JP2013201540A - Communication apparatus, communication system, and adjusting method of communication apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an adjustment according to a connection environment of a network configured by a plurality of devices connected to each other via a cable.SOLUTION: Respective nodes 10, 20 transmit tone signals in a predetermined period and transmit a measurement signal of frequency different from the tone signal between two tone signals. A receiver 15 of the node 10 measures the amplitude of the tone signal and the amplitude of the measurement signal and compares the amplitude value of the tone signal with the amplitude value of the measurement signal to generate a determination signal. A physical logic unit 11 adjusts a reception condition of the receiver 15 based on the determination signal.

Description

  The present invention relates to a communication device, a communication system, and a communication device adjustment method.

  The network is composed of a plurality of devices connected to each other via a cable. For example, IEEE1394. A device connected to a b-standard network can operate in any one of a plurality of different transfer rate modes (see, for example, Patent Document 1).

JP 2009-88891 A

  The transmission / reception circuit provided in each device forming the network is designed so that stable communication is possible even under the worst conditions of the standard. For example, when the reception environment is good, useless power is consumed in the reception circuit designed under the worst conditions. For this reason, in a transmission / reception circuit, adjustment according to the connected environment is desired.

  According to an aspect of the present invention, a transmitter that transmits a first transmission signal having a first frequency and a second transmission signal having a second frequency different from the first frequency, and an amplitude value of the first transmission signal And a receiver for receiving a notification signal corresponding to a result of comparing the amplitude value of the second transmission signal and generating a determination signal, and an adjustment circuit for adjusting a transmission condition of the transmitter based on the determination signal And have.

  According to one aspect of the present invention, adjustment according to a connected environment can be made possible.

It is a block diagram which shows a network. It is a block diagram of a communication apparatus (node). It is a block diagram of a transmitter and a receiver. It is explanatory drawing which shows the transition of a state. It is explanatory drawing of the signal and communication state in a receiver. It is explanatory drawing of operation | movement of a mode signal and a receiver. It is explanatory drawing of the order of an attenuation amount difference, a status code, and optimization. (A)-(d) is explanatory drawing of the signal transmitted / received. It is a time chart which shows communication between nodes. (A), (b) is explanatory drawing of the signal for a measurement. It is a flowchart of a measurement process. It is a flowchart of an optimization process. It is a timing chart which shows operation | movement of a receiver. It is a timing chart which shows operation | movement of a receiver. It is a block diagram of a communication apparatus (node). It is a block diagram of the transmitter and receiver of a second embodiment. It is explanatory drawing which shows the transition of a state. (A) (b) is explanatory drawing of the signal transmitted / received. It is a flowchart of a measurement process. It is a timing chart for demonstrating communication between nodes. It is a timing chart for demonstrating communication between nodes.

(First embodiment)
Hereinafter, a first embodiment will be described with reference to FIGS.
As shown in FIG. 1, a network that operates in accordance with a predetermined standard (for example, the IEEE 1394.b standard) includes a plurality of devices (five units in FIG. 1) that are communicably connected to each other. Each device is, for example, a personal computer (hereinafter, personal computer) 1, a storage device 2, a recorder 3, a display device 4, and an imaging device 5. The storage device 2 is, for example, a hard disk device. The recorder 3 has a hard disk device (HDD) and an optical disk device (DVD device), for example, and is a recorder that records video and the like. The display device 4 is, for example, a TV or a display. The imaging device 5 is, for example, a digital video camera.

  For example, the network can transfer data such as image data and audio data between the personal computer 1 and the storage device 2 and between the personal computer 1 and the recorder 3. Further, data can be transferred between the imaging device 5 and the recorder 3, and image data stored in the recorder 3 can be transferred to the display device 4 and reproduced. Further, the image data recorded in the imaging device 5 can be transferred to the display device 4 via the recorder 3 and reproduced.

  For example, the personal computer 1 and the storage device 2 include the communication device 10 and the communication device 20 shown in FIG. Similarly, the recorder 3, the display device 4, and the imaging device 5 have a communication device for communicating with other devices. FIG. 2 schematically shows communication between the communication device 10 of the personal computer 1 and the device 20 of the storage device 2. The communication devices 10 and 20 are provided as semiconductor devices, for example. The communication devices 10 and 20 have a transmission function for transmitting data and a reception function for receiving data. Here, the communication apparatus is described as a node.

The first node 10 includes a physical logic unit 11, a transmitter 12, a transmission termination unit 13, a reception termination unit 14, and a receiver 15.
The physical logic unit 11 of the first node 10 supplies the transmitter 12 with a transmission signal TS1 based on transmission data transmitted from the personal computer 1 shown in FIG. The transmitter 12 outputs a signal TX1 based on the transmission signal TS1. The signal TX1 is supplied to the second node 20 via the transmission termination unit 13 and the transmission path 30. The receiver 15 supplies the physical logic unit 11 with a reception signal RS1 based on the signal RX1 received via the reception termination unit 14. The physical logic unit 11 receives the reception signal RS1 output from the receiver 15, and generates reception data obtained by encoding the reception signal RS1. The storage device 2 illustrated in FIG. 1 stores received data.

Similarly, the second node 20 includes a physical logic unit 21, a transmitter 22, a transmission termination unit 23, a reception termination unit 24, and a receiver 25.
The physical logic unit 21 of the second node 20 supplies the transmitter 22 with a transmission signal TS2 based on transmission data transmitted from the storage device 2 shown in FIG. The transmitter 22 outputs a signal TX2 based on the transmission signal TS2. The signal TX2 is supplied to the second node 20 via the transmission termination unit 23 and the transmission path 30. The receiver 25 supplies a received signal RS2 based on the signal RX2 received via the reception termination unit 24 to the physical logic unit 21. The physical logic unit 21 receives the reception signal RS2 output from the receiver 25, and generates reception data obtained by encoding the reception signal RS2. A personal computer 1 shown in FIG. 1 processes received data.

  The physical logic units 11, 21 included in both nodes 10, 20 are based on signals communicated between both nodes 10, 20, and transmitters 12, 22 and receivers 15, included in the nodes 10, 20, respectively. 25 is adjusted. The physical logic units 11 and 21 are examples of adjustment circuits.

  The communication performed between the first node 10 and the second node 20 is full-duplex communication that allows transmission and reception of each other at the same time. Therefore, the first node 10 and the second node 20 communicate with each other via two paths. The first path conveys a signal from the transmitter 12 of the first node 10 to the receiver 25 of the second node 20. The second path conveys a signal from the transmitter 22 of the second node 20 to the receiver 15 of the first node 10.

  For example, two sets of the first node 10 and the second node 20 set with the same condition are connected by two transmission lines 30 having different lengths. In this case, the level of the reception signal RX1 received by the second node 20 by one transmission path 30 is higher than the level of the reception signal RX1 received by the second node 20 by another transmission path 30 longer than the transmission path 30. . Therefore, in the second node 20 connected to one transmission line 30, the amplitude of the transmission signal TX2 transmitted from the transmitter 22 can be lowered within a range that the receiver 15 of the first node 10 can receive. Is possible. Similarly, the amplitude of the transmission signal TX1 transmitted from the transmitter 12 of the first node 10 can be lowered within a range that can be received by the receiver 25 of the second node 20. Lowering the amplitudes of the transmission signals TX1 and TX2 reduces the power consumed by the transmitters 12 and 22, respectively.

  Further, the transmitters 12 and 22 and the receivers 15 and 25 include circuits that enable stable communication even under the worst standard conditions. Therefore, when the reception environment is good, it is possible to stop the circuit for stable communication. Such a circuit stop reduces the power consumed in each transmitter 12, 22.

  The state (level, waveform, etc.) of the received signal received by the receiver 25 of the second node 20 is the state of the transmission signal transmitted from the transmitter 12 of the first node 10, that is, the transmission condition of the transmitter 22. This corresponds to the state of the transmission line 30. Therefore, the physical logic unit 11 of the first node 10 adjusts the transmitter 12 based on the signal transmitted by the first path. The physical logic unit 21 of the second node 20 adjusts the receiver 25 based on the signal transmitted by the first path.

  Similarly, the state (level, waveform, etc.) of the reception signal RX1 received by the receiver 15 of the first node 10 is the state of the transmission signal TX2 transmitted from the transmitter 22 of the second node 20, that is, the transmitter. This corresponds to 22 transmission conditions and the state of the transmission line 30. Accordingly, the physical logic unit 11 of the first node 10 adjusts the receiver 15 based on the signal transmitted by the second path. The physical logic unit 21 of the second node 20 adjusts the transmitter 22 based on the signal transmitted by the second path.

