WO2023013017A1

WO2023013017A1 - Transmission device, transmission system, and transmission method

Info

Publication number: WO2023013017A1
Application number: PCT/JP2021/029276
Authority: WO
Inventors: 佑紀岡南; 正樹日比野
Original assignee: 三菱電機株式会社
Priority date: 2021-08-06
Filing date: 2021-08-06
Publication date: 2023-02-09
Also published as: JPWO2023013017A1; JP7439996B2

Abstract

A transmission device 1 provided with: a signal generation unit 15 for generating a data signal, a step signal, and a control signal for controlling the switching of N (where N is 3 or more) types of resistance values of a variable resistance unit 23 provided in a receiver 2; a modulation unit 12 for modulating each signal generated by the signal generation unit 15 to a multilevel signal of two values or more, and outputting the resulting signal to the receiver 2; a waveform detection unit 14 for detecting output terminal voltage of a transmission device 2; a clock generation unit 13 for generating a clock frequency for synchronizing the modulation unit 12 and the waveform detection unit 14; a passing characteristic calculation unit 16 for calculating the passing characteristic of a transmission path 3 from the N types of resistance values switched in accordance with the control signal output from the modulation unit 12 and the output terminal voltage detected by the waveform detection unit 14 in accordance with the step signal output from the modulation unit 12, for each of the N types of resistance values; and a clock determination unit 17 for determining the clock frequency of the clock generation unit 13 on the basis of the passing characteristic calculated by the passing characteristic calculation unit 16.

Description

TRANSMISSION DEVICE, TRANSMISSION SYSTEM, AND TRANSMISSION METHOD

The present disclosure relates to a transmission device, a transmission system, and a transmission method.

Conventionally, there are transmission systems that employ pulse-amplitude modulation (PAM). For example, when this transmission system is used for data communication between devices whose positional relationship changes, such as a device in an elevator car and a device in a control room, the bending and stretching of the transmission line connecting each device causes frequency fluctuations. Characteristics may vary.

Therefore, if the transmission system sets the clock frequency low in order to suppress the effects of fluctuations in the frequency characteristics of the transmission path (for example, an increase in the data error rate of the transmission path), the transmission speed may become slower. On the other hand, if the clock frequency is set high in order to increase the transmission speed, the transmission system may become susceptible to fluctuations in the frequency characteristics of the transmission line.

In this way, there is a demand for a transmission system to set a clock frequency that can suppress a decrease in transmission speed while suppressing the influence of fluctuations in the frequency characteristics of the transmission line.

In response to such a demand, Patent Document 1 discloses that a measuring instrument called a network analyzer is installed in the transmitter and the receiver to measure the frequency characteristics (reflection characteristics, pass characteristics) of the transmission line connecting the transmitter and the receiver. It is stated that Further, in Patent Document 1, based on the measured frequency characteristics (reflection characteristics, pass characteristics), while suppressing the influence of fluctuations in the frequency characteristics of the transmission line, a clock frequency that can suppress a decrease in transmission speed is determined. is stated.

JP 2010-34777 A

However, in the technique disclosed in Patent Document 1, since it is necessary to equip each of the transmitter and the receiver with a measuring instrument for measuring the frequency characteristics of the transmission line, the device is larger than when this configuration is not provided. There was a problem that it would become. Due to this problem, installation in a limited space such as an elevator car may be restricted.

The present disclosure is intended to solve the problems described above, and aims to measure the frequency characteristics of a transmission line with a simple configuration.

A transmission device according to the present disclosure is a transmission device that transmits a signal to a receiver via a transmission path, and includes N types (N is 3 or more) of resistance values possessed by a variable resistance unit included in the receiver. a signal generator for generating a control signal, a step signal, and a data signal for controlling switching; and outputs the signal to the receiver; a waveform detection unit that detects the output end voltage of the transmission device when the step signal is output from the modulation unit; and the modulation and a clock generation unit that generates a clock frequency for synchronizing the waveform detection unit, and the pass characteristic of the transmission path from the N types of resistance values and the output end voltage for each of the N types of resistance values. and a clock determination unit for determining the clock frequency of the clock generation unit based on the pass characteristics calculated by the pass characteristic calculation unit.

According to the present disclosure, it is possible to measure the frequency characteristics of a transmission line with a simple configuration.

