WO2018218422A1 - 信号均值检测方法、装置和系统 - Google Patents

信号均值检测方法、装置和系统 Download PDF

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Publication number
WO2018218422A1
WO2018218422A1 PCT/CN2017/086334 CN2017086334W WO2018218422A1 WO 2018218422 A1 WO2018218422 A1 WO 2018218422A1 CN 2017086334 W CN2017086334 W CN 2017086334W WO 2018218422 A1 WO2018218422 A1 WO 2018218422A1
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Prior art keywords
signal
input signal
mean
input
output
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PCT/CN2017/086334
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English (en)
French (fr)
Inventor
景磊
奥塞尔·彼得
李胜平
余长亮
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华为技术有限公司
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Priority to CN201780077428.8A priority Critical patent/CN110073615B/zh
Priority to PCT/CN2017/086334 priority patent/WO2018218422A1/zh
Publication of WO2018218422A1 publication Critical patent/WO2018218422A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/564—Power control

Definitions

  • the present application relates to the field of communications, and in particular, to a signal mean detection method, apparatus, and system.
  • PON Passive Optical Network
  • OLT Optical Line Terminal
  • Central Office Central Office
  • the Passive Splitter establishes communication with the ONU (Optical Network Unit) of all users on the network.
  • the ONU communicates with the OLT, one communication signal of each ONU is called a burst optical signal. Since the insertion loss of each link between the OLT and the ONU is different, the average power and phase between the burst optical signals arriving at the OLT side are also different. Therefore, the receiver of the OLT should have a fast capture of a certain dynamic range.
  • the ability of the illuminating signal, after converting the burst optical signal into a voltage signal by using a photodetector, detecting the average value of the voltage signal by using the voltage signal as an input signal, and the subsequent circuit can amplify the voltage signal according to the average value The same level.
  • the voltage signal is a signal that switches at high speed between high and low levels.
  • the manner in which the mean value of the voltage signal is detected in the prior art is to use a signal mean detector as shown in FIG.
  • the input of the LPF (Low Pass Filter) composed of the capacitor C and the resistor R2 is the voltage signal (hereinafter referred to as an input signal) V in for convenience of description, and the output V out is the mean of V in .
  • the input signal is switched between a high level and a low level at a certain frequency.
  • the average value of the input signal can be maintained at an ideal mean value, or floating within a small range near the ideal mean value, as shown in the figure.
  • the input signal is switched at a high speed between a high level and a low level, and the mean value of the input signal is a straight line state, which is consistent with the ideal mean value, in a portion where the signal curve is denser.
  • the switching frequency of the input signal between the high level and the low level is slightly lower, and the average value of the input signal fluctuates above and below the ideal average value.
  • the ideal average value is an average value of the input signal in a normal state, and is equal to a common mode voltage of the input signal.
  • the input signal is continuous high level or continuous low level, the average value of the input signal will be greatly deviated from the ideal average value (also called baseline drift). As shown in Figure 1, the input signal is continuous high power.
  • the mean is much larger than the ideal mean, and when the input signal is continuous low, the mean is much lower than the ideal mean.
  • the averaging detector used in the prior art cannot eliminate the deviation between the mean and ideal mean of the input signal when the input signal is continuous high or continuous low.
  • the application provides a signal mean detection method, device and system to eliminate signal mean and ideal mean The deviation between.
  • the present application provides a signal mean value detector, including: a first low pass filter, configured to use a first input signal as an input to obtain a first mean estimation signal of the first input signal; and an input signal a reconstruction module, configured to obtain a second input signal according to the first mean estimation signal and the first input signal, the second input signal has a set common mode voltage, and an output of the second input signal
  • the swing and polarity are the same as the output swing and polarity of the first input signal
  • the second low pass filter is configured to use the second input signal as an input to obtain a second of the second input signal Mean estimation signal, the second low pass filter having the same transfer function as the first low pass filter; and a subtracter for subtracting the first mean estimation signal from the second mean estimation signal And adding an adjustment voltage, the magnitude of the adjustment voltage being the same as the magnitude of the common mode voltage of the second input signal.
  • the mean signal of the second input signal and the mean signal of the first input signal comprise the same deviation component, and then the mean signal of the first input signal is subtracted from the mean signal of the second input signal, The deviation components contained in the two cancel out, thereby eliminating the deviation of the mean of the first input signal, and obtaining the ideal mean of the first input signal.
  • the input signal reconstruction module is a comparator
  • the input of the comparator is the first input signal, the first mean estimation signal And an output of the subtractor, the output of the comparator being the second input signal.
  • the input signal reconstruction module includes: a mean value reconstructor, configured to subtract the first mean estimation signal from a zero line signal to obtain a first Mean estimating the reconstructed signal, and adding the first mean estimate signal to the zero line signal to obtain a second mean estimate reconstructed signal; a comparator for comparing the first mean estimate signal and the first input signal, respectively Comparing the first mean estimated reconstructed signal and the first input signal, and comparing the second mean estimated reconstructed signal with the first input signal; a pulse amplitude modulator having an input of the output of the comparator And an output of the subtractor, the output of which is the second input signal. In this way, the polarity of the first input signal can be obtained more accurately, and the output amplitude of the second input signal can be controlled more accurately using the pulse amplitude modulator.
  • the present application provides a receiver comprising the signal mean detector of the first aspect.
  • the receiver may include: a front end amplifier, the input of the front end amplifier being an optical current signal and an output of the gain controller for converting the photo current signal into a voltage signal according to a magnification determined by the gain controller; a peak detector: an input of the peak detector is an output of the front end amplifier for outputting a peak-to-peak voltage of an output of the front end amplifier; a gain controller, the input of the gain controller being the peak - a peak voltage for determining a magnification of the front end amplifier according to the peak-to-peak voltage; a signal mean detector, an input of the signal mean detector being an output of the front end amplifier for obtaining the front end amplifier The mean of the output.
  • the receiver can be used to obtain the ideal mean of the burst optical signal with higher accuracy.
  • the receiver may further include: a main amplifier, an input of the main amplifier being an output of the front end amplifier, an output of the signal mean detector, and an output of the gain controller for controlling according to the gain
  • the output of the device determines the amplification factor of the main amplifier, and converts the output of the front-end amplifier into a differential signal according to the amplification factor of the main amplifier; a buffer amplifier whose input is the output of the main amplifier, according to the The output of the main amplifier outputs a voltage signal with a fixed impedance.
  • the main amplifier compares the output of the front end amplifier with the output of the signal mean detector, and outputs a differential signal that is more resistant to interference.
  • a buffer can also be connected after the main amplifier, and the buffer is input with the output of the main amplifier to output a differential voltage signal with a fixed impedance for impedance matching after the load is connected.
  • the receiver may further include: a burst start detector, an input of the burst start detector being an output of the front end amplifier for outputting an enable signal to the gain controller and the signal mean detector
  • the enable signal is used to enable the gain controller and the signal mean detector, and the input of the gain controller and the signal mean detector further includes the enable signal; a resetter, An input of the resetter is an output of the main amplifier and an enable signal output by the burst start detector for outputting a reset to the peak detector, the gain controller, the signal mean detector, and the burst start detector A signal, the burst start detector is further configured to output an enable signal to the resetter.
  • the probability of occurrence of errors in the gain controller, the signal mean detector, and the resetter can be reduced.
  • the resetter takes an output of the main amplifier as an input, and when an abnormality occurs in an output of the main amplifier, outputs a reset signal to the gain controller, the peak detector, the signal mean detector, and the burst start detector, so that the The gain controller, peak detector, signal averaging detector, and burst start detector are zeroed to reduce receiver failure.
  • the present application provides an optical line termination, the optical line termination comprising the receiver of the second aspect.
  • the present application provides a passive optical network system, where the passive optical network system includes the optical line terminal of the third aspect.
  • the present application provides a signal mean value detecting method, including: obtaining a first mean value estimation signal by low pass filtering a first input signal; and obtaining a first according to the first mean value estimation signal and the first input signal a second input signal having a set common mode voltage, and an output swing and polarity of the second input signal being the same as an output swing and polarity of the first input signal;
  • the second input signal is low-pass filtered to obtain a second mean estimation signal, a transfer function between the second mean estimation signal and the second input signal, and the first mean estimation signal and the first input signal
  • the transfer function is the same; subtracting the first mean estimate signal from the second mean estimate signal, and adding an adjustment voltage, the magnitude of the adjustment voltage and the common mode voltage of the second input signal The same size.
