JP4814151B2 - Multiplexed signal transmission system and multiplexed signal transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multiplexed signal transmission system and a multiplexed signal transmitting method that can separate original signals from a multiplexed signal with simple constitution. <P>SOLUTION: In a multiplexing transmission device 4, a modulation signal generator 42 generates a modulation signal for multiplexing on the basis of a synchronizing signal, multiplexers Ad2 to Ad4 and an adder Ce use the modulation signal for multiplexing to superpose a plurality of input signals including the synchronizing signal dispersedly in different bands, and a digital sigma modulation circuit 1 performs modulation into a quantized signal having a band where quantization noise is small in the frequency bands where the plurality of input signals are superposed and then outputs the quantized signal. In a demultiplexing reception device 5, an LPF 52a demodulates the synchronizing signal from the quantized signal, and multipliers Ae2 to Ae4 and LPFs 52b to 52d frequency-shift the quantized signal and demodulates it into the plurality of input signals by using a modulation signal for demultiplexing. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a multiplexed signal transmission system and a multiplexed signal transmission method including a multiplexing transmission apparatus that multiplexes and transmits a plurality of signals, and a reception separation apparatus that separates received multiplexed signals, and more particularly to a plurality of signals. The present invention relates to a multiplexed signal transmission system and a multiplexed signal transmission method for transmitting and receiving a quantized signal obtained by multiplexing the signal.

  When transmitting a plurality of signals, the transmitting side transmits a plurality of clock-synchronized signals by time division multiplexing, and the receiving side separates the original signal from the multiplexed signal from the transmitting side, and obtains the original A multiplex transmission method has been proposed in which an original signal is identified based on a synchronization pattern detected from the above signal and an output position of the original signal is determined (see, for example, Patent Document 1).

However, in order to separate the multiplexed signal that has been time-division multiplexed on the receiving side, it is necessary to extract one signal while switching by the switching circuit. However, as the number of multiplexed signals increases, the circuit scale of the switching circuit increases. There is a problem that the overhead for switching increases.
JP-A-10-233745

  The present invention has been made in view of such problems, and an object of the present invention is to separate an original signal from a multiplexed signal with a simple configuration without using a switching circuit for switching signals on the receiving side. It is in the point which provides the multiplexed signal transmission system and multiplexed signal transmission method which can be made to do.

In order to solve the above problems, the present invention has the following configuration.
The multiplexed signal transmission system according to the present invention includes a multiplexing transmitter that transmits a multiplexed signal obtained by quantizing a plurality of input signals at a frequency fs and multiplexing the input signal, and separating the received multiplexed signal into the plurality of input signals. A multiplexed signal transmission system comprising: a receiving / separating device that receives the plurality of input signals including a synchronization signal input signal serving as a synchronization signal; and A multiplexing modulation signal generating means for generating a multiplexing modulation signal for multiplexing a plurality of the input signals, and the multiplexing modulation signal generated by the multiplexing modulation signal generating means. be to frequency shift the other of said input signals other than the signal for the input signal to the return position between the frequency 0 of the frequency fs / 2, a plurality of the comprising an input signal for the synchronization signal A frequency shift adding means for superimposing to the force signal is dispersed to different bands, the output signals from the frequency shift adding means, while the frequency 0 of the frequency fs / 2, the quantization noise band quantization noise becomes small By modulating a plurality of quantized signals at the folding position with a large band between them, the plurality of input signals are dispersed and superimposed in a band where a plurality of quantization noises are reduced. Delta-sigma modulation means for outputting the multiplexed signal as a multiplexed signal, and the reception separation device includes a synchronization signal demodulation means for demodulating the synchronization signal input signal from the multiplexed signal, and the synchronization signal demodulation means. Based on the demodulated input signal for synchronization signal, a separation modulation signal generator for generating a separation modulation signal for separating the plurality of input signals from the multiplexed signal And the other input other than the synchronization signal input signal that is frequency-shifted using the separation modulation signal generated by the separation modulation signal generation means and dispersed and superimposed on the quantized signal. For each signal, frequency shift means for respectively outputting a plurality of the frequency-multiplexed signals by frequency-shifting the multiplexed signal so that the input signal returns to the original frequency band;
Demodulating means for demodulating each of the plurality of multiplexed signals frequency-shifted by the frequency shifting means and demodulating all of the input signals is provided.

Furthermore, in the multiplexed signal transmission system of the present invention, the delta-sigma modulation means includes a plurality of cascaded integration means, an addition means for adding outputs from the integration means, and sampling an output from the addition means. Quantizing means for quantizing based on frequency and outputting a quantized signal; and a negative feedback loop for negatively feeding back the output from the quantizing means to the integrating means in the first stage,
A plurality of delay means for delaying by one sampling period are connected in cascade, a plurality of first delay means for delaying the output by a sampling period corresponding to the number of the delay elements;
Adding means for adding the output from the first delay means to the input respectively;
In the negative feedback loop, the same number of the delay devices as the first delay means are connected in cascade, and the quantization is performed via the second delay means for delaying the input by the same number of sampling periods as the first delay means. The output from the means is negatively fed back to the integrating means in the first stage, and quantization noise is present between the frequency 0 and the frequency fs / 2 in the frequency characteristic of the quantization noise of the quantized signal output from the quantization means. A plurality of smaller bands are formed at folding positions sandwiching a band where quantization noise is large .

  Furthermore, in the multiplexed signal transmission system of the present invention, the synchronization signal demodulating means of the reception separation device is a low-pass filter that allows only baseband to pass, and the multiplexed transmission device is configured to transmit the synchronization signal input signal. A multiplexing low-pass filter that passes only the baseband, and the multiplexing modulation signal generating means is for multiplexing the plurality of input signals based on the synchronization signal input signal that has passed through the low-pass filter. A modulation signal is generated.