1 is a diagram illustrating an example of a functional configuration of a transmission system 100 according to Embodiment 1; FIG. 2 is a diagram showing an example of a hardware configuration of a transmitter 1; FIG. 2 is a diagram showing an example of a hardware configuration of a receiver 2; FIG. 4 is a flow chart showing the operation of the transmitter 1; FIG. 4 is a diagram showing pass characteristics; FIG. 10 is a diagram showing an example of a functional configuration of a transmission system 100 according to a second embodiment; FIG. It is a correspondence table of the SN ratio and the degree of multilevel. FIG. 10 is a flow chart diagram showing an operation for calculating a multilevel degree; FIG. 11 is a diagram showing an example of a functional configuration of a transmission system 100 according to Embodiment 3; It is a flowchart figure which shows the operation|movement which detects abnormality.

・Embodiment 1
FIG. 1 is a diagram showing an example of the functional configuration of a transmission system 100 according to the first embodiment.
The transmission system 100 according to the first embodiment employs a pulse-amplitude modulation (PAM) method, and for example, between devices whose positional relationship fluctuates, such as a device in an elevator car and a device in a control room. Used for data communication. A transmission system 100 includes a transmitter 1 , a receiver 2 and a transmission line 3 . The transmission line 3 is composed of two conductor wires (for example, metal wire, coaxial cable) and connects the transmitter 1 and the receiver 2 . In this disclosure, only an example in which the transmission system 100 performs unidirectional communication from the transmitter 1 to the receiver 2 is disclosed, but bidirectional communication may be performed. Even in this case, either the transmitter 1 or the receiver 2 may be provided with the configuration and functions of the present disclosure.

The transmitter 1 of the transmission system 100 is an example of a transmission device, and includes a control section 10, a modulation section 12, a clock generation section 13, and a waveform detection section 14. The control unit 10 is composed of, for example, a CPU and a memory. The control unit 10 implements functions of a signal generation unit 15 , a pass characteristics calculation unit 16 , and a clock determination unit 17 by executing programs stored in the memory by the CPU.

The signal generation unit 15 generates a control signal for controlling switching of N types (N is 3 or more) of resistance values of the variable resistance unit 23 of the receiver 2, a step signal, and a data signal indicating desired data. . Here, the signal generation unit 15 generates a control signal for switching the resistance of the variable resistance unit 23 to at least three types of short circuit, open circuit, and characteristic impedance of the transmission line 3 . The signal generator 15 may generate a data signal from data acquired inside the transmitter 1 or from the outside. The signal generator 15 also generates a step signal for obtaining a step response (characteristic) of the transmission line 3 .

The modulation unit 12 employs a pulse amplitude modulation method, and encodes the amplitude of the data signal with a series of pulse signals. Specifically, the modulation unit 12 converts the control signal, the step signal, and the data signal generated by the signal generation unit 15 into multilevel pulse signals of 2 or more (hereinafter, when there is no particular need to distinguish ), and outputs the modulated signal to the receiver 2 .

The waveform detection unit 14 is, for example, an AD converter, and detects the voltage waveform at the output end of the transmitter 1 (hereinafter referred to as output end voltage). This output terminal voltage indicates, for example, a reflected waveform from the transmission line 3 when a step signal is output from the modulating section 12 . Also, the output terminal voltage indicates, for example, the noise waveform from the transmission line 3 when the step signal is not output from the modulating section 12 .

The clock generator 13 generates a clock frequency for synchronizing the modulator 12 and the waveform detector 14 . The clock generator 13 is implemented by, for example, a PLL (Phase Locked Loop) circuit, and divides and/or multiplies the clock according to the input signal.

The pass characteristic calculator 16 calculates pass characteristics of the transmission line 3 from the N types of resistance values switched by the signal generator 15 and the output terminal voltage detected by the waveform detector 14 for each of the N types of resistance values. .

The clock determination unit 17 determines the clock frequency of the clock generation unit 13 based on the transmission characteristics calculated by the transmission characteristics calculation unit 16 .

It should be noted that the transmitter 1 may include an AFE (Analog Front End) circuit composed of, for example, an amplifier for adjusting the voltage value of the data signal and/or a filter for reducing noise.

The receiver 2 includes a receiving section 21, a control section 22, and a variable resistance section 23.