  • a common mode voltage of the second input signal is equal to a high level voltage of the first input signal.
  • the obtaining, according to the first mean estimation signal and the first input signal includes: comparing the first input signal and the first mean estimation signal to obtain a polarity of the second input signal; using a feedback signal to control an output swing of the second input signal, Output swing of the second input signal, etc. And an output swing of the first input signal, the feedback signal is a subtraction of the first mean estimation signal and the second mean estimation signal, and an adjustment voltage is added, and the size and the adjustment voltage are The common mode voltage of the second input signal has the same magnitude.
  • the signal mean detection technical solution provided by the embodiment of the present application obtains a reconstructed signal having a specified common mode voltage and having the same output swing and polarity as the input signal according to the average value of the input signal and the input signal (ie, the second The input signal) is such that the mean signal of the reconstructed signal and the mean signal of the input signal comprise the same deviation component, and then the mean signal of the input signal is subtracted from the mean signal of the reconstructed signal, so that the deviation component contained in the two can be Offset, thereby eliminating the deviation of the mean of the input signal, resulting in an ideal mean of the input signal.
  • Figure 1 is a signal average detector in the prior art
  • FIG. 2 is a diagram showing an example of an input signal
  • FIG. 3 is an exemplary diagram of a passive optical network system
  • FIG. 4 is a block diagram of a signal mean detector of the present application.
  • FIG. 5 is a schematic structural diagram of a signal mean detector according to the present application.
  • FIG. 6 is a schematic structural diagram of another signal mean detector according to the present application.
  • FIG. 7 is a schematic structural diagram of a receiver according to the present application.
  • FIG. 8 is a schematic structural diagram of another receiver of the present application.
  • FIG. 9 is a schematic structural diagram of still another receiver of the present application.
  • FIG. 10 is a schematic flow chart of a method for detecting a signal mean value according to the present application.
  • the PON system is composed of an ODN (Optical Distribution Network), an OLT on the central office (central office), an ONU (Optical Network Unit) on the user side, or an Optical Network Terminal (ONT).
  • ODN Optical Distribution Network
  • OLT Central office
  • ONU Optical Network Unit
  • ONT Optical Network Terminal
  • Figure 3 shows. If the ONU directly provides the user port function, such as the Ethernet user port function for PC (Personal Computer) Internet access, it is called ONT. There is no special description.
  • the ONU mentioned below refers to the ONU and ONT.
  • the OLT provides a network side interface for the PON system
  • the ONU provides a user side interface for the PON system.
  • the ODN is a network of optical fibers and passive optical splitting devices used to connect the OLT and ONUs and to distribute or multiplex data signals between the OLT and the ONU.
  • data transmission from the OLT to the ONU is referred to as downlink, and data is transmitted from the ONU to the OLT for uplink.
  • one communication signal of each ONU is called a burst optical signal.
  • the receiver of the OLT captures burst optical signals within a certain dynamic range, After the burst optical signal is converted into a voltage signal by using a photodetector, the average value of the voltage signal is detected by using the voltage signal as an input signal.
  • the mean detection of the input signal is performed by a signal mean detector.
  • the input signal is a voltage signal that switches between a high level and a low level at a high speed. As shown in FIG. 3, in the example of FIG. 3, the common mode voltage of the input signal is 0.725 V, and the output swing is 0.125 V. The high level is 0.85V and the low level is 0.6V.
  • the purpose of the technical solution of the present application is to eliminate the deviation between the mean value and the ideal mean value of the input signal when the input signal is continuous high level or low level.
  • the principle of the technical solution of the present application is to construct a reconstructed signal having a specified common mode voltage, having the same output swing and polarity as the input signal, wherein the polarity refers to the signal switching from a high level to a low level and from a low level. The frequency at which the level switches to a high level.
  • the mean value curve of the reconstructed signal and the shape of the mean curve of the input signal are exactly the same, and the mean value of the reconstructed signal and the mean value of the input signal are also identical, whereby the mean value of the input signal is The mean subtraction of the reconstructed signal cancels out the offsets contained in the two, thereby eliminating the deviation between the mean and the ideal mean of the input signal at the continuous high or continuous low level of the input signal.
  • the signal averaging detector includes:
  • a first low pass filter U401 configured to use the first input signal as an input to obtain a first mean estimation signal of the first input signal
  • An input signal reconstruction module U402 configured to obtain a second input signal according to the first mean estimation signal and the first input signal, the second input signal has a set common mode voltage, and the second input The output swing and polarity of the signal are the same as the output swing and polarity of the first input signal;
  • a second low pass filter U403 configured to use the second input signal as an input to obtain a second mean value estimation signal of the second input signal, the second low pass filter and the first low pass filter Have the same transfer function;
  • a subtracter U404 configured to subtract the first mean estimation signal from the second mean estimation signal, and add an adjustment voltage, a magnitude of the adjustment voltage and a magnitude of a common mode voltage of the second input signal the same.
  • the first input signal is a voltage signal obtained by the receiver of the OLT after capturing the burst optical signal sent by the ONU, and converting the burst optical signal by using a photodetector.
  • the input signal reconstruction module can be implemented by the comparator in FIG. 5 or by the mean value reconstructor, the comparator and the PAM4 in FIG. 6.
  • a comparator is used to obtain a second input signal, which is actually a reconstructed signal of the first input signal, ie, the first input signal A translated copy.
  • the input of the comparator is the first input signal, the first mean estimation signal, and the output of the subtractor in FIG. 5, that is, the difference between the first mean estimation signal and the second mean estimation signal.
  • a signal, the difference signal comprising an adjusted voltage portion.
  • the comparator compares the first input signal and the first mean estimation signal, when the first input signal is at a high level, it is larger than the first mean estimation signal, and the comparator output is also high Level; when the first input signal is low, it is smaller than the first mean estimation signal, and the comparator outputs a low level, such that the output of the comparator and the first input signal
  • the polarity is the same.
  • the output swing of the output level of the comparator is adjusted so that the output swing of the output level of the comparator is the same as the output swing of the first input signal, and the output of the subtractor can be used as a feedback signal to adjust the output of the comparator. level.
  • the provided first input signal common-mode voltage V incm, output swing is H
  • the input signal of the first high level V inh V incm + H
  • low V inl V Incm -H
  • the comparator causes the polarity of the second input signal to be the same as the polarity of the first input signal.
  • the common mode voltage of the set second input signal be V recm .
  • the output of the subtractor can be used as the feedback signal. To control the output swing of the second input signal.
  • V LPF2 V recm +V wander +V incm - V out
  • the output swing of the second input signal is also necessarily H, which is the feedback control process of the output swing of the second input signal.
  • the common mode voltage of the second input signal may be directly set equal to the height of the first input signal.
  • Level, ie V recm V incm +H.
  • the second input signal is obtained using a mean reconstructor, a comparator, and a pulse amplitude modulator PAM4.
  • a mean reconstructor e.g., a mean reconstructor
  • a comparator e.g., a comparator
  • PAM4 pulse amplitude modulator
  • three comparators are used to provide an input signal to the PAM 4
  • three comparators compare the first mean estimate signal and the first input signal, a first mean estimate reconstructed signal, and the The first input signal, the second mean estimation reconstructed signal and the first input signal obtain three comparison result signals, and the polarity of the first input signal can be obtained more accurately using the three comparison result signals.
  • the first mean estimation reconstructed signal is obtained by subtracting the mean estimation signal from a zero line signal
  • the second mean estimation reconstructed signal is obtained by adding the mean estimation signal to a zero line signal
  • the zero level can also be called the Dark level, which is the voltage signal representing 0 in the device.
  • the outputs of the three comparators are input to the PAM 4 such that the polarity of the second input signal output by the PAM 4 is the same as the polarity of the first signal, and has a set common mode voltage for outputting the PAM 4
  • the output swing of the second input signal is the same as the output swing of the first input signal, and the output of the subtractor in FIG. 6 can be used as a feedback signal to control the output swing of the second input signal, and the feedback control
  • the process is the same as the feedback control process in the embodiment shown in FIG.
