CN114499657A - Method and apparatus for frequency response estimation - Google Patents

Method and apparatus for frequency response estimation Download PDF

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Publication number
CN114499657A
CN114499657A CN202011143281.8A CN202011143281A CN114499657A CN 114499657 A CN114499657 A CN 114499657A CN 202011143281 A CN202011143281 A CN 202011143281A CN 114499657 A CN114499657 A CN 114499657A
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frequency
signal
optical signals
response
receiving unit
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CN114499657B (en
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李志沛
余毅
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Priority to PCT/CN2021/112882 priority patent/WO2022083254A1/en
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/079Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
    • H04B10/0795Performance monitoring; Measurement of transmission parameters
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/079Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/079Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
    • H04B10/0799Monitoring line transmitter or line receiver equipment
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/40Transceivers
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60Receivers
    • H04B10/61Coherent receivers
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60Receivers
    • H04B10/61Coherent receivers
    • H04B10/616Details of the electronic signal processing in coherent optical receivers
    • H04B10/6164Estimation or correction of the frequency offset between the received optical signal and the optical local oscillator

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Optical Communication System (AREA)

Abstract

The application provides a method and a device for frequency response estimation, a method and a device for spectral measurement and an optical communication device, which are executed in a communication device configured with a receiving unit, wherein the method for frequency response estimation comprises the following steps: acquiring N first optical signals, wherein the N first optical signals correspond to N frequency points in a target frequency range one by one, N is an integer greater than or equal to 2, and the first optical signals are determined based on optical signals sent by a sending unit and received by a receiving unit; determining a first frequency response according to the signal parameters of the N first optical signals, where the first frequency response includes a frequency response of the sending unit in the target frequency range, a first response value corresponding to a first frequency point in the first frequency response is determined according to the signal parameters of the first optical signals corresponding to a second frequency point, and the signal parameters include at least one of amplitude or phase. Therefore, additional measuring equipment is not needed, and measuring cost can be reduced.

Description

Method and apparatus for frequency response estimation
Technical Field
The embodiments of the present application relate to the field of communications, and more particularly, to a method and an apparatus for estimating frequency responses of a receiving unit and a transmitting unit in an optical communication system, and a method and an apparatus for measuring a spectrum of an optical signal transmitted by the transmitting unit.
Background
In the process of transmitting or receiving an optical signal, the optical signal needs to be processed by a plurality of units (or devices, components or modules), devices or modules. The amount of change (e.g., the amount of phase change and/or the amount of amplitude change) between the input signal and the output signal at different frequencies is also different for each cell, i.e., the amount of change between the input signal and the output signal varies with frequency, and the relationship of this change with respect to frequency is referred to as the frequency response.
The frequency response of an optical module is a very important parameter for an optical transceiver. Especially, when a high-bandwidth high-speed signal is transmitted, it is necessary to estimate (or measure) the frequency responses of the transmitting unit and the receiving unit, respectively, and then compensate the frequency responses at the transmitting unit and the receiving unit, respectively, so as to improve the transmission performance of the system.
In the prior art, an optical signal transmitted by a transmitting unit is first received by a receiving unit of an optical module, and then a frequency response of the optical signal is detected, so that the frequency response includes frequency responses of both the receiving unit and the transmitting unit (denoted as frequency response a), a noise signal is generated by an additional measuring device, and the noise signal is received by the receiving unit, so that the frequency response of the receiving unit is determined (denoted as frequency response b). On the one hand, this prior art needs to be implemented by measuring devices capable of generating noise signals, increasing the cost and conditional constraints of frequency response estimation. On the other hand, since the measuring device itself also has a frequency response, the frequency response of the transmitting unit cannot be accurately obtained based on the frequency response a and the frequency response b obtained as described above.
It is therefore desirable to provide a technique that enables accurate and reliable determination of the frequency response of a transmitting unit and reduces measurement costs.
Disclosure of Invention
The application provides a method and a device for estimating frequency response and an optical communication device, which can accurately and reliably determine the frequency response of a transmitting unit and reduce the measurement cost.