The receiving section 21 receives the data signal, step signal, and control signal output from the transmitter 1 and outputs the received signals to the control section 22 . The receiver 21 may decode the received signal.

The control section 22 is composed of a CPU and a memory, and controls each section of the receiver 2 according to the signal input from the receiving section 21 . Specifically, the control section 22 may output a control signal to the variable resistance section 23 . Also, the control unit 22 may store the data signal in a storage unit (not shown). The variable resistance section 23 is connected between the transmission line 3 and GND of the receiver 2 .

The variable resistance unit 23 is composed of three or more types of resistance values Z _i connected in parallel and a switch. The variable resistance unit 23 switches the resistance value Z _i based on the control signal generated by the signal generation unit 15 and input from the control unit 22 . The switchable resistance value Z _i consists of, for example, a 1 MΩ resistance (open), a 0Ω resistance (short), and a resistance value that matches the impedance Zo of the transmission line 3 (for example, 50 Ω in the case of a single-ended transmission line). be done. Although 1 MΩ is used as the resistance value indicating that the resistor is open, the value is not limited to this value, and any value equal to or higher than a predetermined threshold may be used. In addition, although 0Ω is used as an example of the resistance value indicating the short circuit of the resistor, the value is not limited to this value and may be less than a predetermined threshold value. Also, the switchable resistance values Z _i are not limited to these, and may be four or more.

Note that the receiver 2 may include an AFE circuit including, for example, an amplifier for adjusting the voltage value of the data signal and/or a filter for reducing noise.

FIG. 2 is a diagram showing an example of the hardware configuration of the transmitter 1. As shown in FIG.
The transmitter 1 includes a control circuit 31 , a modulation circuit 32 , a clock generation circuit 33 and a waveform detection circuit 34 . The control circuit 31 implements the functions of the signal generator 15, the pass characteristic calculator 16, and the clock determiner 17 shown in FIG. 1 by executing programs stored in the memory. The memory stores various programs executed by the control circuit 31 and various data used for processing executed by the control circuit 31 . The modulation circuit 32 realizes the function of the modulation section 12 shown in FIG. The clock generation circuit 33 implements the function of the clock generation section 13 shown in FIG. The waveform detection circuit 34 realizes the function of the waveform detection section 14 shown in FIG. Furthermore, the control circuit 31, the modulation circuit 32, the clock generation circuit 33, and the waveform detection circuit 34 may be replaced with single or multiple processing circuits. The processing circuit corresponds to a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof.

FIG. 3 is a diagram showing an example of the hardware configuration of the receiver 2. As shown in FIG.
The receiver 2 includes a receiver circuit 41 , a control circuit 42 and a variable resistance circuit 43 . The control circuit 42 controls each function of the receiver 2 by executing programs stored in the memory. The receiving circuit 41 implements the function of the receiving section 21 shown in FIG. The variable resistance circuit 43 implements the function of the variable resistance section 23 shown in FIG. Furthermore, the control circuit 42, the receiving circuit 41, and the variable resistance circuit 43 may be replaced with single or multiple processing circuits. The processing circuit can be a single circuit, multiple circuits, an ASIC, an FPGA, or a combination thereof.

FIG. 4 is a flow chart diagram showing the operation of the transmission system 100. As shown in FIG.
Here, the first signal transmission method of transmission system 100 will be described. In this first signal transmission method, time domain reflectometry (TDR) is performed using a step signal, and the clock frequency is determined based on transmission characteristics calculated from the measurement results. TDR measurement is a method of injecting a step signal into a transmission line and observing its reflected waveform. In the following description, an example in which the upper limit of the length of the cable (cable length) used as the transmission line 3 is set to 50 m will be described.

Initial value setting operation The control unit 10 transmits a control signal for setting the initial value of the degree of multilevel to the modulation unit 12 . The control unit 10 also transmits a control signal for setting the initial value of the clock frequency to the clock generation unit 13 (S101). Here, it is assumed that the control unit 10 has set binary signal voltages (voltage values V ₀ and 0) as the initial values of the multilevel degree. Further, when the upper limit of the cable length is set, the control unit 10 sets, as the initial value of the clock frequency, a frequency equal to or greater than the cycle covering the round trip time of the propagation delay time of the cable length. For example, if the upper limit of the cable length is 50 m, the initial value of the clock frequency is set to 0.5 MHz.

