WO2011018833A1 - Communication device - Google Patents

Communication device Download PDF

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Publication number
WO2011018833A1
WO2011018833A1 PCT/JP2009/064130 JP2009064130W WO2011018833A1 WO 2011018833 A1 WO2011018833 A1 WO 2011018833A1 JP 2009064130 W JP2009064130 W JP 2009064130W WO 2011018833 A1 WO2011018833 A1 WO 2011018833A1
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WO
WIPO (PCT)
Prior art keywords
stream signal
transmission
data
preamble
adaptive equalizer
Prior art date
Application number
PCT/JP2009/064130
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French (fr)
Japanese (ja)
Inventor
友博 如南
Original Assignee
ティーオーエー株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ティーオーエー株式会社 filed Critical ティーオーエー株式会社
Priority to JP2011526650A priority Critical patent/JP5367823B2/en
Priority to PCT/JP2009/064130 priority patent/WO2011018833A1/en
Publication of WO2011018833A1 publication Critical patent/WO2011018833A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
    • H04L25/03019—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception
    • H04L25/03057—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception with a recursive structure

Definitions

  • the present invention relates to a communication apparatus, and more particularly, communication that performs half-duplex communication with a counterpart device connected via a transmission medium and performs waveform adjustment on a stream signal on the transmission medium using an adaptive equalizer. It relates to the improvement of the apparatus.
  • a communication system that relays transmission / reception of image data and control data between an input device such as a monitoring camera and an output device such as a recording device or a monitor device to communication devices connected to each other by a coaxial cable.
  • an input device such as a monitoring camera
  • an output device such as a recording device or a monitor device
  • communication devices connected to each other by a coaxial cable.
  • the attenuation characteristic deteriorates and not only the signal is attenuated according to the transmission distance but also the transition time of the data bit becomes long and the signal waveform It has been known for a long time.
  • An adaptive equalizer is an adaptive equalizer that automatically adjusts the gain for each frequency component according to the signal state, measures the data bit transition time for the signal on the transmission medium, and adjusts the gain based on the measurement result.
  • the present invention has been made in view of the above circumstances, and can increase the transmission distance without degrading the communication quality when communicating with a counterpart device connected via a transmission medium in a half-duplex manner.
  • An object of the present invention is to provide a communication device that can suppress erroneous recognition of received data after switching from a transmission state to a reception state.
  • a communication device is a communication device that communicates with a counterpart device connected via a transmission medium in a half-duplex manner while alternately switching a transmission phase and a reception phase, and is stored in a transmission buffer.
  • An adaptive equalizer that adjusts a waveform of a stream signal; and a reception unit that extracts reception data from the stream signal after waveform adjustment, the transmission unit includes a preamble stream signal generation unit that generates a preamble stream signal; In the stream signal transmission phase, the transmission means transmits the preamble stream. Transmission of the data stream signal is started, and in the reception phase of the data stream signal, the adaptive equalizer has waveforms for the preamble stream signal and the data stream signal input from the counterpart device. Adjustments are made and the receiving means is configured to extract received data from a data stream signal input via the adaptive equalizer.
  • the data stream signal is input to the adaptive equalizer after stabilizing the feedback operation of the adaptive equalizer of the counterpart device by the preamble stream signal. can do.
  • the reception data is extracted from the stream signal after switching from the transmission phase to the reception phase. False recognition can be suppressed.
  • the adaptive equalizer includes a variable equalizer to which a stream signal from the counterpart device is input, and a transition time measurement to which an output of the variable equalizer is input. And an integrator for controlling the variable equalizer based on the measurement result of the transition time by the transition time measuring device, wherein the preamble stream signal generating means converts a part of the output of the variable equalizer to the transition A preamble stream signal having a time length corresponding to a control loop that is sequentially processed by the time measuring device and the integrator and fed back to the variable equalizer is generated.
  • the feedback operation including the control loop of the adaptive equalizer can be sufficiently stabilized.
  • the communication apparatus is configured such that the preamble stream signal generation means generates a preamble stream signal having a time length longer than the time constant of the integrator.
  • the preamble stream signal generation means generates a preamble stream signal having a time length longer than the time constant of the integrator in the first transmission phase, and then The transmission phase is configured to generate a preamble stream signal having a shorter time length than the time constant.
  • a preamble stream signal and a data stream signal sequentially transmitted to the counterpart device via the transmission medium are both input to the adaptive equalizer,
  • the adaptive equalizer is configured to perform waveform adjustment even during transmission of the stream signal.
  • the preamble stream signal and the data stream signal that are sequentially transmitted to the counterpart device via the transmission medium are input to the adaptive equalizer of the local station, and the waveform adjustment is performed.
  • the feedback operation of the adaptive equalizer can be stabilized. Therefore, when data stream signal transmission is started before the counterpart device, the data stream signal is transmitted after receiving the data stream signal from the counterpart device, compared to the preamble stream signal added to the data stream signal. In this case, the time length of the preamble stream signal added to the data stream signal can be shortened.
  • the feedback operation of the adaptive equalizer of the local station is stabilized by transmitting the preamble stream signal and the data stream signal, when transmitting the data stream signal after receiving the data stream signal from the counterpart device, the data stream signal Even if the time length of the preamble stream signal added to is shortened, the feedback operation of the adaptive equalizer of the counterpart device can be sufficiently stabilized.
  • the communication device of the present invention since the data stream signal is input after the feedback operation of the adaptive equalizer is stabilized by the preamble stream signal, the reception data is extracted from the stream signal after switching from the transmission phase to the reception phase. Misrecognition can be suppressed. Therefore, it is possible to increase the transmission distance without degrading the communication quality when communicating with the counterpart device connected via the transmission medium in the half-duplex method, and the received data after switching from the transmission state to the reception state. Can be prevented from being erroneously recognized.
  • FIG. 1 is a system diagram showing a configuration example of a communication system including a communication device according to an embodiment of the present invention, and a monitoring system 100 is shown as an example of the communication system. It is the block diagram which showed one structural example of communication apparatus 20a, 20b of FIG. It is the figure which showed the example of 1 structure of the adaptive equalizer 25 in the communication apparatuses 20a and 20b of FIG. It is the figure which showed an example of the transmission / reception operation
  • FIG. 2 is a diagram showing an example of a transmission / reception operation in the monitoring system 100 of FIG.
  • FIG. 1 shows a case where there is data accumulation exceeding a certain level in the transmission buffer 23.
  • 2 is a timing chart showing an example of a transmission / reception operation between communication devices 20a and 20b in the monitoring system 100 of FIG.
  • FIG. 3 is a diagram illustrating an example of a transmission operation in the communication devices 20a and 20b of FIG. 2, in which a stream signal transmitted to the counterpart device via the coaxial cable 30 is illustrated.
  • 3 is a flowchart showing an example of an operation at the time of transmission / reception in the communication devices 20a and 20b of FIG. It is the figure which showed an example of the transmission / reception operation
  • FIG. 1 is a system diagram showing a configuration example of a communication system including a communication device according to an embodiment of the present invention, and a monitoring system 100 is shown as an example of the communication system.
  • the monitoring system 100 is a communication system that relays data transmission / reception between physically separated devices to the communication devices 20a and 20b, and image data and control data between the communication devices 20a and 20b connected to each other via a transmission medium. Are transmitted and received in a half-duplex manner.
  • communication devices 20a and 20b are connected via a coaxial cable 30.
  • the camera 11 is connected to one communication device 20a via a LAN (local area network) 12, and the monitor device 13 and the recording device 14 are connected to the other communication device 20b via the LAN 12.
  • LAN local area network
  • the camera 11 is an imaging device that is installed on a wall or ceiling of a building and shoots a monitoring area around the installation location to generate image data.
  • the image data generated by the camera 11 is serially transmitted to the communication device 20a via the LAN 12.
  • the communication device 20a to which the camera 11 is connected performs bi-directional communication with the communication device 20b to which the monitor device 13 and the recording device 14 are connected via a single coaxial cable 30 in a half-duplex manner.
  • Control data for controlling 11 is serially transmitted.
  • the monitor device 13 is a display device that displays a monitor video on the screen based on image data from the camera 11.
  • the recording device 14 is a recording device that records image data from the camera 11 on an HDD or the like.
  • the communication devices 20a and 20b are connected to an input device such as the camera 11 and an output device such as the monitor device 13 via the LAN 12, and to the other device connected via the coaxial cable 30 and image data or Send and receive control data.
  • Image data and control data are transmitted and received on the coaxial cable 30 as a data stream signal composed of continuous data bits.
  • the communication devices 20a and 20b perform half-duplex communication by alternately repeating transmission and reception of data stream signals with the counterpart device.
  • FIG. 2 is a block diagram illustrating a configuration example of the communication devices 20a and 20b in FIG.
  • the communication devices 20a and 20b include a LAN I / F 21, a buffer control unit 22, a transmission buffer 23, a transmission unit 24, an adaptive equalizer 25, and a reception unit 26.
  • the LAN I / F 21 is a communication control unit that is connected to the LAN 12 and communicates with other devices on the LAN 12.
  • the buffer control unit 22 performs an operation of buffering transmission data using the transmission buffer 23. Specifically, transmission data sequentially input from other devices via the LAN I / F 21 is written into the transmission buffer 23, and the transmission buffer is transmitted according to the transfer rate and transmission / reception state of data transmission / reception performed via the coaxial cable 30. The transmission data is read from 23 and output to the transmission unit 24.
  • the transmission buffer 23 is a storage device that temporarily holds transmission data by a FIFO (first-in first-out) method.
  • the transmission unit 24 is a transmitter including a data stream signal generation unit 24a, a preamble stream signal generation unit 24b, and a transmission control unit 24c, and transmits a data stream signal or a preamble stream signal including transmission data to a counterpart device via the coaxial cable 30. Send.
  • the data stream signal generation unit 24a performs an operation of generating a data stream signal composed of continuous data bits based on the transmission data read from the transmission buffer 23 by the buffer control unit 22 and outputting the data stream signal to the transmission control unit 24c. ing.
  • the data stream signal is a bit stream signal composed of an array of a plurality of data bits indicating “0” or “1”.
  • the preamble stream signal generation unit 24b performs an operation of generating a preamble stream signal having a predetermined bit arrangement and outputting the preamble stream signal to the transmission control unit 24c.
  • This preamble stream signal is generated based on the response characteristic of the adaptive equalizer 25, and is constituted by a bit stream signal having a time length corresponding to the response time of the adaptive equalizer 25, for example.
  • the transmission control unit 24c When transmitting the data stream signal, the transmission control unit 24c starts transmitting the data stream signal after transmitting the preamble stream signal, and after receiving the stream signal, extracts the received data from the receiving unit 26. The operation to instruct is performed. Here, it is assumed that the transmission control unit 24c drives the signal line of the coaxial cable 30 so that transmission data is transmitted by the digital baseband transmission method.
  • the adaptive equalizer 25 is an adaptive cable equalizer that performs waveform adjustment on the stream signal on the coaxial cable 30 and outputs the stream signal after the waveform adjustment to the receiving unit 26.
  • the waveform adjustment of the stream signal is performed based on the transition time of the data bits.
  • the adaptive equalizer 25 amplifies the transmission loss of the coaxial cable 30, the distortion of the output waveform of the transmission unit 24, and the high-frequency component of the stream signal attenuated by the matching between the signal line and the reception unit 26, thereby reproducing the signal waveform at the time of transmission. be able to.
  • the waveform adjustment is performed for the preamble stream signal and the data stream signal input from the counterpart device via the coaxial cable 30. That is, at the time of data reception, the feedback operation for waveform adjustment in the adaptive equalizer 25 is stabilized by the preamble stream signal, and then the data stream signal is input to the adaptive equalizer 25.
  • both the preamble stream signal and the data stream signal that are sequentially transmitted to the counterpart device via the coaxial cable 30 are input to the adaptive equalizer 25 of the local station, and the adaptive equalizer is also transmitted during the transmission of these stream signals.
  • 25 performs waveform adjustment. That is, the adaptive equalizer 25 of its own station stabilizes the feedback operation by the preamble stream signal and the data stream signal even during data transmission in preparation for the next data reception.
  • the receiving unit 26 is a receiver that extracts received data from the stream signal after waveform adjustment by the adaptive equalizer 25 and outputs the received data to the LAN I / F 21. Transmission of received data to the LAN I / F 21 is performed based on an extraction instruction from the transmission control unit 24c.
  • the time length of the preamble stream signal to be added to the stream signal differs between when the transmission of the stream signal is started before the counterpart device and in other cases. Specifically, when transmission of a stream signal is started before the counterpart device, the stream signal is transmitted after receiving the stream signal from the counterpart device, compared to the preamble stream signal added to the stream signal. In this case, an operation for shortening the time length of the preamble stream signal added to the stream signal is performed.
  • the communication devices 20a and 20b enter a reception state, and then start transmission of a stream signal at random timing. That is, the preamble stream signal added to the bit stream signal transmitted after the second time is compared with the preamble stream signal added to the bit stream signal transmitted first through the coaxial cable 30 after the communication is started by turning on the power.
  • the time length is getting shorter. With this configuration, it is possible to reduce the time required for data transmission related to the second and subsequent transmissions.
  • the transmission unit 24 adds a flow control stream signal having a predetermined bit arrangement to the stream signal based on the data accumulation amount of the transmission buffer 23, and the data transmission amount based on the flow control stream signal from the counterpart device. The operation of controlling is performed.
  • the flow control stream signal is a bit stream signal composed of dummy data for flow control. For example, when the amount of data stored in the transmission buffer 23 is below a certain level during data transmission, the end of the data stream signal composed of transmission data To be added. In this case, in the transmission unit 24, if the reception unit 26 detects that the flow control stream signal is not added to the stream signal from the counterpart device, an operation for limiting the data transmission amount is performed.
  • the transmission unit 24 when transmission data is not accumulated in the transmission buffer 23 at the time of data transmission, an operation for transmitting only the preamble stream signal and the flow control stream signal to the counterpart device is performed.
  • this monitoring system 100 a bit stream signal composed of a preamble stream signal and a flow control stream signal is transmitted / received via the coaxial cable 30 even during a no-data period in which no transmission data exists in the transmission buffer 23.
  • the feedback operation of the adaptive equalizer 25 can be stabilized in preparation for data reception after the no-data period has elapsed.
  • FIG. 3 is a diagram illustrating a configuration example of the adaptive equalizer 25 in the communication devices 20a and 20b of FIG.
  • the adaptive equalizer 25 includes a signal input unit 42, a variable equalizer 43, a transition time measuring device 44 and an integrator 46.
  • the stream signal from the counterpart device is input to the input terminal 41, and the stream signal after the waveform adjustment based on the data bit transition time is output from the output terminal 45.
  • the signal input unit 42 includes a pull-up resistor and an operational amplifier, and performs an operation of amplifying the stream signal input to the input terminal 41 and outputting the amplified signal to the variable equalizer 43.
  • the variable equalizer 43 is an equalizer that can change the gain for each frequency component, and includes a differentiator 43a, a gain variable amplifier 43b, and an adder 43c.
  • the input signal is branched at the branching point, one is directly input to the adder 43c, and the other is input to the adder 43c via the differentiator 43a and the gain variable amplifier 43b.