Each physical logic unit 11, 21 adjusts the transmitters 12, 22 and the receivers 15, 25 during the period from recognition of the nodes 10, 20 to data communication.
FIG. 4 shows an example of state transition from recognition of the nodes 10 and 20 to data communication.

  The first state ST1 is a tone detection state. Each of the nodes 10 and 20 enters the first state ST1 when the power is turned on, for example. In the first state ST1, each of the nodes 10 and 20 transmits a tone signal. When each of the nodes 10 and 20 detects a tone signal, it transmits a response signal. When the first node 10 detects a response signal transmitted by the second node 20, the first node 10 transits from the first state ST1 to the second state ST2. Similarly, the second node 20 that has detected a response signal transmitted by the first node 10 transitions from the first state ST1 to the second state ST2.

  The second state ST2 is a state in which communication speed setting (speed negotiation) is performed. Each of the nodes 10 and 20 sets a communication speed with the node whose connection has been confirmed. Both nodes 10 and 20 transmit transmission signals including information (speed code) corresponding to the communication speed of each other, and match the communication speed of each other.

  The third state ST3 is a state in which signal measurement and order determination are performed. Each node 10, 20 transmits and receives a signal for adjustment to each other. Each of the nodes 10 and 20 measures a signal for adjustment, and transmits a measurement result to each other's nodes 10 and 20. Each of the nodes 10 and 20 receives the measurement result of the communication partner. And each node 10 and 20 determines the order which adjusts a transmitter and a receiver based on a mutual measurement result.

  The fourth state ST4 is a state in which optimization is performed. Each of the nodes 10 and 20 adjusts the transmitter and the receiver based on the measurement result of the own node and the measurement result of the communication partner node.

  The fifth state ST5 is a state in which synchronization is performed, and the reception circuit performs synchronization with the reception signal based on the synchronization signal. When synchronization is established, each of the nodes 10 and 20 communicates with the partner node with which the connection has been established at the communication speed set in the second state ST2.

Next, various signals transmitted and received between both nodes 10 and 20 will be described.
As shown in FIG. 8A, the tone signal TN is repeatedly transmitted every predetermined time D1. The transmission interval (time D1) of the tone signal TN is a time set according to the standard, for example, 42.67 ms. The tone signal TN is a signal in which a pulse having a frequency (for example, 48 MHz to 64 MHz) corresponding to the standard continues for a time D2 (for example, 666.67 μs).

  The first node 10 and the second node 20 connected to each other via the transmission line 30 shown in FIG. 2 detect the tone signal TN transmitted from the partner node and transmit a response signal. The signal for this response is a reception notification signal (acknowledge signal) ACK after a predetermined time D3 (eg, 2.67 ms) has elapsed from the start of the tone signal TN, as indicated by a broken line in FIG. This receipt notification signal ACK is a pulse signal similar to the tone signal TN. When the first node 10 and the second node 20 detect the reception notification signal ACK, the first node 10 and the second node 20 determine that the communication partner node is connected. As shown in FIG. Transition to state ST2.

  FIG. 8B shows a speed code (speed code TSC) transmitted in order to set the communication speed in the second state ST2. After transmitting the tone signal TN, each of the nodes 10 and 20 transmits the speed code TSC during a predetermined period D4 (for example, 21.33 ms) from the transmission start of the tone signal TN. The speed code TSC is a predetermined number (for example, 6 bits) of signal. Note that the timing for sending the acknowledge signal ACK is reserved. Each of the nodes 10 and 20 transmits each bit of the speed code TSC at the same time D3 after the time D3 has elapsed since the start of transmission of the acknowledge signal ACK.

  Each bit of the speed code TSC is indicated by the presence / absence of a pulse signal continuously output during the period D2, similarly to the tone signal TN. For example, a bit having a value of “1” is a pulse signal that is continuously output during time D2. The bit whose value is “0” is a signal of a predetermined level (for example, ground level) during the time D2. Accordingly, when the circuit on the receiving side (for example, the physical logic unit 24 of the second node 20) detects the pulse signal at a predetermined timing, the corresponding bit value is “1” and the pulse signal is not detected. The value is set to “0”.

  Each of the nodes 10 and 20 transmits a speed code TSC corresponding to the maximum communication speed among the operation modes in which the node can operate. For example, a node that can support the operation modes of S400, S800, S1600, and S3200 transmits a speed code TSC of a bit string “011XX0” corresponding to the mode of S3200. “XX” is a bit corresponding to “FOP Capable” and “PIL Capable”.

  The node that has received the speed code TSC transmits the tone signal TN and the acknowledge signal ACK, and then transmits the speed code TSC corresponding to the operation mode that the node can handle. Both nodes 10 and 20 respectively transmit transmission signals including information (speed code TSC) corresponding to the communication speed of each other. Then, both nodes 10 and 20 exchange the maximum communication speed with each other and set the operation mode corresponding to the slower communication speed.

  For example, the first node 10 can operate in any one of the operation modes of S400, S800, S1600, and S3200. The second node 20 can operate in any one of the operation modes of S400, S800, and S1600. The first node 10 transmits a speed code TSC corresponding to the operation mode of S3200, and the second node 20 transmits a speed code TSC corresponding to the operation mode of S1600.

  The first node 10 that has received the speed code TSC corresponding to the operation mode of S1600 can respond to the operation mode. Therefore, the first node 10 transmits the acknowledge signal ACK and the A speed code TSC corresponding to the operation mode of S1600 is transmitted. Then, the first node 10 sets the operation mode to S1600.

  The second node 20 that has received the speed code TSC corresponding to the operation mode of S3200 cannot support the operation mode. Therefore, after sending the tone signal TN, the second node 20 sends the acknowledge signal ACK and the speed code TSC corresponding to the operation mode of S1600 corresponding to its own maximum speed. Then, the second node 20 sets the operation mode to S1600.

  FIG. 8C shows a measurement signal MC used for measuring a change in signal level according to the path state. The measurement signal MC is a predetermined number (for example, 4 bits). In the measurement of the signal level, the first 3 bits B1 to B3 of the measurement signal MC indicate the measurement period. The last bit B4 of the measurement signal MC indicates between the comparators that compare the measurement results.

  Similarly to the speed code TSC, each of the nodes 10 and 20 transmits the measurement signal MC at a predetermined timing after the transmission of the tone signal TN. Note that a timing for transmitting the acknowledge signal ACK is reserved at a predetermined timing (after the time D3 has elapsed) from the start of transmission of the tone signal TN. Each of the nodes 10 and 20 transmits the first bit B1 of the measurement signal MC after time D3 has elapsed from the transmission timing of the reserved acknowledge signal ACK. And each node 10 and 20 transmits each bit B1-B4 for every same time D3.

  FIG. 8D shows a notification signal RC used for notifying the result of measuring the change in the signal level by the measurement signal MC. The notification signal RC is a predetermined number (4 bits) of signals, for example, like the measurement signal MC. The measurement result is the first 3 bits B1 to B3 of the notification signal RC. The last bit B4 of the notification signal RC is a signal indicating a period for capturing the measurement result.

  The measurement signal MC is a pulse signal (1T pattern) in which “1” and “0” are alternately repeated for a predetermined period. The period during which the measurement signal MC is output is equal to the period D2 during which the tone signal TN is output, for example. The frequency of the measurement signal MC is set to a value that can be distinguished from the tone signal TN. For example, the frequency of the measurement signal MC preferably corresponds to the communication speed of data performed between the nodes 10 and 20. In the communication speed setting (speed negotiation), the nodes 10 and 20 transmit compatible operation modes to each other, and set the maximum speed operation mode common to both the nodes 10 and 20. Accordingly, each of the nodes 10 and 20 transmits a measurement signal MC having a frequency corresponding to the set operation mode.

  For example, the operation mode of both nodes 10 and 20 is S3200. Both nodes 10 and 20 communicate data in the operation mode of S3200. The IDB 1394 standard prescribes the maximum transfer rate corresponding to the operation mode as 500 Mbps (S400), 1 Gbps (S800), 2 Gbps (S1600), and 3.2 Gbps (S3200) (bps: bit per second). In this case, each of the nodes 10 and 20 sets the frequency of the measurement signal MC to 2 GHz, for example. The communication of the pulse signal is equivalent to transmitting data “1” and data “0” in one cycle. Therefore, a 2 GHz pulse signal corresponds to a data communication speed of 4 Gbps.

  The notification signal RC is transmitted at a predetermined timing after the tone signal TN is transmitted, similarly to the measurement signal MC. Note that a timing for transmitting the acknowledge signal ACK is reserved at a predetermined timing (after the time D3 has elapsed) from the start of transmission of the tone signal TN. Each of the nodes 10 and 20 transmits each bit of the measurement signal MC at the same time D3 after the time D3 has elapsed since the start of transmission of the acknowledge signal ACK.

