JP3399768B2 - Signal transmission equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmission device for efficiently transmitting a digital signal according to a 1-bit encoding method obtained by delta sigma modulation or the like.

[0002]

2. Description of the Related Art Conventionally, various transmission methods have been used when transmitting digital signals between digital devices. Widely used transmission methods include, for example, a parallel transmission method in which digital signals of each system are transmitted by different transmission systems, or a digital signal of a plurality of systems is transmitted by time-sharing one transmission system. A serial transmission method can be used.

The serial transmission method is a method in which one transmission system is time-divided and a digital signal of a corresponding system is transmitted for each divided time. In this method, the receiving unit needs to determine which system of digital signals the digital signals transmitted through the transmission system correspond to, and special formatting is performed for that purpose. Therefore, the processing in the transmitter and the receiver becomes complicated. Furthermore, when the information necessary for the determination is transmitted by the transmission system, it is necessary to distinguish the information from the digital signal, which further complicates the processing in the transmitter and the receiver.

Therefore, in order to simplify the structures of the transmitting unit and the receiving unit, a parallel transmission method is often used in which dedicated transmission systems are assigned to the digital signals of the respective systems and the signals are transmitted as they are. In addition, a digital signal transmission method is also used in which digital signals of a plurality of systems are encoded into several bits and are transmitted in parallel by a transmission system for the number of bits.

[0005]

However, in the digital signal transmission method according to the conventional parallel transmission method, there are as many transmission systems as the number of digital signal systems, or
Transmission systems for the number of encoded bits are required. further,
When the digital signal of each system is synchronized with the data clock, the data clock must be transmitted by another transmission system. Therefore, it is difficult to reduce the number of transmission systems. Since each transmission system includes a transmission unit, a reception unit, a transmission line, and the like, such an increase in the transmission system has a problem in that the configuration of the entire transmission means becomes complicated and large. ing.

On the other hand, in the serial transmission system, it is necessary to perform a special format on the digital signal in order for the receiving unit to judge which system the time-division digital signal belongs to. There is a problem in that the configurations of the receiver and the receiver become complicated.

[0007]

In order to solve the above-mentioned problems, a signal transmission device according to claim 1 is a signal transmission device for transmitting and receiving digital signals of a plurality of systems, wherein a transmitting side receives input signals of a plurality of systems. The signal conversion unit for converting into a 1-bit digital signal has the same "L" section and "H" section.
A synchronization signal generator for generating a synchronization signal is Flip, the 1
A synchronization signal that has a multiplexing unit that multiplexes and transmits a bit digital signal and the synchronization signal into a transmission digital signal of one system, and a receiving side includes a synchronization signal that detects the synchronization signal from the received transmission digital signal. A detection unit, a clock generation unit that generates a clock that is synchronized with the transmission digital signal from the synchronization signal, and the transmission digital signal based on the clock, at timings corresponding to the respective systems of the input signal. It is characterized by having a 1-bit demodulation unit for demodulation.

With the above structure, when a plurality of analog signals are input to the transmission side, each of them is converted into a 1-bit digital signal by a signal conversion section such as a ΔΣ modulation circuit. Then, the plurality of systems of 1-bit digital signals are time-division-multiplexed with a synchronization signal generated by a simple circuit and transmitted as one system of transmission digital signals.

On the receiving side, the synchronizing signal is detected from the transmitting digital signal by a simple circuit, and based on the detected synchronizing signal, the transmitting digital signal is demodulated at a timing corresponding to each system. .

That is, for example, based on the above synchronization signal,
A data clock is generated in synchronization with the transmission digital signal and having the same frequency as the transmission digital signal.
Then, a high-speed clock having a frequency that is an integral multiple of the data clock is generated. Based on this high-speed clock, the digital signal for transmission is demodulated at a timing corresponding to each system.

By converting the demodulated signal into an analog signal with a low-pass filter, an analog output signal can be taken out on the receiving side. And the digital signal for transmission
Is input to the low pass filter as it is, the sync signal
Is 0 because the "L" section and the "H" section are the same.
It is assumed that it has a potential of 1 volt, and it is 1 bit
Output as a monaural signal after being averaged with the digital signal.
I will be forced.

Similarly, when a plurality of systems of multi-bit digital signals are input to the transmitting side, each of them is converted into a 1-bit digital signal by the signal converting section.

Therefore, unlike the conventional digital signal transmission method based on the parallel transmission method, only one transmission system is required, and transmission systems corresponding to the number of digital signal systems or transmission systems corresponding to the number of encoded bits are unnecessary. . Further, it is not necessary to transmit the data clock by another transmission system. Therefore, it is possible to reduce the number of transmission systems. Since each transmission system includes a transmission unit, a reception unit, a transmission line, etc., by suppressing an increase in such a transmission system, it is possible to simplify the overall configuration of the transmission means and prevent an increase in size. it can.

On the other hand, unlike the conventional serial transmission system, there is no need to perform a special format on the digital signal in order for the receiving side to judge which system the time-divided digital signal is. , It is possible to send and receive with a simple configuration.