Next, the control unit 10 (signal generation unit 15) transmits a control signal for setting 0 as the initial value of the parameter i of the resistance value Z _i of the variable resistance unit 23 (S102). Here, Z ₀ (=∞) is the resistance value indicating the open circuit of the variable resistance unit 23, Z ₁ (= 0) is the resistance value indicating the short circuit, and Z ₂ (=Zo ). Note that the order of labeling the resistance values need not be limited to the above. When there are three types of resistance values, the maximum value of parameter i is 2, but when there are n (≧4) types of resistance values, the maximum value of parameter i is n−1.

Time domain reflectance measurement process by step signal First, the control unit 10 determines whether the parameter i of the resistance value Z _i of the variable resistance unit 23 satisfies the conditional statement “i<3” (S103). . When the determination of the conditional statement “i<3” is true (S103: Yes), the signal generator 15 generates a control signal for setting the resistance value of the variable resistor Z of the variable resistor 23 to _Zi. . The modulator 12 modulates the control signal generated by the signal generator 15 and outputs the modulated control signal to the receiver 2 . Thereby, the resistance value _Zi is set as the variable resistance Z of the variable resistance section 23 (S104).

Next, the signal generator 15 generates a step signal. Then, the modulating section 12 modulates the step signal generated by the signal generating section 15 and outputs it to the receiver 2 (S105). Thereby, the waveform detection unit 14 detects the voltage waveform (output terminal voltage) at the output terminal of the transmitter 1 (S106). Here, since the modulation section 12 and the waveform detection section 14 are synchronized by the clock generation section 13, the waveform detection section 14 detects the output end voltage indicating the reflected signal of the step signal output from the modulation section 12. will do. Here, the waveform detection unit 14 may be set with a detection time (a detection time of 0.25 us or more in the present disclosure) that takes into consideration the round trip propagation delay time of the transmission line 3 . Next, the control unit 10 stores measurement data indicating the output terminal voltage detected by the waveform detection unit 14 in the memory (S107).

Thereafter, the control unit 10 sets a value obtained by incrementing the parameter i of the resistance value Z _i of the variable resistance unit 23 by 1 (S108), and performs the processing from S103 to S108 by determining the conditional statement "i<3" in S103. is determined to be false (S103: No). If the conditional statement “i<3” is determined to be false (S104: No), the control unit 10 ends the time domain reflectance measurement.

The accuracy of the measurement data may be improved by repeating the time-domain reflectance measurement a plurality of times to obtain the same data and averaging the obtained data.

Processing of calculating transmission characteristics After the measurement of the time domain reflectance, the transmission characteristics calculation unit 16 calculates transmission characteristics based on the measurement data stored in the memory (S109). More specifically, the pass characteristic calculation unit 16 calculates the transmission line 3 from the N resistance values switched by the signal generation unit 15 and the output terminal voltage detected by the waveform detection unit 14 for each of the N resistance values. Calculate pass characteristics. Here, the output end voltage of the transmitter 1 detected by the waveform detection unit 14 when the resistance value of the variable resistance unit 23 is Z _i is tdr ⁽ⁱ⁾ (t), the step function is θ(t), and each frequency is Assuming that ω is an imaginary unit of j, the reflection characteristic s ₁₁ ⁽ⁱ⁾ of the transmission path when the resistance value of the variable resistance section 23 is Z _i is expressed by Equation (1).

where represents the Fourier transform of the expression in brackets. Equation (1) is obtained from the convolution relationship between the frequency response of the output terminal voltage and the frequency response of the step function. Using these, the reflection characteristic s ₁₁ ⁽ⁱ⁾ for each parameter (i=0, 1, 2) is obtained.

The pass characteristic _S21 of the transmission line 3 is given by Equation (2) using the relational expression of the S parameters of the transmission side and the reception side of each parameter (i=0, 1, 2) of the resistance value Z _i of the variable resistance section 23. is represented by

Next, the clock determination unit 17 determines the clock frequency to be set in the clock generation unit 13 based on the pass characteristic _S21 calculated in S109 (S110). As a method for determining the clock frequency of the pulse signal from the pass characteristic _S21 , for example, as shown in FIG. The maximum frequency f ₁ among the frequencies is determined as the clock frequency of the clock generator 13 . However, this method of determining the clock frequency is merely an example and is not limited to this. That is, the predetermined value is not limited to -6 dB, and may be appropriately set according to the system configuration. Moreover, the reference value is not limited to a frequency of 0, and may be set as appropriate according to the configuration of the system.