  The notification signal RC is a pulse signal that is continuously output for a predetermined period, like the measurement signal MC. The period in which the notification signal RC is output is equal to the period D2 in which the tone signal TN is output, for example. The frequency of the notification signal RC is set equal to the frequency of the measurement signal MC, for example.

Next, the outline of the transmitter 12 and the receiver 15 will be described with reference to FIG. In FIG. 3, the transmission termination unit 13 and the reception termination unit 14 shown in FIG. 2 are omitted.
The transmitter 12 outputs a reception signal RS1 based on the reception signal RX1. The transmitter 12 has a de-emphasis 12a that compensates for inter-signal interference caused by a loss in the transmission path. The de-emphasis 12a is turned on / off in response to the control signal CD1 supplied from the physical logic unit 11. The de-emphasis 12a turned on emphasizes the signal on the transmission side. For example, the de-emphasis 12a shapes the waveform so that at least one of the rising portion and the falling portion of the rectangular signal is overshooted. The de-emphasis 12a is an example of a waveform shaping circuit. De-emphasis is sometimes referred to as pre-emphasis or post-emphasis.

  The de-emphasis 12a in the on state improves the communication state between the first node 10 and the second node 20. For example, the shaping of the waveform by the de-emphasis 12a emphasizes the high-frequency component of the data waveform that is lost due to the loss of the transmission path 30. A large high-frequency loss in the transmission path 30 deteriorates the data waveform at the receiving end and inhibits stable data transmission / reception. Therefore, the de-emphasis 12a reduces the deterioration of the data waveform and enables stable data transmission / reception. In the case of a transmission line with a small loss, the deterioration of the data waveform is small, and stable data transmission / reception is possible even when the de-emphasis 12a is not operating.

  Then, on / off of the de-emphasis 12 a changes the power consumption in the transmitter 12. When the de-emphasis 12a is on, the power consumption at the transmitter 12 is greater than the power consumption of the transmitter 12 when the de-emphasis 12a is off. Therefore, turning off the de-emphasis 12a reduces the power consumption of the transmitter 12.

  The transmitter 12 transmits a transmission signal TX1 based on the output signal of the de-emphasis 12a. Furthermore, the transmitter 12 transmits a transmission signal TX1 having an amplitude corresponding to the amplitude control signal CA1. The signal for adjusting the amplitude may be a signal between the input terminal and the output terminal of the transmitter 12, and may be, for example, a signal supplied to the de-emphasis 12a.

  The receiving circuit 41 of the receiver 15 has an equalizer 41a that compensates for transmission loss between two nodes. The equalizer 41a is turned on / off in response to the equalizer control signal CE1 supplied from the physical logic unit 11. The equalizer 41a that is turned on amplifies a signal in a predetermined band among the signal RX1 received by the receiver 15. The equalizer 41a is an example of an amplifier circuit. The receiver 15 outputs a reception signal RS1 corresponding to the signal amplified by the equalizer 41a. The equalizer 41a that is turned off does not perform the amplification. Therefore, the receiver 15 outputs a reception signal RS1 having an amplitude equal to the amplitude of the received signal RX1. The band processed by the equalizer 41a and the gain of amplification are set according to the frequency of the received signal, for example.

  The equalizer 41 a in the on state improves the communication state between the first node 10 and the second node 20. For example, the amplification of the signal of the predetermined band by the equalizer 41a compensates for the high frequency component of the data waveform lost due to the loss of the transmission line 30. A large high-frequency loss in the transmission path 30 deteriorates the data waveform at the receiving end and inhibits stable data transmission / reception. Therefore, the equalizer 41a reduces the deterioration of the data waveform and enables stable data transmission / reception. In the case of a transmission line with a small loss, the deterioration of the data waveform is small, and stable transmission / reception of data is possible even when the equalizer 41a is not operating.

  Then, on / off of the equalizer 41a changes the power consumption in the receiver 15. When the equalizer 41a is in the on state, the power consumption in the receiver 15 is larger than the power consumption in the receiver 15 when the equalizer 41a is in the off state. Therefore, turning off the equalizer 41a reduces the power consumption of the receiver 15.

  Further, the reception circuit 41 outputs a detection signal SGD corresponding to the reception signal RX1 and a predetermined value. The specified value is a threshold value with respect to the level of the reception signal RX1. That is, the reception circuit 41 compares the level of the reception signal RX1 with a predetermined threshold value. The reception circuit 41 outputs the detection signal SGD at the H level when the level of the reception signal RX1 is equal to or higher than the threshold value. The receiving circuit 41 outputs an L level detection signal SGD when the level of the received signal RX1 is smaller than the threshold value. Therefore, the L level detection signal SGD indicates that the reception signal RX1 is not received, as shown in FIG.

  The reception circuit 41 outputs the detection signal SGD at the H level until the predetermined time elapses after the level of the reception signal RX1 becomes smaller than the threshold value. The predetermined time is, for example, 100 μS (microseconds). Accordingly, when the reception signal RX1 is a pulse signal and the L level pulse width is shorter than the predetermined time, the reception circuit 41 continuously outputs the H level detection signal SGD while receiving the reception signal RX1. .

  For example, in the tone signal TN, the cycle of the tone signal TN having a frequency of 50 MHz is 0.02 μS. When the frequency of the measurement signal MC is 2 GHz, the cycle of the measurement signal MC is 0.5 ns (nanoseconds). Therefore, the receiving circuit 41 outputs one pulse as the detection signal SGD as shown in FIG. 13 corresponding to the continuous pulse signal like the tone signal TN. That is, the level of the detection signal SGD indicates the presence / absence of a necessary signal such as the tone signal TN in the reception signal RX1.

  As shown in FIG. 13, the physical logic unit 11 determines the presence or absence of a tone signal TN or the like based on the detection signal SGD, and outputs a mode signal MD generated according to the determination result to the receiver 15. The receiver 15 operates in response to the mode signal MD.

  The mode signal MD is a 2-bit signal, for example. FIG. 6 shows the mode signal MD and the operation of the receiver 15 in response to the mode signal MD. In the following description, a combination of bits is added to the mode signal MD.

  The physical logic unit 11 illustrated in FIG. 3 outputs a mode signal MD [00]. The receiver 15 performs a normal operation in response to the mode signal MD [00]. The normal operation does not include an operation related to amplitude measurement.

  As described above, when the communication logic setting (speed negotiation) is completed, the physical logic unit 11 transitions from the second state ST2 to the third state ST3 shown in FIG. When the tone signal TN is detected in the third state ST3, the mode signal MD [01] is output. The receiver 15 performs an amplitude measurement / comparison operation in response to the mode signal MD [01]. In the amplitude measurement / comparison operation, the receiver 15 measures the amplitude of the tone signal TN and the amplitude of the measurement signal MC, and compares the amplitude values of both the signals TN and MC to generate the determination signal CO1. Then, the receiver 15 outputs the generated determination signal CO1.

  The physical logic unit 11 receives the determination signal CO1 and outputs the mode signal MD [10] at a predetermined timing. For example, as shown in FIG. 13, the mode signal MD [10] is output in response to the detection of the tone signal TN. The receiver 15 performs a measurement result receiving operation in response to the mode signal MD [10]. The receiver 15 detects the notification signal RC included in the reception signal RS1, and generates a determination signal CO2 corresponding to the notification signal RC. Then, the receiver 15 outputs the generated determination signal CO2. The physical logic unit 11 receives the determination signal CO2 and outputs the mode signal MD [00] at a predetermined timing (for example, detection of the tone signal TN).

The receiver 15 includes a tone signal detector (noted as a TN / TSC detector) 42, a measurement signal detector 43, an amplitude measuring device 44, and an amplitude value determining device 45.
The tone signal detector 42 detects the tone signal TN based on the mode signal MD [01]. The tone signal detector 42 detects the tone signal TN and the acknowledge signal ACK based on the mode signal MD [10]. The tone signal detector 42 detects a pulse signal having a predetermined frequency included in the reception signal RX1. The frequency band set in the tone signal detector 42 corresponds to the frequency of the tone signal TN. Such a frequency band is set by, for example, a low-pass filter or a band-pass filter. Therefore, the tone signal detector 42 outputs an H level detection signal RT in response to the tone signal TN, the acknowledge signal ACK, and the speed code TSC included in the received signal RX1. As shown in FIG. 5, the H level detection signal RT indicates that a tone signal (TN) is being received. That is, as shown in FIG. 13, the tone signal detector 42 detects the H level detection signal during the period in which the tone signal TN is transmitted (period D <b> 2 shown in FIG. 8A) when the mode signal MD [01]. Output RT. Further, as shown in FIG. 14, the tone signal detector 42 outputs an H level detection signal RT from the start of the tone signal TN to the end of the acknowledge signal ACK when the mode signal MD [10].