In a first aspect, a method for frequency response estimation is provided, which is performed in a communication device configured with a receiving unit, and includes: acquiring N first optical signals, wherein the N first optical signals correspond to N frequency points in a target frequency range one by one, N is an integer greater than or equal to 2, and the first optical signals are determined based on optical signals sent by a sending unit and received by a receiving unit; and determining a first frequency response according to the signal parameters of the N first optical signals, where the first frequency response includes the frequency response of the sending unit in the target frequency range, and a first response value corresponding to a first frequency point in the first frequency response is determined according to the signal parameters of the first optical signals corresponding to a second frequency point, and the signal parameters include at least one of amplitude or phase.
According to the scheme provided by the application, when the frequency response of the sending unit in the target frequency range needs to be estimated, the first optical signals of the center frequencies corresponding to the multiple frequency points in the target frequency range respectively are obtained, the frequency response of the sending unit in the target frequency range can be determined according to the multiple first optical signals, in addition, no additional measuring equipment is needed, and the measuring cost can be reduced.
In the present application, the "signal parameter of the first optical signal" may also be understood as a signal parameter of a digital signal of a fundamental frequency generated by demodulating, down-converting (or beating), amplifying, and analog-to-digital converting the first optical signal.
Wherein the first frequency point is any one of the N frequency points.
By way of example and not limitation, the frequency value of the first frequency point is 2 times the frequency value of the second frequency point.
In one implementation, the determining a first frequency response from the signal parameters of the N first optical signals includes: and determining the first response value according to a first parameter value in the signal parameters of the first optical signal corresponding to the second frequency point, wherein the first parameter value is a parameter value corresponding to the first frequency point.
For example, the determining the first response value according to the first parameter value in the signal parameter of the first optical signal corresponding to the second frequency point includes: determining a first difference value between the first response value and a second response value according to the first parameter value, wherein the second response value is a response value corresponding to the reference frequency point; and determining the first response value according to the first difference value and the second response value.
In one implementation, the reference frequency point includes a 0 frequency point.
By way of example and not limitation, the frequency intervals between two adjacent frequency points in the N frequency points are the same.
Wherein the smaller the frequency interval, the higher the accuracy of the estimation of the frequency response.
In one implementation, the method further comprises: receiving, by the receiving unit, a second optical signal transmitted by the transmitting unit, a bandwidth of the second optical signal corresponding to the target frequency range; determining a second frequency response according to the signal parameters of the second optical signal, the second frequency response comprising a frequency response of the transmitting unit within a target frequency range and a frequency response of the receiving unit within the target frequency range; determining a third frequency response from the first frequency response and the second frequency response, the third frequency response comprising a frequency response of the receiving unit within the target frequency range.
Thus, the frequency response of the receiving unit can be determined, further improving the utility of the present application.
In one implementation, the acquiring N first optical signals includes: receiving, by the receiving unit, a third optical signal transmitted by the transmitting unit, a bandwidth of the third optical signal corresponding to the target frequency range; performing beat frequency on the first optical signals respectively based on N first local oscillator signals to obtain the N first optical signals, where center frequencies of the N first local oscillator signals correspond to the N frequencies one to one.
Therefore, the method and the device can be applied to the condition that the transmission frequency of the transmission unit is fixed, and further improve the compatibility and the practicability of the application.
In another implementation, the acquiring N first optical signals includes: receiving, by the receiving unit, N fourth optical signals sent by the sending unit, where center frequencies of the N fourth optical signals correspond to the N frequencies one to one; and performing beat frequency on the N fourth optical signals respectively based on a second local oscillator signal to acquire the N first optical signals.
Therefore, the method and the device can be suitable for the condition that the frequency of the local oscillation signal of the receiving unit is fixed, and further improve the compatibility and the practicability of the application.
By way of example and not limitation, the communication device further includes the transmitting unit.