Also, the multiplexed signal transmission method of the present invention includes a multiplexed transmission step of transmitting a multiplexed signal obtained by quantizing a plurality of input signals at a frequency fs and multiplexing the received signal, and the received multiplexed signal as a plurality of the input signals. A multiplexed signal transmission method that receives a plurality of input signals including a synchronization signal input signal to be a synchronization signal, and receives the synchronization signal input signal. And generating a multiplexing modulation signal for multiplexing a plurality of the input signals, and using the generated modulation signal for multiplexing, the other input signals other than the synchronization signal input signal are frequency- converted. 0 be to frequency shift the folded position between the frequency fs / 2, a plurality of the input signal dispersed to the different bands superimposed including an input signal for the synchronizing signal, a plurality of said input signal The tatami signal, while the frequency 0 of the frequency fs / 2, modulating the quantization signals plurality formed sandwiching the folded position while the bands of the band quantization noise becomes smaller quantization noise becomes large Then, the quantized signal is output as the multiplexed signal in which a plurality of the input signals are dispersed and superimposed in a band in which a plurality of quantization noises are small, and in the reception separation step, the synchronization signal is output from the multiplexed signal. Demodulating the signal input signal, generating a separation modulation signal for separating the plurality of input signals from the multiplexed signal based on the demodulated synchronization signal input signal, and generating the generated separation signal For each input signal other than the synchronization signal input signal that is frequency-shifted and dispersed and superimposed on the quantized signal using a modulation signal, the multiplexed signal is converted to the original frequency of the multiplexed signal. band By each frequency shift to return to, that a plurality of the multiplexed signal obtained by frequency-shifted output, respectively, said frequency shifted plurality of the multiplexed signal demodulated respectively demodulates all of the input signals Features.

  Furthermore, in the multiplexed signal transmission method of the present invention, in the reception separation step, the synchronization signal input signal is demodulated from the multiplexed signal using a low-pass filter that passes only baseband, and the multiplexed transmission is performed. The step is characterized in that a multiplexing modulation signal for multiplexing a plurality of the input signals is generated based on the synchronization signal input signal that has passed through the low-pass filter that passes only the baseband.

  In the multiplexed signal transmission system and the multiplexed signal transmission method of the present invention, the multiplexed transmission apparatus accepts a plurality of input signals including a synchronization signal input signal to be a synchronization signal, and a plurality of input signals are received based on the synchronization signal input signal. A synchronization signal input signal is generated by generating a modulation signal for multiplexing to multiplex the input signal and shifting the frequency of other input signals other than the synchronization signal input signal using the generated modulation signal for multiplexing. A plurality of input signals including are distributed and superimposed in different bands, and a signal in which a plurality of input signals are superimposed is overlapped with a frequency band in which a plurality of input signals are dispersed and superimposed. By modulating the quantized signal to be formed, the quantized signal is output as a multiplexed signal in which a plurality of input signals are dispersed and superimposed in a band where a plurality of quantization noises are reduced. And configured to demodulate the synchronization signal input signal from the multiplexed signal in the reception separation device, and based on the demodulated synchronization signal input signal, a separation modulation signal for separating a plurality of input signals from the multiplexed signal. The multiplexed signal is generated for each input signal other than the synchronization signal input signal that is frequency-shifted and dispersed and superimposed on the quantized signal using the generated separation modulation signal. By respectively shifting the frequency so as to return to the frequency band, the frequency-shifted multiplexed signals are output, and the frequency-shifted multiplexed signals are respectively demodulated into a plurality of input signals. Even when the multiplexing transmitter on the transmitting side and the receiving / separating device on the receiving side are not synchronized, the synchronization signal input signal superimposed on the multiplexed signal is used. By simply demodulating the frequency-shifted multiplexed signal using the modulation signal generated in this way, it is possible to separate a plurality of signals that have been frequency-shifted and superimposed on the multiplexed signal. There is an effect that the original signal can be separated from the multiplexed signal with a simple configuration without using a switching circuit.

  Furthermore, in the multiplexed signal transmission system and the multiplexed signal transmission method of the present invention, a band where the quantization noise is reduced is formed at the folded position sandwiching the band where the quantization noise is increased by the delta-sigma modulation means. It is possible to secure a plurality of signal bands to be superimposed on the quantized signal, and to have a plurality of signals superimposed on the quantized signal. .

  Furthermore, in the multiplexed signal transmission system and the multiplexed signal transmission method of the present invention, the receiving / separating device is configured to demodulate the synchronization signal input signal from the multiplexed signal using a low-pass filter that passes only the baseband. In addition, the multiplexing transmitter is provided with a low-pass filter that passes only the baseband of the synchronization signal input signal, and a plurality of input signals are multiplexed based on the synchronization signal input signal that has passed through the low-pass filter. By configuring so as to generate a modulation signal for multiplexing, the synchronization signal used on the transmission side and the reception side can have the same waveform, and a plurality of signals shifted in frequency and superimposed on the multiplexed signal can be obtained. There is an effect that it can be accurately separated.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an embodiment of a multiplexed signal transmission system according to the present invention.

Referring to FIG. 1, the multiplexed signal transmission system 3 according to the present embodiment multiplexes an input signal X ₁ and input signals X _{2 to} X ₄ used as synchronization signals, modulates them into quantized signals, and modulates the quantized quantum signals. a multiplexing transmission apparatus 4 for transmitting a signal, the quantized signal received from the multiplexing transmission apparatus 4, was separated demodulated using an input signal X ₁ that are multiplexed, the input signal X ₂ from the output terminal P22 the corresponding output signal Y _2, the output signal Y ₃ corresponding to the input signal X ₃ from the output terminal P23, the output signal Y ₄ corresponding to the input signal X ₄ from the output terminal P24 from the reception separator 5 for outputs Become.