  • the adder 43 c performs an operation of adding these signals and outputting them to the transition time measuring device 44.
  • the transition time measuring unit 44 includes a comparator 44a, a differentiator 44b, a full-wave rectifier 44c, and a subtractor 44d.
  • the output of the variable equalizer 43 is input to measure the transition time of the data bit, and the transition time measurement result. The operation of outputting the bit stream signal after waveform adjustment based on the above to the output terminal 45 is performed.
  • the comparator 44a is a quantizer that compares the signal level of the input signal from the adder 43c with a predetermined threshold, generates a signal of a predetermined level based on the comparison result, and outputs the signal to the output terminal 45.
  • the input signal to the comparator 44a is input to the subtractor 44d through the differentiator 44b and the full wave rectifier 44c.
  • the output signal of the comparator 44a is input to the subtractor 44d via the differentiator 44b and the full wave rectifier 44c.
  • the subtractor 44d performs an operation of subtracting these signals and outputting them to the integrator 46.
  • the integrator 46 includes an amplifier 46a, a resistance element 46b, and a capacitor 46c.
  • the integrator 46 controls the gain variable amplifier 43b of the variable equalizer 43 based on the measurement result of the transition time by the transition time measuring unit 44, and sets the gain for each frequency component. The operation to adjust is performed.
  • the input signal from the subtractor 44d is amplified by the amplifier 46a, and is output to the control terminal of the gain variable amplifier 43b through the resistance element 46b and the capacitor 46c, each of which is grounded.
  • the gain is adjusted so that the transition time matches between the input signal to the comparator 44a and the output signal of the comparator 44a.
  • the time constant of the integrator 46 is a parameter that determines the response time of the adaptive equalizer 25, and is determined by the resistance value of the resistance element 46b and the capacitance value of the capacitor 46c.
  • the adaptive equalizer 25 performs a feedback operation including a control loop in which a part of the output of the variable equalizer 43 is sequentially processed by the transition time measuring device 44 and the integrator 46 and fed back to the variable equalizer 43.
  • the feedback operation for waveform adjustment in the adaptive equalizer 25 is a gain adjustment operation performed by the variable equalizer 43 using this control loop.
  • the following (1) and (2) are conceivable for the preamble stream signal generated by the preamble stream signal generation unit 24b immediately after power-on, during a no-data period, or during normal data transmission.
  • a time length corresponding to the response time of the adaptive equalizer 25, that is, a time length longer than the time constant of the integrator 46 A T1 preamble stream signal is generated.
  • a preamble stream signal having a time length T2 shorter than T1 is generated.
  • the data stream signal is transmitted after the feedback operation of the adaptive equalizer 25 is stabilized in the counterpart device by transmitting the preamble stream signal having the time length T1 prior to the data stream signal or the flow control stream signal. And a flow control stream signal can be received.
  • the preamble stream signal, the data stream signal, and the flow control stream signal transmitted during data transmission in the no-data period and the normal half-duplex method are also input to the adaptive equalizer 25 of the own station. That is, at the end of transmission of these stream signals, the feedback operation of the adaptive equalizer 25 of the own station is sufficiently stable.
  • the time length of the received preamble stream signal may be shorter than T1 when switching to the reception operation after the transmission of the preamble stream signal or the data stream signal is completed. Specifically, after the transmission of the stream signal is completed, a preamble stream signal having a time length T2 corresponding to a period from when switching to the reception operation to reception of the preamble stream signal from the counterpart device is generated.
  • the time T3 required to stabilize the feedback operation is shorter than the time constant of the integrator 46. short. Therefore, if the time length T2 is sufficiently longer than the time T3, the adaptive equalizer 25 of the own station can be stabilized by receiving the preamble stream signal having such a time length T2.
  • the transmission of the stream signal is started before the counterpart device and the preamble stream signal having the time length T1 is transmitted, and then the preamble stream is transmitted.
  • a preamble stream signal of time length T2 is generated.
  • the transmission of the stream signal is started before the counterpart device and the preamble stream signal of time length T1 is transmitted, and then the preamble stream signal Is transmitted, or when a preamble stream signal is transmitted after receiving a preamble stream signal of time length T1 from the counterpart device, a preamble stream signal of time length T2 is generated.
  • a preamble stream signal and a flow control stream signal are transmitted and received even during a no-data period. That is, the feedback operation of the adaptive equalizer 25 of the own station is always sufficiently stable at the end of transmission of these stream signals during the no-data period.
  • the time length of the preamble stream signal transmitted first may be shorter than T1.
  • a preamble stream signal having a time length T2 corresponding to a period from when switching to reception operation to reception of a preamble stream signal from a counterpart device is generated Is done.
  • FIG. 4 and 5 are explanatory diagrams schematically showing an example of the transmission / reception operation in the monitoring system 100 of FIG. 1, showing a half-duplex communication mode.
  • FIG. 4A shows a no-data period without transmission data.
  • the communication apparatus A transmits the flow stream stream signal 2 after transmitting the preamble stream signal 1.
  • the communication apparatus B receives these stream signals, and after the reception ends, starts transmission at a predetermined timing, and sequentially transmits the preamble stream signal 3 and the flow control stream signal 2. Such an operation is repeated during the no-data period.
  • This example shows a case where the communication apparatus A starts transmission of a stream signal before the communication apparatus B of the communication partner, and the first stream signal transmitted includes the second and subsequent stream signals.
  • a preamble stream signal 1 having a longer time length than the added preamble stream signal 3 is added.
  • the response time of the adaptive equalizer 25 is included in the stream signal transmitted first from the communication apparatus A.
  • a preamble stream signal 1 having a time length T1 longer than the time constant of the integrator 46 is added.
  • the preamble stream signal 3 having a time length T2 shorter than T1 is added.
  • FIG. 4B shows a case where there is data accumulation below a certain level in the transmission buffer 23.
  • the preamble stream signal 3, the data stream signal 4, and the flow control stream signal 2 are transmitted and received as the normal transmission mode. That is, after transmitting the preamble stream signal 3, the communication device A transmits the data stream signal 4 composed of the transmission data stored in the transmission buffer 23. And after transmitting all the transmission data in the transmission buffer 23, the flow control stream signal 2 is transmitted.
  • the communication apparatus B receives these stream signals, and after the reception ends, starts transmission at a predetermined timing, and sequentially transmits the preamble stream signal 3, the data stream signal 4, and the flow control stream signal 2. Such an operation is repeated during a period in which the amount of data stored in the transmission buffer 23 is below a certain level.
  • transmission data stored in the transmission buffer 23 is packetized, and a data stream signal 4 composed of data packets is transmitted and received.
  • One data packet is composed of, for example, a predetermined start code, transmission data of a certain size, and a predetermined end code, and such a plurality of data packets are transmitted in time series.
  • the preamble stream signals 1 and 3 and the flow control stream signal 2 are transmitted and received. For this reason, when data transmission / reception by the half-duplex method is started after a non-data period, the preamble stream signal 3 transmitted first by the communication apparatus A may have a time length T2 shorter than T1.
  • FIG. 5 shows a case where there is data accumulation exceeding a certain level in the transmission buffer 23 of the communication apparatus A.
  • the communication apparatus A transmits only the preamble stream signal 3 and the data stream signal 4 without adding the flow control stream signal 2.
  • the communication device B since the communication device B receives the stream signal from the communication device A and the flow control stream signal 2 is not added to the data stream signal 4, the data storage amount of the communication device A exceeds a certain level. The amount of data transmission is limited.
  • transmission data is transmitted for one packet regardless of the amount of data stored in the transmission buffer 23 of the own station.
  • only the preamble stream signal 3 and the flow control stream signal 2 are transmitted without adding transmission data. Such an operation is repeated during the period when the data accumulation amount of the transmission buffer 23 of one communication apparatus exceeds a certain level.
  • communication is started in a state in which transmission data is not accumulated in the transmission buffers 23 of the communication apparatuses A and B, and a preamble stream added to a stream signal transmitted first and then to a stream signal transmitted later
  • the preamble stream signal 1 having a longer time length than the signal 3 is added
  • communication may be started in a state where transmission data is accumulated in the transmission buffer 23 of any communication device. It is the same. That is, when communication is started in a state where transmission data is accumulated in the transmission buffer 23 of at least one communication device, the stream signal transmitted first is added to the stream signal transmitted thereafter. A preamble stream signal 1 having a longer time length than the preamble stream signal 3 is added.
  • FIG. 6 is a timing chart showing an example of a transmission / reception operation between the communication devices 20a and 20b in the monitoring system 100 of FIG. 1, and schematically shows a state transition state of each of the communication devices A and B.
  • the communication devices A and B are in a receiving state, and thereafter, if there is no reception from the counterpart device, transmission starts at a predetermined timing. In this example, the case where the communication apparatus A starts transmission before the communication apparatus B is shown.
  • the communication device A first transmits a preamble stream signal (time length T1), and then transmits a predetermined transmission marker.
  • the transmission marker is a bit stream signal composed of a predetermined communication control code. At this time, if transmission data is not accumulated in the transmission buffer 23, a flow control stream signal composed of dummy data is transmitted next.
  • the communication device A enters the standby state for switching to the reception state after the transmission of the flow control stream signal is completed, and enters the reception state after a predetermined time T has elapsed.
  • the communication device B enters a reception state while the communication device A transmits a bit stream signal. When reception of the bit stream signal from the communication device A ends, the communication device B starts transmission at a predetermined timing through a standby state.
  • the communication apparatus B first transmits a preamble stream signal (time length T2), and then transmits a predetermined transmission marker. If transmission data is accumulated in the transmission buffer 23, the communication device B transmits a data stream signal composed of transmission data next, transmits a transmission marker again, and then transmits a flow control stream signal composed of dummy data. To do. Then, after the transmission of the flow control stream signal is completed, the communication device B enters a standby state for switching to the reception state, and enters a reception state after a predetermined time T has elapsed.
  • the time length T1 of the preamble stream signal added by the communication device A to the first transmitted stream signal is compared with the time length T2 of the preamble stream signal added by the communication device B to the next transmitted stream signal. Is getting longer.
  • FIGS. 7A to 7D are diagrams showing an example of the transmission operation in the communication apparatuses 20a and 20b of FIG. 2, in which a bit stream signal transmitted to the counterpart device via the coaxial cable 30 is shown. ing.
  • FIG. 7A shows a bit stream signal transmitted first during a no data period
  • FIG. 7B shows a bit stream signal transmitted after the second time during the no data period. Has been.
  • the preamble stream signals 1 and 3, the transmission markers 5 and 6, and the flow control stream signal 2 are sequentially transmitted.
  • the bit stream signal transmitted first has a longer time than the preamble stream signal 3 added to the bit stream signal transmitted after the second time. A long preamble stream signal 1 is added.
  • the transfer rate is set to 60 Mbps, and the preamble stream signal 1 having a time length of about 12 ms is added to the bitstream signal transmitted first.
  • a preamble stream signal 3 having a time length of about 16 ⁇ s is added to the bit stream signal transmitted after the second time.
  • the bit arrangement of the preamble stream signals 1 and 3 is selected to be appropriate for stabilizing the feedback operation of the adaptive equalizer 25. For example, a bit arrangement is selected so that the learning effect by the integrator 46 lasts.
  • the feedback operation of the adaptive equalizer 25 of the own station can be stabilized in preparation for data reception.
  • the feedback operation of the adaptive equalizer 25 of the local station is stabilized by the transmission of the bit stream signal, when the bit stream signal is transmitted after receiving the bit stream signal from the counterpart device, the time length of the preamble stream signal
  • the feedback operation of the adaptive equalizer 25 of the counterpart device can be sufficiently stabilized even if the time is shortened.
  • FIG. 7 (c) shows a bit stream signal transmitted when there is data accumulation below a certain level in the transmission buffer 23.
  • the preamble stream signal 3, the transmission marker 6, the data stream signal 4, and the flow control stream signal 2 are transmitted.
  • the preamble stream signal 3, the transmission marker 6, the data packet, the transmission marker 6, the data packet, the transmission marker 6, and the flow control stream signal 2 are transmitted in this order.
  • FIG. 7D shows a bit stream signal transmitted when there is data accumulation exceeding a certain level in the transmission buffer 23.
  • the preamble stream signal 3, the transmission marker 6, and the data stream signal 4 are transmitted.
  • the preamble stream signal 3, the transmission marker 6, the data packet, the transmission marker 6, the data packet, and the transmission marker 6 are transmitted in this order.
  • the received bit stream signal indicates whether or not the data accumulation amount of the transmission buffer 23 of the counterpart device exceeds a certain level. Can be identified by whether or not the flow control stream signal 2 is added to the.
  • Steps S101 to S113 in FIG. 8 are flowcharts showing an example of operations at the time of transmission / reception in the communication devices 20a and 20b in FIG.
  • the transmission unit 24 starts transmission at a predetermined timing if it is not receiving.
  • a preamble stream signal is added to the flow control stream signal made up of dummy data and transmitted to the counterpart device to switch to the reception state (steps S101, S102, S105, S106). ).
  • the data stream signal is transmitted after transmitting the preamble stream signal, and the transmission data in the transmission buffer 23 is transmitted.
  • a flow control stream signal is transmitted to switch to the reception state (steps S101 to S106).
  • the data stream signal is transmitted after the preamble stream signal is transmitted, and the transmission in the transmission buffer 23 is performed.
  • the flow control stream signal is switched to the reception state without transmitting (steps S101 to S103, S107, S106).
  • the receiving unit 26 repeats the operation of extracting the received data from the stream signal input from the adaptive equalizer 25 and outputting it to the LAN I / F 21 until the reception is completed (steps S108 and S109).
  • the reception unit 26 switches to the normal transmission mode if a flow control stream signal composed of dummy data is added to the stream signal received from the counterpart device (steps S110 and S111).
  • the mode is switched to the transmission amount restriction mode for restricting the data transmission amount (steps S110 and S113).
  • step S101 If it is being received in step S101, the processing procedure after step S108 is executed. Further, the processing procedure from step S102 to step S111 or S113 is repeated until the communication is completed (step S112).
  • the reception data is extracted from the stream signal after switching from the transmission state to the reception state. Misrecognition can be suppressed. Further, since the data transmission amount is controlled based on the flow control stream signal from the counterpart device, the data transmission amount is limited when the data accumulation amount of the transmission buffer 23 of the counterpart device exceeds a certain level. Thus, it is possible to suppress an increase in the load related to the reception process of the counterpart device.
  • the stream signal is input to the adaptive equalizer 25 of the local station at the time of transmission of the stream signal.
  • the present invention is not limited to this, and transmission of the stream signal is not limited thereto.
  • the stream signal is not input to the adaptive equalizer 25 of the own station.
  • FIGS. 9A and 9B are diagrams illustrating an example of the transmission / reception operation of the communication apparatus according to another embodiment of the present invention, in which the stream signal being transmitted is not input to the adaptive equalizer 25 of the own station It is shown.
  • FIG. 9A shows a no-data period without transmission data
  • FIG. 9B shows a case where the transmission buffer 23 has data accumulation below a certain level.