In a second aspect, there is provided a method of spectral measurement, performed in a communication device configured with a receiving unit, the method comprising: acquiring N first optical signals, wherein the N first optical signals correspond to N frequency points in a target frequency range one by one, N is an integer greater than or equal to 2, and the first optical signals are determined based on optical signals sent by a sending unit and received by a receiving unit; and determining a first spectrum according to the amplitudes of the N first optical signals, where the first spectrum includes the spectrum of the optical signal corresponding to the target frequency range sent by the sending unit, and a first amplitude corresponding to a first frequency point in the first spectrum is determined according to the amplitude of a first optical signal corresponding to a second frequency point.
According to the scheme provided by the application, when the spectrum of the optical signal in the target frequency range of the sending unit needs to be measured, the first optical signals of the plurality of frequency points with the center frequencies respectively corresponding to the target frequency range are respectively obtained, the spectrum of the optical signal corresponding to the target frequency range sent by the sending unit can be determined according to the plurality of first optical signals, in addition, no extra measuring equipment is needed, and the measuring cost can be reduced.
Wherein the first frequency point is any one of the N frequency points.
By way of example and not limitation, the frequency value of the first frequency point is 2 times the frequency value of the second frequency point.
In one implementation, the determining a first spectrum from the amplitudes of the N first optical signals includes: and determining the first amplitude according to a first value in the first optical signal corresponding to the second frequency point, wherein the first value is the value of the amplitude corresponding to the first frequency point in the first optical signal corresponding to the second frequency point.
For example, the determining, by the root, the first amplitude according to the first value in the first optical signal corresponding to the second frequency point includes: determining a first difference value between the first amplitude and a second amplitude according to the first value, wherein the second amplitude is an amplitude corresponding to a frequency point 0; determining the first amplitude according to the first difference and the second amplitude.
By way of example and not limitation, the frequency intervals between two adjacent frequency points in the N frequency points are the same.
Wherein the smaller the frequency interval, the higher the accuracy of the estimation of the frequency response.
In one implementation, the acquiring N first optical signals includes: receiving, by the receiving unit, a third optical signal transmitted by the transmitting unit, a bandwidth of the third optical signal corresponding to the target frequency range; performing beat frequency on the first optical signals respectively based on N first local oscillator signals to obtain the N first optical signals, where center frequencies of the N first local oscillator signals correspond to the N frequencies one to one.
Therefore, the method and the device can be applied to the condition that the transmission frequency of the transmission unit is fixed, and further improve the compatibility and the practicability of the application.
In another implementation, the acquiring N first optical signals includes: receiving, by the receiving unit, N fourth optical signals sent by the sending unit, where center frequencies of the N fourth optical signals correspond to the N frequencies one to one; and performing beat frequency on the N fourth optical signals respectively based on a second local oscillator signal to acquire the N first optical signals.
Therefore, the method and the device can be suitable for the condition that the frequency of the local oscillation signal of the receiving unit is fixed, and further improve the compatibility and the practicability of the application.
By way of example and not limitation, the communication device further includes the transmitting unit.
In a third aspect, an apparatus for frequency response estimation is provided, the apparatus comprising: the receiving unit is used for acquiring N first optical signals, the N first optical signals correspond to N frequency points in a target frequency range one by one, N is an integer greater than or equal to 2, and the first optical signals are determined based on the optical signals sent by the sending unit and received by the receiving unit; and the processing unit is configured to determine a first frequency response according to the signal parameters of the N first optical signals, where the first frequency response includes a frequency response of the transmitting unit in the target frequency range, a first response value corresponding to a first frequency point in the first frequency response is determined according to a signal parameter of a second optical signal corresponding to a second frequency point, and the signal parameter includes at least one of amplitude or phase.
Wherein the first frequency point is any one of the N frequency points.
By way of example and not limitation, the frequency value of the first frequency point is 2 times the frequency value of the second frequency point.