Next, the configuration and multiplexed modulation operation of the multiplexing transmitter 4 shown in FIG. 1 will be described in detail with reference to FIGS.
2 is a block diagram showing an electrical configuration of the delta-sigma modulation circuit used in the multiplexing transmission apparatus shown in FIG. 1, and FIG. 3 is a block diagram showing a configuration example of the delay unit shown in FIG. 4 is a graph showing the frequency characteristics of the quantization noise distribution in the delta-sigma modulation circuit shown in FIG. 2, FIG. 5 is a block diagram modeling the delta-sigma modulation circuit, and FIG. 6 is shown in FIG. FIG. 7 is an explanatory diagram for explaining the frequency characteristic of the quantization noise distribution of the quantized signal output from the delta sigma modulation circuit, and FIG. 7 is a second-order delta sigma modulation using a delay device that is delayed by two sampling periods. FIG. 8 is a block diagram in which a circuit is modeled. FIG. 8 is a graph showing frequency characteristics of a quantization noise distribution of a quantized signal output from the second-order delta-sigma modulation circuit shown in FIG. Figure FIG. 10 is a block diagram showing a configuration of a seventh-order delta-sigma modulation circuit using seven integration elements in the delta-sigma modulation circuit shown in FIG. 10, and FIG. 10 is output from the seventh-order delta-sigma modulation circuit shown in FIG. FIG. 11 is a graph showing frequency characteristics of a quantization noise distribution of a quantized signal, and FIG. 11 is an explanatory diagram for explaining a multiplexing modulation operation in the multiplexing transmission apparatus shown in FIG.

Referring to FIG. 1, the multiplexing transmission device 4 includes a low pass filter (LPF) 41 that generates only a baseband (band near frequency 0) in the input signal X ₁ and generates a synchronization signal. Using the generated synchronization signal, a carrier signal having a frequency fs / 4 modulated by a sin signal, a carrier signal having a frequency fs / 4 modulated by a cos signal, and a carrier signal having a frequency fs / 2 are generated. a modulation signal generating unit 42, by using a carrier signal of a frequency fs / 4 which is modulated by the sin signal, the input signal _{X 2} causes the phase modulation, the multiplier Ad2 to frequency shift the frequency fs / 4, cos signal by using a carrier signal of a frequency fs / 4 which is modulated by position on the basis of an input signal X ₃ to sin signal Modulated with phase-to-modulated in component orthogonal to the input signal X _2, a multiplier Ad3 to frequency shift the frequency fs / 4, by using a carrier signal of a frequency fs / 2, the input signal X ₄ a frequency fs / a multiplier Ad4 to frequency shifted to 2, and the input signal X _1, is phase-modulated based on a sin signal, the input signal X _2, which is frequency shifted to a frequency fs / 4, is phase-modulated on the basis of the cos signal, the frequency fs / 4 the input signal X ₃ that is frequency shifted to an adder Ce for adding the input signal X ₄ that is frequency shifted to a frequency fs / 2, the quantized signal to multi-bit signal output from the adder Ce A delta sigma modulation circuit 1 that modulates the signal to the delta sigma, and a transmission unit 43 that transmits the quantized signal output from the delta sigma modulation circuit 1. Note that fs is a sampling frequency.

  Referring to FIG. 2, the delta sigma modulation circuit 1 used in the multiplexing transmission device 4 converts N types (N of different analog signals or multi-bit digital signals input as input signals X to the input terminal P1). Is an n-order (n: integer greater than or equal to 1) delta-sigma modulation circuit that converts the converted quantized signal into a quantized signal represented by a representative value and outputs the converted quantized signal as an output signal Y from the output terminal P2. , Fan connected in cascade with each other, and multipliers Aa1 to Aan interposed in front of each of the integrating elements Fa1 to Fan, respectively. Each of the integration elements Fa1 to Fan delays the output by m sampling periods (Ts: 1 / frequency fs) (m: an integer equal to or larger than 2; m = 4 in the multiplexing transmitter 4 shown in FIG. 1). ~ Dan and adders Ca1 ~ Can that add and output the outputs from the delay units Da1 ~ Dan to the input, respectively. The output signals are added to create an output signal for the next stage.

  An analog signal or a multi-bit digital signal input as the input signal X to the input terminal P1 is input to the first-stage integration element Fa1 via the adder Cb and the first-stage multiplier Aa1. The outputs of the integration elements Fa1 to Fa (n−1) are respectively input to the integration elements Fa2 to Fan of the next stage via the multipliers Aa2 to Aan, and the outputs from the integration elements Fa1 to Fan are added to the adder Cc. Are added to each other and input to the quantizer 10. The quantizer 10 has a function of converting an input signal into a quantized signal into a signal represented by different representative values of N types (N is an integer). In this embodiment, the quantizer 10 The signal is converted into a signal (1-bit signal) represented by two types (+1 and −1) of representative values. Specifically, for each frequency fs, the output from the adder Cc is compared with a predetermined value, for example, 0 level, and when the output from the adder Cc is greater than a predetermined value, for example, 0 level, the output terminal P2 The output signal Y is “1”, and is “−1” when it is less than a predetermined value. Further, the output signal Y from the quantizer 10 is negatively fed to the adder Cb interposed in the preceding stage of the first-stage multiplier Aa1 through the delayer Db and the multiplier Ab delayed by m sampling periods. It has been returned.

  As the delay elements Da1 to Dan of the integration elements Fa1,..., Fan and the delay element Db of the negative feedback loop, for example, as shown in FIG. 3, m delay elements D that delay the output by one sampling period are cascaded. A connected one can be used.

  Instead of the delay elements Da1 to Dan of the integration elements Fa1,..., Fan and the delay element Db of the negative feedback loop, the conventional delta-sigma modulation circuit using the delay element D that delays the output by one sampling period has a quantization noise. The delta sigma modulation circuit 1 used in the multiplexed signal transmission system of the present embodiment has the noise shaping effect peculiar to the delta sigma modulation circuit that shifts the signal to the high frequency band side. As shown in c), a plurality of bands where the quantization noise is reduced on the frequency distribution are formed. FIG. 4 (a) shows the frequency characteristics of the quantization noise distribution when two delay devices D are connected in cascade and delay devices Da1 to Dan and delay device Db that are delayed by two sampling periods are used. A band in which new quantization noise is reduced is formed in the vicinity of the frequency fs / 2, and two bands in which the quantization noise is reduced are formed at a position folded at the frequency fs / 4. FIG. 4B shows the frequency characteristics of the quantization noise distribution in the case of using the delay units Da1 to Dan and the delay unit Db that are delayed by 3 sampling periods in which three delay units D are connected in cascade. A band in which new quantization noise is reduced is formed in the vicinity of the frequency fs / 3, and a band in which two quantization noises are reduced is formed at a position folded at the frequency fs / 6. FIG. 4 (c) shows the frequency characteristics of the quantization noise distribution when four delay devices D are connected in cascade and the delay devices Da1 to Dan and the delay device Db that are delayed by four sampling periods are used. In the vicinity of the frequency fs / 4 and in the vicinity of the frequency fs / 2, a band in which new quantization noise is reduced is formed, and at each position where the frequency fs / 8 and the frequency fs · 3/8 are turned back, A band in which the quantization noise is small is formed. In this way, m = 2p delay devices D are connected in cascade, delay devices Da1 to Dan and delay device Db that are delayed by 2p sampling cycles, or m = 2p + 1 delay devices D are connected in cascade, 2p + 1 sampling cycles By using the delay devices Da1 to Dan and the delay device Db that are delayed by a certain amount, the band where the quantization noise is small on the frequency distribution is the folding position between which the band where the quantization noise is large, that is, fs * k / p + 1 locations are formed in a frequency band in which m is a natural number and k is an integer in the range of 0 ≦ k <(m + 1) / 2.