  The measurement signal detector 43 generates a detection signal RM and a comparison signal EN corresponding to the measurement signal MC and the notification signal RC based on the detection signal RT and the detection signal SGD. The measurement signal detector 43 outputs an L level detection signal RM and an L level comparison signal EN in response to an H level detection signal RT. Further, the measurement signal detector 43 outputs the detection signal RM and the comparison signal EN based on the detection signal SGD corresponding to the measurement signal MC in response to the L level detection signal RT. Specifically, as shown in FIGS. 13 and 14, the measurement signal detector 43 includes a detection signal SGD (four pulse signals) corresponding to the measurement signal MC from the first pulse signal to the last pulse signal. During this period, an H level detection signal RM is output. The measurement signal detector 43 outputs a comparison signal EN that is equal to the last pulse signal among the four pulse signals corresponding to the measurement signal MC. For example, the measurement signal detector 43 counts the number of pulses of the detection signal SGD or includes a counter. After the detection signal RT changes from H level to L level, the detection signal RM and the comparison signal EN are changed according to the count value. Output.

  The amplitude measuring device 44 performs a measurement operation in response to the mode signal MD [01]. In this measurement operation, the amplitude measuring device 44 measures the amplitude of the reception signal RS1 in response to the detection signal SGD at the H level. Then, as shown in FIG. 13, the amplitude measuring device 44 outputs an amplitude value AT equal to the measured value during the period in which the detection signal RM is at the L level. Further, as shown in FIG. 13, the amplitude measuring device 44 outputs an amplitude value AM equal to the measured value during the period in which the detection signal RM is at the H level. When the detection signal RM is at the L level and the detection signal SGD is at the H level, the reception signal RS1 is a signal other than the measurement signal MC. In the measurement period, signals other than the measurement signal MC are tone signals TN. Accordingly, the amplitude measuring device 44 measures the amplitude of the tone signal TN and outputs an amplitude value AT. When the detection signal RM is at the H level and the detection signal SGD is at the H level, the reception signal RS1 is the measurement signal MC. Accordingly, the amplitude measuring device 44 measures the amplitude of the measurement signal MC and outputs an amplitude value AM. As shown in FIG. 5, the H level detection signal RM indicates that the measurement signal group is being received. The measurement signal group indicates three bits B1 to B3 (see FIG. 8C) of the measurement signal MC.

  The amplitude measuring device 44 performs a receiving operation in response to the mode signal MD [10]. In this reception operation, the amplitude measuring device 44 outputs a signal AT having a level equal to the detection signal RM output from the measurement signal detector 43.

  As shown in FIG. 13, the amplitude value determination unit 45 compares the amplitude value AT and the amplitude value AM in response to the H level comparison signal EN when the mode signal MD [01], and determines according to the level fluctuation. A signal CO1 is generated. That is, the H level comparison signal EN indicates that the measurement results (AT, AM) are being compared, as shown in FIG. The amplitude value determiner 45 calculates a difference value AW of the amplitude value AM of the measurement signal MC with respect to the amplitude value AT of the tone signal TN. For example, the amplitude value determiner 45 calculates the difference value AW logarithmically as in the following equation.

AW = 20 × log10 (AM ÷ AT) (1)
Then, the amplitude value determiner 45 compares the difference value AW with the determination threshold value Dth, and generates a determination signal CO1 according to the comparison result. The determination threshold value Dth is set to “3 dB”, for example. The amplitude value determiner 45 generates a determination signal CO1 according to the sign of the difference value (amplitude difference) AW and the comparison result between the difference value AW (absolute value) and the determination threshold value Dth.

  The determination signal CO1 is, for example, a 3-bit signal. As shown in FIG. 7, the amplitude value determiner 45 generates a determination signal CO1 corresponding to the measurement result. The determination signal CO1 of [0xx] indicates that measurement is impossible. Inability to measure is when there is no amplitude value of the measurement signal MC or when the measurement signal MC is too low to be measured. [X] indicates that either [0] or [1] may be used. The determination signal CO1 of [100] indicates when the difference value AW is equal to or less than the threshold value −Dth (AW ≦ −Dth). The determination signal CO1 of [101] indicates when the difference value AW is greater than the threshold value −Dth and less than “0” (−Dth <AW <0). The determination signal CO1 of [110] indicates when the difference value AW is “0” or more and less than the threshold value Dth (0 ≦ AW <Dth). The determination signal CO1 of [111] indicates when the difference value AW is less than or equal to the threshold value Dth (Dth ≦ AW).

  Further, as shown in FIG. 14, the amplitude value determiner 45 generates a determination signal CO2 corresponding to the notification signal RC received from the communication partner when the mode signal MD [10]. The amplitude value determination unit 45 takes in the three detection signals SGD in response to the H level signal AT output from the amplitude measurement unit 44, and generates a determination signal CO2 of a bit string corresponding to the detection signal SGD. This determination signal CO2 indicates the measurement result transmitted by the communication partner. 2 is configured in the same manner as the transmitter 12 in the node 10, the receiver 25 is configured in the same manner as the receiver 15, and the physical logic unit 21 is configured in the same manner as the physical logic unit 11. Has been. The physical logic unit 11 receives the determination signal CO1 from the receiver 15, and generates a notification signal RC corresponding to the determination signal CO1 as shown in FIG. Then, the physical logic unit 11 transmits the tone signal TN, the acknowledge signal ACK, and the notification signal RC to the partner node via the transmitter 12. Therefore, the determination signal CO2 received by the physical logic unit 11 shown in FIG. 3 shows the result of measuring the amplitudes of the tone signal TN and the measurement signal MC at the node 20 shown in FIG.

  That is, the physical logic units 11 and 21 of the nodes 10 and 20 transmit the respective reception results to the counterpart node. The physical logic unit 11 of the first node 10 sends the transmitter 12 and the receiver 15 based on the determination signal CO1 indicating the measurement result in the own node 10 and the determination signal CO2 indicating the measurement result in the communication partner node 20. adjust. Similarly, the physical logic unit 21 of the second node 20 receives the transmitter 22 and the reception based on the determination signal CO1 indicating the measurement result at the own node 20 and the determination signal CO2 indicating the measurement result at the communication partner node 10. Adjust vessel 25.

  Next, a schematic processing flow of amplitude measurement and notification of measurement results between both nodes 10 and 20 will be described with reference to FIG. Since the processes executed by the nodes 10 and 20 are the same, the operation of the node 10 will be mainly described, and the operation of the node 20 will be described as necessary.

In step 51, the first node 10 transmits a tone signal TN.
Next, in step 52, the first node 10 determines whether or not the tone signal TN has been received. This determination is made based on whether or not the physical logic units 11 and 21 shown in FIG. 2 have received the tone signal TN and the acknowledge signal ACK shown in FIG. If the first node 10 does not receive the tone signal TN, the first node 10 proceeds to step 51. The first node 10 that has received the tone signal TN proceeds to Step 53. That is, the first node 10 repeatedly executes the processing of steps 51 and 52 until the tone signal TN is received. Note that the first node 10 may intermittently execute the processing of steps 51 and 52. In addition, the first node 10 may stop the operation after continuously executing the processing of steps 51 and 52 for a predetermined period.

  Next, in step 53, the first node 10 measures the amplitude of the received tone signal TN. Next, in step 54, the first node 10 determines whether there is a measurement signal MC following the tone signal TN. When there is no measurement signal MC, the first node 10 ends the amplitude measurement process. In this case, the first node 10 transitions to step ST5 shown in FIG. 4 and performs synchronization. In step 54, when the first node 10 detects the measurement signal MC following the tone signal TN, the first node 10 proceeds to step 55. In step 55, the first node 10 measures the amplitude of the measurement signal MC.

  Next, in step 56, the first node 10 calculates a difference value (amplitude difference) AW based on the amplitude value AT of the tone signal TN and the amplitude value AM of the measurement signal MC. Next, in step 57, the first node 10 generates a determination signal CO1 corresponding to the difference value AW. In step 58, the first node 10 transmits a transmission signal TX1 including the generated determination signal CO1. Next, in step 59, the first node 10 determines whether or not the determination signal CO2 has been received from the second node 20 that is the communication partner. The first node 10 executes step 59 until it receives the determination signal CO2, that is, waits. And the 1st node 10 will complete | finish the process of an amplitude measurement and the notification of a measurement result, if the determination signal CO2 is received.

  Next, adjustment of the transmitter and the receiver will be described. The first node 10 and the second node 20 are configured in the same manner. Therefore, the adjustment at the first node 10 will be described, and the description of the adjustment at the second node 20 will be omitted.