In this way, the transmission system 100 (transmitter 1, transmission device) measures the frequency characteristics (pass characteristics S ₂₁ ) of the transmission path 3 only with the transmitter 1 without providing a measuring device (network analyzer) in the receiver 2. can be measured. That is, the transmission system 100 can measure the frequency characteristics of the transmission line with a simple configuration. Thus, the transmission system 100 can set a clock frequency that can suppress a decrease in transmission speed while suppressing the influence of fluctuations in the frequency characteristics of the transmission line.

・Embodiment 2
In the first embodiment, the clock frequency is determined from the pass characteristic _S21 of the transmission path 3, but in the second embodiment, the ratio of signal power to noise power (SN ratio) is calculated to determine the multilevel degree of the pulse signal. . Thus, when the multi-level degree of the pulse signal is increased, the amount of data that can be transmitted at one time increases compared to the case where the multi-level degree of the pulse signal is not increased.

FIG. 6 is a diagram showing an example of the functional configuration of the transmission system 100 according to the second embodiment.
In the transmission system 100 according to the second embodiment, in addition to the signal generation unit 15, the pass characteristics calculation unit 16, and the clock determination unit 17, the SN The transmission system 100 differs from the transmission system 100 according to the first embodiment in that it implements the functions of the ratio calculator 18 and the multilevel degree determiner 19 .

The SN ratio calculator 18 calculates the ratio of signal power to noise power (hereinafter referred to as SN ratio) from the noise power and the signal power. Here, the noise power is calculated from the output end voltage detected by the waveform detection section 14 and the resistance value of the variable resistance section 23 when the modulation section 12 is not outputting a pulse signal. Also, the signal power is calculated from the resistance value of the variable resistance unit 23 , the maximum settable multilevel degree N, and the pass characteristics calculated by the pass characteristics calculation unit 16 .

The multilevel degree determination unit 19 determines the multilevel degree of the multilevel signal to be modulated by the modulation unit 12 based on the SN ratio calculated by the SN ratio calculation unit 18 . Here, the multi-level degree determining unit 19 determines the multi-level degree according to the correspondence table between the SN ratio and the multi-level degree shown in FIG. FIG. 7 is an example of table values when the maximum multilevel degree is 10 (PAM-10). For example, the SN ratio “22 dB or more and less than 28 dB” calculated by the SN ratio calculation unit 18 and the multi-value degree “6 values (PAM-6)” are registered in association with each other in the correspondence table between the SN ratio and the multi-level degree. there is When the SN ratio is "22 dB or more and less than 28 dB", the multi-level degree determination unit 19 determines the multi-level degree to be "6 levels (PAM-6)". Note that the correspondence table between the SN ratio and the degree of multilevel may be stored in the memory of the control unit 10 or the like. Note that the values registered in the correspondence table between the SN ratio and the degree of multilevel are not limited to the values shown in FIG.

FIG. 8 is a flow chart diagram showing the operation of the transmission system 100. As shown in FIG.
Here, the second signal transmission method of transmission system 100 will be described. In this second signal transmission method, the SN ratio is calculated, and the multilevel degree of the pulse signal is determined using the calculated SN ratio. However, it is assumed that the clock frequency of the pulse signal is determined by the first signal transmission method before implementing the second signal transmission method.

The control unit 10 (signal generation unit 15) transmits a control signal and sets the resistance value R of the variable resistance unit 23 (S201). Here, the resistance value R is desirably the same resistance value as the characteristic impedance of the transmission line 3 .

Next, the control unit 10 stops outputting the signal from the modulation unit 12 so that no signal is exchanged between the transmitter 1 and the receiver 2 (S202).

Next, the waveform detection unit 14 measures the output terminal voltage and stores the measured output terminal voltage in the memory as a noise voltage waveform (S203). Here, it is preferable that the measurement time is, for example, equal to or longer than the period of the clock frequency of the signal.

Next, the SN ratio calculation unit 18 calculates noise power from the root mean square (RMS value) of the noise voltage waveform detected by the waveform detection unit 14 and the resistance value R of the variable resistance unit 23 (S204).