  Next, the frequency characteristic of the quantization noise distribution in the delta sigma modulation circuit 1 used in the multiplexed signal transmission system of this embodiment is verified using the block diagram shown in FIG. 5 that models the delta sigma modulation circuit. In FIG. 5, G corresponds to the integration elements Fa1,..., Fan, H corresponds to the delay device Db, and the quantizer 10 is added with a uniform noise N in each band.

  In the model shown in FIG. 5, the transfer function Q of the noise N can be expressed as Q = 1 / (1 + GH), and the transfer function P of the input signal x can be expressed as P = G / (1 + GH), where P = 1. In this case, G = 1 / Q and H = 1-Q.

Here, in the primary delta-sigma modulation circuit, the frequency characteristic of the quantization noise distribution shifted to the high frequency band side as shown in FIG. ^6A can be expressed by Q = (1-Z ⁻¹ ). , G = 1 / (1-Z ⁻¹ ), H = Z ⁻¹ , and instead of the delay elements Da1 to Dan of the integration elements Fa1,... This corresponds to a conventional delta-sigma modulation circuit using a delay device D that is delayed by a delay time.

On the other hand, in the first-order delta-sigma modulation circuit, a quantization noise distribution in which a band in which the quantization noise is small is formed in a low frequency band and a band in the vicinity of the frequency fs / 2 as shown in FIG. Can be expressed by Q = (1-Z ⁻¹ ) (1 + Z ⁻¹ ), G = 1 / (1-Z ⁻² ), H = Z ⁻² , and two delay devices D Corresponding to a first-order delta-sigma modulation circuit 1 using delay devices Da1 to Dan and a delay device Db that are delayed by two sampling periods.

In the second-order delta-sigma modulation circuit, the frequency of the quantization noise distribution in which a band in which the quantization noise is small is formed between the low frequency band and the band near the frequency fs / 2 as shown in FIG. The characteristic can be represented by Q = (1-Z- ¹ ) ² (1 + Z- ¹ ) ² , G = 1 / (1-Z- ² ) ² , H = 1- (1-Z- ² ) ^2. This corresponds to a second-order delta-sigma modulation circuit 1 using two delay devices D connected in cascade and using delay devices Da1 to Dan and a delay device Db that are delayed by two sampling periods.

  The second-order delta-sigma modulation circuit 1 can be modeled as shown in FIG. 7, and the frequency characteristic of the quantization noise distribution simulated using the model shown in FIG. 7 and the sampling frequency fs = 2.8 MHz is As shown in FIG. 8, it was proved that a band in which the quantization noise is small is formed in the low frequency (0) band and the band in the vicinity of the frequency fs / 2 = 1.4 MHz.

  Referring to FIG. 9, the seventh-order delta sigma modulation circuit 2 using the seven integration elements Fa1 to Fa7 in the delta sigma modulation circuit 1 includes seven integration elements Fa1,. , And multipliers Aa1 to Aa7 respectively interposed in front stages of the integration elements Fa1 to Fa7. Each of the integration elements Fa1 to Fa7 adds a delay device that delays the output by m sampling periods (Ts: 1 / frequency fs) (m: an integer equal to or greater than 2) and an output from the delay device to the input and outputs the result. Therefore, the output signal from the previous stage is added to the input signal from the previous stage by the m sampling period, and the output signal to the next stage is created.

  An analog signal or a multi-bit digital signal input as the input signal X to the input terminal P1 is input to the first stage integration element Fa1 via the adder Cb and the first stage multiplier Aa1. Input to the integration element Fa1 of the stage, and outputs of the integration elements Fa1 to Fa6 are respectively input to the integration elements Fa2 to Fa7 of the next stage via the multipliers Aa2 to Aa7, and are output from the integration elements Fa1 to Fa7. Are added to each other by the adder Cc and then input to the quantizer 10. The quantizer 10 compares the output from the adder Cc with a predetermined value, for example, 0 level for each frequency fs, and when the output from the adder Cc is a predetermined value, for example, 0 level or more, the output terminal P2 The output signal Y to “1” is “1”, and is “−1” when it is less than a predetermined value. Further, the output signal Y from the quantizer 10 is negatively fed to the adder Cb interposed in the preceding stage of the first-stage multiplier Aa1 through the delayer Db and the multiplier Ab delayed by m sampling periods. It has been returned.

  Further, adders Cd1 to Cd3 are interposed in front of the integration elements Fa2, Fa4, and Fa6, respectively, and delay elements Dc1 to Dc3 in which outputs of the integration elements Fa3, Fa5, and Fa7 are delayed by m sampling periods and multiplications. Three partial negative feedback loops are respectively fed back to the adders Cd1 to Cd3 interposed in the preceding stage of the first-stage multiplier Aa1 through the units Ac1 to Ac3, respectively.