  As shown in FIG. 3, the transmitter 12 includes a de-emphasis 12a and adjusts the amplitude of the transmission signal TX1. The receiving circuit 41 includes an equalizer 41a. Adjustment items in the transmitter 12 and the receiver 15 included in the first node 10 are on / off of the de-emphasis 12a included in the transmitter 12, amplitude adjustment of the transmission signal TX1, and an equalizer 41a included in the reception circuit 41. ON / OFF. The priority order of these adjustment items is set corresponding to the determination signal COx (CO1, CO2) as shown in FIG.

  For example, when the determination signal COx (CO1, CO2) is [100]: 1. Turn on the equalizer (EQ) 41a / de-emphasis (DE) 12a. This is the order of the output amplitude of the transmitter 12. When the determination signal COx (CO1, CO2) is [101], 1. output amplitude of transmitter 12; On / off of the equalizer (EQ) 41a / de-emphasis (DE) 12a. When the determination signal COx (CO1, CO2) is [110], 1. output amplitude of transmitter 12; On / off of the equalizer (EQ) 41a / de-emphasis (DE) 12a. When the determination signal COx (CO1, CO2) is [111], 1. Equalizer (EQ) 41a / de-emphasis (DE) 12a off. Output amplitude of the transmitter 12.

  The adjustment order of the transmitter 12 and the receiver 15 is set according to the timing at which the first node 10 transmits a predetermined signal and the timing at which the second node 20 transmits the predetermined signal. The predetermined signal is, for example, a group of transmission signals TX1 including the measurement signal MC.

  FIG. 9 shows the transmission timing of the transmission signal TX1 of the first node 10 and the transmission signal TX2 of the second node 20. 9 includes the tone signal TN and various signals (acknowledge signal ACK, speed code TSC, measurement signal MC, notification signal RC) transmitted between the tone signal TN and the next tone signal TN. . These are described as one “tone”. In FIG. 9, “tones” including the same signal will be described with the same reference numerals. A “tone” that does not include the acknowledge signal ACK is indicated as “tone T”, and a “tone” that includes the acknowledge signal ACK is indicated as “tone R”.

  The second node 20 transmits a tone T02 including the speed code TSC, and the first node 10 transmits a tone T01 including the speed code TSC. When the communication speed is determined, the first node 10 transmits a tone T10 including a measurement signal MC that is a 1T pattern of the determined communication speed. The second node 20 measures the amplitude of the tone T10 transmitted from the first node 10. Similarly, the second node 20 transmits a tone T20 including a measurement signal MC that is a 1T pattern of the determined communication speed. The first node 10 measures the amplitude of the tone T20 transmitted from the second node 20.

  In the case of the timing shown in FIG. 9, the first node 10 is receiving the tone T20 including the measurement signal MC transmitted from the second node 20 when the transmission of T10 is completed. On the other hand, when the second node 20 completes the transmission of the tone T20 including the measurement signal MC, the second node 20 has completed the reception of the tone T10 including the measurement signal MC transmitted by the first node 10. Accordingly, the first node 10 transmits the tone T101 including the notification signal RC corresponding to the measurement result of the tone T20.

  The second node 20 that has received the tone T101 determines the priority order of optimization of the parameters of the transmitter 22 based on the notification signal RC included in the tone T101, that is, the measurement result in the first node 10. On the other hand, the first node 10 that has transmitted the tone T101 determines the priority order of parameter optimization of the receiver 15 based on the notification signal RC included in the tone T101, that is, the measurement result of the own node.

  Next, the second node 20 transmits a tone T201 including a notification signal RC corresponding to the measurement result of the tone T10. The first node 10 that has received the tone T201 determines the priority of parameter optimization of the transmitter 12 based on the notification signal RC included in the tone T201, that is, the measurement result in the second node 20. On the other hand, the second node 20 that has transmitted the tone T201 determines the priority order of optimization of the parameters of the receiver 25 based on the notification signal RC included in the tone T201, that is, the measurement result of the own node.

  When the second node 20 is transmitting the tone T201 including the measurement result, the first node 10 has already completed transmission of the tone T101 including the measurement result. For this reason, the first node 10 determines that the transmission timing of the own node is earlier than the transmission timing of the counterpart node (the own node is first). The second node 20 determines that the transmission timing of the own node is later than the transmission timing of the counterpart node (the counterpart node is first).

  Therefore, the first node 10 first optimizes the transmitter 12 and then optimizes the receiver 15. The second node 20 first optimizes the receiver 25 and then optimizes the transmitter 22. In other words, when the first node 10 optimizes the transmitter 12, the second node 20 optimizes the receiver 25. Then, when the first node 10 optimizes the receiver 15, the second node 20 optimizes the transmitter 22.

FIG. 12 shows an outline of the optimization process.
In step 61, the first node 10 determines whether or not the transmission of the tone T20 of the second node 20 that is the communication partner precedes the transmission of the tone T10 (see FIG. 9) including the measurement signal MC. If the transmission of the communication partner is first, in step 62, the receiver 15 is optimized. Next, in step 63, the first node 10 optimizes the transmitter 12. On the other hand, if it is determined in step 61 that the own node has transmitted first, the first node 10 optimizes the transmitter 12 in step 64. Next, in step 65, the first node 10 optimizes the receiver 15.

The optimization process will be described.
The first node 10 adjusts the parameters of the transmitter 12 according to the determined priority. For example, the determination signals CO1 and CO2 are each [111]. The first node 10 determines the order of parameters for adjusting the transmitter 12 based on the determination signal CO2. The second node 20 determines the order of parameters for adjusting the receiver 25 based on the determination signal CO1.

  First, the first node 10 controls the de-emphasis 12a of the transmitter 12 to be in an off state, and transmits a tone T11. For example, as shown in FIG. 10A, the tone T11 includes a measurement signal MC having the same amplitude as the tone signal TN. The second node 20 measures the amplitude of the tone T11 and transmits a tone R21 including the notification signal RC. Then, the first node 10 receives tone R21 and transmits tone T11. The second node 20 controls the equalizer 41a of the receiver 25 to be turned off, and measures the amplitude of the received tone T11. Then, the second node 20 transmits a tone R22 including a notification signal RC corresponding to the measurement result.

  The first node 10 then receives the tone R22 and adjusts the amplitude value of the transmitter 12. Then, the first node 10 transmits the tone T12 including the adjusted amplitude measurement signal MC. The amplitude of the measurement signal MC is based on the determination signal CO2. As shown in FIG. 7, the determination signal CO2 of [111] indicates that the difference between the amplitude value of the tone signal TN and the amplitude value of the measurement signal MC is larger than a threshold value Dth (for example, +3 dB). Accordingly, the first node 10 sets the transmission signal lower by a predetermined value (for example, 200 mV). In FIG. 9, the overall amplitude of the tone T12 is shown smaller than the amplitude of the tone T11. However, the tone T12 includes a measurement signal MC having an amplitude smaller than that of the tone signal TN, as shown in FIG.

The second node 20 measures the amplitude of the received tone T12 and transmits a tone R23 including a notification signal RC according to the measurement result.
When the adjustment in one path is completed by such transmission / reception, each of the nodes 10 and 20 starts adjusting the next path. That is, the second node 20 transmits a tone T21 including the measurement signal MC. The first node 10 measures the amplitude of the received tone T21 and transmits a tone R11 including a notification signal RC corresponding to the measurement result. The subsequent processing is the same as the processing in the first pass, although illustration and description are omitted. By such transmission / reception, each of the nodes 10 and 20 performs adjustment in the second path.

As described above, according to the present embodiment, the following effects can be obtained.
(1-1) Each of the nodes 10 and 20 transmits a tone signal TN at a predetermined cycle, and transmits a measurement signal MC having a frequency different from that of the tone signal TN between the two tone signals TN. The receiver 15 of the node 10 measures the amplitude of the tone signal TN and the amplitude of the measurement signal MC, and compares the amplitude value AT of the tone signal TN and the amplitude value AM of the measurement signal MC to generate the determination signal CO1. . The physical logic unit 11 adjusts the reception condition of the receiver 15 based on the determination signal CO1. The amplitude value AT of the tone signal TN changes according to the characteristics of the path including the transmission line 30 at the frequency of the tone signal TN. Similarly, the amplitude value AM of the measurement signal MC changes according to the characteristics of the path including the transmission line 30 at the frequency of the measurement signal MC. Therefore, the reception condition of the receiver 15 can be adjusted according to the state of the path including the transmission path 30. For example, the power consumption can be reduced by stopping the equalizer 41a included in the reception circuit 41 of the receiver 15 depending on the frequency characteristic of the measurement signal MC.