  • a second low-pass filter is used to obtain an average signal of the second input signal, that is, a second mean estimation signal.
  • the second input signal is a translated copy of the first input signal.
  • the transfer function of the second low pass filter should be The transfer function of the first low pass filter is the same, so the same filter as the first low pass filter can be selected as the second low pass filter.
  • the second mean value estimate signal obtained from the second input signal and the first mean value estimate signal comprise the same deviation components. Subtracting the first mean estimation signal and the second mean estimation signal such that the deviation components included in the two cancel out, thereby eliminating the deviation of the first mean estimation signal (ie, the mean signal of the first input signal) and using the adjustment Performing a translational adjustment of the result of the subtraction so that the output of the translation is equal to the common mode voltage of the first input signal, thereby obtaining an ideal mean of the first input signal, the ideal mean being equal to the first input The common mode voltage of the signal.
  • the signal mean detection method provided by the present application is designed to reconstruct a reconstructed signal (second input signal) having a specified common mode voltage and having the same output swing and polarity as the input signal (ie, the first input signal).
  • the mean signal of the signal and the mean signal of the input signal contain the same deviation component, and then the mean signal of the input signal is subtracted from the mean signal of the reconstructed signal, so that the deviation components contained in the two can be cancelled, thereby eliminating the mean value of the input signal.
  • the deviation gives the ideal mean of the input signal.
  • the present application provides a signal mean detector, as shown in FIG. 5, the signal mean detector includes:
  • the output of the first low pass filter (labeled LPF 1 in the figure) is a first mean value estimate signal (labeled Threshold in the figure), and the input of the first low pass filter is first Input signal (labeled as Input signal in the figure);
  • the input of the comparator (labeled as CO 1 ) is the first input signal, the first mean estimation signal, and an output of the subtractor, and the output of the comparator is a second input signal.
  • the second input signal has a set common mode voltage, and the output swing and polarity of the second input signal are the same as the output swing and polarity of the first input signal;
  • the output of the second low pass filter (labeled LPF 2 in the figure) is a second mean value estimate signal (labeled Reconstructed baseline wander in the figure), the input signal of the second low pass filter
  • the second low pass filter has the same transfer function as the first low pass filter
  • the forward input of the subtractor is the first mean estimation signal V LPF1
  • the negative input of the subtractor is the second mean estimation signal V LPF2
  • V ajust is an adjustment voltage
  • the magnitude of the adjustment voltage is the same as the magnitude of the common mode voltage of the second input signal.
  • the first input signal is used by the receiver of the OLT to capture the burst optical signal sent by the ONU.
  • the photodetector converts the voltage signal formed by the burst optical signal.
  • the common mode voltage of the second input signal can be set equal to the high level voltage of the first input signal.
  • the second low pass filter should have the same transfer function as the first low pass filter, so that the same filter as the first low pass filter structure can be directly selected as the second low pass filter.
  • the present application further provides another signal mean detector.
  • the signal mean detector includes:
  • the output of the first low pass filter (labeled LPF 1 in the figure) is a first mean value estimate signal (labeled Threshold in the figure), and the input of the first low pass filter is first Input signal (labeled as Input signal in the figure);
  • a mean value reconstructor (labeled Threshold reconstruction) for subtracting the first mean estimate signal from a zero line signal to obtain a first mean estimate reconstructed signal, and the first mean estimate signal Adding a zero line signal to obtain a second mean estimation reconstructed signal;
  • a comparator for respectively comparing the first mean estimation signal and the first input signal, the first mean estimated reconstructed signal and the first input signal, and comparing the second mean estimated reconstructed signal and the Determining a first input signal to obtain a polarity of the first input signal
  • a pulse amplitude modulator having an input of an output of the comparator and an output of the subtractor, the output of which is a second input signal, the second input signal having a set common mode voltage, and an output of the second input signal
  • the swing and polarity are the same as the output swing and polarity of the first input signal
  • the output of the second low pass filter (labeled LPF 2 in the figure) is a second mean value estimate signal, and the input of the second low pass filter is the second input signal
  • the second low pass filter has the same transfer function as the first low pass filter
  • the forward input of the subtractor is the first mean estimation signal V LPF1
  • the negative input of the subtractor is the second mean estimation signal V LPF2
  • V ajust is an adjustment voltage
  • the magnitude of the adjustment voltage is the same as the magnitude of the common mode voltage of the second input signal.
  • the first input signal is a voltage signal obtained by the receiver of the OLT after capturing the burst optical signal sent by the ONU, and converting the burst optical signal by using a photodetector.
  • the zero line signal (marked as Dark or zero level in the figure) is a voltage signal representing 0 in the device.
  • the first mean estimation signal is labeled VTH1
  • the first input signal is V in
  • the zero line signal is V ZERO
  • the second The mean estimate reconstruction signal VTH2 VTH1 + V ZERO .
  • the comparator compares V in and VTH1, V in and VTH0, V in and VTH2, respectively.
  • the comparator may be composed of three comparators for respectively comparing the three sets of voltages, for example, the comparator includes a first comparator (labeled as CO 1 in the figure) and a second comparator (marked as CO 2 in the figure). and a third comparator (indicated as CO 3), wherein a first comparator for comparing V in and VTHl; a second comparator for comparing V in and VTH0; third comparator for comparing the V in and VTH2. If V in is greater than VTHl, the first comparator output is high, if V in is less than VTHl, the first comparator output is low, and so on. A more accurate polarity of the first input signal can be obtained using three comparators.
  • the pulse amplitude modulator is PAM4 (labeled PAM4 modulator in the figure).
  • the common mode voltage of the second input signal may be set to be equal to a high level voltage of the first input signal.
  • the second low pass filter may directly select the same filter as the first low pass filter.
  • the signal mean detector obtaineds a reconstructed signal (ie, a second input signal) according to an input signal (ie, a first input signal) and an average of the input signal, the reconstructed signal having a specified common mode voltage and input
  • the output swing and polarity of the signal are the same, such that the mean signal of the reconstructed signal and the mean signal of the input signal contain the same deviation component, and then the mean signal of the input signal is subtracted from the mean signal of the reconstructed signal, so that the two The included bias components are offset, thereby eliminating the deviation of the mean of the input signal and obtaining the ideal mean of the input signal.
  • the present application also provides a receiver that uses the signal mean detector shown in FIG. 4, as shown in FIG. 7, the receiver may include:
  • the front end amplifier A1 the input of the front end amplifier is an optical current signal and an output of the gain controller, for converting the photo current signal into a voltage signal according to a magnification determined by the gain controller;
  • Peak Det Peak Det: an input of the peak detector is an output of the front end amplifier for outputting a peak-to-peak voltage of an output of the front end amplifier;
  • Gain Control a gain controller (Gain Control), wherein the input of the gain controller is the peak-to-peak voltage, and the amplification factor of the front-end amplifier is determined according to the peak-to-peak voltage;
  • a signal mean detector (Avg. Det), the input of the signal mean detector being the output of the front end amplifier for obtaining the mean of the output of the front end amplifier.
  • the photocurrent signal is an output of the photodetector, and the photodetector is converted into a photocurrent signal after receiving the burst optical signal.
  • the receiver does not include the photodetector, and the The receiver may comprise the photodetector or be independent of the photodetector and connected to the photodetector.
  • the function of the photodetector here is to convert the burst optical signal into a photocurrent signal.
  • another photodetector can also convert the burst optical signal into a voltage signal, or from here.
  • the combination of the photodetector and the front-end amplifier converts the burst optical signal into a voltage signal.
  • the front end amplifier receives the photocurrent signal and receives a control signal output by the gain controller, and converts the photocurrent signal into a voltage signal according to a magnification determined by a control signal output by the gain controller.
  • the gain controller determines the amplification of the front-end amplifier based on the peak-to-peak voltage of the output of the front-end amplifier and outputs a corresponding control signal, which is obtained by the peak detector and output to the gain controller.
  • the voltage signal output by the front-end amplifier is used as an input to the signal averaging detector, and the ideal mean value of the voltage signal is obtained by the signal averaging detector.