  • the preamble stream signal 1 having the time length T1 is included in the stream signal transmitted first by the communication device A or the communication device B. Added.
  • the communication device A and the communication device B will transmit the stream signal next time, which is shorter than T1 and longer than T2.
  • the preamble stream signal 3a is added.
  • the communication apparatuses A and B transmit the stream signal by adding the preamble stream signal 1 having the time length T1 in the first transmission phase, and add the preamble stream signal 3a having the time length T4 in the subsequent transmission phase. To send a stream signal.
  • This time length T4 is determined according to the period from the end of reception of the preamble stream signal or data stream signal until the next reception of the preamble stream signal from the counterpart device. That is, when the feedback operation of the adaptive equalizer 25 of the own station becomes unstable due to the discharge of the capacitor 46c during the above period, the time T5 required for stabilization of the feedback operation is shorter than the time constant of the integrator 46. , Longer than T3. Therefore, if the time length T4 is sufficiently longer than the time T5, the adaptive equalizer 25 of the own station can be stabilized by receiving the preamble stream signal having such a time length T4.
  • the present invention includes those that do not transmit these stream signals during the no-data period.
  • FIGS. 10A and 10B are diagrams illustrating an example of a transmission / reception operation of a communication apparatus according to another embodiment of the present invention, in which a stream signal is not transmitted during a no-data period. .
  • FIG. 10A shows a no-data period without transmission data
  • FIG. 10B shows a case where the transmission buffer 23 has data accumulation below a certain level.
  • the preamble stream signal to be performed is the preamble stream signal 1 having a time length of T1.
  • FIGS. 11A and 11B are diagrams showing another example of the transmission / reception operation of the communication apparatus according to another embodiment of the present invention, in which the stream signal being transmitted is input to the adaptive equalizer 25 of its own station No stream signal is transmitted in the no-data period.
  • FIG. 11A shows a no-data period without transmission data
  • FIG. 11B shows a case where the transmission buffer 23 has data accumulation below a certain level.
  • the preamble stream signal, the data stream signal, and the flow control stream signal are not input to the adaptive equalizer 25 of the local station and the preamble stream signal and the flow control stream signal are not transmitted / received during the no-data period, a half-time passes after the no-data period.
  • the preamble stream signal 1 having the time length T1 is added to the stream signal transmitted first by the communication device A or the communication device B.
  • the communication device A and the communication device B will transmit the stream signal next time, which is shorter than T1 and longer than T2.
  • the preamble stream signal 3a is added.
  • the present invention is not limited to this. It is not something that can be done.
  • the present invention can be applied to a half-duplex communication mode in which a transmission phase and a reception phase are alternately switched based on some rule. For example, the transmission phase and the reception phase may be switched at regular intervals.
  • Preamble stream signal 2 Flow control stream signal 4 Data stream signal 11 Camera 12 LAN 13 Monitor device 14 Recording device 20a, 20b Communication device 21 LAN I / F 22 buffer control unit 23 transmission buffer 24 transmission unit 24a data stream signal generation unit 24b preamble stream signal generation unit 24c transmission control unit 25 adaptive equalizer 26 reception unit 30 coaxial cable 42 signal input unit 43 variable equalizer 44 transition time measuring unit 46 integration 100 Monitoring system T1, T2, T4 Time length of preamble stream signal

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Abstract

Provided is a communication device capable of lengthening a transmission distance without degrading communication quality and capable of suppressing the erroneous recognition of received data. The communication device comprises: a transmission unit (24) for generating a data stream signal on the basis of the transmission data in a transmission buffer (23) and transmitting through a transmission medium to the other party’s device; an adaptive equalizer (25) for adjusting the waveform of a stream signal on the transmission medium on the basis of the transition time of a data bit; and a receiving unit (26) for extracting received data from the stream signal after the waveform adjustment.  In a transmission phase, the transmission unit (24) transmits a preamble stream signal and then starts to transmit the data stream signal.  In a reception phase, the adaptive equalizer (25) adjusts the waveforms of the preamble stream signal and the data stream signal from the other party’s device, and the receiving unit (26) extracts the received data from the data stream signal inputted via the adaptive equalizer (25).

Description

通信装置Communication device
　本発明は、通信装置に係り、さらに詳しくは、伝送媒体を介して接続された相手先機器と半二重方式で通信し、アダプティブイコライザを用いて伝送媒体上のストリーム信号について波形調整を行う通信装置の改良に関する。 The present invention relates to a communication apparatus, and more particularly, communication that performs half-duplex communication with a counterpart device connected via a transmission medium and performs waveform adjustment on a stream signal on the transmission medium using an adaptive equalizer. It relates to the improvement of the apparatus.
　監視カメラなどの入力装置と、録画機器やモニター装置などの出力装置との間で画像データや制御データの送受信を同軸ケーブルで互いに接続された通信装置に中継させる通信システムがある。この様な通信システムにおいて、同軸ケーブルなどの伝送媒体による伝送距離が長くなると、減衰特性が劣化し、信号が伝送距離に応じて減衰するだけでなく、データビットの遷移時間が長くなって信号波形が崩れてしまうということが従来から知られている。 There is a communication system that relays transmission / reception of image data and control data between an input device such as a monitoring camera and an output device such as a recording device or a monitor device to communication devices connected to each other by a coaxial cable. In such a communication system, when the transmission distance by a transmission medium such as a coaxial cable becomes long, the attenuation characteristic deteriorates and not only the signal is attenuated according to the transmission distance but also the transition time of the data bit becomes long and the signal waveform It has been known for a long time.
　そこで、相手先機器から同軸ケーブルを介して入力される信号をアダプティブイコライザに波形調整を行わせることにより、通信品質を低下させることなく伝送距離を長くする技術が提案されている（例えば、特許文献１）。アダプティブイコライザは、信号状態に応じて周波数成分ごとのゲインを自動調整する適応型のイコライザであり、伝送媒体上の信号についてデータビットの遷移時間を測定し、その測定結果に基づいてゲインが調整される。しかしながら、この様なアダプティブイコライザを備えた通信装置では、送信状態から受信状態への切り替え後、アダプティブイコライザにおける波形調整のためのフィードバック動作が安定するまでに受信したデータを誤認識してしまうという問題があった。 In view of this, a technique has been proposed in which a signal input from a counterpart device via a coaxial cable is subjected to waveform adjustment by an adaptive equalizer, thereby extending the transmission distance without degrading communication quality (for example, Patent Documents). 1). An adaptive equalizer is an adaptive equalizer that automatically adjusts the gain for each frequency component according to the signal state, measures the data bit transition time for the signal on the transmission medium, and adjusts the gain based on the measurement result. The However, in a communication apparatus equipped with such an adaptive equalizer, there is a problem that after switching from the transmission state to the reception state, the received data is erroneously recognized until the feedback operation for waveform adjustment in the adaptive equalizer is stabilized. was there.
特開２００８－１３５９４７号公報JP 2008-135947 A
　本発明は、上記事情に鑑みてなされたものであり、伝送媒体を介して接続された相手先機器と半二重方式で通信する際の通信品質を低下させることなく伝送距離を長くすることができ、送信状態から受信状態への切り替え後に受信データを誤認識するのを抑制することができる通信装置を提供することを目的とする。 The present invention has been made in view of the above circumstances, and can increase the transmission distance without degrading the communication quality when communicating with a counterpart device connected via a transmission medium in a half-duplex manner. An object of the present invention is to provide a communication device that can suppress erroneous recognition of received data after switching from a transmission state to a reception state.
　第１の本発明による通信装置は、伝送媒体を介して接続された相手先機器と送信フェーズ及び受信フェーズを交互に切り替えながら半二重方式で通信する通信装置であって、送信バッファに蓄積された送信データに基づいて連続するデータビットからなるデータストリーム信号を生成し、上記伝送媒体を介して上記相手先機器へ送信する送信手段と、データビットの遷移時間に基づいて、上記伝送媒体上のストリーム信号について波形調整を行うアダプティブイコライザと、波形調整後のストリーム信号から受信データを抽出する受信手段とを備え、上記送信手段が、プリアンブルストリーム信号を生成するプリアンブルストリーム信号生成手段を有し、データストリーム信号の送信フェーズでは、上記送信手段が、上記プリアンブルストリーム信号を送信してから上記データストリーム信号の送信を開始し、データストリーム信号の受信フェーズでは、上記アダプティブイコライザが、上記相手先機器から入力される上記プリアンブルストリーム信号及び上記データストリーム信号について波形調整を行い、上記受信手段が、上記アダプティブイコライザを介して入力されるデータストリーム信号から受信データを抽出するように構成される。 A communication device according to a first aspect of the present invention is a communication device that communicates with a counterpart device connected via a transmission medium in a half-duplex manner while alternately switching a transmission phase and a reception phase, and is stored in a transmission buffer. A transmission means for generating a data stream signal composed of continuous data bits based on the transmitted data and transmitting the data stream signal to the counterpart device via the transmission medium; and on the transmission medium based on the transition time of the data bits. An adaptive equalizer that adjusts a waveform of a stream signal; and a reception unit that extracts reception data from the stream signal after waveform adjustment, the transmission unit includes a preamble stream signal generation unit that generates a preamble stream signal; In the stream signal transmission phase, the transmission means transmits the preamble stream. Transmission of the data stream signal is started, and in the reception phase of the data stream signal, the adaptive equalizer has waveforms for the preamble stream signal and the data stream signal input from the counterpart device. Adjustments are made and the receiving means is configured to extract received data from a data stream signal input via the adaptive equalizer.
　この通信装置では、プリアンブルストリーム信号を送信してからデータストリーム信号の送信を開始するので、プリアンブルストリーム信号によって相手先機器のアダプティブイコライザのフィードバック動作を安定させてからデータストリーム信号を当該アダプティブイコライザに入力することができる。この様な構成によれば、プリアンブルストリーム信号によってアダプティブイコライザのフィードバック動作を安定させてからデータストリーム信号が入力されるので、送信フェーズから受信フェーズへの切り替え後にストリーム信号から受信データを抽出する際の誤認識を抑制することができる。 In this communication apparatus, since transmission of the data stream signal is started after transmitting the preamble stream signal, the data stream signal is input to the adaptive equalizer after stabilizing the feedback operation of the adaptive equalizer of the counterpart device by the preamble stream signal. can do. According to such a configuration, since the data stream signal is input after the feedback operation of the adaptive equalizer is stabilized by the preamble stream signal, the reception data is extracted from the stream signal after switching from the transmission phase to the reception phase. False recognition can be suppressed.
　第２の本発明による通信装置は、上記構成に加え、上記アダプティブイコライザが、上記相手先機器からのストリーム信号が入力される可変型イコライザと、上記可変型イコライザの出力が入力される遷移時間測定器と、上記遷移時間測定器による遷移時間の測定結果に基づいて上記可変型イコライザを制御する積分器とからなり、上記プリアンブルストリーム信号生成手段が、上記可変型イコライザの出力の一部を上記遷移時間測定器及び上記積分器で順に処理させて当該可変型イコライザに帰還させる制御ループに対応する時間長のプリアンブルストリーム信号を生成するように構成される。 In the communication device according to the second aspect of the present invention, in addition to the above-described configuration, the adaptive equalizer includes a variable equalizer to which a stream signal from the counterpart device is input, and a transition time measurement to which an output of the variable equalizer is input. And an integrator for controlling the variable equalizer based on the measurement result of the transition time by the transition time measuring device, wherein the preamble stream signal generating means converts a part of the output of the variable equalizer to the transition A preamble stream signal having a time length corresponding to a control loop that is sequentially processed by the time measuring device and the integrator and fed back to the variable equalizer is generated.
　この様な構成によれば、アダプティブイコライザの制御ループに対応する時間長のプリアンブルストリーム信号が生成されるので、アダプティブイコライザの制御ループからなるフィードバック動作を十分に安定させることができる。 According to such a configuration, since a preamble stream signal having a length corresponding to the control loop of the adaptive equalizer is generated, the feedback operation including the control loop of the adaptive equalizer can be sufficiently stabilized.
　第３の本発明による通信装置は、上記構成に加え、上記プリアンブルストリーム信号生成手段が、上記積分器の時定数よりも時間長の長いプリアンブルストリーム信号を生成するように構成される。 In addition to the above configuration, the communication apparatus according to the third aspect of the present invention is configured such that the preamble stream signal generation means generates a preamble stream signal having a time length longer than the time constant of the integrator.
　第４の本発明による通信装置は、上記構成に加え、上記プリアンブルストリーム信号生成手段が、最初の送信フェーズでは、上記積分器の時定数よりも時間長の長いプリアンブルストリーム信号を生成し、その後の送信フェーズでは、上記時定数よりも時間長の短いプリアンブルストリーム信号を生成するように構成される。 In the communication device according to the fourth aspect of the present invention, in addition to the above configuration, the preamble stream signal generation means generates a preamble stream signal having a time length longer than the time constant of the integrator in the first transmission phase, and then The transmission phase is configured to generate a preamble stream signal having a shorter time length than the time constant.
　第５の本発明による通信装置は、上記構成に加え、上記伝送媒体を介して上記相手先機器へ順次に送信されるプリアンブルストリーム信号及びデータストリーム信号がいずれも上記アダプティブイコライザに入力され、これらのストリーム信号の送信中にも当該アダプティブイコライザが波形調整を行うように構成される。 In the communication device according to the fifth aspect of the present invention, in addition to the above configuration, a preamble stream signal and a data stream signal sequentially transmitted to the counterpart device via the transmission medium are both input to the adaptive equalizer, The adaptive equalizer is configured to perform waveform adjustment even during transmission of the stream signal.
　この様な構成によれば、伝送媒体を介して相手先機器へ順次に送信されるプリアンブルストリーム信号及びデータストリーム信号が自局のアダプティブイコライザに入力され、波形調整を行わせるので、これらのストリーム信号によって当該アダプティブイコライザのフィードバック動作を安定させておくことができる。従って、相手先機器よりも前にデータストリーム信号の送信を開始する場合に当該データストリーム信号に付加するプリアンブルストリーム信号に比べて、相手先機器からのデータストリーム信号を受信した後にデータストリーム信号を送信する場合に当該データストリーム信号に付加するプリアンブルストリーム信号の時間長を短くすることができる。つまり、プリアンブルストリーム信号及びデータストリーム信号の送信によって自局のアダプティブイコライザのフィードバック動作が安定するので、相手先機器からのデータストリーム信号を受信した後にデータストリーム信号を送信する場合には、データストリーム信号に付加するプリアンブルストリーム信号の時間長を短くしても、相手先機器のアダプティブイコライザのフィードバック動作を十分に安定させることができる。 According to such a configuration, the preamble stream signal and the data stream signal that are sequentially transmitted to the counterpart device via the transmission medium are input to the adaptive equalizer of the local station, and the waveform adjustment is performed. Thus, the feedback operation of the adaptive equalizer can be stabilized. Therefore, when data stream signal transmission is started before the counterpart device, the data stream signal is transmitted after receiving the data stream signal from the counterpart device, compared to the preamble stream signal added to the data stream signal. In this case, the time length of the preamble stream signal added to the data stream signal can be shortened. That is, since the feedback operation of the adaptive equalizer of the local station is stabilized by transmitting the preamble stream signal and the data stream signal, when transmitting the data stream signal after receiving the data stream signal from the counterpart device, the data stream signal Even if the time length of the preamble stream signal added to is shortened, the feedback operation of the adaptive equalizer of the counterpart device can be sufficiently stabilized.
