 13.

The digital signal processor 13 transfers necessary data from the memories 14A and 14B under the control of the necessary program and the microcomputer 15 for controlling the digital signal processor 13 to the input digital signal. Perform the required digital signal processing. The memories 14A and 14B are also used for storing digital delay data and for data expansion of the microcomputer 15.

A front output digital signal and a rear output digital signal from the digital signal processor 13 are supplied to a front D / A converter 16A and a back D / A converter 16B, respectively. It is supplied separately and converted into an analog signal. The analog output signal of the D / A converter 16A is supplied to the amplifier 17A for the left channel and the amplifier 17B for the right channel to be amplified, and the speakers 18A and 18B are driven separately.

Similarly, the output analog signals of the D / A converter 16B are supplied to the amplifier 17C for the left channel and the amplifier 17D for the right channel to be amplified, and the speakers 18C and 18D are driven separately.

[0007]

[Problems to be solved by the device]

 However, signal processing in the digital signal processor is realized by software. Therefore, the characteristics of the equalizer are changed by changing the coefficient data of the digital filter. At this time, even if the filters have the same characteristics, the filter coefficients differ depending on the sampling frequency of the input digital signal, and therefore the microcomputer usually must have the filter coefficients for all sampling frequencies as a data table.

Therefore, there is a problem that the data amount becomes very large as the number of equalizer bands increases. Also, when performing delay processing in sound field reproduction, data that gives the delay amount is required. Such data also needs to be changed when the sampling frequency changes, and there is a problem that the amount of data increases.

As described above, in the digital signal processing by the digital signal processor, the higher the signal processing, the more data is handled, and the more the number of sampling frequencies is increased, the more data is handled. There was a problem that it would increase.

An object of the present invention is to provide an audio amplifier that can significantly reduce the required data amount by unifying the sampling frequencies of processed digital signals in a digital signal processor.

[0011]

[Means for Solving the Problems]

 The audio amplifier of the present invention is equipped with a digital signal processor, and in an audio amplifier to which digital signals sampled at different sampling frequencies are input, converts the input digital signal into a signal having a unified sampling frequency and outputs the output digital signal. Is provided to the digital signal processor.

[0012]

[Action]

 According to the audio amplifier of the present invention, since the sampling frequency is unified by the sampling frequency conversion means and the signal of the unified sampling frequency is supplied to the digital signal processor, the digital signal processor is unified sampling. It is only necessary to perform signal processing on the frequency signal, and it is not necessary to prepare data for each sampling frequency, and the required data amount will be greatly reduced.

[0013]

【Example】

 Hereinafter, the present invention will be described with reference to examples. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In this embodiment, the same components as those of the conventional example shown in FIG. 3 are designated by the same reference numerals, and detailed description thereof is omitted to avoid duplication.

The output from the A / D converter 11 and the output from the DIR 12 are supplied to the changeover switch circuit 19, and one of them is selected based on the changeover signal supplied to the changeover switch circuit 19 to the sampling frequency converter 20. Regardless of the sampling frequency of the signal supplied and input, the sampling frequency converter 20 converts the signal into a digital signal having a uniform sampling frequency and supplies the digital signal to the digital signal processor 13. The subsequent stage of the digital signal processor 13 is constructed in the same manner as in the conventional example.

Although various configurations of the sampling frequency converter 20 have been proposed, for example, by performing oversampling, conversion is performed to increase the rate to the data of the sampling frequency of the least common multiple of the sampling frequency of the input digital signal, and then It down-samples at a predetermined sampling frequency to lower the sampling frequency and converts it into a digital signal with a uniform sampling frequency.

Therefore, the analog signal input from the external device is converted into a digital signal by the A / D converter 11. On the other hand, the digital signal input is demodulated by the DIR 12. One of these two inputs is selected by the changeover switch circuit 19 and input to the sampling frequency converter 20. At this time, there are currently three sampling frequencies for digital signals, 48 kHz, 44.1 kHz, and 32 kHz for audio signals.

The digital signal selected by the changeover switch circuit 19 is supplied to the sampling frequency converter 20, for example, converted into a digital signal having a uniform sampling frequency of 48 kHz, and supplied to the digital signal processor 13. The digital signal processor 13 performs signal processing such as filtering processing represented by an equalizer, sound field reproduction processing, and decoding processing of Dolby Pro Logic.

The stage subsequent to the digital signal processor 13 is configured similarly to the case of the conventional example, and the signal processing output from the digital signal processor 13 is supplied to the D / A converters 16A and 16B and converted into analog signals. It is converted, amplified by amplifiers 17A-17D, and drives speakers 18A-18D at the output.

However, the sampling frequency converter 20 converts the signal into a digital signal having a uniform sampling frequency, and the signal processing by the digital signal processor 13 is a signal processing for a digital signal having a uniform sampling frequency. Conventionally, the data required individually for digital signals of each sampling frequency is only for the data of uniform sampling frequency, and the required amount of data will be greatly reduced.

Next, an application example of this embodiment will be described. FIG. 2 is a block diagram showing the configuration of an application example of this embodiment. In this application example, the digital signal processed by the digital signal processor 13 is supplied to the sampling frequency converter 21 to convert the sampling frequency, and the output digital signal of the sampling frequency converter 21 is converted into a digital audio interface transmitter ( In the following description, it will be referred to as DIT) 22 so that the DIT 22 also outputs a digital signal.

Therefore, the sampling frequency of the digital signal processed by the digital signal processor 13 is converted by the sampling frequency converter 21 and output via the DIT 22.

As a result, even if a device with a new sampling frequency appears, it can be dealt with without changing the data of the digital signal processor 13.

[0023]

[Effect of the device]

 As described above, according to the present invention, it is possible to unify the sampling frequencies of the digital signals input to the digital signal processor, and this unification can significantly reduce the data amount of the digital signal processor.

Furthermore, there is also an effect that the control of the micro computer that controls the digital signal processor becomes easier as the amount of data is reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an application example of an embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional example.

[Explanation of symbols]

 11 A / D Converter 12 DIR 13 Digital Signal Processor 14A and 14B Memory 15 Microcomputer 16A and 16B D / A Converter 19 Changeover Switch Circuit 20 and 21 Sampling Frequency Converter 22 DIT

Claims (1)

[Scope of utility model registration request] 1. An audio amplifier including a digital signal processor, into which digital signals sampled at different sampling frequencies are input, converts the input digital signal into a signal having a uniform sampling frequency, and outputs the output digital signal to the digital signal processor. An audio amplifier comprising a sampling frequency conversion means for supplying.