  • the present application also provides another receiver, as shown in FIG. 8, the receiver includes:
  • the front end amplifier A1 the input of the front end amplifier is an optical current signal and an output of the gain controller, for converting the photo current signal into a voltage signal according to a magnification determined by the gain controller;
  • Peak Det Peak Det: an input of the peak detector is an output of the front end amplifier for outputting a peak-to-peak voltage of an output of the front end amplifier;
  • Gain Control a gain controller (Gain Control), wherein the input of the gain controller is the peak-to-peak voltage, and the amplification factor of the front-end amplifier is determined according to the peak-to-peak voltage;
  • a signal mean detector (Avg. Det), the input of the signal mean detector being the output of the front end amplifier for obtaining the mean of the output of the front end amplifier.
  • a main amplifier A2 the input of the main amplifier being an output of the front end amplifier, an output of the signal mean detector, and an output of the gain controller for determining a main amplifier amplification factor according to an output of the gain controller Converting an output of the front end amplifier into a differential signal according to the main amplifier amplification factor;
  • the buffer amplifier A3 the input of the buffer amplifier is an output of the main amplifier for outputting a voltage signal with a fixed impedance according to an output of the main amplifier.
  • the receiver shown in FIG. 8 has a main amplifier and a buffer amplifier added to the receiver shown in FIG. 7.
  • the amplification factor of the main amplifier is determined according to a control signal output from the gain controller, and is related to the gain of the main amplifier itself.
  • the amplification factor of the main amplifier and the amplification factor of the front end amplifier are not necessarily the same.
  • the main amplifier compares the output of the front end amplifier with the output of the signal mean detector, and outputs a differential signal that is more resistant to interference.
  • a buffer can also be connected after the main amplifier, and the buffer is input with the output of the main amplifier to output a differential voltage signal with a fixed impedance for impedance matching after the load is connected.
  • the present application further provides a receiver, as shown in FIG. 9, the receiver includes:
  • the front end amplifier A1 the input of the front end amplifier is an optical current signal and an output of the gain controller, for converting the photo current signal into a voltage signal according to a magnification determined by the gain controller;
  • Peak Det Peak Det: an input of the peak detector is an output of the front end amplifier for outputting a peak-to-peak voltage of an output of the front end amplifier;
  • Gain Control a gain controller (Gain Control), wherein the input of the gain controller is the peak-to-peak voltage, and the amplification factor of the front-end amplifier is determined according to the peak-to-peak voltage;
  • a signal mean detector (Avg. Det), the input of the signal mean detector being the output of the front end amplifier for obtaining the mean of the output of the front end amplifier.
  • a main amplifier A2 the input of the main amplifier being an output of the front end amplifier, an output of the signal mean detector, and an output of the gain controller for determining a main amplification according to an output of the gain controller Amplifying the output of the front-end amplifier into a differential signal according to the amplification factor of the main amplifier;
  • Buffer amplifier A3 the input of the buffer amplifier is an output of the main amplifier for outputting a voltage signal with a fixed impedance according to an output of the main amplifier;
  • SOB Det a burst start detector
  • the input of the burst start detector being an output of the front end amplifier for outputting an enable signal to the gain controller and the signal mean detector
  • the input of the resetter being an output of the main amplifier and an enable signal output by the burst start detector for the peak detector, the gain controller, and the signal mean
  • the detector and the burst start detector output a reset signal, and the burst start detector is further configured to output an enable signal to the resetter.