  (1-2) Each of the nodes 10 and 20 is configured to transmit a measurement signal MC having a frequency corresponding to a communication speed set by speed negotiation. Each node 10 and 20 communicates data and the like at a communication speed set by speed negotiation. Therefore, by transmitting the measurement signal MC having a frequency corresponding to the set communication speed, it is possible to measure the signal level that varies depending on the characteristics of the communication speed in the path including the transmission path 30, and for data communication. Transmitter 12 and receiver 15 can be adjusted to suit.

  (1-3) The receiver 15 decodes the notification signal RC transmitted from the node 20 to generate the determination signal CO2. The physical logic unit 11 of the node 10 adjusts the transmission condition of the transmitter 12 based on the determination signal CO2. For example, the amplitude of the transmission signal TX1 transmitted by the transmitter 12 is adjusted according to the state of the path including the transmission path 30. By reducing the amplitude of the transmission signal TX1, the power consumption in the transmitter 12 can be interrupted. Further, by increasing the amplitude of the transmission signal TX1, stable communication can be performed between the nodes 10 and 20.

  (1-4) The transmitter 12 includes a de-emphasis 12a that shapes the waveform of the transmission signal TX1. The transmitter 12 transmits a transmission signal TX1 having an amplitude corresponding to the amplitude control signal CA1 output from the physical logic unit 11. The physical logic unit 11 determines the priority of amplitude adjustment of the transmitter 12 and adjustment of the operation state of the de-emphasis 12a based on the determination signal CO1. For example, when the difference value (amplitude difference) AW (logarithmic value) is equal to or greater than a predetermined threshold value Dth, the physical logic unit 11 prioritizes the adjustment to turn off the de-emphasis 12a over the amplitude adjustment of the transmitter 12. Do it. When the difference value AW is 0 or more and less than the threshold value Dth, the amplitude adjustment of the transmitter 12 is performed with priority over the on / off of the de-emphasis 12a. By adjusting in this way, the transmitter 12 can be optimally adjusted according to the state of the path including the transmission path 30.

(Second embodiment)
Hereinafter, the second embodiment will be described with reference to FIGS.
In addition, in this embodiment, the same code | symbol is attached | subjected about the same member as said 1st embodiment, and all or one part of description is abbreviate | omitted.

  As shown in FIG. 15, the communication device 80 and the communication device 90 are connected to each other via a transmission line 30 so as to communicate with each other. The communication device 80 is provided in the personal computer 1 shown in FIG. 1, for example, and the communication device 90 is provided in the storage device 2 shown in FIG. 1, for example. Hereinafter, the communication apparatus will be described as a node.

The first node 80 includes a physical logic unit 81, a transmitter 12, a transmission termination unit 13, a reception termination unit 14, and a receiver 85.
The physical logic unit 81 of the first node 80 supplies a transmission signal TS1 based on transmission data transmitted from the personal computer 1 shown in FIG. The transmitter 12 outputs a signal TX1 based on the transmission signal TS1. The signal TX1 is supplied to the second node 20 via the transmission termination unit 13 and the transmission path 30. The receiver 85 supplies the received signal RS1 based on the signal RX1 received via the reception termination unit 14 to the physical logic unit 81. The physical logic unit 81 receives the reception signal RS1 output from the receiver 85, and generates reception data obtained by encoding the reception signal RS1. The storage device 2 illustrated in FIG. 1 stores received data.

The second node 90 includes a physical logic unit 91, a transmitter 22, a transmission termination unit 23, a reception termination unit 24, and a receiver 95.
The physical logic unit 91 of the second node 90 supplies the transmitter 22 with a transmission signal TS2 based on transmission data transmitted from the storage device 2 shown in FIG. The transmitter 22 outputs a signal TX2 based on the transmission signal TS2. The signal TX2 is supplied to the second node 90 via the transmission termination unit 23 and the transmission path 30. The receiver 95 supplies a reception signal RS2 based on the signal RX2 received via the reception termination unit 24 to the physical logic unit 91. The physical logic unit 91 receives the reception signal RS2 output from the receiver 95, and generates reception data obtained by encoding the reception signal RS2. A personal computer 1 shown in FIG. 1 processes received data.

The physical logic units 81 and 91 adjust the transmitters 12 and 22 and the receivers 15 and 25 during the period from recognition of the nodes 80 and 90 to data communication.
FIG. 17 shows an example of state transition from recognition of the nodes 80 and 90 to data communication.

  The first state ST11 is a tone detection state. Each of the nodes 80 and 90 enters the first state ST11 when the power is turned on, for example. In the first state ST11, each of the nodes 80 and 90 transmits a tone signal. When each of the nodes 80 and 90 detects the tone signal, it transmits a signal for response. When the first node 80 detects a response signal transmitted by the second node 90, the first node 80 transits from the first state ST11 to the second state ST12. Similarly, the second node 90 that has detected a response signal transmitted by the first node 80 transitions from the first state ST11 to the second state ST12.

  The second state ST12 is a state for setting a communication state. The communication state setting is a state in which communication speed setting (speed negotiation), signal measurement, and order determination are performed. Each of the nodes 80 and 90 sets the communication speed with the node whose connection has been confirmed. Both nodes 80 and 90 transmit a transmission signal including information (speed code) according to the communication speed of each other, thereby matching the communication speed of each other. Each node 80 and 90 transmits and receives a signal for adjustment to each other. Each of the nodes 80 and 90 measures a signal for adjustment, and transmits the measurement result to each other's nodes 80 and 90.

  The third state ST13 is a state in which optimization is performed. Each of the nodes 80 and 90 adjusts the transmitter and the receiver based on the measurement result of the own node and the measurement result of the counterpart node.

  The fourth state ST14 is a state in which synchronization is performed, and the reception circuit performs synchronization with the reception signal based on the synchronization signal. When synchronization is established, each of the nodes 80 and 90 communicates with the partner node with which the connection has been established at the communication speed set in the second state ST12.

Next, various signals transmitted and received between both nodes 80 and 90 will be described.
Both nodes 80 and 90 transmit a tone signal TN shown in FIG. 8A in order to confirm the connection of the communication partner. The nodes 80 and 90 that have received the tone signal TN transmit the tone signal TN and a reception notification signal (acknowledge signal ACK) for response. When the nodes 10 and 20 detect the acknowledge signal ACK, the nodes 10 and 20 determine that the communication partner node is connected, and transition from the first state ST11 to the second state ST12 shown in FIG.

  FIG. 18A shows a signal transmitted to set a communication state in the second state ST2. This signal includes a tone signal TN, a speed code TSC, and a measurement signal MCa. Each of the nodes 80 and 90 transmits the measurement signal MCa at a predetermined timing in the period from the transmission of the speed code TSC to the next tone signal TN. For example, each of the nodes 80 and 90 starts transmitting the measurement signal MCa after a predetermined time D3 has elapsed from the timing of transmitting the last bit of the speed code TSC. The nodes 80 and 90 transmit the bits B1 to B3 of the measurement signal MCa every predetermined time D3. The measurement signal MCa is a predetermined number (for example, 3 bits) of signals. The 3-bit measurement signal MCa indicates a measurement period. That is, the measurement signal MCa of the present embodiment is equal to the first bit B1 to the third bit B3 of the measurement signal MC of the first embodiment.

  FIG. 18B shows a signal transmitted to set a communication state in the second state ST2. This signal includes a tone signal TN, an acknowledge signal ACK, a speed code TSC, and a notification signal RCa. Each node 80, 90 includes a speed code TSC and a measurement signal MCa. Each of the nodes 80 and 90 transmits the notification signal RCa at a predetermined timing in the period from the transmission of the speed code TSC to the next tone signal TN. For example, each of the nodes 80 and 90 starts transmitting the notification signal RCa after a predetermined time D3 has elapsed from the timing of transmitting the last bit of the speed code TSC. The notification signal RCa is a predetermined number (for example, 3 bits). This 3-bit notification signal RCa is used to notify the result of measuring the change in signal level by the measurement signal MCa. That is, the notification signal RCa of the present embodiment is equal to the first bit to the third bit B3 of the notification signal RC of the first embodiment.

Next, the outline of the receiver 85 will be described with reference to FIG. In FIG. 16, the transmission termination unit 13 and the reception termination unit 14 shown in FIG. 15 are omitted.
As shown in FIG. 16, the receiver 85 includes a receiving circuit 41, a tone signal detector (denoted as a TN / TSC detector) 102, a measurement signal detector 103, an amplitude measuring device 44, and an amplitude value determining device 105. .

  When the tone signal detector 102 detects the tone signal TN, the tone signal detector 102 outputs an H level detection signal RTa for a predetermined period from the start timing of the tone signal TN. The period during which the H level detection signal RTa is output, that is, the H level pulse width includes a period during which the tone signal TN, the acknowledge signal ACK, and the speed code TSC are transmitted. For example, each of the nodes 80 and 90 outputs the detection signal RTa at the H level during the period D4 shown in FIG. This period D4 is equal to the period from the start of transmission of the tone signal TN until the measurement signal MCa shown in FIG. That is, each of the nodes 80 and 90 outputs the detection signal RTa at the H level from the start of transmission of the tone signal TN until the measurement signal MCa is output.