Therefore, it is possible to transmit a plurality of systems of signals using a single system of digital signals and with a simple circuit configuration. Therefore, the configuration of the entire signal transmission device can be simplified and the economical efficiency can be improved.

The signal transmission device according to claim 2 has a plurality of systems.
In a signal transmission device that transmits and receives digital signals of
On the receiving side, input signals of multiple systems are converted into 1-bit digital signals.
A signal converter that converts to a sync signal and a sync signal that generates a sync signal
A generator, the 1-bit digital signal, and the synchronization signal
Multiplex transmission to one system of digital signal for transmission
And the receiving side has a digital part for transmission.
A sync signal detection unit for detecting the sync signal from the sync signal,
Synchronized from the sync signal to the digital signal for transmission
A clock generator that generates a clock and the above clock
Based on the digital signal for transmission,
1-bit recovery that demodulates at each timing according to the system
A contrast portion, without separating the digital signal of each path of the input signal from the transmission digital signal received, characterized by having a <br/> pass filter in which the transmission digital signal is directly input There is.

With the above structure, when the digital signal for transmission is passed through the low-pass filter, the synchronizing signal has the same "L" section and "H" section, and therefore has a potential of 0 volt. It is said that Therefore, it is averaged with the 1-bit digital signal other than the synchronization signal. Therefore, a monaural signal output can be obtained.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The following will describe one embodiment of the present invention in reference to FIG. 1 and FIG. Here, two analog signals are transmitted. The signal transmission device according to the present embodiment has a transmission device 14 and a reception device 27, as shown in FIG.

The transmitter 14 has a ΔΣ (delta sigma) modulation circuit (signal conversion section) 11, a synchronization signal generation circuit (synchronization signal generation section) 12, and a multiplexing circuit (multiplexing section) 13. The ΔΣ modulation circuit 11 converts an analog signal into a 1-bit digital signal and outputs it. The synchronization signal generation circuit 12 generates a clock C11 which is three times as high as the data clock of the 1-bit digital signal. The multiplexing circuit 13 multiplexes the 1-bit digital signal and the clock C11.

The receiving device 27 includes a synchronization signal detection circuit (synchronization signal detection unit) 21 and a PLL circuit (clock generation unit) 2.
4, a 1-bit demodulation circuit (1-bit demodulation unit) 25 and a low-pass filter 26. The sync signal detection circuit 21 detects a sync signal from the input signal as described later. The PLL circuit 24 includes a PLL oscillator 22 that oscillates a high-speed clock C22 that is an integral multiple (here, eight times) of the input clock, and the input clock C22.
And a counter 23 for counting on rising, and outputs a clock C24 from the counter 23. The 1-bit demodulation circuit 25 demodulates and outputs a 1-bit digital signal from an input digital signal at the rising or falling edge of the input clock C24.

First, two types of analog signals, that is, A1 and A2, are input to the transmitter 14. Then,
The analog signal is converted by the ΔΣ modulation circuit 11 into 1-bit digital signals D11 and D12 and input to the multiplexing circuit 13. Here, in order to prevent the 1-bit digital signals D11 and D12 from being alternately output by the receiving device 27 after transmission, the synchronization signal generation circuit 12 generates a clock C11 which is three times the data clock of the 1-bit digital signal. 1-bit digital signals D11 and D1 generated by the multiplexing circuit 13
By being multiplexed with 2, it becomes a synchronization signal. In this way, the multiplexed digital signal D21 (digital signal for transmission) is obtained.

The multiplexed digital signal D21 is received by the receiver 2
7, the sync signal detection circuit 21 detects the minimum "H" section, that is, the "H" section of the sync signal, and generates a clock C21 that takes two different values at each falling edge of the sync signal.

The PLL circuit 24 causes the PLL oscillating unit 22 to oscillate the clock C22 which is eight times the clock C21. Then, obtain a clock C24 in counter 23 for counting on the rising of the input clock. This clock C
24 and the multiplexed digital signal D21 are input to the 1-bit demodulation circuit 25, the multiplexed digital signal D21 is read at the rising edge of the clock C24, and the 1-bit digital signal D is read.
11 'is output. Output D11 'as clock C2
It reads again at the trailing edge of 4 and outputs a 1-bit digital signal D11 ″.

The multiplexed digital signal D21 is read at the falling edge of the clock C24 and a 1-bit digital signal D12 "is output.

Therefore, the 1-bit demodulation circuit 25 causes the output D1 of the ΔΣ modulation circuit 11 of the transmitter 14 to be output.
1-bit digital signal D1 which is almost the same as D1
1 ″ and D12 ″ can be demodulated.

Then, the 1-bit digital signals D11 "and D12" obtained by the 1-bit demodulation circuit 25 are passed through the low-pass filter 26, and the analog signal A11,
Demodulate A12.

When the multiplexed digital signal D21 treated as the transmission signal of the present invention is directly input to the low-pass filter 26, since the synchronizing signal has the same "L" section and "H" section, the potential of 0 volt. And is averaged with the 1-bit digital signal other than the synchronization signal and output as a monaural signal (a21).