  • the receiver shown in Fig. 9 has a burst start detector and a resetter added to the receiver shown in Fig. 8.
  • the burst start detector is input with an output of the front end amplifier for outputting an enable signal to the gain controller and the signal mean detector after the front end amplifier starts operating, enabling the gain A controller and the signal averaging detector cause the gain controller and the signal averaging detector to begin operation.
  • the burst start detector also outputs an enable signal to the resetter to cause the resetter to start operating.
  • the resetter takes an output of the main amplifier as an input, and when an abnormality occurs in an output of the main amplifier, outputs a reset signal to the gain controller, the peak detector, the signal mean detector, and the burst start detector, so that the The gain controller, peak detector, signal averaging detector, and burst start detector are zeroed to reduce receiver failure.
  • the application also provides an optical line termination comprising a receiver as shown in any of Figures 7-9.
  • the application also provides a passive optical network system, the passive optical network system comprising the optical line termination.
  • a method for detecting a signal mean value provided by the present application, where the method includes:
  • Step S1001 the first input signal is obtained by low-pass filtering to obtain a first mean estimation signal
  • Step S1002 obtaining a second input signal according to the first mean value estimation signal and the first input signal, the second input signal having a set common mode voltage, and an output swing of the second input signal
  • the polarity is the same as the output swing and polarity of the first input signal
  • Step S1003 the second input signal is subjected to low-pass filtering to obtain a second mean value estimation signal, a transfer function between the second mean value estimation signal and the second input signal, and the first mean value estimation signal and the first
  • the transfer function between an input signal is the same;
  • Step S1004 subtracting the first mean estimation signal from the second mean estimation signal, and adding a tone The entire voltage, the magnitude of the adjustment voltage being the same as the magnitude of the common mode voltage of the second input signal.
  • the acquisition of the first mean estimation signal and the second mean estimation signal is the same as the method of using the low pass filter to obtain the signal mean in the prior art.
  • the common mode voltage of the second input signal may be directly set to be equal to the high level voltage of the first input signal.
  • the obtaining the second input signal according to the first mean estimation signal and the first input signal may specifically include:
  • the signal is subtracted from the second mean estimation signal and an adjustment voltage is added, the magnitude of the adjustment voltage being the same as the magnitude of the common mode voltage of the second input signal.
  • the second input signal can be obtained using a comparator as shown in FIG. 5, or an average reconstructor, a comparator, and a PAM 4 as described in FIG. 6.

Abstract

本申请实施例提供了一种信号均值检测方法、装置和系统。通过设计具有指定共模电压且与输入信号的输出摆幅和极性相同的重构信号，使该重构信号的均值信号与输入信号的均值信号包含相同的偏差成分，然后将输入信号的均值信号与重构信号的均值相减，将两者包含的偏差成分抵消，从而消除输入信号的均值的偏差，得到输入信号的理想均值。

Description

信号均值检测方法、装置和系统 技术领域
本申请涉及通信领域，尤其涉及一种信号均值检测方法、装置和系统。
背景技术
PON(Passive Optical Network，无源光网络)系统采用P2MP(Point to Multiple Point，点对多点主站)的接入方式，局(中心局)侧的OLT(Optical Line Terminal，光线路终端)通过分光器(Passive Splitter)与该网络中所有用户侧的ONU(Optical Network Unit，光网络单元)建立通讯联系。ONU与OLT通讯时，每一个ONU的一次通讯信号称为一次突发光信号。由于OLT和ONU之间各个链路的插入损耗各不相同，到达OLT侧的突发光信号之间平均功率和相位也各不相同，因此OLT的接收机应当具有快速捕获一定动态范围内的突发光信号的能力，在使用光探测器将所述突发光信号转换为电压信号后，以该电压信号为输入信号检测该电压信号的均值，后续电路可以根据该均值将该电压信号放大到同一水平。实际上，该电压信号为在高低电平之间高速切换的信号。
现有技术中检测所述电压信号的均值的方式，是使用如图2所示的信号均值检测器。其中，电容C与电阻R2构成的LPF(Low Pass Filter，低通滤波器)的输入为所述电压信号(为方便描述，以下称之为输入信号)Vin，输出Vout为Vin的均值。正常状态下，该输入信号在高电平和低电平之间以一定的频率切换，这种情况下输入信号的均值可以保持在理想均值，或者在理想均值附近很小的范围内浮动，如图1中，信号曲线很密集的部分，输入信号在高电平和低电平之间的以一定的频率高速切换，输入信号的均值为直线状态，与理想均值一致，在信号曲线较密集的部分，输入信号在高电平和低电平之间的切换频率稍低，输入信号的均值在理想均值上下波动。其中，所述理想均值为输入信号在正常状态下的均值，等于所述输入信号的共模电压。但当输入信号是连续的高电平或连续的低电平时，输入信号的均值将和理想均值之间产生很大的偏差(亦称为基线漂移)，如图1中输入信号为连续高电平时，均值远大于理想均值，而输入信号为连续低电平时，均值远低于理想均值。现有技术所使用的均值检测器无法消除当输入信号为连续高电平或连续低电平时输入信号的均值与理想均值之间的偏差。