  FIG. 10 shows the quantization noise of the delta-sigma modulation circuit 2 using four delay devices D connected in cascade and using delay devices Da1 to Dan, a delay device Db, and delay devices Dc1, Dc2, and Dc3 that are delayed by four sampling periods. The frequency characteristics of the distribution are shown, and a band in which a new quantization noise is reduced is formed near the frequency fs / 4 and near the frequency fs / 2, and the frequency fs / 8 and the frequency fs · 3/8 are obtained. Bands where the quantization noise is reduced at three locations are formed at each folded position, and the rise and fall of the quantization noise distribution in each band where the quantization noise is reduced by three partial negative feedback loops Three dips are formed in each. The shape of the dip can be changed by appropriately selecting the multiplication coefficients of the multipliers Aa1 to Aa7, the multipliers Ab and Ac1 to Ac3, and the width of each band where the quantization noise that becomes the effective frequency band is reduced. The dynamic range within the band can be set as appropriate.

The delta-sigma modulation circuit 1 in the multiplexing transmission device 4 uses delay units Da1 to Dan and a delay unit Db that are delayed by 4 sampling periods in which four delay units D are connected in cascade, and output quantization As shown in FIG. 11, the signal has frequency characteristics of a quantization noise distribution in which a band in which the quantization noise is small is formed in the vicinity of frequency 0, in the vicinity of frequency fs / 4, and in the vicinity of frequency fs / 2. Input signals X _{1 to} X ₄ are superimposed on a band near frequency 0. Note that the input signals X _{2 to} X ₄ are band-limited within (fs / 2) / 4 by a band-limiting low-pass filter (not shown) provided in the previous stage of the delta-sigma modulation circuit 1.

  The transmission unit 43 is a transmission unit that transmits the quantized signal output from the delta-sigma modulation circuit 1 directly or on a carrier wave using a transmission medium such as an electric wire, various cables, an optical fiber, an infrared ray, and a radio wave. .

Referring to FIG. 11, an input signal X ₁ used as a synchronization signal input from the input terminal P 11 is input to the adder Ce and input to the LPF 41, and the input signal X ₁ input to the LPF 41 is input by the LPF 41. A synchronization signal is generated. The input signal X ₁ is a waveform such as easy synchronization signal notice rising edge even over the LPF41 is obtained. In the present embodiment, the signal band that can be input to each of the input signals X _{1 to} X ₄ is a band of fs / 8 or less from the noise characteristics of the delta-sigma modulation circuit 1. phase serving as a reference synchronizing signal of the carrier signal generated, i.e. as the input signal X ₁ is, fs / 8 or less (in fact, well below fs / 8 in consideration of the influence of the noise of the delta-sigma modulation Frequency) signal can be used.

  The modulation signal generation unit 42 uses the synchronization signal generated by the LPF 41 as a reference for the phase of the carrier signal, and uses the carrier signal having the frequency fs / 4 modulated by the sin signal and the frequency fs / 4 modulated by the cos signal. And a carrier signal having the frequency fs / 2 modulated by the sin signal are generated in the multiplier Ad2, and a carrier signal having the frequency fs / 4 modulated by the cos signal is generated. A carrier signal having a frequency fs / 2 is output to the multiplier Ad3 to the multiplier Ad4.

Input signal _{X 2} inputted from the input terminal P12 is input to a multiplier Ad2, multiplier Ad2, by using the carrier signal of a frequency fs / 4 which is modulated by the sin signal, as shown in FIG. 11, the input signal X ₂ causes phase-modulated, is frequency shifted to a frequency fs / 4, is phase-modulated based on a sin signal, the input signal X _2, which is frequency shifted to a frequency fs / 4 is input to the adder Ce .

Input signal _{X 3} inputted from the input terminal P13 is input to a multiplier Ad3, multiplier Ad3, by using the carrier signal of a frequency fs / 4 modulated by cos signal, as shown in FIG. 11, the input signal X ₃ causes phase modulation component orthogonal to the input signal X _2, which is phase-modulated based on sin signal, the frequency shift to the frequency fs / 4, is phase-modulated on the basis of the cos signal, the frequency fs / 4 input signal X ₃ that is frequency shifted is input to the adder Ce.

Input signal _{X 4} input from the input terminal P14 is input to a multiplier Ad4, multiplier Ad4, by using the carrier signal of a frequency fs / 2, as shown in FIG. 11, the frequency of the input signal _{X 4} fs / 2 to cause the frequency shifted input signal _{X 4} that is frequency shifted to a frequency fs / 2 is input to the adder Ce.

By the adder Ce, as shown in FIG. 11, the input signal X _1, is phase-modulated based on a sin signal, the input signal X _2, which is frequency shifted to a frequency fs / 4, it is phase-modulated on the basis of the cos signal , the input signal X ₃ that is frequency shifted to a frequency fs / 4, the multi-bit output and input signal X ₄ that is frequency shifted to a frequency fs / 2 is added is inputted to the delta sigma modulation circuit 1, a delta-sigma modulation circuit 1, by performing a delta sigma modulation to the multi-bit output from the adder Ce, as shown in FIG. 11, the quantization noise of the input signal X ₁ is a baseband (band around frequency 0) the small becomes band, the input signal X _2, which is phase-modulated based on the sin signal, is phase-modulated on the basis of the cos signal, orthogonalized input signal X ₃ and is frequency for the input signal X ₂ fs / 4 to the band quantization noise is small in the vicinity, and outputs the input signal X ₄ is a frequency fs / 2 near the quantization noise is superimposed on each of the small becomes the band quantized signal, the electric wire by the transmission unit 43, It is transmitted using various media such as cables, optical fibers, infrared rays, and radio waves. Note that the delta-sigma modulation circuit 1 uses delay devices Da1 to Dan and a delay device Db that are delayed by four sampling periods in which four delay devices D are connected in cascade. Further, the output of the delta-sigma modulation circuit 1 is a quantized signal that is a digital signal in which the _four input signals X _{1 to} X ₄ are multiplexed, and has an advantage that it is not easily affected by a transmission path and is resistant to errors. is doing.

Next, the configuration and signal processing operation of the reception separating apparatus 5 shown in FIG. 1 will be described in detail with reference to FIGS.
FIG. 12 is an explanatory diagram for explaining a demultiplexing / demodulating operation in the receiving and separating apparatus shown in FIG.