  The measurement signal detector 103 generates a detection signal RM corresponding to the measurement signal MC and the notification signal RCa based on the detection signal RTa and the detection signal SGD. The measurement signal detector 103 outputs an L level detection signal RM in response to the H level detection signal RTa. In addition, the measurement signal detector 103 outputs a detection signal RM based on the detection signal SGD corresponding to the measurement signal MC in response to the L level detection signal RTa. Specifically, as shown in FIGS. 20 and 21, the measurement signal detector 103 outputs an H level detection signal RM during the detection signal SGD corresponding to the measurement signal MC. For example, the measurement signal detector 43 counts the number of pulses of the detection signal SGD or includes a counter, and outputs the detection signal RM according to the count value after the detection signal RT changes from H level to L level.

  The amplitude measuring device 44 performs a measurement operation in response to the mode signal MD [01]. For example, as shown in FIG. 20, the amplitude measuring device 44 measures the amplitude of the reception signal RS1 in response to the detection signal SGD at the H level during the period when the detection signal RM is at the L level. The amplitude measuring device 44 outputs an amplitude value AT equal to the measured value. Further, the amplitude measuring device 44 measures the amplitude of the reception signal RS1 in response to the detection signal SGD at the H level during the period when the detection signal RM is at the H level, and outputs an amplitude value AM equal to the measurement value.

  The amplitude measuring device 44 performs a receiving operation in response to the mode signal MD [10]. In this reception operation, the amplitude measuring device 44 outputs a signal AT having a level equal to the detection signal RM output from the measurement signal detector 43.

  As shown in FIG. 20, the amplitude value determiner 105 compares the amplitude value AT and the amplitude value AM in response to the detection signal SGD at the H level when the mode signal MD [01], and determines according to the level fluctuation. A signal CO1 is generated. The amplitude value determiner 105 calculates the difference value AW of the amplitude value AM of the measurement signal MC with respect to the amplitude value AT of the tone signal TN, for example, similarly to the amplitude value determiner 45 of the first embodiment. Then, the amplitude value determiner 105 compares the difference value AW with the determination threshold value Dth, and generates a determination signal CO1 according to the comparison result. The determination threshold value Dth is set to “3 dB”, for example. The amplitude value determiner 105 generates a determination signal CO1 according to the sign of the difference value (amplitude difference) AW and the comparison result between the difference value AW (absolute value) and the determination threshold value Dth.

  Further, as shown in FIG. 20, the amplitude value determiner 105 generates a determination signal CO2 corresponding to the notification signal RC received from the communication partner when the mode signal MD [10]. The amplitude value determination unit 105 takes in the three detection signals SGD in response to the H level signal AT output from the amplitude measurement unit 44, and generates a determination signal CO2 of a bit string corresponding to the detection signal SGD.

  Next, a schematic processing flow of amplitude measurement and measurement result notification between both nodes 80 and 90 will be described with reference to FIG. Since the processes executed by the nodes 80 and 90 are the same, the operation of the node 80 will be mainly described, and the operation of the node 90 will be described as necessary.

  In step 111, the first node 80 receives the tone signal TN and the speed code TSC. Next, in step 112, the first node 80 measures the amplitudes of the received tone signal TN and speed code TSC. In step 113, the first node 80 determines the communication speed based on the received speed code TSC. In FIG. 19, step 113 is shown to be executed after step 112, but the processing in steps 112 and 113 includes, for example, the receiver 85 (amplitude measuring device 44) and physical logic shown in FIG. 16. It is executed in parallel by the unit 81.

  Next, in step 114, the first node 80 determines whether or not there is a measurement signal MCa following the speed code TSC. When there is no measurement signal MCa, the first node 80 ends the communication state setting process. In this case, the first node 80 transitions to step ST4 shown in FIG. 17 and performs synchronization. In step 114, when the first node 80 detects the measurement signal MC following the speed code TSC, the first node 80 proceeds to step 115. In step 115, the first node 80 measures the amplitude of the measurement signal MCa.

  Next, in step 116, the first node 80 calculates a difference value (amplitude difference) AW based on the amplitude value AT of the tone signal TN and the speed code TSC and the amplitude value AM of the measurement signal MCa. Next, in step 117, the first node 80 generates a determination signal CO1 corresponding to the difference value AW. In step 118, the first node 80 transmits a transmission signal TX1 including the generated determination signal CO1. Next, in step 119, the first node 80 determines whether or not the determination signal CO2 is received from the second node 90 that is the communication partner. The first node 80 executes Step 119, that is, waits until receiving the determination signal CO2. Then, when receiving the determination signal CO2, the first node 80 ends the amplitude measurement and measurement result notification processing.

  In the present embodiment, as shown in FIG. 18A, each node 80, 90 transmits a speed code TSC and a measurement signal MCa following the tone signal TN. Each node 80 and 90 measures the amplitude of the tone signal TN and the 6-bit speed code TSC, and obtains an amplitude value AT. Each node 80 and 90 measures the amplitude of the 3-bit measurement signal MCa to obtain an amplitude value AM. As shown in FIG. 18B, an acknowledge signal ACK, a speed code TSC, and a notification signal RCa are transmitted following the tone signal TN.

The operation of the node 80 will be described.
As shown in FIG. 20, in the node 80, the reception circuit 41 of the receiver 85 generates the detection signal SGD in response to the reception signal RX1. The tone signal detector 102 generates a detection signal RTa based on the reception signal RX1. The measurement signal detector 103 generates a detection signal RM based on the reception signal RS1 and the detection signal SGD output from the reception circuit 41 and the detection signal RTa output from the tone signal detector 102. The amplitude measuring device 44 outputs an amplitude value AT obtained by measuring the amplitude of the tone signal TN and the speed code TSC included in the reception signal RX1 (RS1) based on the detection signal SGD and the detection signal RM. Further, the amplitude measuring device 44 outputs an amplitude value AM obtained by measuring the amplitude of the measurement signal MCa included in the reception signal RX1 (RS1) based on the detection signal SGD and the detection signal RM. Based on the detection signal SGD, the amplitude value determiner 105 compares the amplitude value AT and the amplitude value AM to generate a determination signal CO1.

  The physical logic unit 81 transmits the determination signal CO1 by including the communication speed of the own node set based on the received speed code TSC in a signal (tone) transmitted to the node 90 of the communication partner. That is, the physical logic unit 81 compares the operation mode corresponding to the speed code TSC measured in FIG. 20 with the operation mode of its own node, and determines an operation mode in which both nodes 80 and 90 can communicate with each other. Then, as illustrated in FIG. 21, the physical logic unit 81 causes the transmitter 12 to transmit the transmission signal TX1 including the speed code TSC corresponding to the determined operation mode. Subsequently, the physical logic unit 81 causes the transmitter 12 to transmit a 3-bit notification signal RCa corresponding to the determination signal CO1.

  As illustrated in FIG. 21, the physical logic unit 81 causes the transmitter 12 to transmit a tone signal TN and an acknowledge signal ACK. Subsequently, the physical logic unit 81 causes the transmitter 12 to transmit the speed code TSC corresponding to the operation mode of the own node 80. Subsequently, the physical logic unit 81 causes the transmitter 12 to transmit a 3-bit notification signal RCa corresponding to the determination signal CO1.

  The physical logic unit 81 transmits a determination signal CO1 to the communication partner node 90. That is, as shown in FIG. 21, the physical logic unit 81 causes the transmitter 12 to transmit the tone signal TN and the acknowledge signal ACK. Subsequently, the physical logic unit 81 causes the transmitter 12 to transmit the speed code TSC corresponding to the operation mode of the own node 80. Subsequently, the physical logic unit 81 causes the transmitter 12 to transmit a 3-bit notification signal RCa corresponding to the determination signal CO1 ([110] in FIG. 21).

  The physical logic unit 81 causes the transmitter 12 to transmit the transmission signal TX1 including the measurement signal MCa. The communication partner node 90 transmits a signal including the notification signal RCa corresponding to the result of measuring the tone signal TN, the speed code TSC, and the measurement signal MCa included in the received signal. Therefore, as shown in FIG. 21, the receiver 85 receives the reception signal RX1 including the notification signal RCa. This reception signal RX1 includes a speed code TSC corresponding to the operation mode of the node 90 of the communication partner. Therefore, the physical logic unit 81 determines the communication speed with the communication partner node 90 based on the speed code TSC. The receiver 85 decodes the notification signal RCa included in the reception signal RX1 to generate a determination signal CO2 ([101] in FIG. 21).

