JPH0714371A - Digital audio equipment - Google Patents

Abstract

PURPOSE:To effectively use an input/output section for monitoring and to monitor a signal processed to be a digital signal. CONSTITUTION:Digital audio signals Din1, Din2 are inputted to this equipment, and the equipment is provided with a digital signal processing section 12 which processes signals by digital mixing and a master PLL circuit 20 which generates a system clock. An output of the digital signal processing section 12 is outputted to an external equipment through a D/A converter 16. Switches 15, 19 output one signal out of a signal processed by digital processing with the system clock, an output signal of a receiving/PLL circuit 13 and an output signal of a receiving/PLL circuit 14 through a D/A converter 17 as a monitoring signal. Switches 18, 24 select a signal being an original signal of the system clock out of output signals of the receiving/PLL circuits 13, 14 and an output signal of a crystal oscillator 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital audio device such as a digital mixer, and more particularly to a digital audio device having a monitor function.

[0002]

2. Description of the Related Art When a digital output signal of an audio device such as a digital mixer is digitally recorded by an external device such as DAT (Digital Audio Tape), it is necessary to confirm whether the DAT during recording is surely receiving the digital signal. Sometimes you want to monitor. This type of monitor is often performed by a digital signal from an external device that has a playback function.
In particular, a dedicated monitor circuit is conventionally provided inside the digital mixer based on the demand for monitoring during recording through the same reproducing system as an amplifier, a speaker, and headphones as during mixing processing by the digital mixer.

FIG. 2 is a block diagram showing the configuration of a conventional digital mixer. The analog input signals Ain of a plurality of channels are A / D converted by the A / D converter 1, and the DSP
Digital mixing processing is performed by a digital signal processing unit 2 such as (Digital Signal Processor). The first digital audio signals Din1 of a plurality of systems are also mixed by the digital signal processing unit 2 via the reception / PLL circuit 3. The master PLL circuit 4 removes the jitter from the clock signal regenerated by the reception / PLL circuit 3,
It is supplied as a system clock to each digital processing unit of the system. The system clock is also generated from the output obtained by dividing the output of the crystal unit 5 by the frequency dividing circuit 6. The mixing output from the digital signal processing unit 2 is output to the outside as a digital output signal Dout and also converted to an analog output signal Aout1 via the D / A converter 7 and output.

Further, a plurality of systems of second digital audio signals Din2 are also input to this digital mixer, and these signals Din2 are received / PLL circuit 8 and D / A.
The analog output signal Aout2 for monitoring is output via the monitor system including the converter 9. DA for this monitor system
It is possible to monitor the mixing output by introducing a digital mixing signal that has passed through an external device such as T.

A consumer DAT or the like as a recording / reproducing device connected to the outside of the digital mixer operates at the time of reproduction with a clock generated by an oscillator of the device itself. Further, the digital mixer also has an oscillator inside, and each unit inside the main body is operated by a system clock independent of external equipment. On the other hand, in the case of only the monitor, since it is not necessary to synchronize the clock of the digital signal processing unit 2 of the digital mixer with the clock of the external device, the monitor system circuit is an independent system unrelated to the digital mixing process. Has become.

[0006]

However, in the above-mentioned conventional digital audio equipment, since the monitor system is completely independent of the digital signal processing system, a dedicated signal input / output section is provided only for the monitor. There is a problem that it must be.

The present invention has been made in view of the above problems, and an object thereof is to effectively use an input / output unit for a monitor in a digital audio device having a monitor function.

[0008]

A first digital audio apparatus according to the present invention is a system clock generating means for inputting a digital audio signal and generating a system clock for operating a system from the digital audio signal, and the system clock generating means. A digital signal processing system having a digital signal processing means for processing the digital audio signal based on the digital audio signal, and a monitor system for inputting the digital audio signal and outputting a monitor signal based on the digital audio signal via a monitor output section. A digital audio device comprising: a first audio signal supplied to the monitor system to the system clock generating means and the digital signal processing means;
Is provided.