发明内容
本申请提供了一种信号均值检测方法、装置和系统，以消除信号均值与理想均值 之间的偏差。
第一方面，本申请提供了一种信号均值检测器，包括：第一低通滤波器，用于以第一输入信号为输入，得到所述第一输入信号的第一均值估计信号；输入信号重构模块，用于根据所述第一均值估计信号和所述第一输入信号得到第二输入信号，所述第二输入信号具有设定的共模电压，且所述第二输入信号的输出摆幅和极性与所述第一输入信号的输出摆幅和极性相同；第二低通滤波器，用于以所述第二输入信号为输入，得到所述第二输入信号的第二均值估计信号，所述第二低通滤波器与所述第一低通滤波器具有相同的传输函数；减法器，用于将所述第一均值估计信号与所述第二均值估计信号相减，并加上调整电压，所述调整电压的大小和所述第二输入信号的共模电压的大小相同。这种实现方式下，第二输入信号的均值信号与第一输入信号的均值信号包含相同的偏差成分，然后将第一输入信号的均值信号与第二输入信号的均值信号相减，即可将两者包含的偏差成分抵消，从而消除第一输入信号的均值的偏差，得到第一输入信号的理想均值。
结合第一方面，在第一方面第一种可能的实现方式中，所述输入信号重构模块为比较器，所述比较器的输入为所述第一输入信号、所述第一均值估计信号以及所述减法器的输出，所述比较器的输出为所述第二输入信号。
结合第一方面，在第一方面第二种可能的实现方式中，所述输入信号重构模块，包括：均值重建器，用于将所述第一均值估计信号与零线信号相减得到第一均值估计重建信号，以及将所述第一均值估计信号与零线信号相加得到第二均值估计重建信号；比较器，用于分别比较所述第一均值估计信号和所述第一输入信号、比较所述第一均值估计重建信号和所述第一输入信号，以及比较所述第二均值估计重建信号和所述第一输入信号；脉冲幅度调制器，其输入为所述比较器的输出以及所述减法器的输出，其输出为所述第二输入信号。这种方式可以得到更准确的所述第一输入信号的极性，使用脉冲幅度调制器可以更准确得控制所述第二输入信号的输出摆幅。
第二方面，本申请提供了一种接收机，所述接收机包含第一方面所述的信号均值检测器。所述接收机可以包括：前端放大器，所述前端放大器的输入为光电流信号以及增益控制器的输出，用于根据所述增益控制器决定的放大倍数将所述光电流信号转化为电压信号；峰值检测器：所述峰值检测器的输入为所述前端放大器的输出，用于输出所述前端放大器的输出的峰-峰值电压；增益控制器，所述增益控制器的输入为所述峰-峰值电压，用于根据所述峰-峰值电压决定所述前端放大器的放大倍数；信号均值检测器，所述信号均值检测器的输入为所述前端放大器的输出，用于得到所述前端放大器的输出的均值。使用所述接收机能够得到突发光信号的理想均值，具有更高的准确性。
所述接收机还可以包括：主放大器，所述主放大器的输入为所述前端放大器的输出、所述信号均值检测器的输出以及所述增益控制器的输出，用于根据所述增益控制 器的输出决定主放大器放大倍数，根据所述主放大器放大倍数将所述前端放大器的输出转换为差分信号；缓冲放大器，所述缓冲放大器的输入为所述主放大器的输出，用于根据所述主放大器的输出以固定阻抗输出电压信号。主放大器比较所述前端放大器的输出和所述信号均值检测器的输出，输出差分信号，所述差分信号具有更强的抗干扰能力。主放大器之后还可以连接缓冲器，所述缓冲器以所述主放大器的输出为输入，以固定阻抗输出差分电压信号，用于接上负载后进行阻抗匹配。
所述接收机还可以包括：突发开始检测器，所述突发开始检测器的输入为所述前端放大器的输出，用于向所述增益控制器和所述信号均值检测器输出使能信号，所述使能信号用于使能所述增益控制器和所述信号均值检测器，所述增益控制器和所述信号均值检测器的输入还包括所述使能信号；复位器，所述复位器的输入为所述主放大器的输出以及所述突发开始检测器输出的使能信号，用于向所述峰值检测器、增益控制器、信号均值检测器以及突发开始检测器输出复位信号，所述突发开始检测器还用于向所述复位器输出使能信号。通过所述突发开始检测器的使能控制，可以降低增益控制器、信号均值检测器和复位器发生错误的概率。所述复位器以所述主放大器的输出为输入，当主放大器的输出出现异常时，向所述增益控制器、峰值检测器、信号均值检测器以及突发开始检测器输出复位信号，使所述增益控制器、峰值检测器、信号均值检测器和突发开始检测器归零，减少接收机故障。
第三方面，本申请提供了一种光线路终端，所述光线路终端包含第二方面所述的接收机。
第四方面，本申请提供了一种无源光网络系统，所述无源光网络系统包含第三方面所述的光线路终端。
第五方面，本申请提供了一种信号均值检测方法，包括：将第一输入信号通过低通滤波得到第一均值估计信号；根据所述第一均值估计信号和所述第一输入信号得到第二输入信号，所述第二输入信号具有设定的共模电压，且所述第二输入信号的输出摆幅和极性与所述第一输入信号的输出摆幅和极性相同；将所述第二输入信号通过低通滤波得到第二均值估计信号，所述第二均值估计信号和所述第二输入信号之间的传递函数与所述第一均值估计信号和所述第一输入信号之间的传输函数相同；将所述第一均值估计信号与所述第二均值估计信号相减，并加上调整电压，所述调整电压的大小和所述第二输入信号的共模电压的大小相同。
结合第五方面，在第五方面第一种可能的实现方式中，所述第二输入信号的共模电压等于所述第一输入信号的高电平电压。
结合第五方面或第五方面第一种可能的实现方式，在第五方面第二种可能的实现方式中，所述根据所述第一均值估计信号和所述第一输入信号得到所述第二输入信号，包括：比较所述第一输入信号和所述第一均值估计信号得到所述第二输入信号的极性；使用反馈信号控制所述第二输入信号的输出摆幅，使所述第二输入信号的输出摆幅等 于所述第一输入信号的输出摆幅，所述反馈信号为将所述第一均值估计信号与所述第二均值估计信号相减，并加上调整电压，所述调整电压的大小和所述第二输入信号的共模电压的大小相同。
本申请实施例所提供的信号均值检测技术方案，根据输入信号和输入信号的均值得到具有指定共模电压、且与输入信号的输出摆幅和极性相同的重构信号(即所述第二输入信号)，使该重构信号的均值信号与输入信号的均值信号包含相同的偏差成分，然后将输入信号的均值信号与重构信号的均值信号相减，便可以将两者包含的偏差成分抵消，从而消除输入信号的均值的偏差，得到输入信号的理想均值。
附图说明
图1为现有技术中的信号均值检测器；
图2为输入信号示例图；
图3为无源光网络系统示例图；
图4为本申请一种信号均值检测器的框图；
图5为本申请一种信号均值检测器的结构示意图；
图6为本申请另一种信号均值检测器的结构示意图；
图7为本申请一种接收机的结构示意图；
图8为本申请另一种接收机的结构示意图；
图9为本申请又一种接收机的结构示意图；
图10为本申请一种信号均值检测方法的流程示意图。
具体实施方式
PON系统由ODN(Optical Distribution Network，光分配网络)、局(中心局)侧的OLT和用户侧的ONU(Optical Network Unit，光网络单元)或者ONT(Optical Network Terminal，光网络终端)组成，如图3所示。如果ONU直接提供用户端口功能，如PC(Personal Computer，个人计算机)上网用的以太网用户端口功能，则称为ONT，无特殊说明，下文提到的ONU统指ONU和ONT。
OLT为PON系统提供网络侧接口，ONU为PON系统提供用户侧接口。ODN是由光纤和无源分光器件组成的网络，用于连接OLT和ONU，以及分发或复用OLT和ONU之间的数据信号。在PON系统中，数据从OLT传输至ONU称为下行，数据从ONU传输至OLT为上行。ONU与OLT进行上行通讯时，每一个ONU的一次通讯信号称为一次突发光信号。OLT的接收机捕获一定动态范围内的突发光信号，在 使用光探测器将所述突发光信号转换为电压信号后，以该电压信号为输入信号检测该电压信号的均值。OLT的接收机中，所述输入信号的均值检测由信号均值检测器完成。所述输入信号为高速地在高电平和低电平之间切换的电压信号，如图3所示，图3的示例中，输入信号的共模电压为0.725V，输出摆幅为0.125V，高电平为0.85V，低电平为0.6V。
本申请技术方案的目的在于消除输入信号是连续的高电平或低电平时输入信号的均值和理想均值之间的偏差。本申请技术方案的原理是构造具有指定共模电压、与输入信号具有相同输出摆幅和极性的重构信号，其中，所述极性指信号从高电平切换到低电平以及从低电平切换到高电平的频率。这样，重构信号的均值曲线和输入信号的均值曲线的形状是完全相同的，重构信号的均值和输入信号的均值所包含的偏差部分也是完全相同的，由此，将输入信号的均值和重构信号的均值相减便可以抵消两者包含的偏差部分，从而能够消除输入信号在连续高电平或连续低电平时输入信号的均值与理想均值之间的偏差。
参见图4，为本申请提供的一种信号均值检测器，如图4所示，所述信号均值检测器包括：
第一低通滤波器U401，用于以第一输入信号为输入，得到所述第一输入信号的第一均值估计信号；
输入信号重构模块U402，用于根据所述第一均值估计信号和所述第一输入信号得到第二输入信号，所述第二输入信号具有设定的共模电压，且所述第二输入信号的输出摆幅和极性与所述第一输入信号的输出摆幅和极性相同；
第二低通滤波器U403，用于以所述第二输入信号为输入，得到所述第二输入信号的第二均值估计信号，所述第二低通滤波器与所述第一低通滤波器具有相同的传输函数；
减法器U404，用于将所述第一均值估计信号与所述第二均值估计信号相减，并加上调整电压，所述调整电压的大小和所述第二输入信号的共模电压的大小相同。
其中，所述第一输入信号为OLT的接收机捕获ONU发送的突发光信号后，使用光探测器转换所述突发光信号而成的电压信号。
其中，所述输入信号重构模块可以由图5中的比较器实现，或者由图6中的均值重建器、比较器和PAM4实现。
在一种实施方式中，如图5所示，使用比较器来得到第二输入信号，所述第二输入信号实际上为所述第一输入信号的重构信号，即所述第一输入信号的一个平移后的拷贝。所述比较器的输入为所述第一输入信号、所述第一均值估计信号以及图5中减法器的输出，也就是所述第一均值估计信号与所述第二均值估计信号的差值信号，所述差值信号包含调整电压部分。