As described above, according to this embodiment, in addition to the effects of the first embodiment, the following effects can be obtained.
(2-1) Each node 80, 90 transmits a speed code TSC for setting the communication speed of each node 80, 90 following the tone signal TN, and the measurement signal MCa, notification following the speed code TSC. The signal RCa is transmitted. In the communication system including the nodes 80 and 90, for example, when communication is interrupted by disconnection of the transmission path 30 connecting the nodes, the communication speed between the nodes is determined after performing a bus reset and recognizing the connected nodes. . Each node included in the communication system can suppress the bus reset and resume the communication after confirming the communication speed when the communication temporarily stops due to noise or the like with respect to the signal transmitted through the transmission path 30. In such a communication system, by transmitting the speed code TSC and the measurement signal MCa or the notification signal RCa between the two tone signals TN, the amplitude measurement of the measurement signal MCa is performed in the state ST2 in which the communication speed is set. Then, the measurement result can be notified. Accordingly, it is possible to restart the communication in a short time, that is, the time required to restart the communication.

  (2-2) The receiver 85 measures the amplitudes of the tone signal TN and the speed code TSC, and generates an amplitude value AT. Therefore, the amplitude value AT corresponding to the characteristics in the frequency band including the frequencies of the tone signal TN and the speed code TSC can be stably measured without being affected by, for example, noise.

In addition, you may implement the said embodiment in the following aspects.
The 1T pattern that repeats “1” and “0” is used as the measurement signals MC and MCa for detecting a change in signal level, but other signals may be used. For example, a K28.5 pattern of 8b10b encoding or a pseudorandom bit stream (PRBS) may be used. By using these patterns, it is possible to perform measurement in consideration of the influence of waveform amplitude due to intersymbol interference. Further, one of 1T patterns to 5T patterns included in the communication data may be used.

  Also, two measurement signals having different patterns may be used. For example, the tone signal TN, the K28.5 pattern first measurement signal, and the 1T pattern second measurement signal are used. The amplitude of the first measurement signal with the K28.5 pattern changes according to the characteristics of the lower frequency band as compared with the second measurement signal with the 1T pattern. For example, the amplitude of the first measurement signal (K28.5) is larger than the amplitude of the tone signal TN, and the amplitude of the second measurement signal (1T) is larger than the amplitude of the first measurement signal (TN <K28.5). In the case of <1T), for example, the gain at high frequency is lowered in the equalizer (EQ) included in the receiver. The amplitude of the second measurement signal (1T) is larger than the amplitude of the tone signal TN, and the amplitude of the first measurement signal (K28.5) is larger than the amplitude of the second measurement signal (TN <1T <K28). In the case of .5), for example, a gain at a low frequency is lowered in an equalizer (EQ) included in the receiver. The amplitude of the second measurement signal (1T) is smaller than the amplitude of the tone signal TN, and the amplitude of the first measurement signal (K28.5) is smaller than the amplitude of the second measurement signal (K28.5 <1T). In the case of <TN), for example, a gain at a low frequency is increased in an equalizer (EQ) included in the receiver. Also, the amplitude of the first measurement signal (K28.5) is smaller than the amplitude of the tone signal TN, and the amplitude of the second measurement signal (1T) is smaller than the amplitude of the first measurement signal (1T <K28.5). In the case of <TN), for example, the gain at high frequency is increased in the equalizer (EQ) included in the receiver. Note that it is desirable to perform the equalizer adjustment with priority over the de-emphasis adjustment.

  -You may change suitably the frequency of the notification signals RC and RCa which notify a measurement result. For example, the frequency is the same as that of the tone signal TN. By setting such a frequency, the notification signals RC and RCa can be reliably received. When the same frequency is used for the tone signal TN, for example, a signal may be used as a notification signal RC, RCa after a predetermined time has elapsed since the reception of the tone signal TN using a timer.

The number of bits of the measurement signals MC and MCa may be changed as appropriate, such as 2 bits or less or 4 bits or more.
The number of bits of the notification signals RC and RCa may be changed as appropriate, such as 2 bits or less or 4 bits or more.

The timing for transmitting the measurement signals MC and MCa may be changed as appropriate.
-You may change suitably the timing which transmits notification signal RC, RCa.
-You may change the signal in the receivers 15 and 85 suitably. For example, in the receiver 15 shown in FIG. 6, the detection signal RT may be supplied to the amplitude measuring device 44 and the amplitude value AT may be output in response to the detection signal RT at the H level.

  In each of the above embodiments, the change in the signal level in the path is detected using two signals having different frequencies such as the tone signal TN and the measurement signals MC and MCa, but three or more different frequencies are used. You may make it detect the change of a signal level using a signal.

10, 20 Communication device (node)
30 Transmission path 11, 21 Physical logic unit 12, 22 Transmitter 12a De-emphasis 15, 25 Receiver 41 Receiver circuit 41a Equalizer 42, 102 Tone signal detector 43, 103 Measuring signal detector 44 Amplitude measuring device 45, 105 Amplitude value determination unit 81, 91 Physical logic unit 85, 95 Receiver CO1, CO2 determination signal TN tone signal ACK reception notification signal (acknowledge signal)
TSC speed code (speed code)
MC, MCa Measurement signal RC, RCa Notification signal

Claims (11)

A transmitter for transmitting a first transmission signal of a first frequency and a second transmission signal of a second frequency different from the first frequency;
A receiver that receives a notification signal according to a result of comparing the amplitude value of the first transmission signal and the amplitude value of the second transmission signal and generates a determination signal;
An adjustment circuit for adjusting a transmission condition of the transmitter based on the determination signal;
A communication device. The amplitude of the first received signal at the first frequency and the amplitude of the second received signal at the second frequency different from the first frequency are measured, and the amplitude value of the first received signal and the amplitude of the second received signal are measured. A receiver that generates a determination signal according to a result of comparing the amplitude value;
An adjustment circuit for adjusting a reception condition of the receiver based on the determination signal;
A communication device. The adjustment circuit causes a notification signal corresponding to the determination signal to be transmitted from a transmitter following the first transmission signal of the first frequency,
The communication device according to claim 2.   The communication device according to any one of claims 1 to 3, wherein the second frequency is a frequency corresponding to a communication speed set by the two communication devices. The transmitter includes a waveform shaping circuit that shapes a waveform of a signal to be transmitted;
The adjustment circuit, based on the determination signal, to set the priority of the amplitude adjustment of the signal transmitted by the transmitter and the adjustment of the operation state of the waveform shaping circuit;
The communication apparatus according to claim 1. The transmitter transmits the first transmission signal with a predetermined amplitude;
The adjusting circuit adjusts an amplitude of the second transmission signal in accordance with the determination signal;
The communication device according to claim 1 or 5. The transmitter is
Transmitting the first transmission signal in a predetermined cycle;
Between the two first transmission signals, the two communication devices transmit a speed code for setting a communication speed with each other, and the second transmission signal;
The communication device according to claim 1, 5 or 6. The receiver includes an amplifier circuit that amplifies a signal included in a predetermined band of the received signal;
The adjustment circuit adjusts an operating state of the amplifier circuit based on the determination signal;
The communication apparatus according to claim 1 or 2, characterized by the above. A communication system including a first communication device and a second communication device connected to each other,
The first communication device and the second communication device are respectively
A transmitter for transmitting a first transmission signal of a first frequency and a second transmission signal of a second frequency different from the first frequency;
Receiving a first notification signal corresponding to a result of comparing the amplitude value of the first transmission signal and the amplitude value of the second transmission signal, generating a first determination signal, and generating a first determination signal; A receiver that compares the amplitude value of the first received signal with the amplitude value of the second received signal at the second frequency to generate a second determination signal;
A notification signal corresponding to the second determination signal is transmitted from the transmitter following the first transmission signal, a transmission condition of the transmitter is adjusted based on the first determination signal, and the second An adjustment circuit for adjusting the reception condition of the receiver based on the determination signal of
Including,
A communication system characterized by the above. Transmitting a first transmission signal of a first frequency from a transmitter and a second transmission signal of a second frequency different from the first frequency;
A notification signal corresponding to a result of comparing the amplitude value of the first transmission signal and the amplitude value of the second transmission signal is received by a receiver to generate a determination signal,
Adjusting transmission conditions of the transmitter based on the determination signal;
A method for adjusting a communication device characterized by the above. The amplitude of the first received signal of the first frequency received by the receiver and the amplitude of the second received signal of the second frequency different from the first frequency are measured, and the amplitude value of the first received signal and the amplitude Generating a determination signal according to the result of comparing the amplitude value of the second received signal;
Adjusting reception conditions of the receiver based on the determination signal;
A method for adjusting a communication device characterized by the above.