Next, the SN ratio calculator 18 calculates the maximum voltage V of the signal, the pass characteristic value S ₂₁ (f ₀ ) [dB] at the clock frequency f ₀ calculated by the second signal transmission method (Embodiment 1), Then, the signal power P _S is calculated from the settable maximum multilevel degree N (for example, N=10 for PAM-10) and the resistance value R of the variable resistance section 23 (S205). The signal power _PS is represented by Equation (3). The signal power _PS is calculated by modifying the transmit power by the pass characteristic at the clock frequency.

Next, the SN ratio calculator 18 calculates the SN ratio from the noise power calculated in S204 and the signal power calculated in S205 (S206). To determine the multilevel degree of a signal from the calculated SN ratio, for example, a table is stored in advance in a memory, and the table values are read out to determine the multilevel degree.

In this way, the transmission system 100 can determine the multilevel degree of the signal to be transmitted based on the SN ratio of the transmission line 3 whose frequency characteristics fluctuate. That is, the transmission system 100 (transmitter 1, transmission device) can set a clock frequency that can suppress a decrease in transmission speed while suppressing the influence of fluctuations in the frequency characteristics of the transmission path.

・Embodiment 3
The transmission system 100 may detect an abnormality in the transmission line 3 when the resistance value of the variable resistance unit 23 is open (Z ₀ =∞) in the first embodiment.

FIG. 9 is a diagram showing an example of the functional configuration of the transmission system 100 according to the third embodiment.
In the transmission system 100 according to the third embodiment, in addition to the signal generation unit 15, the pass characteristic calculation unit 16, and the clock determination unit 17, the control unit 10 executes the program stored in the memory by the CPU. It is different from the transmission system 100 according to the first embodiment in that each function of the detection unit 11 is implemented.

The abnormality detection unit 11 detects disconnection or short circuit of the transmission line 3 based on the resistance value obtained by converting the output terminal voltage detected by the waveform detection unit 14 when the resistance value of the variable resistance unit 23 is open. . Note that this resistance value may include an impedance value.

FIG. 10 is a flow chart showing the operation of detecting an abnormality in the transmission system 100. As shown in FIG.
Here, it is assumed that the transmission system 100 detects the voltage waveform (output end voltage) at the output end of the transmitter 1 before starting the operation of detecting an abnormality.

The abnormality detection unit 11 converts the output terminal voltage V(t) into an impedance value Z(t) according to Equation (4) (S301).

Here, V _incident represents the incident waveform incident on the transmission line 3. FIG. When a pulse wave is applied with a resistance value matching the impedance of the transmission line 3, V _incident =V ₀ /2.

Next, the abnormality detection unit 11 determines whether an abnormality determination condition is satisfied (S302). Here, as an abnormality determination condition, it is assumed that if the impedance value Z(t) is larger than the first threshold value (200Ω), it is broken, and if it is equal to or smaller than the second threshold value (10Ω), it is shorted. It should be noted that this criterion for determining abnormality of the transmission line 3 is merely an example, and another criterion may be defined.

Next, when the abnormality detection unit 11 determines that the abnormality determination condition is satisfied, it stops the flow and notifies the abnormality (S304). The abnormality detection unit 11 may notify the abnormality through, for example, a speaker or a display unit (not shown).

On the other hand, when the abnormality detection unit 11 determines that the abnormality determination condition is not satisfied, it determines that there is no abnormality in the transmission line 3 and continues the process (S304).

In this way, the transmission system 100 can detect disconnection or short-circuiting of the transmission line 3 with a simple configuration of only the transmitter 1 without installing a measuring device (network analyzer) in the receiver 2 .

100 transmission system, 1 transmitter, 10 control unit, 12 modulation unit, 13 clock generation unit, 14 waveform detection unit, 15 signal generation unit, 16 transmission characteristics calculation unit, 17 clock determination unit, 11 abnormality detection unit, 18 SN ratio Calculation unit 19 Multilevel degree determination unit 2 Receiver 21 Reception unit 22 Control unit 23 Variable resistance unit 3 Transmission line 31 Control circuit 32 Modulation circuit 33 Clock generation circuit 34 Waveform detection circuit 41 Receiving circuit, 42 control circuit, 43 variable resistance circuit.