A second digital audio device according to the present invention is an audio device comprising the digital signal processing system and the monitor system, wherein the signal output from the digital signal processing means is supplied to the monitor output section. It is characterized in that it is provided with a second signal supply means.

A third digital audio device according to the present invention is an audio device including the digital signal processing system and the monitor system, wherein the digital audio signal input to the digital signal processing system is monitored by the monitor system. Is provided with a third signal supply means for supplying to the.

[0011]

According to the first aspect of the invention, since the digital audio signal input to the monitor system can be supplied to the system clock generating means and the digital signal processing means by the first signal supplying means, the input from the monitor system is possible. The generated signal can also be subjected to digital signal processing such as digital mixing, and the versatility of the signal input unit can be increased.

According to the second aspect of the invention, the output signal output from the digital signal processing means can be output from the monitor system via the monitor output section by the second signal supply means. It is possible to directly monitor the signal while supplying the latter signal to the external device. Further, the signals after the signal processing can be simultaneously supplied to a plurality of external devices, and the versatility of the signal output unit is increased.

Further, according to the third invention, since the digital audio signal inputted to the digital signal processing system can be supplied to the monitor system by the third signal supplying means, it is inputted to the digital signal processing system. Signal can be monitored by the monitor system, increasing the versatility of the signal input section.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing the configuration of a digital mixer according to an embodiment of the present invention. In FIG. 1, solid arrows indicate signal flows, and dotted arrows indicate system clock flows.

A plurality of channels of analog input signals Ain, a first digital audio signal Din1 and a second digital audio signal Din2, which are digital signals of different formats or a plurality of systems of the same format, are input to the mixer. The analog signal Ain is
The signals are A / D converted by the A / D converters 11 of a plurality of systems and input to the digital signal processing unit 12. The first digital audio signal Din1 is received by a plurality of systems / PLL.
The second digital audio signal Din2 is respectively received and clock-reproduced by the circuit 13, and the second digital audio signal Din2
The LL circuit 14 receives and regenerates the clock, respectively.
Output signals from the reception / PLL circuits 13 and 14 are also input to the digital signal processing unit 12, respectively. Further, these output signals are respectively supplied to the b terminal and the c terminal of the switch 15.

The digital signal processing unit 12 performs digital mixing processing on the input digital signal, and is composed of a DSP or the like. Digital signal processor 1
The output of 2 is output to a digital external device as a digital output signal Dout, and also converted to an analog output signal Aout1 via the D / A converter 16 and output. Also,
Another output signal from the digital signal processing unit 12 is supplied to the terminal a of the switch 15. The signal from the switch 15 is input to the D / A converter 17, D / A converted, and output as the analog output signal Aout2.

On the other hand, the clock signals reproduced by the reception / PLL circuits 13 and 14 are supplied to the d terminal and the e terminal of the switch 18, respectively, and to the b terminal and the c terminal of the switch 19, respectively. The clock signal from the switch 18 is input to the master PLL circuit 20.

The master PLL circuit 20 has a P in the input stage.
It absorbs the jitter that could not be removed by LL and generates a stable system clock.
The phase-locked loop is composed of a CO (voltage controlled oscillator) 22 and a frequency dividing circuit 23. Switch 18
The clock signal from is input to the phase comparator 21. The output of the VCO 22 is input to the frequency dividing circuit 23 via the f terminal of the switch 24. Also, the crystal unit 2
A clock signal obtained by dividing the output of 5 by the frequency dividing circuit 26 is input to the frequency dividing circuit 23 via the g terminal of the switch 24.

The system clock generated by the master PLL circuit 20 is supplied to the A / D converter 11, the digital signal processing section 12 and the D / A converter 16, and
It is also supplied to the D / A converter 17 via the a terminal of the switch 19 to drive them.

In the digital mixer thus constructed, each of the switches 15, 18 and 24 can be manually selected independently. Also, switch 15
And the switch 19 are interlocked with each other. Now
When the switches 15 and 19 are connected to the a terminal and the switch 24 is connected to the g terminal, respectively, the entire signal processing system operates with the accurate and stable system clock generated by the crystal unit 25,
The signals Dout and Aout1 subjected to digital mixing processing can be output and supplied to an external device, and the same signal Aout2 subjected to digital mixing processing as the signal supplied to the external device can be used as a monitor signal. .