By way of example and not limitation, the receiving unit is further configured to receive a second optical signal transmitted by the transmitting unit, a bandwidth of the second optical signal corresponding to the target frequency range; the processing unit is further configured to determine a second frequency response according to the signal parameter of the second optical signal, where the second frequency response includes a frequency response of the transmitting unit in a target frequency range and a frequency response of the receiving unit in the target frequency range, and determine a third frequency response according to the first frequency response and the second frequency response, where the third frequency response includes a frequency response of the receiving unit in the target frequency range.
In an implementation manner, the receiving unit is specifically configured to receive a third optical signal sent by the sending unit, where a bandwidth of the third optical signal corresponds to the target frequency range, and perform beat frequency on the first optical signal based on N first local oscillation signals respectively to obtain the N first optical signals, where center frequencies of the N first local oscillation signals correspond to the N frequencies one to one.
In another implementation manner, the receiving unit is specifically configured to receive N fourth optical signals sent by the sending unit, where center frequencies of the N fourth optical signals correspond to the N frequencies in a one-to-one correspondence manner, and perform beat frequency on the N fourth optical signals respectively based on a second local oscillator signal to obtain the N first optical signals.
For example, the processing unit is specifically configured to determine the first response value according to a first parameter value in a signal parameter of a first optical signal corresponding to the second frequency point, where the first parameter value is a parameter value corresponding to the first frequency point.
And the processing unit is specifically configured to determine a first difference between the first response value and a second response value according to the first parameter value, where the second response value is a response value corresponding to a reference frequency point, and determine the first response value according to the first difference and the second response value.
By way of example and not limitation, the reference frequency points include a 0 frequency point
By way of example and not limitation, the frequency intervals between two adjacent frequency points in the N frequency points are the same.
In one possible implementation, the communication device further includes the sending unit.
In a fourth aspect, there is provided an apparatus for spectral measurement, the apparatus comprising: the receiving unit is used for acquiring N first optical signals, the N first optical signals correspond to N frequency points in a target frequency range one by one, N is an integer greater than or equal to 2, and the first optical signals are determined based on the optical signals sent by the sending unit and received by the receiving unit; and the processing unit is configured to determine a first spectrum according to the amplitudes of the N first optical signals, where the first spectrum includes the spectrum of the optical signal corresponding to the target frequency range sent by the sending unit, and a first amplitude corresponding to a first frequency point in the first spectrum is determined according to the amplitude of the first optical signal corresponding to a second frequency point.
Wherein the first frequency point is any one of the N frequency points.
For example, the frequency value of the first frequency point is 2 times that of the second frequency point
In an implementation manner, the processing unit is specifically configured to determine the first amplitude according to a first value in the first optical signal corresponding to the second frequency point, where the first value is a value of the amplitude corresponding to the first frequency point in the first optical signal corresponding to the second frequency point.
For example, the processing unit is specifically configured to determine, according to the first value, a first difference between the first amplitude and a second amplitude, where the second amplitude is an amplitude corresponding to a reference frequency point; determining the first amplitude according to the first difference and the second amplitude.
In one implementation, the reference frequency point includes a 0 frequency point.
By way of example and not limitation, the frequency intervals between two adjacent frequency points in the N frequency points are the same.
Wherein the smaller the frequency interval, the higher the accuracy of the estimation of the frequency response.
In one implementation, the receiving unit is specifically configured to receive a third optical signal sent by the sending unit, where a bandwidth of the third optical signal corresponds to the target frequency range; performing beat frequency on the first optical signals respectively based on N first local oscillator signals to obtain the N first optical signals, where center frequencies of the N first local oscillator signals correspond to the N frequencies one to one.
Therefore, the method and the device can be applied to the condition that the transmission frequency of the transmission unit is fixed, and further improve the compatibility and the practicability of the application.
In another implementation manner, the receiving unit is specifically configured to receive N fourth optical signals sent by the sending unit, where center frequencies of the N fourth optical signals correspond to the N frequencies one to one; and performing beat frequency on the N fourth optical signals respectively based on a second local oscillator signal to acquire the N first optical signals.