所述比较器比较所述第一输入信号和所述第一均值估计信号，所述第一输入信号为高电平时，其比所述第一均值估计信号大，所述比较器输出的也是高电平；所述第一输入信号为低电平时，其比所述第一均值估计信号小，所述比较器输出的也是低电平，这样所述比较器的输出和所述第一输入信号的极性相同。同时调整比较器输出电平的输出摆幅，使比较器输出电平的输出摆幅和所述第一输入信号的输出摆幅相同，可以将减法器的输出作为反馈信号来调整比较器输出电平。
具体地，设所述第一输入信号的共模电压为Vincm，输出摆幅为H，则所述第一输入信号的高电平Vinh＝Vincm+H，低电平Vinl＝Vincm-H，第一低通滤波器的输出也就是第一均值估计信号VLPF1＝Vincm+Vwander，其中Vwander为偏差(即基线漂移)，Vwander可以为正值也可以为负值。比较器使得所述第二输入信号的极性与所述第一输入信号的极性相同。设所设定的第二输入信号的共模电压为Vrecm。为使所述第二输入信号的输出摆幅为H，从而使第二低通滤波器的输出也就是第二均值估计信号VLPF2＝Vrecm+Vwander，可以使用减法器的输出作为反馈信号来控制所述第二输入信号的输出摆幅。减法器的输出Vout＝Vajust+VLPF1-VLPF2＝Vrecm+VLPF1-VLPF2＝Vrecm+Vincm+Vwander-VLPF2，则VLPF2＝Vrecm+Vwander+Vincm-Vout，控制所述第二输入信号的输出摆幅，使得Vout＝Vincm，也就是使减法器的输出与所述第一输入信号的共模电压相同，则VLPF2必然等于Vrecm+Vwander，所述第二输入信号的输出摆幅也必然为H，这就是所述第二输入信号的输出摆幅的反馈控制过程。
为方便设定所述第二输入信号的共模电压，避免多余的共模电压计算和考察，可以将所述第二输入信号的共模电压直接设定为等于所述第一输入信号的高电平，也就是Vrecm＝Vincm+H。
在另一种实施方式中，如图6所示，使用均值重建器、比较器和脉冲幅度调制器PAM4来得到所述第二输入信号。根据PAM4对输入信号的要求，使用三个比较器来为PAM4提供输入信号，三个比较器分别比较所述第一均值估计信号和所述第一输入信号、第一均值估计重建信号和所述第一输入信号、第二均值估计重建信号和所述第一输入信号，得到三个比较结果信号，使用这三个比较结果信号能够更准确地得到所述第一输入信号的极性。其中所述第一均值估计重构信号由所述均值估计信号与零线信号相减得到，所述第二均值估计重构信号由所述均值估计信号与零线信号相加得到，所述零线信号(Zero level)也可以称为暗电平(Dark level)，为设备中表示0的电压信号。
三个比较器的输出作为PAM4的输入，这样PAM4输出的所述第二输入信号的极性与所述第一信号的极性相同，同时具有一个设定的共模电压，为使PAM4输出的所述第二输入信号的输出摆幅与所述第一输入信号的输出摆幅相同，可以使用图6中减法器的输出作为反馈信号控制所述第二输入信号的输出摆幅，反馈控制的过程和图5所示实施例中的反馈控制过程相同。
得到所述第二输入信号后，使用第二低通滤波器得到所述第二输入信号的均值信号，即第二均值估计信号。所述第二输入信号是所述第一输入信号的一个平移后的拷贝，为使第二均值估计信号和第一均值估计信号的形状一致，所述第二低通滤波器的传输函数应当与所述第一低通滤波器的传输函数相同，因此可以选择与第一低通滤波器结构相同的滤波器为第二低通滤波器。
由第二输入信号得到的第二均值估计信号和第一均值估计信号所包含的偏差成分是相同的。将第一均值估计信号和第二均值估计信号相减，使得两者包含的偏差成分抵消，便能够消除第一均值估计信号(即所述第一输入信号的均值信号)的偏差，并使用调整电压对相减的结果进行平移调整，使平移调整后的输出等于所述第一输入信号的共模电压，从而得到所述第一输入信号的理想均值，所述理想均值等于所述第一输入信号的共模电压。
本申请所提供的信号均值检测方法，设计具有指定共模电压且与输入信号(即第一输入信号)的输出摆幅和极性相同的重构信号(第二输入信号)，使该重构信号的均值信号与输入信号的均值信号包含相同的偏差成分，然后将输入信号的均值信号与重构信号的均值信号相减，便可以将两者包含的偏差成分抵消，从而消除输入信号的均值的偏差，得到输入信号的理想均值。
具体的，本申请提供了一种信号均值检测器，如图5所示，所述信号均值检测器包括：
第一低通滤波器，所述第一低通滤波器(图中标为LPF1)的输出为第一均值估计信号(图中标为Threshold)，所述第一低通滤波器的输入为第一输入信号(图中标为Input signal)；
比较器，所述比较器(图中标为CO1)的输入为所述第一输入信号、所述第一均值估计信号以及减法器的输出，所述比较器的输出为第二输入信号，所述第二输入信号具有设定的共模电压，且所述第二输入信号的输出摆幅和极性与所述第一输入信号的输出摆幅和极性相同；
第二低通滤波器，所述第二低通滤波器(图中标为LPF2)的输出为第二均值估计信号(图中标为Reconstructed baseline wander)，所述第二低通滤波器的输入信号为所述第二输入信号，所述第二低通滤波器与所述第一低通滤波器具有相同的传输函数；
减法器，所述减法器的正向输入为所述第一均值估计信号VLPF1，所述减法器的负向输入为所述第二均值估计信号VLPF2，所述减法器的输出(图中标为Adjusted threshold)＝Vajust+VLPF1-VLPF2，Vajust为调整电压，所述调整电压的大小和所述第二输入信号的共模电压的大小相同。
其中，所述第一输入信号为OLT的接收机捕获ONU发送的突发光信号后，使用 光探测器转换所述突发光信号而成的电压信号。为避免多余的共模电压计算和考察，所述第二输入信号的共模电压可以设定为等于所述第一输入信号的高电平电压。所述第二低通滤波器应当与所述第一低通滤波器具有相同的传输函数，因此可以直接选用和第一低通滤波器结构相同的滤波器作为第二低通滤波器。
具体的，本申请还提供了另一种信号均值检测器，如图6所示，所述信号均值检测器包括：
第一低通滤波器，所述第一低通滤波器(图中标为LPF1)的输出为第一均值估计信号(图中标为Threshold)，所述第一低通滤波器的输入为第一输入信号(图中标为Input signal)；
均值重建器，所述均值重建器(图中标为Threshold reconstruction)用于将所述第一均值估计信号与零线信号相减得到第一均值估计重建信号，以及将所述第一均值估计信号与零线信号相加得到第二均值估计重建信号；
比较器，用于分别比较所述第一均值估计信号和所述第一输入信号、所述第一均值估计重建信号和所述第一输入信号，以及比较所述第二均值估计重建信号和所述第一输入信号，从而得到所述所述第一输入信号的极性；
脉冲幅度调制器，其输入为所述比较器的输出以及减法器的输出，其输出为第二输入信号，所述第二输入信号具有设定共模电压，且所述第二输入信号的输出摆幅和极性与所述第一输入信号的输出摆幅和极性相同；
第二低通滤波器，所述第二低通滤波器(图中标为LPF2)的输出为第二均值估计信号，所述第二低通滤波器的输入为所述第二输入信号，所述第二低通滤波器与所述第一低通滤波器具有相同的传输函数；
减法器，所述减法器的正向输入为所述第一均值估计信号VLPF1，所述减法器的负向输入为所述第二均值估计信号VLPF2，所述减法器的输出(图中标为Adjusted threshold)＝Vajust+VLPF1-VLPF2，Vajust为调整电压，所述调整电压的大小和所述第二输入信号的共模电压的大小相同。
其中，所述第一输入信号为OLT的接收机捕获ONU发送的突发光信号后，使用光探测器转换所述突发光信号而成的电压信号。所述零线信号(图中标为Dark or zero level)为设备中表示0的电压信号。图6中第一均值估计信号标为VTH1，设第一输入信号为Vin，零线信号为VZERO，均值重建器的输出为第一均值估计重建信号VTH0＝VTH1-VZERO，和第二均值估计重建信号VTH2＝VTH1+VZERO。所述比较器分别比较Vin和VTH1、Vin和VTH0、Vin和VTH2。所述比较器可以由三个比较器组成，分别对上述三组电压进行比较，例如所述比较器包含第一比较器(图中标为CO1)、第二比较器(图中标为CO2)和第三比较器(图中标为CO3)，其中，第一比较器用于比较Vin和VTH1；第二比较器用于比较Vin和VTH0；第三比较器用于比较Vin和VTH2。若Vin大于VTH1，则第一比较器输出为高电平，若Vin小于VTH1，则第一 比较器输出为低电平，依此类推。使用三个比较器可以得到更准确的所述第一输入信号的极性。
所述脉冲幅度调制器为PAM4(图中标为PAM4modulator)。所述第二输入信号的共模电压可以设定为等于所述第一输入信号的高电平电压。所述第二低通滤波器可以直接选用和第一低通滤波器结构相同的滤波器。
本申请所提供的信号均值检测器，根据输入信号(即第一输入信号)和输入信号的均值获得重构信号(即第二输入信号)，所述重构信号具有指定共模电压且与输入信号的输出摆幅和极性相同，这样该重构信号的均值信号与输入信号的均值信号包含相同的偏差成分，然后将输入信号的均值信号与重构信号的均值信号相减，使两者包含的偏差成分抵消，从而能够消除输入信号的均值的偏差，得到输入信号的理想均值。
本申请还提供一种接收机，所述接收机使用图4所示的信号均值检测器，如图7所示，所述接收机可以包括：
前端放大器A1，所述前端放大器的输入为光电流信号以及增益控制器的输出，用于根据所述增益控制器决定的放大倍数将所述光电流信号转化为电压信号；
峰值检测器(Peak Det)：所述峰值检测器的输入为所述前端放大器的输出，用于输出所述前端放大器的输出的峰-峰值电压；
增益控制器(Gain Control)，所述增益控制器的输入为所述峰-峰值电压，用于根据所述峰-峰值电压决定所述前端放大器的放大倍数；
信号均值检测器(Avg.Det)，所述信号均值检测器的输入为所述前端放大器的输出，用于得到所述前端放大器的输出的均值。
其中，光电流信号为光探测器的输出，该光探测器接收到突发光信号后转换为光电流信号，本实施例中，所述接收机未包含所述光探测器，实际上所述接收机可以包含所述光探测器，也可以与所述光探测器相独立并与所述光探测器连接。需要说明的是，此处光探测器的作用是将突发光信号转换为光电流信号，实际过程中，另一种光探测器也可以将突发光信号转换为电压信号，或者由此处的光探测器和前端放大器组合来讲突发光信号转换为电压信号。