　本発明による通信装置によれば、プリアンブルストリーム信号によってアダプティブイコライザのフィードバック動作を安定させてからデータストリーム信号が入力されるので、送信フェーズから受信フェーズへの切り替え後にストリーム信号から受信データを抽出する際の誤認識を抑制することができる。従って、伝送媒体を介して接続された相手先機器と半二重方式で通信する際の通信品質を低下させることなく伝送距離を長くすることができ、送信状態から受信状態への切り替え後に受信データを誤認識するのを抑制することができる。 According to the communication device of the present invention, since the data stream signal is input after the feedback operation of the adaptive equalizer is stabilized by the preamble stream signal, the reception data is extracted from the stream signal after switching from the transmission phase to the reception phase. Misrecognition can be suppressed. Therefore, it is possible to increase the transmission distance without degrading the communication quality when communicating with the counterpart device connected via the transmission medium in the half-duplex method, and the received data after switching from the transmission state to the reception state. Can be prevented from being erroneously recognized.
本発明の実施の形態による通信装置を含む通信システムの一構成例を示したシステム図であり、通信システムの一例として監視システム１００が示されている。1 is a system diagram showing a configuration example of a communication system including a communication device according to an embodiment of the present invention, and a monitoring system 100 is shown as an example of the communication system. 図１の通信装置２０ａ，２０ｂの一構成例を示したブロック図である。It is the block diagram which showed one structural example of communication apparatus 20a, 20b of FIG. 図２の通信装置２０ａ，２０ｂにおけるアダプティブイコライザ２５の一構成例を示した図である。It is the figure which showed the example of 1 structure of the adaptive equalizer 25 in the communication apparatuses 20a and 20b of FIG. 図１の監視システム１００における送受信動作の一例を示した図であり、送信データなしの期間と一定レベル以下のデータ蓄積がある場合とが示されている。It is the figure which showed an example of the transmission / reception operation | movement in the monitoring system 100 of FIG. 1, and the case where there exists data accumulation below a fixed level and the period without transmission data is shown. 図１の監視システム１００における送受信動作の一例を示した図であり、送信バッファ２３に一定レベルを越えるデータ蓄積がある場合が示されている。FIG. 2 is a diagram showing an example of a transmission / reception operation in the monitoring system 100 of FIG. 1, and shows a case where there is data accumulation exceeding a certain level in the transmission buffer 23. 図１の監視システム１００における通信装置２０ａ，２０ｂ間の送受信動作の一例を示したタイミングチャートである。2 is a timing chart showing an example of a transmission / reception operation between communication devices 20a and 20b in the monitoring system 100 of FIG. 図２の通信装置２０ａ，２０ｂにおける送信動作の一例を示した図であり、同軸ケーブル３０を介して相手先機器に送信されるストリーム信号が示されている。FIG. 3 is a diagram illustrating an example of a transmission operation in the communication devices 20a and 20b of FIG. 2, in which a stream signal transmitted to the counterpart device via the coaxial cable 30 is illustrated. 図２の通信装置２０ａ，２０ｂにおける送受信時の動作の一例を示したフローチャートである。3 is a flowchart showing an example of an operation at the time of transmission / reception in the communication devices 20a and 20b of FIG. 本発明の他の実施の形態による通信装置の送受信動作の一例を示した図であり、送信中のストリーム信号をイコライザ２５に入力しない場合が示されている。It is the figure which showed an example of the transmission / reception operation | movement of the communication apparatus by other embodiment of this invention, and the case where the stream signal in transmission is not input into the equalizer 25 is shown. 本発明の他の実施の形態による通信装置の送受信動作の一例を示した図であり、無データ期間にはストリーム信号を送信しない場合が示されている。It is the figure which showed an example of the transmission / reception operation | movement of the communication apparatus by other embodiment of this invention, and the case where a stream signal is not transmitted in a no-data period is shown. 本発明の他の実施の形態による通信装置の送受信動作の他の一例を示した図である。It is the figure which showed another example of the transmission / reception operation | movement of the communication apparatus by other embodiment of this invention.
＜監視システム＞
　図１は、本発明の実施の形態による通信装置を含む通信システムの一構成例を示したシステム図であり、通信システムの一例として監視システム１００が示されている。監視システム１００は、物理的に離れた機器間のデータ送受信を通信装置２０ａ，２０ｂに中継させる通信システムであり、伝送媒体を介して互いに接続された通信装置２０ａ及び２０ｂ間において画像データや制御データが半二重方式で送受信される。 <Monitoring system>
FIG. 1 is a system diagram showing a configuration example of a communication system including a communication device according to an embodiment of the present invention, and a monitoring system 100 is shown as an example of the communication system. The monitoring system 100 is a communication system that relays data transmission / reception between physically separated devices to the communication devices 20a and 20b, and image data and control data between the communication devices 20a and 20b connected to each other via a transmission medium. Are transmitted and received in a half-duplex manner.
　この監視システム１００では、通信装置２０ａ，２０ｂが同軸ケーブル３０を介して接続されている。一方の通信装置２０ａには、カメラ１１がＬＡＮ（ローカルエリアネットワーク）１２を介して接続され、他方の通信装置２０ｂには、モニター装置１３及び録画機器１４がＬＡＮ１２を介して接続されている。 In this monitoring system 100, communication devices 20a and 20b are connected via a coaxial cable 30. The camera 11 is connected to one communication device 20a via a LAN (local area network) 12, and the monitor device 13 and the recording device 14 are connected to the other communication device 20b via the LAN 12.
　カメラ１１は、建物の壁や天井などに設置され、設置場所周辺の監視エリアを撮影して画像データを生成する撮像装置である。カメラ１１によって生成された画像データは、ＬＡＮ１２を介して通信装置２０ａにシリアル伝送される。 The camera 11 is an imaging device that is installed on a wall or ceiling of a building and shoots a monitoring area around the installation location to generate image data. The image data generated by the camera 11 is serially transmitted to the communication device 20a via the LAN 12.
　カメラ１１が接続された通信装置２０ａは、モニター装置１３及び録画機器１４が接続された通信装置２０ｂと１本の同軸ケーブル３０を介して半二重方式で双方向通信を行い、画像データやカメラ１１を制御するための制御データがシリアル伝送される。モニター装置１３は、カメラ１１からの画像データに基づいて監視映像を画面表示する表示装置である。録画機器１４は、カメラ１１からの画像データをＨＤＤなどに記録する記録装置である。 The communication device 20a to which the camera 11 is connected performs bi-directional communication with the communication device 20b to which the monitor device 13 and the recording device 14 are connected via a single coaxial cable 30 in a half-duplex manner. Control data for controlling 11 is serially transmitted. The monitor device 13 is a display device that displays a monitor video on the screen based on image data from the camera 11. The recording device 14 is a recording device that records image data from the camera 11 on an HDD or the like.
　この様にして、通信装置２０ａ，２０ｂは、カメラ１１などの入力装置やモニター装置１３などの出力装置がＬＡＮ１２を介して接続され、同軸ケーブル３０を介して接続された相手先機器と画像データや制御データなどを送受信する。画像データや制御データは、連続するデータビットからなるデータストリーム信号として同軸ケーブル３０上を送受信される。通信装置２０ａ，２０ｂは、データストリーム信号の送受信を相手先機器との間で交互に繰り返すことにより、半二重通信を行っている。 In this way, the communication devices 20a and 20b are connected to an input device such as the camera 11 and an output device such as the monitor device 13 via the LAN 12, and to the other device connected via the coaxial cable 30 and image data or Send and receive control data. Image data and control data are transmitted and received on the coaxial cable 30 as a data stream signal composed of continuous data bits. The communication devices 20a and 20b perform half-duplex communication by alternately repeating transmission and reception of data stream signals with the counterpart device.
＜通信装置＞
　図２は、図１の通信装置２０ａ，２０ｂの一構成例を示したブロック図である。この通信装置２０ａ，２０ｂは、ＬＡＮＩ／Ｆ２１、バッファ制御部２２、送信バッファ２３、送信部２４、アダプティブイコライザ２５及び受信部２６により構成される。ＬＡＮＩ／Ｆ２１は、ＬＡＮ１２に接続され、ＬＡＮ１２上の他の機器と通信するための通信制御部である。 <Communication device>
FIG. 2 is a block diagram illustrating a configuration example of the communication devices 20a and 20b in FIG. The communication devices 20a and 20b include a LAN I / F 21, a buffer control unit 22, a transmission buffer 23, a transmission unit 24, an adaptive equalizer 25, and a reception unit 26. The LAN I / F 21 is a communication control unit that is connected to the LAN 12 and communicates with other devices on the LAN 12.
　バッファ制御部２２は、送信バッファ２３を用いて送信データをバッファリングする動作を行っている。具体的には、ＬＡＮＩ／Ｆ２１を介して他の機器から順次に入力される送信データを送信バッファ２３に書き込み、同軸ケーブル３０を介して行われるデータ送受信の転送レートや送受信状態に応じて送信バッファ２３から送信データを読み出して送信部２４へ出力する。送信バッファ２３は、ＦＩＦＯ（先入れ先出し）方式で送信データを一時的に保持する記憶装置である。 The buffer control unit 22 performs an operation of buffering transmission data using the transmission buffer 23. Specifically, transmission data sequentially input from other devices via the LAN I / F 21 is written into the transmission buffer 23, and the transmission buffer is transmitted according to the transfer rate and transmission / reception state of data transmission / reception performed via the coaxial cable 30. The transmission data is read from 23 and output to the transmission unit 24. The transmission buffer 23 is a storage device that temporarily holds transmission data by a FIFO (first-in first-out) method.
　送信部２４は、データストリーム信号生成部２４ａ、プリアンブルストリーム信号生成部２４ｂ及び送信制御部２４ｃからなるトランスミッターであり、同軸ケーブル３０を介して相手先機器へ送信データからなるデータストリーム信号やプリアンブルストリーム信号を送信する。 The transmission unit 24 is a transmitter including a data stream signal generation unit 24a, a preamble stream signal generation unit 24b, and a transmission control unit 24c, and transmits a data stream signal or a preamble stream signal including transmission data to a counterpart device via the coaxial cable 30. Send.
　データストリーム信号生成部２４ａは、バッファ制御部２２により送信バッファ２３から読み出された送信データに基づいて、連続するデータビットからなるデータストリーム信号を生成し、送信制御部２４ｃへ出力する動作を行っている。上記データストリーム信号は、「０」又は「１」を示す複数のデータビットの配列によって構成されるビットストリーム信号である。 The data stream signal generation unit 24a performs an operation of generating a data stream signal composed of continuous data bits based on the transmission data read from the transmission buffer 23 by the buffer control unit 22 and outputting the data stream signal to the transmission control unit 24c. ing. The data stream signal is a bit stream signal composed of an array of a plurality of data bits indicating “0” or “1”.
　プリアンブルストリーム信号生成部２４ｂは、所定のビット配列からなるプリアンブルストリーム信号を生成し、送信制御部２４ｃへ出力する動作を行っている。このプリアンブルストリーム信号は、アダプティブイコライザ２５の応答特性に基づいて生成され、例えば、アダプティブイコライザ２５の応答時間に対応する時間長のビットストリーム信号によって構成される。 The preamble stream signal generation unit 24b performs an operation of generating a preamble stream signal having a predetermined bit arrangement and outputting the preamble stream signal to the transmission control unit 24c. This preamble stream signal is generated based on the response characteristic of the adaptive equalizer 25, and is constituted by a bit stream signal having a time length corresponding to the response time of the adaptive equalizer 25, for example.
　送信制御部２４ｃは、データストリーム信号を送信する場合に、プリアンブルストリーム信号を送信してからデータストリーム信号の送信を開始し、ストリーム信号の送信終了後に、受信部２６に対して受信データの抽出を指示する動作を行っている。ここでは、送信制御部２４ｃが、同軸ケーブル３０の信号線を駆動することによって、送信データがデジタルベースバンド伝送方式で伝送されるものとする。 When transmitting the data stream signal, the transmission control unit 24c starts transmitting the data stream signal after transmitting the preamble stream signal, and after receiving the stream signal, extracts the received data from the receiving unit 26. The operation to instruct is performed. Here, it is assumed that the transmission control unit 24c drives the signal line of the coaxial cable 30 so that transmission data is transmitted by the digital baseband transmission method.
　アダプティブイコライザ２５は、同軸ケーブル３０上のストリーム信号について波形調整を行い、波形調整後のストリーム信号を受信部２６へ出力する適応型のケーブルイコライザである。ストリーム信号の波形調整は、データビットの遷移時間に基づいて行われる。アダプティブイコライザ２５により、同軸ケーブル３０の伝送ロス、送信部２４の出力波形の歪み、信号線と受信部２６とのマッチングによって減衰したストリーム信号の高周波成分が増幅され、送信時の信号波形を再現することができる。 The adaptive equalizer 25 is an adaptive cable equalizer that performs waveform adjustment on the stream signal on the coaxial cable 30 and outputs the stream signal after the waveform adjustment to the receiving unit 26. The waveform adjustment of the stream signal is performed based on the transition time of the data bits. The adaptive equalizer 25 amplifies the transmission loss of the coaxial cable 30, the distortion of the output waveform of the transmission unit 24, and the high-frequency component of the stream signal attenuated by the matching between the signal line and the reception unit 26, thereby reproducing the signal waveform at the time of transmission. be able to.
　このアダプティブイコライザ２５では、同軸ケーブル３０を介して相手先機器から入力されるプリアンブルストリーム信号及びデータストリーム信号について波形調整が行われる。つまり、データ受信時には、プリアンブルストリーム信号によってアダプティブイコライザ２５における波形調整のためのフィードバック動作を安定させてから、データストリーム信号が当該アダプティブイコライザ２５に入力される。 In the adaptive equalizer 25, the waveform adjustment is performed for the preamble stream signal and the data stream signal input from the counterpart device via the coaxial cable 30. That is, at the time of data reception, the feedback operation for waveform adjustment in the adaptive equalizer 25 is stabilized by the preamble stream signal, and then the data stream signal is input to the adaptive equalizer 25.
　また、同軸ケーブル３０を介して相手先機器に順次に送信されるプリアンブルストリーム信号及びデータストリーム信号は、いずれも自局のアダプティブイコライザ２５に入力され、これらのストリーム信号の送信中にも当該アダプティブイコライザ２５が波形調整を行う。つまり、自局のアダプティブイコライザ２５は、次のデータ受信に備えて、データ送信時にもプリアンブルストリーム信号及びデータストリーム信号によってフィードバック動作の安定化が図られる。 Further, both the preamble stream signal and the data stream signal that are sequentially transmitted to the counterpart device via the coaxial cable 30 are input to the adaptive equalizer 25 of the local station, and the adaptive equalizer is also transmitted during the transmission of these stream signals. 25 performs waveform adjustment. That is, the adaptive equalizer 25 of its own station stabilizes the feedback operation by the preamble stream signal and the data stream signal even during data transmission in preparation for the next data reception.