Referring to FIG. 1, the reception / separation device 5 receives only the reception unit 51 that receives the quantized signal transmitted from the multiplexing transmission device 4 and the baseband (band near frequency 0) in the input quantized signal. by passing, it extracts only the input signal X _1, and the low-pass filter (LPF) 52a to generate a synchronization signal using a synchronization signal generated by LPF52a as a phase reference for the carrier signal, modulated by sin signal A modulated signal generating unit 53 for generating a carrier signal having a frequency fs / 4, a carrier signal having a frequency fs / 4 modulated by the cos signal, and a carrier signal having a frequency fs / 2; and the frequency fs modulated by the sin signal. When the carrier signal of / 4 is used, the input signals X _{1 to} X ₄ superimposed on the quantized signal are phase-modulated. Both multipliers Ae2 to frequency shift, by using a carrier signal of a frequency fs / 4 modulated by cos signal, an input signal X ₁ to X ₄ which are superimposed on the quantized signal, both to the phase modulation, By using the multiplier Ae3 that shifts the frequency and the carrier signal having the frequency fs / 2, the multiplier Ae4 that shifts the frequency of the input signals X _{1 to} X ₄ superimposed on the quantized signal and the output of the multiplier Ae2 in the only by passing an analog signal baseband (band around frequency 0), and a low-pass filter (LPF) 52 b extract only the input signal X ₂ as an analog signal from the output of the multiplier Ae2, the output of the multiplier Ae3 By passing only the baseband (band near frequency 0) as an analog signal, the output of the multiplier Ae3 A low pass filter (LPF) 52c extracts only the input signal X ₃ as an analog signal from the force, only the base band at the output of the multiplier AE4 (band around frequency 0) by passing an analog signal, the output of the multiplier AE4 and a low pass filter (LPF) 52 d extracted as an analog signal only input signal _{X 4} from.

Referring to FIG. 12, the quantized signal received by the receiving unit 51 is input to the LPF 52a, the multiplier Ae2, the multiplier Ae3, and the multiplier Ae4, respectively. Input quantization signal to LPF52a, depending LPF52a which passes only base band (band around frequency 0), only the input signal _{X 1} is taken out, the synchronization signal is generated.

  The modulation signal generation unit 53 uses the synchronization signal generated by the LPF 52a, the carrier signal having the frequency fs / 4 modulated by the sin signal, the carrier signal having the frequency fs / 4 modulated by the cos signal, and the frequency fs. / 2 carrier signal, the carrier signal having the frequency fs / 4 modulated by the sin signal to the multiplier Ad2, the carrier signal having the frequency fs / 4 modulated by the cos signal to the multiplier Ad3, and the frequency fs. The carrier signal of / 2 is output to the multiplier Ad4.

Input quantization signal to the multiplier Ae2 includes multipliers by Ae2, by using a carrier signal of a frequency fs / 4 which is modulated by the sin signal, the input signal X ₁ to X ₄ which are superimposed on the quantized signal Are phase-modulated and frequency-shifted and input to the LPF 52b. Thus, the output from the multiplier Ae2, as shown in FIG. 12, the band quantization noise is small for the input signal X ₂ baseband (band around frequency 0), the input signal X and the input signal X _{4 1} and the frequency fs / 4 near the quantization noise in the small becomes bands, the input signal X ₂ frequency fs / 2 near the quantization noise is respectively superimposed quantized signal into small becomes bands.

The output from multiplier Ae2 is by the low-pass filter (LPF) 52 b to pass only the baseband (band around frequency 0), as shown in FIG. 14, only the input signal X ₂ is taken out as an analog signal, an output terminal It is output as an output signal _{Y 2} from P22.

Input quantization signal to the multiplier Ae3 includes multipliers by Ae3, by using a carrier signal of a frequency fs / 4 modulated by cos signal, an input signal X ₁ to X ₄ which are superimposed on the quantized signal Are phase-modulated and frequency-shifted and input to the LPF 52c. Thus, the output from the multiplier Ae3, as shown in FIG. 12, the band quantization noise is small for the input signal X ₃ baseband (band around frequency 0), the input signal X and the input signal X ₄ the band ₁ and the frequency fs / 4 near the quantization noise is small, the input signal X ₃ is the quantization noise around the frequency fs / 2 is respectively superimposed quantized signal into small becomes bands.

The output from multiplier Ae3 is by the low-pass filter (LPF) 52c to pass only the baseband (band around frequency 0), as shown in FIG. 14, only the input signal X ₃ is taken out as an analog signal, an output terminal It is output as an output signal _{Y 3} from P23.

Input quantization signal to the multiplier AE4 is by a multiplier AE4, by using a carrier signal of a frequency fs / 2, the input signal X ₁ to X ₄ which are superimposed on the quantized signal, the frequency shift, Input to the LPF 52d. Thus, the output from the multiplier Ae4, as shown in FIG. 14, the band quantization noise is small for the input signal X ₄ baseband (band around frequency 0), the input signal X ₂ and the input signal X ₃ and the band frequency fs / 4 near the quantization noise becomes small, the input signal X ₁ frequency fs / 2 near the quantization noise is respectively superimposed quantized signal into small becomes bands.

The output from multiplier Ae4 is by the low-pass filter (LPF) 52 d to pass only the baseband (band around frequency 0), as shown in FIG. 14, only the input signal X ₄ is taken out as an analog signal, an output terminal It is output as an output signal _{Y 4} from P24.

In this way, 4 multiplexed to the quantized signal output from the multiplexing transmission device 4 by the reception / separation device 5 having a simple configuration including the multipliers Ae2 to Ae4 and the low pass filters (LPF) 52a to 52d. The two input signals X _{1 to} X ₄ can be easily separated, and the other input signals X _{2 to} X ₄ superimposed on the quantized signal are separated using the input signal X ₁ as a synchronization signal. Therefore, even when the multiplexing transmission device 4 and the reception separation device 5 are not synchronized, the input signals X _{2 to} X ₄ superimposed on the quantized signal are accurately separated accurately. Can be made.