前端放大器接收所述光电流信号，并接收增益控制器输出的控制信号，根据增益控制器输出的控制信号决定的放大倍数将所述光电流信号转化为电压信号。增益控制器根据前端放大器的输出的峰-峰值电压来决定前端放大器的放大倍数并输出相应的控制信号，所述峰-峰值电压则由峰值检测器得到并输出至增益控制器。前端放大器输出的电压信号作为信号均值检测器的输入，经信号均值检测器得到所述电压信号的理想均值。
使用所述接收机能够得到突发光信号的理想均值，相比现有技术具有更高的准确 性。
本申请还提供另一种接收机，如图8所示，所述接收机包括：
前端放大器A1，所述前端放大器的输入为光电流信号以及增益控制器的输出，用于根据所述增益控制器决定的放大倍数将所述光电流信号转化为电压信号；
峰值检测器(Peak Det)：所述峰值检测器的输入为所述前端放大器的输出，用于输出所述前端放大器的输出的峰-峰值电压；
增益控制器(Gain Control)，所述增益控制器的输入为所述峰-峰值电压，用于根据所述峰-峰值电压决定所述前端放大器的放大倍数；
信号均值检测器(Avg.Det)，所述信号均值检测器的输入为所述前端放大器的输出，用于得到所述前端放大器的输出的均值。
主放大器A2，所述主放大器的输入为所述前端放大器的输出、所述信号均值检测器的输出以及所述增益控制器的输出，用于根据所述增益控制器的输出决定主放大器放大倍数，根据所述主放大器放大倍数将所述前端放大器的输出转换为差分信号；
缓冲放大器A3，所述缓冲放大器的输入为所述主放大器的输出，用于根据所述主放大器的输出以固定阻抗输出电压信号。
图8所示接收机相比图7所示接收机增加了主放大器和缓冲放大器，所述主放大器的放大倍数根据增益控制器输出的控制信号决定，与所述主放大器本身的增益有关，所述主放大器的放大倍数和所述前端放大器的放大倍数不一定相同。主放大器比较所述前端放大器的输出和所述信号均值检测器的输出，输出差分信号，所述差分信号具有更强的抗干扰能力。主放大器之后还可以连接缓冲器，所述缓冲器以所述主放大器的输出为输入，以固定阻抗输出差分电压信号，用于接上负载后进行阻抗匹配。
本申请还提供又一种接收机，如图9所示，所述接收机包括：
前端放大器A1，所述前端放大器的输入为光电流信号以及增益控制器的输出，用于根据所述增益控制器决定的放大倍数将所述光电流信号转化为电压信号；
峰值检测器(Peak Det)：所述峰值检测器的输入为所述前端放大器的输出，用于输出所述前端放大器的输出的峰-峰值电压；
增益控制器(Gain Control)，所述增益控制器的输入为所述峰-峰值电压，用于根据所述峰-峰值电压决定所述前端放大器的放大倍数；
信号均值检测器(Avg.Det)，所述信号均值检测器的输入为所述前端放大器的输出，用于得到所述前端放大器的输出的均值。
主放大器A2，所述主放大器的输入为所述前端放大器的输出、所述信号均值检测器的输出以及所述增益控制器的输出，用于根据所述增益控制器的输出决定主放大 器放大倍数，根据所述主放大器放大倍数将所述前端放大器的输出转换为差分信号；
缓冲放大器A3，所述缓冲放大器的输入为所述主放大器的输出，用于根据所述主放大器的输出以固定阻抗输出电压信号；
突发开始检测器(SOB Det)，所述突发开始检测器的输入为所述前端放大器的输出，用于向所述增益控制器和所述信号均值检测器输出使能信号，所述使能信号用于使能所述增益控制器和所述信号均值检测器，所述增益控制器和所述信号均值检测器的输入还包括所述使能信号；
复位器(Reset Gen.)，所述复位器的输入为所述主放大器的输出以及所述突发开始检测器输出的使能信号，用于向所述峰值检测器、增益控制器、信号均值检测器以及突发开始检测器输出复位信号，所述突发开始检测器还用于向所述复位器输出使能信号。
图9所示接收机相比图8所示接收机增加了突发开始检测器和复位器。所述突发开始检测器以所述前端放大器的输出为输入，用于在所述前端放大器开始工作后向所述增益控制器和所述信号均值检测器输出使能信号，使能所述增益控制器和所述信号均值检测器，使所述增益控制器和所述信号均值检测器开始工作。在有复位器时，所述突发开始检测器还向所述复位器输出使能信号，使所述复位器开始工作。通过所述突发开始检测器的使能控制，可以降低增益控制器、信号均值检测器和复位器发生错误的概率。
所述复位器以所述主放大器的输出为输入，当主放大器的输出出现异常时，向所述增益控制器、峰值检测器、信号均值检测器以及突发开始检测器输出复位信号，使所述增益控制器、峰值检测器、信号均值检测器和突发开始检测器归零，减少接收机故障。
本申请还提供一种光线路终端，所述光线路终端包含如图7至9任一所示的接收机。本申请还提供一种无源光网络系统，所述无源光网络系统包含所述光线路终端。
参见图10，为本申请提供的一种信号均值检测方法，所述方法包括：
步骤S1001，将第一输入信号通过低通滤波得到第一均值估计信号；
步骤S1002，根据所述第一均值估计信号和所述第一输入信号得到第二输入信号，所述第二输入信号具有设定的共模电压，且所述第二输入信号的输出摆幅和极性与所述第一输入信号的输出摆幅和极性相同；
步骤S1003，将第二输入信号经过低通滤波得到第二均值估计信号，所述第二均值估计信号和所述第二输入信号之间的传递函数与所述第一均值估计信号和所述第一输入信号之间的传输函数相同；
步骤S1004，将所述第一均值估计信号与所述第二均值估计信号相减，并加上调 整电压，所述调整电压的大小和所述第二输入信号的共模电压的大小相同。
其中，第一均值估计信号和第二均值估计信号的获取与现有技术中使用低通滤波器获取信号均值的方法相同。
为减少第二输入信号的共模电压的计算和监测，可以直接设置所述第二输入信号的共模电压等于所述第一输入信号的高电平电压。
其中，所述根据所述第一均值估计信号和所述第一输入信号得到所述第二输入信号，具体可以包括：
比较所述第一输入信号和所述第一均值估计信号得到所述第二输入信号的极性；
使用反馈信号控制所述第二输入信号的输出摆幅，使所述第二输入信号的输出摆幅等于所述第一输入信号的输出摆幅，所述反馈信号为将所述第一均值估计信号与所述第二均值估计信号相减，并加上调整电压，所述调整电压的大小和所述第二输入信号的共模电压的大小相同。
具体地，可以使用如图5中所示的比较器，或如图6中所述的均值重建器、比较器和PAM4来得到所述第二输入信号。
需要说明的是，在本文中，诸如“第一”和“第二”等之类的关系术语仅仅用来将一个对象与另一个对象区分开来，而不一定要求或者暗示这些对象之间存在任何这种实际的关系或者逆序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的电路、过程、方法或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种电路、过程、方法或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括所述要素的电路、过程、方法或者设备中还存在另外的相同要素。
本说明书中各个实施例之间相同相似的部分互相参见即可。尤其，对于方法实施例而言，由于其基本相似于设备实施例，所以描述的比较简单，相关之处参见设备实施例中的说明即可。

Claims (9)

  1. 一种信号均值检测器，其特征在于，包括：
    第一低通滤波器，用于以第一输入信号为输入，得到所述第一输入信号的第一均值估计信号；
    输入信号重构模块，用于根据所述第一均值估计信号和所述第一输入信号得到第二输入信号，所述第二输入信号具有设定的共模电压，且所述第二输入信号的输出摆幅和极性与所述第一输入信号的输出摆幅和极性相同；
    第二低通滤波器，用于以所述第二输入信号为输入，得到所述第二输入信号的第二均值估计信号，所述第二低通滤波器与所述第一低通滤波器具有相同的传输函数；
    减法器，用于将所述第一均值估计信号与所述第二均值估计信号相减，并加上调整电压，所述调整电压的大小和所述第二输入信号的共模电压的大小相同。
  2. 如权利要求1所述的信号均值检测器，其特征在于，所述输入信号重构模块为比较器，所述比较器的输入为所述第一输入信号、所述第一均值估计信号以及所述减法器的输出，所述比较器的输出为所述第二输入信号。
  3. 如权利要求1所述的信号均值检测器，其特征在于，所述输入信号重构模块，包括：
    均值重建器，用于将所述第一均值估计信号与零线信号相减得到第一均值估计重建信号，以及将所述第一均值估计信号与零线信号相加得到第二均值估计重建信号；
    比较器，用于分别比较所述第一均值估计信号和所述第一输入信号、比较所述第一均值估计重建信号和所述第一输入信号，以及比较所述第二均值估计重建信号和所述第一输入信号；
    脉冲幅度调制器，其输入为所述比较器的输出以及所述减法器的输出，其输出为所述第二输入信号。
  4. 一种接收机，所述接收机包含如权利要求1-3任一项所述的信号均值检测器。
  5. 一种光线路终端，其特征在于，包含如权利要求4所述的接收机。
  6. 一种无源光网络系统，其特征在于，包含如权利要求5所述的光线路终 端。
  7. 一种信号均值检测方法，其特征在于，包括：
    将第一输入信号通过低通滤波得到第一均值估计信号；
    根据所述第一均值估计信号和所述第一输入信号得到第二输入信号，所述第二输入信号具有设定的共模电压，且所述第二输入信号的输出摆幅和极性与所述第一输入信号的输出摆幅和极性相同；
    将所述第二输入信号通过低通滤波得到第二均值估计信号，所述第二均值估计信号和所述第二输入信号之间的传递函数与所述第一均值估计信号和所述第一输入信号之间的传输函数相同；
    将所述第一均值估计信号与所述第二均值估计信号相减，并加上调整电压，所述调整电压的大小和所述第二输入信号的共模电压的大小相同。
  8. 如权利要求7所述的方法，其特征在于，所述第二输入信号的共模电压等于所述第一输入信号的高电平电压。
  9. 如权利要求7或8所述的方法，其特征在于，所述根据所述第一均值估计信号和所述第一输入信号得到所述第二输入信号，包括：
    比较所述第一输入信号和所述第一均值估计信号得到所述第二输入信号的极性；
    使用反馈信号控制所述第二输入信号的输出摆幅，使所述第二输入信号的输出摆幅等于所述第一输入信号的输出摆幅，所述反馈信号为将所述第一均值估计信号与所述第二均值估计信号相减，并加上调整电压，所述调整电压的大小和所述第二输入信号的共模电压的大小相同。
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