　受信部２６は、アダプティブイコライザ２５による波形調整後のストリーム信号から受信データを抽出し、ＬＡＮＩ／Ｆ２１へ出力するレシーバーである。受信データのＬＡＮＩ／Ｆ２１への送出は、送信制御部２４ｃからの抽出指示に基づいて行われる。 The receiving unit 26 is a receiver that extracts received data from the stream signal after waveform adjustment by the adaptive equalizer 25 and outputs the received data to the LAN I / F 21. Transmission of received data to the LAN I / F 21 is performed based on an extraction instruction from the transmission control unit 24c.
　送信部２４では、相手先機器よりも前にストリーム信号の送信を開始する場合とその他の場合とでストリーム信号に付加するプリアンブルストリーム信号の時間長を異ならせている。具体的には、相手先機器よりも前にストリーム信号の送信を開始する場合に当該ストリーム信号に付加するプリアンブルストリーム信号に比べて、相手先機器からのストリーム信号を受信した後にストリーム信号を送信する場合に当該ストリーム信号に付加するプリアンブルストリーム信号の時間長を短くする動作が行われる。 In the transmission unit 24, the time length of the preamble stream signal to be added to the stream signal differs between when the transmission of the stream signal is started before the counterpart device and in other cases. Specifically, when transmission of a stream signal is started before the counterpart device, the stream signal is transmitted after receiving the stream signal from the counterpart device, compared to the preamble stream signal added to the stream signal. In this case, an operation for shortening the time length of the preamble stream signal added to the stream signal is performed.
　ここで、通信装置２０ａ，２０ｂは、電源が投入されれば受信状態となり、その後、ランダムなタイミングでストリーム信号の送信を開始する。つまり、電源投入による通信開始後に、同軸ケーブル３０を最初に伝送されるビットストリーム信号に付加されるプリアンブルストリーム信号に比べて、２回目以降に伝送されるビットストリーム信号に付加されるプリアンブルストリーム信号は、その時間長が短くなっている。この様に構成することにより、２回目以降の伝送に係るデータ送信に要する時間を短縮することができる。 Here, when the power is turned on, the communication devices 20a and 20b enter a reception state, and then start transmission of a stream signal at random timing. That is, the preamble stream signal added to the bit stream signal transmitted after the second time is compared with the preamble stream signal added to the bit stream signal transmitted first through the coaxial cable 30 after the communication is started by turning on the power. The time length is getting shorter. With this configuration, it is possible to reduce the time required for data transmission related to the second and subsequent transmissions.
　また、送信部２４では、送信バッファ２３のデータ蓄積量に基づいて、所定のビット配列からなるフロー制御ストリーム信号をストリーム信号に付加し、相手先機器からのフロー制御ストリーム信号に基づいてデータ送信量を制御する動作が行われる。 Further, the transmission unit 24 adds a flow control stream signal having a predetermined bit arrangement to the stream signal based on the data accumulation amount of the transmission buffer 23, and the data transmission amount based on the flow control stream signal from the counterpart device. The operation of controlling is performed.
　フロー制御ストリーム信号は、フロー制御用のダミーデータからなるビットストリーム信号であり、例えば、送信バッファ２３のデータ蓄積量がデータ送信時に一定レベル以下である場合に、送信データからなるデータストリーム信号の末尾に付加される。この場合、送信部２４では、受信部２６により相手先機器からのストリーム信号にフロー制御ストリーム信号が付加されていないことが検知されれば、データ送信量を制限する動作が行われる。 The flow control stream signal is a bit stream signal composed of dummy data for flow control. For example, when the amount of data stored in the transmission buffer 23 is below a certain level during data transmission, the end of the data stream signal composed of transmission data To be added. In this case, in the transmission unit 24, if the reception unit 26 detects that the flow control stream signal is not added to the stream signal from the counterpart device, an operation for limiting the data transmission amount is performed.
　具体的には、相手先機器からのストリーム信号にフロー制御ストリーム信号が付加されていれば、次にデータ送信する際に、送信バッファ２３内の全送信データが送信される。一方、相手先機器からのストリーム信号にフロー制御ストリーム信号が付加されていない場合には、送信データの絞り込みが行われる。 Specifically, if a flow control stream signal is added to the stream signal from the counterpart device, all transmission data in the transmission buffer 23 is transmitted when data is next transmitted. On the other hand, when the flow control stream signal is not added to the stream signal from the counterpart device, transmission data is narrowed down.
　この様に構成することにより、送信バッファ２３のデータ蓄積量に基づいてフロー制御ストリーム信号をデータストリーム信号に付加するので、相手先機器の送信バッファ２３のデータ蓄積量が一定レベルを越えているか否かをフロー制御ストリーム信号の有無によって識別することができる。 With this configuration, since the flow control stream signal is added to the data stream signal based on the data accumulation amount of the transmission buffer 23, whether or not the data accumulation amount of the transmission buffer 23 of the counterpart device exceeds a certain level. Can be identified by the presence or absence of a flow control stream signal.
　また、送信部２４では、データ送信時、送信バッファ２３内に送信データが蓄積されていなければ、プリアンブルストリーム信号及びフロー制御ストリーム信号のみを相手先機器へ送信する動作が行われる。つまり、この監視システム１００では、送信バッファ２３内に送信データが存在しない無データ期間であっても、プリアンブルストリーム信号及びフロー制御ストリーム信号からなるビットストリーム信号が同軸ケーブル３０を介して送受信される。この様に構成することにより、無データ期間経過後のデータ受信に備えて、アダプティブイコライザ２５のフィードバック動作を安定させておくことができる。 Further, in the transmission unit 24, when transmission data is not accumulated in the transmission buffer 23 at the time of data transmission, an operation for transmitting only the preamble stream signal and the flow control stream signal to the counterpart device is performed. In other words, in this monitoring system 100, a bit stream signal composed of a preamble stream signal and a flow control stream signal is transmitted / received via the coaxial cable 30 even during a no-data period in which no transmission data exists in the transmission buffer 23. With this configuration, the feedback operation of the adaptive equalizer 25 can be stabilized in preparation for data reception after the no-data period has elapsed.
＜アダプティブイコライザ＞
　図３は、図２の通信装置２０ａ，２０ｂにおけるアダプティブイコライザ２５の一構成例を示した図である。このアダプティブイコライザ２５は、信号入力部４２、可変型イコライザ４３、遷移時間測定器４４及び積分器４６により構成される。 <Adaptive equalizer>
FIG. 3 is a diagram illustrating a configuration example of the adaptive equalizer 25 in the communication devices 20a and 20b of FIG. The adaptive equalizer 25 includes a signal input unit 42, a variable equalizer 43, a transition time measuring device 44 and an integrator 46.
　相手先機器からのストリーム信号は入力端子４１に入力され、データビットの遷移時間に基づく波形調整後のストリーム信号は出力端子４５から出力される。信号入力部４２は、プルアップ抵抗やオペアンプからなり、入力端子４１に入力されたストリーム信号を増幅して可変型イコライザ４３へ出力する動作を行っている。 The stream signal from the counterpart device is input to the input terminal 41, and the stream signal after the waveform adjustment based on the data bit transition time is output from the output terminal 45. The signal input unit 42 includes a pull-up resistor and an operational amplifier, and performs an operation of amplifying the stream signal input to the input terminal 41 and outputting the amplified signal to the variable equalizer 43.
　可変型イコライザ４３は、周波数成分ごとのゲインが変更可能なイコライザであり、微分器４３ａ、ゲイン可変アンプ４３ｂ及び加算器４３ｃからなる。入力信号は、分岐点で分岐され、一方はそのまま加算器４３ｃに入力され、他方は微分器４３ａ、ゲイン可変アンプ４３ｂを経て加算器４３ｃに入力される。加算器４３ｃは、これらの信号を加算処理して遷移時間測定器４４へ出力する動作を行っている。 The variable equalizer 43 is an equalizer that can change the gain for each frequency component, and includes a differentiator 43a, a gain variable amplifier 43b, and an adder 43c. The input signal is branched at the branching point, one is directly input to the adder 43c, and the other is input to the adder 43c via the differentiator 43a and the gain variable amplifier 43b. The adder 43 c performs an operation of adding these signals and outputting them to the transition time measuring device 44.
　遷移時間測定器４４は、コンパレータ４４ａ、微分器４４ｂ、全波整流器４４ｃ及び減算器４４ｄからなり、可変型イコライザ４３の出力が入力され、データビットの遷移時間を測定して、遷移時間の測定結果に基づく波形調整後のビットストリーム信号を出力端子４５へ出力する動作を行っている。 The transition time measuring unit 44 includes a comparator 44a, a differentiator 44b, a full-wave rectifier 44c, and a subtractor 44d. The output of the variable equalizer 43 is input to measure the transition time of the data bit, and the transition time measurement result. The operation of outputting the bit stream signal after waveform adjustment based on the above to the output terminal 45 is performed.
　コンパレータ４４ａは、加算器４３ｃからの入力信号の信号レベルを所定の閾値と比較し、その比較結果に基づいて所定レベルの信号を生成し、出力端子４５へ出力する量子化器である。コンパレータ４４ａへの入力信号は、微分器４４ｂ、全波整流器４４ｃを経て減算器４４ｄに入力される。また、コンパレータ４４ａの出力信号は、微分器４４ｂ、全波整流器４４ｃを経て減算器４４ｄに入力される。減算器４４ｄは、これらの信号を減算処理して積分器４６へ出力する動作を行っている。 The comparator 44a is a quantizer that compares the signal level of the input signal from the adder 43c with a predetermined threshold, generates a signal of a predetermined level based on the comparison result, and outputs the signal to the output terminal 45. The input signal to the comparator 44a is input to the subtractor 44d through the differentiator 44b and the full wave rectifier 44c. The output signal of the comparator 44a is input to the subtractor 44d via the differentiator 44b and the full wave rectifier 44c. The subtractor 44d performs an operation of subtracting these signals and outputting them to the integrator 46.
　積分器４６は、アンプ４６ａ、抵抗素子４６ｂ及びコンデンサー４６ｃからなり、遷移時間測定器４４による遷移時間の測定結果に基づいて可変型イコライザ４３のゲイン可変アンプ４３ｂを制御し、周波数成分ごとのゲインを調整する動作を行っている。減算器４４ｄからの入力信号は、アンプ４６ａで増幅され、一端がそれぞれ接地された抵抗素子４６ｂ、コンデンサー４６ｃを経てゲイン可変アンプ４３ｂの制御端子へ出力される。 The integrator 46 includes an amplifier 46a, a resistance element 46b, and a capacitor 46c. The integrator 46 controls the gain variable amplifier 43b of the variable equalizer 43 based on the measurement result of the transition time by the transition time measuring unit 44, and sets the gain for each frequency component. The operation to adjust is performed. The input signal from the subtractor 44d is amplified by the amplifier 46a, and is output to the control terminal of the gain variable amplifier 43b through the resistance element 46b and the capacitor 46c, each of which is grounded.
　遷移時間の測定結果に基づくゲイン可変アンプ４３ｂの制御により、コンパレータ４４ａへの入力信号とコンパレータ４４ａの出力信号との間で遷移時間が一致するようにゲインが調整される。 By controlling the variable gain amplifier 43b based on the measurement result of the transition time, the gain is adjusted so that the transition time matches between the input signal to the comparator 44a and the output signal of the comparator 44a.
　送信部２４のプリアンブルストリーム信号生成部２４ｂでは、積分器４６の時定数よりも時間長の長いプリアンブルストリーム信号を生成する動作が行われる。積分器４６の時定数は、アダプティブイコライザ２５の応答時間を決めるパラメータであり、抵抗素子４６ｂの抵抗値と、コンデンサー４６ｃの容量値とにより決定される。 In the preamble stream signal generation unit 24b of the transmission unit 24, an operation of generating a preamble stream signal having a time length longer than the time constant of the integrator 46 is performed. The time constant of the integrator 46 is a parameter that determines the response time of the adaptive equalizer 25, and is determined by the resistance value of the resistance element 46b and the capacitance value of the capacitor 46c.
　アダプティブイコライザ２５では、可変型イコライザ４３の出力の一部を遷移時間測定器４４及び積分器４６で順に処理させ、可変型イコライザ４３に帰還させる制御ループからなるフィードバック動作が行われる。アダプティブイコライザ２５における波形調整のためのフィードバック動作とは、この制御ループを用いて可変型イコライザ４３が行うゲインの調整動作のことであり、データストリーム信号に先立ってプリアンブルストリーム信号を入力させることにより、制御ループに基づくゲインの調整動作を安定させることができる。 The adaptive equalizer 25 performs a feedback operation including a control loop in which a part of the output of the variable equalizer 43 is sequentially processed by the transition time measuring device 44 and the integrator 46 and fed back to the variable equalizer 43. The feedback operation for waveform adjustment in the adaptive equalizer 25 is a gain adjustment operation performed by the variable equalizer 43 using this control loop. By inputting the preamble stream signal prior to the data stream signal, The gain adjustment operation based on the control loop can be stabilized.
　電源投入直後や無データ期間、通常のデータ送信時において、プリアンブルストリーム信号生成部２４ｂにより生成されるプリアンブルストリーム信号には、以下の（１）及び（２）が考えられる。
（１）電源投入後、相手先機器よりも前にストリーム信号の送信を開始する場合には、アダプティブイコライザ２５の応答時間に応じた時間長、すなわち、積分器４６の時定数よりも長い時間長Ｔ１のプリアンブルストリーム信号が生成される。
（２）時間長Ｔ１のプリアンブルストリーム信号の送信後、次にプリアンブルストリーム信号を送信する場合、或いは、相手先機器から時間長Ｔ１のプリアンブルストリーム信号を受信した後にプリアンブルストリーム信号を送信する場合には、Ｔ１よりも短い時間長Ｔ２のプリアンブルストリーム信号が生成される。 The following (1) and (2) are conceivable for the preamble stream signal generated by the preamble stream signal generation unit 24b immediately after power-on, during a no-data period, or during normal data transmission.
(1) When transmission of a stream signal is started before the counterpart device after power is turned on, a time length corresponding to the response time of the adaptive equalizer 25, that is, a time length longer than the time constant of the integrator 46 A T1 preamble stream signal is generated.
(2) When transmitting the preamble stream signal next after the transmission of the preamble stream signal of time length T1, or when transmitting the preamble stream signal after receiving the preamble stream signal of time length T1 from the counterpart device , A preamble stream signal having a time length T2 shorter than T1 is generated.
　上記（１）の場合、データストリーム信号やフロー制御ストリーム信号に先立って時間長Ｔ１のプリアンブルストリーム信号を送信することにより、相手先機器では、アダプティブイコライザ２５のフィードバック動作が安定してからデータストリーム信号やフロー制御ストリーム信号を受信することができる。 In the case of (1) above, the data stream signal is transmitted after the feedback operation of the adaptive equalizer 25 is stabilized in the counterpart device by transmitting the preamble stream signal having the time length T1 prior to the data stream signal or the flow control stream signal. And a flow control stream signal can be received.