Further, when the switches 15 and 19 are connected to the b terminal, the receiving / PLL circuit 13 and the D / A converter 17 can be configured as a monitor system similar to the conventional one, and the digital audio signal Din1 is directly output as an analog signal. It can be monitored as signal Aout2. At this time, D /
The A converter 17 operates according to the clock signal reproduced by the reception / PLL circuit 13. Switch 15 and 19 to c
When connected to the terminals, the receiving / PLL circuit 14 and the D / A converter 17 can be configured as a monitor system similar to the conventional one, and the digital audio signal Din2 can be directly monitored as the analog output signal Aout2. At this time, the D / A converter 17 operates by the clock signal reproduced by the reception / PLL circuit 14.

If the switch 18 is connected to the d terminal while the switch 24 is connected to the f terminal, the system clock is generated by the master PLL circuit 20 from the clock signal generated by the digital audio signal Din1, When 18 is connected to the e terminal, the system clock becomes the master PL from the clock signal generated by the digital audio signal Din2.
It is generated by the L circuit 20. Master PLL circuit 2
0 produces a system clock in synchronization as long as it receives a sampling frequency Fs for any input signal.

As described above, according to the digital mixer of this embodiment, the input digital audio signals Din1,
Any of Din2 can be subjected to digital mixing processing and the mixed signal can be monitored from one output terminal, or can be directly monitored without mixing. The reference system clock can also be generated from the input signal or can be generated from a stable signal from the crystal oscillator 25.

In this embodiment, the signals output from the reception / PLL circuits 13 and 14 are directly input to the digital signal processing unit 12, but they are selectively input via another switch interlocked with the switch 18, for example. You may allow it.

[0025]

As described above, according to the present invention,
The first and second signal supply means can supply a signal input to the digital signal processing system to the monitor system and a signal input to the monitor system to the digital signal processing system. This has the effect of increasing the versatility of the output section.

[Brief description of drawings]

FIG. 1 is a block diagram of a digital mixer according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional digital mixer.

[Explanation of symbols]

1, 11 ... A / D converter, 2, 12 ... Digital signal processing unit, 3, 8, 13, 14 ... Reception / PLL circuit, 4, 20
… Master PLL circuit, 5, 25… Crystal oscillator, 6, 2
3, 26 ... Dividing circuit, 7, 9, 16, 17 ... D / A converter, 15, 18, 19, 24 ... Switch, 21 ... Phase comparator, 22 ... VCO.

Claims (3)

[Claims] 1. A system clock generating means for inputting a digital audio signal and generating a system clock for operating a system from the digital audio signal, and a digital signal processing means for processing the digital audio signal as a digital signal based on the system clock. A digital audio device having a digital signal processing system and a monitor system for inputting a digital audio signal and outputting a monitor signal based on the digital audio signal through a monitor output section, the digital audio device being input to the monitor system. A digital audio device comprising a first signal supply means for supplying a digital audio signal to the system clock generation means and the digital signal processing means. 2. A system clock generating means for inputting a digital audio signal and generating a system clock for operating a system from the digital audio signal, and a digital signal processing means for processing the digital audio signal as a digital signal based on the system clock. A digital audio device having a digital signal processing system having the digital audio processing system, and a monitor system for inputting a digital audio signal and outputting a monitor signal based on the digital audio signal via a monitor output unit, wherein the digital signal processing unit outputs the signal. A digital audio device comprising a second signal supply means for supplying the generated signal to the monitor output section. 3. A system clock generating means for inputting a digital audio signal and generating a system clock for operating a system from the digital audio signal, and a digital signal processing means for processing the digital audio signal as a digital signal based on the system clock. In a digital audio device including a digital signal processing system having the digital audio signal and a monitor system for inputting a digital audio signal and outputting a monitor signal based on the digital audio signal via a monitor output unit, A digital audio device comprising a third signal supply means for supplying a digital audio signal to the monitor system.