In the present embodiment, delay devices Da1 to Dan and delay device Db that are connected by four delay devices D cascaded and delayed by four sampling periods are used, and the vicinity of frequency 0, the vicinity of frequency fs / 4, The four input signals X _{1 to} X ₄ are multiplexed by the delta-sigma modulation circuit 1 having the frequency characteristic of the quantization noise distribution in which the bands where the quantization noise is small are formed at three places near the frequency fs / 2. However, by changing the number of cascade connections of the delay device D, the number of bands in which the quantization noise in the frequency characteristic of the quantization noise distribution is small can be arbitrarily set, and the quantization noise is small. The number of input signals to be multiplexed by being superimposed on a certain band can be arbitrarily set.

In the present embodiment, the _two signals of the input signals X ₂ and X ₃ that are orthogonalized in a band where the quantization noise in the vicinity of the frequency fs / 4 is reduced are superimposed, but the frequency fs / 4 is used. band quantization noise is small in the vicinity, without performing the phase modulation, may be to superimpose only the input signal X _2.

  Further, in the present embodiment, the multiplexed signal is demodulated into an analog signal by the low-pass filters (LPF) 52a to 52d, but the multiplexed signal is a PCM that is a multi-bit digital signal by using a digital low-pass filter. A (Pulse-Code Modulation) signal may be modulated.

  As described above, according to the present embodiment, the multiplexing transmission apparatus 4 accepts a plurality of input signals including a synchronization signal input signal to be a synchronization signal, and the modulation signal generation unit 42 inputs the synchronization signal input. Based on the signal, a modulation signal for multiplexing for multiplexing a plurality of input signals is generated, and other than the synchronization signal input signal by using the multiplexing modulation signal by the multipliers Ad2 to Ad4 and the adder Ce. The input signal including the synchronizing signal input signal is dispersed and superimposed in different bands, and a signal obtained by superimposing the plurality of input signals by the delta-sigma modulation circuit 1 is By modulating the quantized signal to form a band where the quantization noise is reduced in the frequency band where the input signal is distributed and superimposed, the quantized signal is quantized multiple times. It is configured to output a multiplexed signal in which a plurality of input signals are dispersed and superimposed in a band where noise is reduced, and in the receiving and separating device 5, it is passed through a low-pass filter (LPF) 52 a so that the multiplexed signal can be output. Demodulating the synchronization signal input signal, the modulation signal generation unit 53 generates a separation modulation signal for separating a plurality of input signals from the multiplexed signal, based on the synchronization signal input signal, and the multipliers Ae2 to Ae2. By Ae4, the multiplexed signal is converted to the original frequency for each input signal other than the synchronization signal input signal that is frequency-shifted and dispersed and superimposed on the quantized signal using the separation modulation signal. By shifting each frequency so as to return to the band, each of the frequency-shifted multiplexed signals is output, and the low-pass filter (LPF) 52b to 52d By configuring each multiplexed signal shifted several times to be demodulated into a plurality of input signals, the multiplexed transmission device 4 on the transmission side and the reception separation device 6 on the reception side are not synchronized. Even in this case, the frequency-shifted multiplexed signal is simply demodulated by the modulation signal generated using the synchronization signal input signal superimposed on the multiplexed signal, and the frequency-shifted signal is superimposed on the multiplexed signal. Since a plurality of signals can be separated, the original signal can be separated from the multiplexed signal with a simple configuration without using a switching circuit for switching signals on the receiving side.

  Furthermore, according to the present embodiment, the delta-sigma modulation circuit 1 modulates a quantized signal in which a band where the quantization noise is small is formed at a turn-back position sandwiching a band where the quantization noise is large. With this configuration, it is possible to secure a plurality of signal bands to be superimposed on the quantized signal, and it is possible to superimpose a plurality of signals on the quantized signal.

  Furthermore, according to the present embodiment, the reception separation device 5 is configured to demodulate the synchronization signal input signal from the multiplexed signal using the low-pass filter 52a that passes only the baseband, and the multiplexed transmission device. 4 is provided with a low-pass filter 41 that allows only the baseband of the synchronization signal input signal to pass therethrough, and a multiplexed modulation signal for multiplexing a plurality of input signals based on the synchronization signal input signal that has passed through the low-pass filter 41. The synchronization signal used on the transmission side and the reception side can have the same waveform, and a plurality of signals that are frequency-shifted and superimposed on the multiplexed signal can be accurately separated. There is an effect that can be.

  Note that the present invention is not limited to the above-described embodiments, and it is obvious that the embodiments can be appropriately changed within the scope of the technical idea of the present invention. In addition, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to a suitable number, position, shape, and the like in practicing the present invention. In each figure, the same numerals are given to the same component.

It is a block diagram which shows the structure of embodiment of the multiplexed signal transmission system which concerns on this invention. FIG. 2 is a block diagram showing an electrical configuration of a delta sigma modulation circuit used in the multiplexing transmission apparatus shown in FIG. 1. FIG. 3 is a block diagram illustrating a configuration example of a delay device illustrated in FIG. 2. 3 is a graph showing frequency characteristics of quantization noise distribution in the delta-sigma modulation circuit shown in FIG. 2. It is the block diagram which modeled the delta-sigma modulation circuit. It is explanatory drawing for demonstrating the frequency characteristic of the quantization noise distribution of the quantization signal output from the delta-sigma modulation circuit shown in FIG. FIG. 5 is a block diagram modeling a second-order delta-sigma modulation circuit using a delay device that is delayed by two sampling periods. It is a graph which shows the frequency characteristic of the quantization noise distribution of the quantization signal output from the secondary delta-sigma modulation circuit shown in FIG. FIG. 3 is a block diagram illustrating a configuration of a seventh-order delta sigma modulation circuit using seven integration elements in the delta sigma modulation circuit illustrated in FIG. 2. 10 is a graph showing frequency characteristics of a quantization noise distribution of a quantized signal output from the seventh-order delta sigma modulation circuit shown in FIG. 9. It is explanatory drawing for demonstrating the multiplexing modulation | alteration operation | movement in the multiplexing transmission apparatus shown in FIG. It is explanatory drawing for demonstrating the isolation | separation demodulation operation in the receiving separation apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Delta-sigma modulation circuit 3 Multiplexed signal transmission system 4 Multiplexing transmission apparatus 5 Reception separation apparatus 10 Quantizer 41 Low pass filter (LPF)
42 modulation signal generation unit 43 transmission unit 51 reception unit 52a to 52d low-pass filter (LPF)
53 Modulation signal generator Aa1-Aan, Ab, Ac1-Ac3, Ad2-Ad4, Ae2-Ae4 Multiplier Ca1-Can, Cb, Cc, Cd1-Cd3, Ce adder D1-D4, Da1-Dan, Db, Dc1 ~Dc3 delayer Fa1~Fan integral element P1 to P4, P11-P14 input terminal P21~P24 output terminal _X, X 1 ~X ₄ input signals _Y, Y 1 ~Y ₄ output signal