　無データ期間及び通常の半二重方式によるデータ送信時に送信されるプリアンブルストリーム信号やデータストリーム信号、フロー制御ストリーム信号は、自局のアダプティブイコライザ２５にも入力される。つまり、これらのストリーム信号の送信終了時点では、自局のアダプティブイコライザ２５のフィードバック動作が十分に安定していることとなる。 The preamble stream signal, the data stream signal, and the flow control stream signal transmitted during data transmission in the no-data period and the normal half-duplex method are also input to the adaptive equalizer 25 of the own station. That is, at the end of transmission of these stream signals, the feedback operation of the adaptive equalizer 25 of the own station is sufficiently stable.
　このため、プリアンブルストリーム信号やデータストリーム信号の送信終了後、受信動作に切り替えられた際に、受信されるプリアンブルストリーム信号は、その時間長がＴ１よりも短くて良い。具体的には、ストリーム信号の送信終了後、受信動作に切り替えられてから、相手先機器からのプリアンブルストリーム信号を受信するまでの期間に応じた時間長Ｔ２のプリアンブルストリーム信号が生成される。 For this reason, the time length of the received preamble stream signal may be shorter than T1 when switching to the reception operation after the transmission of the preamble stream signal or the data stream signal is completed. Specifically, after the transmission of the stream signal is completed, a preamble stream signal having a time length T2 corresponding to a period from when switching to the reception operation to reception of the preamble stream signal from the counterpart device is generated.
　ここで、上記期間中のコンデンサー４６ｃの放電によって自局のアダプティブイコライザ２５のフィードバック動作が不安定となった際に、当該フィードバック動作の安定化に要する時間Ｔ３は、積分器４６の時定数よりも短い。このため、時間長Ｔ２が時間Ｔ３よりも十分に長ければ、その様な時間長Ｔ２のプリアンブルストリーム信号を受信することにより、自局のアダプティブイコライザ２５を安定化させることができる。 Here, when the feedback operation of the adaptive equalizer 25 of the local station becomes unstable due to the discharge of the capacitor 46c during the above period, the time T3 required to stabilize the feedback operation is shorter than the time constant of the integrator 46. short. Therefore, if the time length T2 is sufficiently longer than the time T3, the adaptive equalizer 25 of the own station can be stabilized by receiving the preamble stream signal having such a time length T2.
　この様な観点から、通常の半二重方式によるデータ送受信期間中に、相手先機器よりも前にストリーム信号の送信を開始して時間長Ｔ１のプリアンブルストリーム信号を送信した後、次にプリアンブルストリーム信号を送信する場合や、相手先機器から時間長Ｔ１のプリアンブルストリーム信号を受信した後にプリアンブルストリーム信号を送信する場合には、時間長Ｔ２のプリアンブルストリーム信号が生成される。 From such a point of view, during the data transmission / reception period of the normal half-duplex method, the transmission of the stream signal is started before the counterpart device and the preamble stream signal having the time length T1 is transmitted, and then the preamble stream is transmitted. When transmitting a signal, or when transmitting a preamble stream signal after receiving a preamble stream signal of time length T1 from the counterpart device, a preamble stream signal of time length T2 is generated.
　また、無データ期間中においても通常のデータ送受信期間中と同様に、相手先機器よりも前にストリーム信号の送信を開始して時間長Ｔ１のプリアンブルストリーム信号を送信した後、次にプリアンブルストリーム信号を送信する場合や、相手先機器から時間長Ｔ１のプリアンブルストリーム信号を受信した後にプリアンブルストリーム信号を送信する場合には、時間長Ｔ２のプリアンブルストリーム信号が生成される。 Also, during the non-data period, as in the normal data transmission / reception period, the transmission of the stream signal is started before the counterpart device and the preamble stream signal of time length T1 is transmitted, and then the preamble stream signal Is transmitted, or when a preamble stream signal is transmitted after receiving a preamble stream signal of time length T1 from the counterpart device, a preamble stream signal of time length T2 is generated.
　さらに、本実施の形態では、無データ期間であっても、プリアンブルストリーム信号やフロー制御ストリーム信号が送受信される。つまり、無データ期間中、これらのストリーム信号の送信終了時点では、常に、自局のアダプティブイコライザ２５のフィードバック動作が十分に安定していることとなる。 Furthermore, in this embodiment, a preamble stream signal and a flow control stream signal are transmitted and received even during a no-data period. That is, the feedback operation of the adaptive equalizer 25 of the own station is always sufficiently stable at the end of transmission of these stream signals during the no-data period.
　このため、無データ期間を経て半二重方式によるデータ送受信が開始された際、最初に送信されるプリアンブルストリーム信号は、その時間長がＴ１よりも短くて良い。ここでは、無データ期間の最後にストリーム信号を送信した後、受信動作に切り替えられてから、相手先機器からのプリアンブルストリーム信号を受信するまでの期間に応じた時間長Ｔ２のプリアンブルストリーム信号が生成される。 For this reason, when data transmission / reception by the half-duplex method is started after a no-data period, the time length of the preamble stream signal transmitted first may be shorter than T1. Here, after a stream signal is transmitted at the end of the no-data period, a preamble stream signal having a time length T2 corresponding to a period from when switching to reception operation to reception of a preamble stream signal from a counterpart device is generated Is done.
　図４及び図５は、図１の監視システム１００における送受信動作の一例を模式的に示した説明図であり、半二重方式の通信態様が示されている。図４（ａ）には、送信データなしの無データ期間が示されている。 4 and 5 are explanatory diagrams schematically showing an example of the transmission / reception operation in the monitoring system 100 of FIG. 1, showing a half-duplex communication mode. FIG. 4A shows a no-data period without transmission data.
　通信装置Ａ及びＢの送信バッファ２３内に送信データが蓄積されていない場合、プリアンブルストリーム信号１，３及びフロー制御ストリーム信号２のみが送受信される。すなわち、通信装置Ａは、プリアンブルストリーム信号１を送信した後、フロー制御ストリーム信号２を送信する。通信装置Ｂは、これらのストリーム信号を受信し、受信終了後、所定のタイミングで送信を開始し、プリアンブルストリーム信号３、フロー制御ストリーム信号２を順次に送信する。無データ期間中は、この様な動作が繰り返される。 When no transmission data is accumulated in the transmission buffers 23 of the communication apparatuses A and B, only the preamble stream signals 1 and 3 and the flow control stream signal 2 are transmitted and received. That is, the communication apparatus A transmits the flow stream stream signal 2 after transmitting the preamble stream signal 1. The communication apparatus B receives these stream signals, and after the reception ends, starts transmission at a predetermined timing, and sequentially transmits the preamble stream signal 3 and the flow control stream signal 2. Such an operation is repeated during the no-data period.
　この例では、通信装置Ａが、通信相手の通信装置Ｂよりも前にストリーム信号の送信を開始する場合が示されており、最初に送信されるストリーム信号には、２回目以降のストリーム信号に付加されるプリアンブルストリーム信号３よりも時間長の長いプリアンブルストリーム信号１が付加されている。 This example shows a case where the communication apparatus A starts transmission of a stream signal before the communication apparatus B of the communication partner, and the first stream signal transmitted includes the second and subsequent stream signals. A preamble stream signal 1 having a longer time length than the added preamble stream signal 3 is added.
　無データ期間中に電源が投入され、通信装置Ａが通信装置Ｂよりも前にストリーム信号の送信を開始する場合、通信装置Ａから最初に送信されるストリーム信号には、アダプティブイコライザ２５の応答時間に応じた時間長、すなわち、積分器４６の時定数よりも長い時間長Ｔ１のプリアンブルストリーム信号１が付加される。 When power is turned on during the no-data period and the communication apparatus A starts transmission of a stream signal before the communication apparatus B, the response time of the adaptive equalizer 25 is included in the stream signal transmitted first from the communication apparatus A. A preamble stream signal 1 having a time length T1 longer than the time constant of the integrator 46 is added.
　通信装置Ａが時間長Ｔ１のプリアンブルストリーム信号１の送信後、次にプリアンブルストリーム信号を送信する場合、或いは、通信装置Ｂが時間長Ｔ１のプリアンブルストリーム信号を受信した後にプリアンブルストリーム信号を送信する場合には、相手先機器のアダプティブイコライザ２５がストリーム信号の送信によって安定化されているので、Ｔ１よりも短い時間長Ｔ２のプリアンブルストリーム信号３が付加される。 When communication apparatus A transmits a preamble stream signal next after transmission of preamble stream signal 1 of time length T1, or when communication apparatus B transmits a preamble stream signal after receiving a preamble stream signal of time length T1 Since the adaptive equalizer 25 of the counterpart device is stabilized by transmission of the stream signal, the preamble stream signal 3 having a time length T2 shorter than T1 is added.
　図４（ｂ）には、送信バッファ２３に一定レベル以下のデータ蓄積がある場合が示されている。通信装置Ａ及びＢの送信バッファ２３に一定レベル以下の送信データが蓄積されている場合には、通常送信モードとして、プリアンブルストリーム信号３、データストリーム信号４及びフロー制御ストリーム信号２が送受信される。すなわち、通信装置Ａは、プリアンブルストリーム信号３を送信した後、送信バッファ２３内に蓄積された送信データからなるデータストリーム信号４を送信する。そして、送信バッファ２３内の全送信データを送信した後、フロー制御ストリーム信号２を送信する。 FIG. 4B shows a case where there is data accumulation below a certain level in the transmission buffer 23. When transmission data of a certain level or less is accumulated in the transmission buffers 23 of the communication apparatuses A and B, the preamble stream signal 3, the data stream signal 4, and the flow control stream signal 2 are transmitted and received as the normal transmission mode. That is, after transmitting the preamble stream signal 3, the communication device A transmits the data stream signal 4 composed of the transmission data stored in the transmission buffer 23. And after transmitting all the transmission data in the transmission buffer 23, the flow control stream signal 2 is transmitted.
　通信装置Ｂは、これらのストリーム信号を受信し、受信終了後、所定のタイミングで送信を開始し、プリアンブルストリーム信号３、データストリーム信号４、フロー制御ストリーム信号２を順次に送信する。送信バッファ２３のデータ蓄積量が一定レベル以下である期間中は、この様な動作が繰り返される。 The communication apparatus B receives these stream signals, and after the reception ends, starts transmission at a predetermined timing, and sequentially transmits the preamble stream signal 3, the data stream signal 4, and the flow control stream signal 2. Such an operation is repeated during a period in which the amount of data stored in the transmission buffer 23 is below a certain level.
　この例では、送信バッファ２３内に蓄積された送信データがパケット化され、データパケットからなるデータストリーム信号４が送受信されている。１つのデータパケットは、例えば、所定の開始コードと、一定サイズの送信データと、所定の終了コードによって構成され、その様な複数のデータパケットが時系列に送信される。 In this example, transmission data stored in the transmission buffer 23 is packetized, and a data stream signal 4 composed of data packets is transmitted and received. One data packet is composed of, for example, a predetermined start code, transmission data of a certain size, and a predetermined end code, and such a plurality of data packets are transmitted in time series.
　無データ期間であっても、プリアンブルストリーム信号１，３やフロー制御ストリーム信号２が送受信される。このため、無データ期間を経て半二重方式によるデータ送受信が開始された際に、通信装置Ａが最初に送信するプリアンブルストリーム信号３は、その時間長Ｔ２がＴ１よりも短くて良い。 Even in the no-data period, the preamble stream signals 1 and 3 and the flow control stream signal 2 are transmitted and received. For this reason, when data transmission / reception by the half-duplex method is started after a non-data period, the preamble stream signal 3 transmitted first by the communication apparatus A may have a time length T2 shorter than T1.
　図５には、通信装置Ａの送信バッファ２３に一定レベルを越えるデータ蓄積がある場合が示されている。通信装置Ａの送信バッファ２３に一定レベルを越える送信データが蓄積されている場合、通信装置Ａは、フロー制御ストリーム信号２を付加せずにプリアンブルストリーム信号３及びデータストリーム信号４のみを送信する。 FIG. 5 shows a case where there is data accumulation exceeding a certain level in the transmission buffer 23 of the communication apparatus A. When transmission data exceeding a certain level is accumulated in the transmission buffer 23 of the communication apparatus A, the communication apparatus A transmits only the preamble stream signal 3 and the data stream signal 4 without adding the flow control stream signal 2.
　一方、通信装置Ｂは、通信装置Ａからのストリーム信号を受信した後、データストリーム信号４にフロー制御ストリーム信号２が付加されていないことから通信装置Ａのデータ蓄積量が一定レベルを越えていると判断し、データ送信量を制限する。 On the other hand, since the communication device B receives the stream signal from the communication device A and the flow control stream signal 2 is not added to the data stream signal 4, the data storage amount of the communication device A exceeds a certain level. The amount of data transmission is limited.
　例えば、自局の送信バッファ２３のデータ蓄積量に関わらず、送信データは１パケット分だけ送信する。或いは、送信データを付加せずに、プリアンブルストリーム信号３及びフロー制御ストリーム信号２のみを送信する。一方の通信装置の送信バッファ２３のデータ蓄積量が一定レベルを越えている期間中は、この様な動作が繰り返される。 For example, transmission data is transmitted for one packet regardless of the amount of data stored in the transmission buffer 23 of the own station. Alternatively, only the preamble stream signal 3 and the flow control stream signal 2 are transmitted without adding transmission data. Such an operation is repeated during the period when the data accumulation amount of the transmission buffer 23 of one communication apparatus exceeds a certain level.
　ここでは、通信装置Ａ，Ｂの送信バッファ２３内に送信データが蓄積されていない状態で通信が開始され、最初に送信されるストリーム信号に、その後に送信されるストリーム信号に付加されるプリアンブルストリーム信号３よりも時間長の長いプリアンブルストリーム信号１が付加される場合の例について説明したが、いずれかの通信装置の送信バッファ２３に送信データが蓄積されている状態で通信が開始される場合も同様である。すなわち、少なくとも一方の通信装置の送信バッファ２３内に送信データが蓄積されている状態で通信が開始される場合、最初に送信されるストリーム信号には、その後に送信されるストリーム信号に付加されるプリアンブルストリーム信号３よりも時間長の長いプリアンブルストリーム信号１が付加される。 Here, communication is started in a state in which transmission data is not accumulated in the transmission buffers 23 of the communication apparatuses A and B, and a preamble stream added to a stream signal transmitted first and then to a stream signal transmitted later Although an example in which the preamble stream signal 1 having a longer time length than the signal 3 is added has been described, communication may be started in a state where transmission data is accumulated in the transmission buffer 23 of any communication device. It is the same. That is, when communication is started in a state where transmission data is accumulated in the transmission buffer 23 of at least one communication device, the stream signal transmitted first is added to the stream signal transmitted thereafter. A preamble stream signal 1 having a longer time length than the preamble stream signal 3 is added.