The techniques disclosed in JP-A-6-66138 and JP-A-6-85683 are all 1
The method of multiplexing bit signals is described, but the processing method after transmission is not described. The present invention determines which system input signal (for example, stereo audio signals Lch and Rch) is transmitted after being multiplexed, and when performing demodulation, this determination can be performed by a simple circuit. The signals are multiplexed as described above.

[0029]

As described above, the signal transmission device according to claim 1 of the present invention is a signal transmission device for transmitting and receiving digital signals of a plurality of systems, and at the transmission side, an input signal of a plurality of systems is a 1-bit digital signal. A signal conversion unit for converting to
A synchronization signal generation unit for generating a synchronization signal having the same "L" section and "H" section, and the 1-bit digital signal and the synchronization signal are multiplexed into a single transmission digital signal. And a synchronization signal detection unit for detecting the synchronization signal from the received transmission digital signal, and a clock synchronized with the transmission digital signal from the synchronization signal on the reception side. The clock generation unit and the 1-bit demodulation unit that demodulates the transmission digital signal based on the clock at a timing corresponding to each system of the input signal.

Therefore, there is an effect that the overall structure of the signal transmission device can be simplified and the economical efficiency can be improved. In addition, the above digital signal for transmission is low as it is.
When input to the pass filter, the sync signal is
Since it is the same as the "H" section, it has a potential of 0 volt.
And a 1-bit digital signal other than the sync signal
It is possible to obtain the output of a monaural signal which is averaged
Has the effect.

A signal transmission device according to claim 2 of the present invention is
For signal transmission equipment that transmits and receives digital signals of multiple systems
On the transmitting side, the input signals of multiple systems are
Signal converter that converts to a digital signal, and generates a sync signal
The same as the sync signal generator and the 1-bit digital signal.
The transmission signal and the digital signal for transmission of one system are multiplexed and sent.
It has a multiplex part that receives the
Sync signal detection to detect the above sync signal from the digital signal for
From the output part and the synchronization signal to the digital signal for transmission
A clock generator that generates a synchronized clock and the clock
Based on the lock, input the above digital signal for transmission to the above
Demodulate at each timing according to each signal system 1
A bit demodulation unit and a low-pass filter to which the digital signal for transmission is directly input without separating the digital signal of each system of the input signal from the received digital signal for transmission.

Therefore, the structure of the entire signal transmission device is simplified.
And has the effect of improving economic efficiency.
To do. In addition to the above effects, an effect that a monaural signal output can be obtained is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a signal transmission device according to the present invention.

FIG. 2 is a timing chart of signals handled by the configuration of FIG.

[Explanation of symbols]

Reference Signs List 11 ΔΣ modulation circuit (signal conversion unit) 12 synchronization signal generation circuit (synchronization signal generation unit) 13 multiplex circuit (multiplexing unit) 14 transmitter 21 synchronization signal detection circuit (synchronization signal detection unit) 22 PLL oscillation unit 23 counter 24 PLL circuit (Clock generation unit) 25 1-bit demodulation circuit (1-bit demodulation unit) 26 Low-pass filter 27 Receiver A1, A2, A11, A12, a21 Analog signals C11, C21, C22, C24 Clocks D11, D12, D11 ", D11 ' , D12 "1
Bit digital signal D21 Multiplexed digital signal (Transmission digital signal)

Claims (2)

(57) [Claims] 1. In a signal transmission device for transmitting and receiving digital signals of a plurality of systems, on the transmission side, a signal conversion section for converting an input signal of a plurality of systems into a 1-bit digital signal, and a section of "L" and "H". The receiving section includes a synchronization signal generation unit that generates a synchronization signal having the same section, and a multiplexing unit that multiplexes the 1-bit digital signal and the synchronization signal into a transmission digital signal of one system and transmits the multiplexed signal. On the side, a synchronization signal detection unit that detects the synchronization signal from the received transmission digital signal, a clock generation unit that generates a clock synchronized with the transmission digital signal from the synchronization signal, and based on the clock, A signal transmission device, comprising: a 1-bit demodulation unit that demodulates the transmission digital signal at a timing corresponding to each system of the input signal. 2. A signal for transmitting and receiving digital signals of a plurality of systems
In the transmission device, on the transmission side, input signals of multiple systems are sent as 1-bit digital signals.
Signal conversion unit for converting into a signal, a synchronization signal generation unit for generating a synchronization signal, the 1-bit digital signal and the synchronization signal in one system
Of the digital signal for transmission of
Then, on the receiving side, the above from the received digital signal for transmission
A sync signal detection unit for detecting a sync signal, and the above-mentioned sync signal are synchronized with the above digital signal for transmission.
A clock generator that generates a clock, and the digital signal for transmission above
Demodulate at the timing according to each input signal system
A 1-bit demodulator, from the transmission digital signal received without separating digital signals of each path of the input signal, and having a low-pass filter in which the transmission digital signal is directly input Signal transmission equipment.