Claims

A transmission device that transmits a signal to a receiver via a transmission line,
a signal generation unit that generates a control signal, a step signal, and a data signal for controlling switching of N types (N is 3 or more) of resistance values of a variable resistance unit included in the receiver;
a modulation unit that modulates the control signal, the step signal, and the data signal generated by the signal generation unit into the signals with a multilevel degree of 2 or more and outputs the signals to the receiver;
a waveform detection unit that detects an output end voltage of the transmission device when the step signal is output from the modulation unit;
a clock generation unit that generates a clock frequency for synchronizing the modulation unit and the waveform detection unit;
a pass characteristic calculation unit that calculates the pass characteristic of the transmission line from the N types of resistance values and the output end voltage for each of the N types of resistance values;
and a clock determination unit that determines the clock frequency of the clock generation unit based on the pass characteristic calculated by the pass characteristic calculation unit.
The signal generator is
2. The transmission device according to claim 1, wherein a control signal is generated for switching the resistance of said variable resistance unit to at least three types of short circuit, open circuit, and characteristic impedance of said transmission line.
The pass characteristic calculation unit,
Calculate the pass characteristic according to the following formula

tdr (i) (t) represents the output end voltage detected by the waveform detection unit when the resistance value of the variable resistance unit is Zi , θ(t) represents a step function, ω represents frequency, 3. The transmission apparatus according to claim 1, wherein j indicates an imaginary unit, s11 (i) indicates the reflection characteristic of the transmission line, and s11 indicates the transmission characteristic.
The transmission device further
noise power calculated from the output end voltage detected by the waveform detection unit and the resistance value of the variable resistance unit when the modulation unit is not outputting a signal;
An SN ratio calculation unit for calculating a ratio of signal power to noise power from the resistance value of the variable resistance unit, the maximum number of levels that can be set, and the signal power calculated from the pass characteristic calculated by the pass characteristic calculation unit. and,
Claims 1 to 3, further comprising: a multi-level degree determination unit that determines a multi-level degree of the multi-level signal modulated by the modulation unit from the ratio of signal power to noise power calculated by the SN ratio calculation unit. The transmission device according to any one of 1.
The transmission device further
an abnormality detection unit that detects disconnection or short circuit of the transmission line based on the resistance value of the output terminal voltage detected by the waveform detection unit when the resistance of the variable resistance unit is open. The transmission device according to any one of claims 1 to 4, wherein:
A transmission system for transmitting a signal from a transmitter to a receiver via a transmission line,
The transmitter is
a signal generation unit that generates a control signal, a step signal, and a data signal for controlling switching of N types (N is 3 or more) of resistance values of a variable resistance unit included in the receiver;
a modulation unit that modulates the control signal, the step signal, and the data signal generated by the signal generation unit into the signals with a multilevel degree of 2 or more and outputs the signals to the receiver;
a waveform detection unit for detecting an output end voltage of the transmitter when the step signal is output from the modulation unit;
a clock generation unit that generates a clock frequency for synchronizing the modulation unit and the waveform detection unit;
a pass characteristic calculation unit that calculates pass characteristics of the transmission line from the N types of resistance values and the output terminal voltage for each of the N types of resistance values;
a clock determination unit that determines the clock frequency of the clock generation unit based on the transmission characteristics calculated by the transmission characteristics calculation unit;
The receiver is
a receiver that receives the signal transmitted from the transmitter;
a variable resistance circuit that switches between N types of resistance values (where N is 3 or more) according to the control signal included in the signal received by the receiving unit;
A transmission system characterized by:
A transmission method for a transmission device that transmits a signal to a receiver via a transmission line,
A signal generation step of generating a control signal, a step signal, and a data signal for controlling switching of N types (N is 3 or more) of resistance values possessed by a variable resistance unit provided in the receiver;
a modulating step of modulating the control signal, the step signal, and the data signal generated in the signal generating step into the signal with a multilevel degree of 2 or more, and outputting the signal to the receiver;
a waveform detection step of detecting an output end voltage of the transmission device when the step signal is output in the modulation step;
a clock generating step for generating a clock frequency for synchronizing the modulating step and the waveform detecting step;
a pass characteristic calculation step of calculating pass characteristics of the transmission line from the N types of resistance values and the output end voltage for each of the N types of resistance values;
and a clock determination step of determining a clock frequency of the clock generation step based on the transmission characteristics calculated in the transmission characteristics calculation step.