　図６は、図１の監視システム１００における通信装置２０ａ，２０ｂ間の送受信動作の一例を示したタイミングチャートであり、各通信装置Ａ，Ｂの状態遷移の様子が模式的に示されている。通信装置Ａ，Ｂは、電源が投入されると、受信状態となり、その後、相手先機器からの受信がなければ、所定のタイミングで送信を開始する。この例では、通信装置Ａが、通信装置Ｂよりも前に送信を開始する場合が示されている。 FIG. 6 is a timing chart showing an example of a transmission / reception operation between the communication devices 20a and 20b in the monitoring system 100 of FIG. 1, and schematically shows a state transition state of each of the communication devices A and B. When the power is turned on, the communication devices A and B are in a receiving state, and thereafter, if there is no reception from the counterpart device, transmission starts at a predetermined timing. In this example, the case where the communication apparatus A starts transmission before the communication apparatus B is shown.
　通信装置Ａは、まず、プリアンブルストリーム信号（時間長Ｔ１）を送信し、その後、所定の送信マーカを送信する。送信マーカは、所定の通信制御コードからなるビットストリーム信号である。このとき、送信バッファ２３内に送信データが蓄積されていなければ、ダミーデータからなるフロー制御ストリーム信号を次に送信する。 The communication device A first transmits a preamble stream signal (time length T1), and then transmits a predetermined transmission marker. The transmission marker is a bit stream signal composed of a predetermined communication control code. At this time, if transmission data is not accumulated in the transmission buffer 23, a flow control stream signal composed of dummy data is transmitted next.
　通信装置Ａは、フロー制御ストリーム信号の送信終了後、受信状態への切り替えのための待機状態となり、一定時間Ｔの経過後、受信状態となる。通信装置Ｂは、通信装置Ａがビットストリーム信号を送信している間、受信状態となり、通信装置Ａからのビットストリーム信号の受信が終了すると、待機状態を経て所定のタイミングで送信を開始する。 The communication device A enters the standby state for switching to the reception state after the transmission of the flow control stream signal is completed, and enters the reception state after a predetermined time T has elapsed. The communication device B enters a reception state while the communication device A transmits a bit stream signal. When reception of the bit stream signal from the communication device A ends, the communication device B starts transmission at a predetermined timing through a standby state.
　このとき、通信装置Ｂは、まず、プリアンブルストリーム信号（時間長Ｔ２）を送信し、その後、所定の送信マーカを送信する。通信装置Ｂは、送信バッファ２３内に送信データが蓄積されていれば、送信データからなるデータストリーム信号を次に送信し、再度送信マーカを送信してからダミーデータからなるフロー制御ストリーム信号を送信する。そして、通信装置Ｂは、フロー制御ストリーム信号の送信終了後、受信状態への切り替えのための待機状態となり、一定時間Ｔの経過後、受信状態となる。 At this time, the communication apparatus B first transmits a preamble stream signal (time length T2), and then transmits a predetermined transmission marker. If transmission data is accumulated in the transmission buffer 23, the communication device B transmits a data stream signal composed of transmission data next, transmits a transmission marker again, and then transmits a flow control stream signal composed of dummy data. To do. Then, after the transmission of the flow control stream signal is completed, the communication device B enters a standby state for switching to the reception state, and enters a reception state after a predetermined time T has elapsed.
　通信開始後、最初に送信されるストリーム信号に通信装置Ａが付加するプリアンブルストリーム信号の時間長Ｔ１は、次に送信されるストリーム信号に通信装置Ｂが付加するプリアンブルストリーム信号の時間長Ｔ２に比べて長くなっている。 After the start of communication, the time length T1 of the preamble stream signal added by the communication device A to the first transmitted stream signal is compared with the time length T2 of the preamble stream signal added by the communication device B to the next transmitted stream signal. Is getting longer.
　図７（ａ）～（ｄ）は、図２の通信装置２０ａ，２０ｂにおける送信動作の一例を示した図であり、同軸ケーブル３０を介して相手先機器に送信されるビットストリーム信号が示されている。図７（ａ）には、無データ期間中に最初に送信されるビットストリーム信号が示され、図７（ｂ）には、無データ期間中の２回目以降に送信されるビットストリーム信号が示されている。 FIGS. 7A to 7D are diagrams showing an example of the transmission operation in the communication apparatuses 20a and 20b of FIG. 2, in which a bit stream signal transmitted to the counterpart device via the coaxial cable 30 is shown. ing. FIG. 7A shows a bit stream signal transmitted first during a no data period, and FIG. 7B shows a bit stream signal transmitted after the second time during the no data period. Has been.
　送信バッファ２３内に送信データが蓄積されていない無データ期間中は、プリアンブルストリーム信号１，３、送信マーカ５，６及びフロー制御ストリーム信号２が順次に送信される。相手先機器よりも前にビットストリーム信号の送信を開始する場合、最初に送信されるビットストリーム信号には、２回目以降に送信されるビットストリーム信号に付加されるプリアンブルストリーム信号３よりも時間長の長いプリアンブルストリーム信号１が付加される。 During the no-data period in which no transmission data is accumulated in the transmission buffer 23, the preamble stream signals 1 and 3, the transmission markers 5 and 6, and the flow control stream signal 2 are sequentially transmitted. When transmission of the bit stream signal is started before the counterpart device, the bit stream signal transmitted first has a longer time than the preamble stream signal 3 added to the bit stream signal transmitted after the second time. A long preamble stream signal 1 is added.
　この例では、転送レートを６０Ｍｂｐｓとし、最初に送信されるビットストリーム信号には、１２ｍｓ程度の時間長のプリアンブルストリーム信号１が付加されている。また、２回目以降に送信されるビットストリーム信号には、１６μｓ程度の時間長のプリアンブルストリーム信号３が付加されている。 In this example, the transfer rate is set to 60 Mbps, and the preamble stream signal 1 having a time length of about 12 ms is added to the bitstream signal transmitted first. In addition, a preamble stream signal 3 having a time length of about 16 μs is added to the bit stream signal transmitted after the second time.
　プリアンブルストリーム信号１，３のビット配列は、アダプティブイコライザ２５のフィードバック動作を安定させるのに適切なものが選択される。例えば、積分器４６による学習効果が持続するようなビット配列が選択される。 The bit arrangement of the preamble stream signals 1 and 3 is selected to be appropriate for stabilizing the feedback operation of the adaptive equalizer 25. For example, a bit arrangement is selected so that the learning effect by the integrator 46 lasts.
　無データ期間中、プリアンブルストリーム信号１，３及びフロー制御ストリーム信号２を送信することにより、データ受信に備えて自局のアダプティブイコライザ２５のフィードバック動作を安定させておくことができる。また、ビットストリーム信号の送信によって自局のアダプティブイコライザ２５のフィードバック動作が安定するので、相手先機器からのビットストリーム信号を受信した後にビットストリーム信号を送信する場合には、プリアンブルストリーム信号の時間長を短くしても、相手先機器のアダプティブイコライザ２５のフィードバック動作を十分に安定させることができる。 By transmitting the preamble stream signals 1 and 3 and the flow control stream signal 2 during the no-data period, the feedback operation of the adaptive equalizer 25 of the own station can be stabilized in preparation for data reception. In addition, since the feedback operation of the adaptive equalizer 25 of the local station is stabilized by the transmission of the bit stream signal, when the bit stream signal is transmitted after receiving the bit stream signal from the counterpart device, the time length of the preamble stream signal The feedback operation of the adaptive equalizer 25 of the counterpart device can be sufficiently stabilized even if the time is shortened.
　図７（ｃ）には、送信バッファ２３に一定レベル以下のデータ蓄積がある場合に送信されるビットストリーム信号が示されている。送信バッファ２３内に一定レベル以下の送信データが蓄積されている場合には、プリアンブルストリーム信号３、送信マーカ６、データストリーム信号４及びフロー制御ストリーム信号２が送信される。この例では、プリアンブルストリーム信号３、送信マーカ６、データパケット、送信マーカ６、データパケット、送信マーカ６、フロー制御ストリーム信号２の順で送信されている。 FIG. 7 (c) shows a bit stream signal transmitted when there is data accumulation below a certain level in the transmission buffer 23. When transmission data of a certain level or less is accumulated in the transmission buffer 23, the preamble stream signal 3, the transmission marker 6, the data stream signal 4, and the flow control stream signal 2 are transmitted. In this example, the preamble stream signal 3, the transmission marker 6, the data packet, the transmission marker 6, the data packet, the transmission marker 6, and the flow control stream signal 2 are transmitted in this order.
　図７（ｄ）には、送信バッファ２３に一定レベルを越えるデータ蓄積がある場合に送信されるビットストリーム信号が示されている。送信バッファ２３内に一定レベルを越える送信データが蓄積されている場合には、プリアンブルストリーム信号３、送信マーカ６及びデータストリーム信号４が送信される。この例では、プリアンブルストリーム信号３、送信マーカ６、データパケット、送信マーカ６、データパケット、送信マーカ６の順で送信されている。 FIG. 7D shows a bit stream signal transmitted when there is data accumulation exceeding a certain level in the transmission buffer 23. When transmission data exceeding a certain level is accumulated in the transmission buffer 23, the preamble stream signal 3, the transmission marker 6, and the data stream signal 4 are transmitted. In this example, the preamble stream signal 3, the transmission marker 6, the data packet, the transmission marker 6, the data packet, and the transmission marker 6 are transmitted in this order.
　送信バッファ２３のデータ蓄積量に基づいてフロー制御ストリーム信号２をビットストリーム信号に付加するので、相手先機器の送信バッファ２３のデータ蓄積量が一定レベルを越えているか否かを受信したビットストリーム信号にフロー制御ストリーム信号２が付加されているか否かによって識別することができる。 Since the flow control stream signal 2 is added to the bit stream signal based on the data accumulation amount of the transmission buffer 23, the received bit stream signal indicates whether or not the data accumulation amount of the transmission buffer 23 of the counterpart device exceeds a certain level. Can be identified by whether or not the flow control stream signal 2 is added to the.
　図８のステップＳ１０１～Ｓ１１３は、図２の通信装置２０ａ，２０ｂにおける送受信時の動作の一例を示したフローチャートである。まず、送信部２４は、電源投入後、受信中でなければ、所定のタイミングで送信を開始する。このとき、送信バッファ２３内に送信データがなければ、ダミーデータからなるフロー制御ストリーム信号にプリアンブルストリーム信号を付加して相手先機器に送信し、受信状態に切り替える(ステップＳ１０１，Ｓ１０２，Ｓ１０５，Ｓ１０６）。 Steps S101 to S113 in FIG. 8 are flowcharts showing an example of operations at the time of transmission / reception in the communication devices 20a and 20b in FIG. First, after the power is turned on, the transmission unit 24 starts transmission at a predetermined timing if it is not receiving. At this time, if there is no transmission data in the transmission buffer 23, a preamble stream signal is added to the flow control stream signal made up of dummy data and transmitted to the counterpart device to switch to the reception state (steps S101, S102, S105, S106). ).
　一方、送信バッファ２３内に送信データがあり、かつ、そのデータ蓄積量が一定レベル以下である場合には、プリアンブルストリーム信号を送信してからデータストリーム信号を送信し、送信バッファ２３内の送信データを全て送信し終えると、フロー制御ストリーム信号を送信して受信状態に切り替える(ステップＳ１０１～Ｓ１０６）。 On the other hand, when there is transmission data in the transmission buffer 23 and the data accumulation amount is below a certain level, the data stream signal is transmitted after transmitting the preamble stream signal, and the transmission data in the transmission buffer 23 is transmitted. When all transmissions are completed, a flow control stream signal is transmitted to switch to the reception state (steps S101 to S106).
　また、送信バッファ２３内に送信データがあり、かつ、そのデータ蓄積量が一定レベルを越えている場合には、プリアンブルストリーム信号を送信してからデータストリーム信号を送信し、送信バッファ２３内の送信データを全て送信し終えると、フロー制御ストリーム信号を送信せずに受信状態に切り替える(ステップＳ１０１～Ｓ１０３，Ｓ１０７，Ｓ１０６）。 When there is transmission data in the transmission buffer 23 and the data accumulation amount exceeds a certain level, the data stream signal is transmitted after the preamble stream signal is transmitted, and the transmission in the transmission buffer 23 is performed. When all the data has been transmitted, the flow control stream signal is switched to the reception state without transmitting (steps S101 to S103, S107, S106).
　次に、受信部２６は、アダプティブイコライザ２５から入力されるストリーム信号から受信データを抽出してＬＡＮＩ／Ｆ２１へ出力する動作を受信が終了するまで繰り返す（ステップＳ１０８，Ｓ１０９）。受信部２６は、受信終了時に、相手先機器から受信したストリーム信号にダミーデータからなるフロー制御ストリーム信号が付加されていれば、通常送信モードに切り替える（ステップＳ１１０，Ｓ１１１）。 Next, the receiving unit 26 repeats the operation of extracting the received data from the stream signal input from the adaptive equalizer 25 and outputting it to the LAN I / F 21 until the reception is completed (steps S108 and S109). At the end of reception, the reception unit 26 switches to the normal transmission mode if a flow control stream signal composed of dummy data is added to the stream signal received from the counterpart device (steps S110 and S111).
　一方、相手先機器から受信したストリーム信号にフロー制御ストリーム信号が付加されていない場合には、データ送信量を制限する送信量制限モードに切り替える（ステップＳ１１０，Ｓ１１３）。 On the other hand, when the flow control stream signal is not added to the stream signal received from the counterpart device, the mode is switched to the transmission amount restriction mode for restricting the data transmission amount (steps S110 and S113).
　ステップＳ１０１で受信中であれば、ステップＳ１０８以降の処理手順が実行される。また、ステップＳ１０２からステップＳ１１１又はＳ１１３の処理手順は、通信が終了するまで繰り返される（ステップＳ１１２）。 If it is being received in step S101, the processing procedure after step S108 is executed. Further, the processing procedure from step S102 to step S111 or S113 is repeated until the communication is completed (step S112).
　本実施の形態によれば、プリアンブルストリーム信号によってアダプティブイコライザ２５のフィードバック動作を安定させてからデータストリーム信号が入力されるので、送信状態から受信状態への切り替え後にストリーム信号から受信データを抽出する際の誤認識を抑制することができる。また、相手先機器からのフロー制御ストリーム信号に基づいてデータ送信量を制御するので、相手先機器の送信バッファ２３のデータ蓄積量が一定レベルを越えている場合に、データ送信量を制限することによって、当該相手先機器の受信処理に係る負荷の増大を抑制することができる。 According to the present embodiment, since the data stream signal is input after the feedback operation of the adaptive equalizer 25 is stabilized by the preamble stream signal, the reception data is extracted from the stream signal after switching from the transmission state to the reception state. Misrecognition can be suppressed. Further, since the data transmission amount is controlled based on the flow control stream signal from the counterpart device, the data transmission amount is limited when the data accumulation amount of the transmission buffer 23 of the counterpart device exceeds a certain level. Thus, it is possible to suppress an increase in the load related to the reception process of the counterpart device.
　なお、本実施の形態では、ストリーム信号の送信時に当該ストリーム信号が自局のアダプティブイコライザ２５に入力される場合の例について説明したが、本発明はこれに限られるものではなく、ストリーム信号の送信時に当該ストリーム信号を自局のアダプティブイコライザ２５に入力しないものも本発明には含まれる。 In the present embodiment, an example in which the stream signal is input to the adaptive equalizer 25 of the local station at the time of transmission of the stream signal has been described. However, the present invention is not limited to this, and transmission of the stream signal is not limited thereto. Sometimes the stream signal is not input to the adaptive equalizer 25 of the own station.