Claims (5)

A multiplexed signal comprising a multiplexing transmitter for transmitting a multiplexed signal obtained by quantizing and multiplexing a plurality of input signals at frequency fs, and a receiving / separating device for separating the received multiplexed signal into a plurality of input signals. A transmission system,
The multiplexing transmission device receives a plurality of the input signals including a synchronization signal input signal to be a synchronization signal, and multiplex modulation for multiplexing the plurality of input signals based on the synchronization signal input signal Multiplex modulation signal generating means for generating a signal;
Using the multiplexing modulation signal generated by the multiplexing modulation signal generating means, the input signal other than the synchronization signal input signal is frequency-shifted to a folding position between frequency 0 and frequency fs / 2 . Thus, frequency shift addition means for dispersing and superimposing the plurality of input signals including the synchronization signal input signal in different bands,
A plurality of output signals from the frequency shift adding means are formed at a folding position between a frequency 0 and a frequency fs / 2, and a band where the quantization noise is small and a band where the quantization noise is large. Delta-sigma modulation means for modulating the quantized signal to output the multiplexed signal as the multiplexed signal in which a plurality of the input signals are dispersed and superimposed in a band where a plurality of quantization noises are reduced. ,
The reception separation device includes a synchronization signal demodulation unit that demodulates the synchronization signal input signal from the multiplexed signal;
A separation modulation signal generation means for generating a separation modulation signal for separating the plurality of input signals from the multiplexed signal based on the synchronization signal input signal demodulated by the synchronization signal demodulation means;
For each of the input signals other than the synchronization signal input signal that is frequency-shifted using the separation modulation signal generated by the separation modulation signal generation means and dispersed and superimposed on the quantized signal And a frequency shift means for respectively outputting a plurality of the frequency-shifted multiplexed signals by shifting the frequency of the multiplexed signals so that the input signal returns to the original frequency band.
A multiplexed signal transmission system comprising: a demodulating unit that demodulates each of the plurality of multiplexed signals frequency-shifted by the frequency shifting unit and demodulates all of the input signals . The delta-sigma modulation means includes a plurality of cascaded integration means, an addition means for adding outputs from the integration means, and an output from the addition means is quantized based on a sampling frequency to output a quantized signal. And a negative feedback loop for negatively feeding back the output from the quantizing means to the integrating means in the first stage,
A plurality of delay means for delaying by one sampling period are connected in cascade, a plurality of first delay means for delaying the output by a sampling period corresponding to the number of the delay elements;
Adding means for adding the output from the first delay means to the input respectively;
In the negative feedback loop, the same number of the delay devices as the first delay means are connected in cascade, and the quantization is performed via the second delay means for delaying the input by the same number of sampling periods as the first delay means. The output from the means is negatively fed back to the integrating means in the first stage, and quantization noise is present between the frequency 0 and the frequency fs / 2 in the frequency characteristic of the quantization noise of the quantized signal output from the quantization means. 2. The multiplexed signal transmission system according to claim 1 , wherein a plurality of smaller bands are formed at folding positions sandwiching a band where quantization noise is large . The synchronization signal demodulating means of the reception separation device is a low-pass filter that allows only baseband to pass through,
The multiplexed transmission device includes a low-pass filter that allows only the baseband of the synchronization signal input signal to pass through,
The multiplexing modulation signal generating means generates a multiplexing modulation signal for multiplexing a plurality of the input signals based on the synchronization signal input signal that has passed through the low-pass filter. 3. A multiplexed signal transmission system according to 1 or 2. A multiplexed signal comprising: a multiplexing transmission step for transmitting a multiplexed signal obtained by quantizing and multiplexing a plurality of input signals at frequency fs; and a reception separation step for separating the received multiplexed signal into a plurality of input signals. A transmission method,
In the multiplexed transmission step, a plurality of the input signals including a synchronization signal input signal to be a synchronization signal are received,
Based on the synchronization signal input signal, a multiplexing modulation signal for multiplexing the plurality of input signals is generated,
By using the generated modulation signal for multiplexing, the input signal other than the synchronization signal input signal is frequency-shifted to a folding position between frequency 0 and frequency fs / 2, so that the synchronization signal input A plurality of the input signals including signals are distributed and superimposed in different bands;
A plurality of signals formed by superimposing a plurality of the input signals are formed at a folding position between a frequency 0 and a frequency fs / 2, with a band where quantization noise is small sandwiched between bands where quantization noise is large. By modulating the quantized signal, the quantized signal is output as the multiplexed signal in which a plurality of the input signals are dispersed and superimposed in a band in which a plurality of quantization noises are reduced,
In the reception separation step, the synchronization signal input signal is demodulated from the multiplexed signal,
Based on the demodulated input signal for synchronization signal, a separation modulation signal for separating the plurality of input signals from the multiplexed signal is generated,
Using the generated modulation signal for separation, for each of the input signals other than the synchronization signal input signal that is frequency-shifted and distributed and superimposed on the quantized signal, By respectively shifting the frequency so that the input signal returns to the original frequency band, each of the plurality of multiplexed signals frequency-shifted is output,
A multiplexed signal transmission method comprising demodulating each of the plurality of multiplexed signals shifted in frequency and demodulating all of the input signals . In the reception separation step, the synchronization signal input signal is demodulated from the multiplexed signal using a low-pass filter that passes only baseband,
The multiplexing transmission step generates a modulation signal for multiplexing for multiplexing the plurality of input signals based on the input signal for synchronization signals that has passed through a low-pass filter that passes only baseband. The multiplexed signal transmission method according to claim 4.

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