　図９（ａ）及び（ｂ）は、本発明の他の実施の形態による通信装置の送受信動作の一例を示した図であり、送信中のストリーム信号を自局のアダプティブイコライザ２５に入力しない場合が示されている。図９（ａ）には、送信データなしの無データ期間が示され、図９（ｂ）には、送信バッファ２３に一定レベル以下のデータ蓄積がある場合が示されている。 FIGS. 9A and 9B are diagrams illustrating an example of the transmission / reception operation of the communication apparatus according to another embodiment of the present invention, in which the stream signal being transmitted is not input to the adaptive equalizer 25 of the own station It is shown. FIG. 9A shows a no-data period without transmission data, and FIG. 9B shows a case where the transmission buffer 23 has data accumulation below a certain level.
　プリアンブルストリーム信号やデータストリーム信号、フロー制御ストリーム信号を自局のアダプティブイコライザ２５に入力しない場合、通信装置Ａや通信装置Ｂが最初に送信するストリーム信号には、時間長Ｔ１のプリアンブルストリーム信号１が付加される。 When the preamble stream signal, the data stream signal, and the flow control stream signal are not input to the adaptive equalizer 25 of the local station, the preamble stream signal 1 having the time length T1 is included in the stream signal transmitted first by the communication device A or the communication device B. Added.
　そして、通信装置Ａ及び通信装置Ｂは、時間長Ｔ１のプリアンブルストリーム信号１を付加したストリーム信号の送信後、次にストリーム信号を送信する際に、Ｔ１よりも短く、Ｔ２よりも長い時間長Ｔ４のプリアンブルストリーム信号３ａを付加する。 Then, after transmitting the stream signal to which the preamble stream signal 1 having the time length T1 is added, the communication device A and the communication device B will transmit the stream signal next time, which is shorter than T1 and longer than T2. The preamble stream signal 3a is added.
　つまり、通信装置Ａ及びＢは、最初の送信フェーズにおいて、時間長Ｔ１のプリアンブルストリーム信号１を付加してストリーム信号を送信し、その後の送信フェーズでは、時間長Ｔ４のプリアンブルストリーム信号３ａを付加してストリーム信号を送信する。 That is, the communication apparatuses A and B transmit the stream signal by adding the preamble stream signal 1 having the time length T1 in the first transmission phase, and add the preamble stream signal 3a having the time length T4 in the subsequent transmission phase. To send a stream signal.
　この時間長Ｔ４は、プリアンブルストリーム信号やデータストリーム信号の受信が終了してから、相手先機器からのプリアンブルストリーム信号を次に受信するまでの期間に応じて決定される。すなわち、上記期間中のコンデンサー４６ｃの放電によって自局のアダプティブイコライザ２５のフィードバック動作が不安定となった際に、当該フィードバック動作の安定化に要する時間Ｔ５は、積分器４６の時定数よりも短く、Ｔ３よりも長い。このため、時間長Ｔ４が時間Ｔ５よりも十分に長ければ、その様な時間長Ｔ４のプリアンブルストリーム信号を受信することにより、自局のアダプティブイコライザ２５を安定化させることができる。 This time length T4 is determined according to the period from the end of reception of the preamble stream signal or data stream signal until the next reception of the preamble stream signal from the counterpart device. That is, when the feedback operation of the adaptive equalizer 25 of the own station becomes unstable due to the discharge of the capacitor 46c during the above period, the time T5 required for stabilization of the feedback operation is shorter than the time constant of the integrator 46. , Longer than T3. Therefore, if the time length T4 is sufficiently longer than the time T5, the adaptive equalizer 25 of the own station can be stabilized by receiving the preamble stream signal having such a time length T4.
　また、本実施の形態では、無データ期間であってもプリアンブルストリーム信号１，３やフロー制御ストリーム信号２が送受信される場合の例について説明したが、本発明はこれに限られるものではなく、無データ期間中にはこれらのストリーム信号を送信しないものも本発明には含まれる。 In the present embodiment, an example in which the preamble stream signals 1 and 3 and the flow control stream signal 2 are transmitted and received even in the no-data period has been described, but the present invention is not limited to this, The present invention includes those that do not transmit these stream signals during the no-data period.
　図１０（ａ）及び（ｂ）は、本発明の他の実施の形態による通信装置の送受信動作の一例を示した図であり、無データ期間にはストリーム信号を送信しない場合が示されている。図１０（ａ）には、送信データなしの無データ期間が示され、図１０（ｂ）には、送信バッファ２３に一定レベル以下のデータ蓄積がある場合が示されている。 FIGS. 10A and 10B are diagrams illustrating an example of a transmission / reception operation of a communication apparatus according to another embodiment of the present invention, in which a stream signal is not transmitted during a no-data period. . FIG. 10A shows a no-data period without transmission data, and FIG. 10B shows a case where the transmission buffer 23 has data accumulation below a certain level.
　無データ期間中、プリアンブルストリーム信号やフロー制御ストリーム信号が送受信されない場合、無データ期間を経て半二重方式によるデータ送受信が開始された際、通信装置Ａが通信装置Ｂよりも前に送信を開始するプリアンブルストリーム信号は、時間長がＴ１のプリアンブルストリーム信号１である。 If no preamble stream signal or flow control stream signal is transmitted / received during the no-data period, communication device A starts transmission before communication device B when half-duplex data transmission / reception starts after the no-data period. The preamble stream signal to be performed is the preamble stream signal 1 having a time length of T1.
　通信装置Ａが時間長Ｔ１のプリアンブルストリーム信号１の送信後、次にプリアンブルストリーム信号を送信する際、或いは、通信装置Ｂが時間長Ｔ１のプリアンブルストリーム信号を受信した後にプリアンブルストリーム信号を送信する際には、Ｔ１よりも短い時間長Ｔ２のプリアンブルストリーム信号３ｂが付加される。 When communication apparatus A transmits a preamble stream signal next after transmission of preamble stream signal 1 of time length T1, or when communication apparatus B transmits a preamble stream signal after receiving a preamble stream signal of time length T1 Is appended with a preamble stream signal 3b having a time length T2 shorter than T1.
　図１１（ａ）及び（ｂ）は、本発明の他の実施の形態による通信装置の送受信動作の他の一例を示した図であり、送信中のストリーム信号を自局のアダプティブイコライザ２５に入力せず、無データ期間にはストリーム信号を送信しない場合が示されている。図１１（ａ）には、送信データなしの無データ期間が示され、図１１（ｂ）には、送信バッファ２３に一定レベル以下のデータ蓄積がある場合が示されている。 FIGS. 11A and 11B are diagrams showing another example of the transmission / reception operation of the communication apparatus according to another embodiment of the present invention, in which the stream signal being transmitted is input to the adaptive equalizer 25 of its own station No stream signal is transmitted in the no-data period. FIG. 11A shows a no-data period without transmission data, and FIG. 11B shows a case where the transmission buffer 23 has data accumulation below a certain level.
　プリアンブルストリーム信号やデータストリーム信号、フロー制御ストリーム信号を自局のアダプティブイコライザ２５に入力せず、無データ期間中には、プリアンブルストリーム信号やフロー制御ストリーム信号が送受信されない場合、無データ期間を経て半二重方式によるデータ送受信が開始された際に、通信装置Ａや通信装置Ｂが最初に送信するストリーム信号には、時間長Ｔ１のプリアンブルストリーム信号１が付加される。 If the preamble stream signal, the data stream signal, and the flow control stream signal are not input to the adaptive equalizer 25 of the local station and the preamble stream signal and the flow control stream signal are not transmitted / received during the no-data period, a half-time passes after the no-data period. When the data transmission / reception by the duplex method is started, the preamble stream signal 1 having the time length T1 is added to the stream signal transmitted first by the communication device A or the communication device B.
　そして、通信装置Ａ及び通信装置Ｂは、時間長Ｔ１のプリアンブルストリーム信号１を付加したストリーム信号の送信後、次にストリーム信号を送信する際に、Ｔ１よりも短く、Ｔ２よりも長い時間長Ｔ４のプリアンブルストリーム信号３ａを付加する。 Then, after transmitting the stream signal to which the preamble stream signal 1 having the time length T1 is added, the communication device A and the communication device B will transmit the stream signal next time, which is shorter than T1 and longer than T2. The preamble stream signal 3a is added.
　なお、本実施の形態では、送信部２４が受信部２６に受信データの抽出を指示することによって送信フェーズから受信フェーズに動作モードが切り替えられる場合の例について説明したが、本発明はこれに限られるものではない。本発明は、何らかのルールに基づいて送信フェーズ及び受信フェーズが交互に切り替えられる半二重方式の通信形態に対して適用することができる。例えば、一定時間ごとに送信フェーズ及び受信フェーズを切り替えるものであっても良い。 In the present embodiment, an example in which the operation mode is switched from the transmission phase to the reception phase by the transmission unit 24 instructing the reception unit 26 to extract received data has been described. However, the present invention is not limited to this. It is not something that can be done. The present invention can be applied to a half-duplex communication mode in which a transmission phase and a reception phase are alternately switched based on some rule. For example, the transmission phase and the reception phase may be switched at regular intervals.
１，３，３ａ，３ｂ　プリアンブルストリーム信号
２　フロー制御ストリーム信号
４　データストリーム信号
１１　カメラ
１２　ＬＡＮ
１３　モニター装置
１４　録画機器
２０ａ，２０ｂ　通信装置
２１　ＬＡＮＩ／Ｆ
２２　バッファ制御部
２３　送信バッファ
２４　送信部
２４ａ　データストリーム信号生成部
２４ｂ　プリアンブルストリーム信号生成部
２４ｃ　送信制御部
２５　アダプティブイコライザ
２６　受信部
３０　同軸ケーブル
４２　信号入力部
４３　可変型イコライザ
４４　遷移時間測定器
４６　積分器
１００　監視システム
Ｔ１，Ｔ２，Ｔ４　プリアンブルストリーム信号の時間長 1, 3, 3a, 3b Preamble stream signal 2 Flow control stream signal 4 Data stream signal 11 Camera 12 LAN
13 Monitor device 14 Recording device 20a, 20b Communication device 21 LAN I / F
22 buffer control unit 23 transmission buffer 24 transmission unit 24a data stream signal generation unit 24b preamble stream signal generation unit 24c transmission control unit 25 adaptive equalizer 26 reception unit 30 coaxial cable 42 signal input unit 43 variable equalizer 44 transition time measuring unit 46 integration 100 Monitoring system T1, T2, T4 Time length of preamble stream signal

Claims (5)

  1. 　伝送媒体を介して接続された相手先機器と送信フェーズ及び受信フェーズを交互に切り替えながら半二重方式で通信する通信装置において、
    　送信バッファに蓄積された送信データに基づいて連続するデータビットからなるデータストリーム信号を生成し、上記伝送媒体を介して上記相手先機器へ送信する送信手段と、
    　データビットの遷移時間に基づいて、上記伝送媒体上のストリーム信号について波形調整を行うアダプティブイコライザと、
    　波形調整後のストリーム信号から受信データを抽出する受信手段とを備え、
    　上記送信手段が、プリアンブルストリーム信号を生成するプリアンブルストリーム信号生成手段を有し、
    　データストリーム信号の送信フェーズでは、上記送信手段が、上記プリアンブルストリーム信号を送信してから上記データストリーム信号の送信を開始し、
    　データストリーム信号の受信フェーズでは、上記アダプティブイコライザが、上記相手先機器から入力される上記プリアンブルストリーム信号及び上記データストリーム信号について波形調整を行い、上記受信手段が、上記アダプティブイコライザを介して入力されるデータストリーム信号から受信データを抽出することを特徴とする通信装置。     In a communication device that communicates with a counterpart device connected via a transmission medium in a half-duplex manner while alternately switching a transmission phase and a reception phase,
    Transmission means for generating a data stream signal composed of continuous data bits based on transmission data stored in a transmission buffer and transmitting the data stream signal to the counterpart device via the transmission medium;
    An adaptive equalizer that adjusts the waveform of the stream signal on the transmission medium based on the transition time of the data bits;
    Receiving means for extracting received data from the stream signal after waveform adjustment,
    The transmission means includes preamble stream signal generation means for generating a preamble stream signal;
    In the data stream signal transmission phase, the transmission means starts transmitting the data stream signal after transmitting the preamble stream signal,
    In the data stream signal reception phase, the adaptive equalizer adjusts the waveform of the preamble stream signal and the data stream signal input from the counterpart device, and the receiving means is input via the adaptive equalizer. A communication apparatus that extracts received data from a data stream signal.
  2. 　上記アダプティブイコライザは、上記相手先機器からのストリーム信号が入力される可変型イコライザと、上記可変型イコライザの出力が入力される遷移時間測定器と、上記遷移時間測定器による遷移時間の測定結果に基づいて上記可変型イコライザを制御する積分器とからなり、
    　上記プリアンブルストリーム信号生成手段が、上記可変型イコライザの出力の一部を上記遷移時間測定器及び上記積分器で順に処理させて当該可変型イコライザに帰還させる制御ループに対応する時間長のプリアンブルストリーム信号を生成することを特徴とする請求項１に記載の通信装置。     The adaptive equalizer includes a variable equalizer to which a stream signal from the counterpart device is input, a transition time measuring device to which the output of the variable equalizer is input, and a transition time measurement result by the transition time measuring device. And an integrator for controlling the variable equalizer based on
    A preamble stream signal having a time length corresponding to a control loop in which the preamble stream signal generation means sequentially processes a part of the output of the variable equalizer by the transition time measuring device and the integrator and feeds back to the variable equalizer. The communication apparatus according to claim 1, wherein:
  3. 　上記プリアンブルストリーム信号生成手段が、上記積分器の時定数よりも時間長の長いプリアンブルストリーム信号を生成することを特徴とする請求項２に記載の通信装置。 3. The communication apparatus according to claim 2, wherein the preamble stream signal generation means generates a preamble stream signal having a time length longer than a time constant of the integrator.
  4. 　上記プリアンブルストリーム信号生成手段が、最初の送信フェーズでは、上記積分器の時定数よりも時間長の長いプリアンブルストリーム信号を生成し、その後の送信フェーズでは、上記時定数よりも時間長の短いプリアンブルストリーム信号を生成することを特徴とする請求項２に記載の通信装置。 The preamble stream signal generating means generates a preamble stream signal having a time length longer than the time constant of the integrator in the first transmission phase, and in a subsequent transmission phase, a preamble stream having a time length shorter than the time constant. The communication device according to claim 2, wherein the signal is generated.
  5. 　上記伝送媒体を介して上記相手先機器へ順次に送信されるプリアンブルストリーム信号及びデータストリーム信号がいずれも上記アダプティブイコライザに入力され、これらのストリーム信号の送信中にも当該アダプティブイコライザが波形調整を行うことを特徴とする請求項２に記載の通信装置。 Both the preamble stream signal and the data stream signal that are sequentially transmitted to the counterpart device via the transmission medium are input to the adaptive equalizer, and the adaptive equalizer performs waveform adjustment during the transmission of these stream signals. The communication device according to claim 2.
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