Therefore, the method and the device can be suitable for the condition that the frequency of the local oscillation signal of the receiving unit is fixed, and further improve the compatibility and the practicability of the application.
By way of example and not limitation, the communication device further includes the transmitting unit.
In a fifth aspect, there is provided an optical signal processing apparatus comprising means for performing the method of any one of the first or second aspects and any one of its possible implementations.
A sixth aspect provides an optical communication device comprising the apparatus of any of the third or fourth aspects and any possible implementation manner thereof.
In a seventh aspect, a processing apparatus is provided, which includes a processor coupled with a memory and operable to perform the method of the first aspect or the second aspect and possible implementations thereof. Optionally, the processing device further comprises a memory. Optionally, the processing device further comprises a communication interface, the processor being coupled to the communication interface.
In one implementation, the processing device is a processing apparatus. In this case, the communication interface may be a transceiver, or an input/output interface.
In another implementation, the processing device is a chip or a system of chips. In this case, the communication interface may be an input/output interface, an interface circuit, an output circuit, an input circuit, a pin or related circuit, etc. on the chip or system of chips. The processor may also be embodied as a processing circuit or a logic circuit.
In an eighth aspect, there is provided a processing apparatus comprising: input circuit, output circuit and processing circuit. The processing circuit is configured to receive signals via the input circuit and transmit signals via the output circuit such that the method of the first or second aspect and any possible implementation thereof is implemented.
In a specific implementation process, the processing device may be a chip, the input circuit may be an input pin, the output circuit may be an output pin, and the processing circuit may be a transistor, a gate circuit, a flip-flop, various logic circuits, and the like. The input signal received by the input circuit may be received and input by, for example and without limitation, a receiver, the signal output by the output circuit may be, for example and without limitation, output to and transmitted by a transmitter, and the input circuit and the output circuit may be different circuits or the same circuit, in which case the circuits function as the input circuit and the output circuit, respectively, at different times. The embodiment of the present application does not limit the specific implementation manner of the processor and various circuits.
In a ninth aspect, a processing apparatus is provided that includes a processor and a memory. The processor is configured to read instructions stored in the memory and to receive signals via the receiver and transmit signals via the transmitter to perform the methods of the first or second aspect and its various possible implementations.
Optionally, the number of the processors is one or more, and the number of the memories is one or more.
Alternatively, the memory may be integral to the processor or provided separately from the processor.
In a specific implementation, the memory may be a non-transitory (non-transitory) memory, such as a Read Only Memory (ROM), which may be integrated on the same chip as the processor, or may be separately disposed on different chips.
It will be appreciated that the associated data interaction process, for example, sending the indication information, may be a process of outputting the indication information from the processor, and receiving the capability information may be a process of receiving the input capability information from the processor. In particular, the data output by the processor may be output to a transmitter and the input data received by the processor may be from a receiver. The transmitter and receiver may be collectively referred to as a transceiver, among others.
The processor in the above ninth aspect may be a chip, and the processor may be implemented by hardware or software, and when implemented by hardware, the processor may be a logic circuit, an integrated circuit, or the like; when implemented in software, the processor may be a general-purpose processor implemented by reading software code stored in a memory, which may be integrated with the processor, located external to the processor, or stand-alone.
In a tenth aspect, there is provided a computer program product comprising: a computer program (which may also be referred to as code, or instructions), which when executed, causes a computer to perform the method of any of the possible implementations of the first or second aspect and aspects thereof.
In an eleventh aspect, there is provided a computer-readable medium storing a computer program (which may also be referred to as code, or instructions) which, when run on a computer, causes the computer to perform the method of any of the possible implementations of the first or second aspect and aspects thereof described above.
Drawings
Fig. 1 is a schematic diagram of an example of an optical communication apparatus to which the frequency response estimation method and the spectrum measurement method of the present application are applied.
Fig. 2 is a schematic flowchart of an example of the frequency response estimation method according to the present application.
Fig. 3 shows a schematic diagram of the effect of the frequency response of the transmitting unit and the frequency response of the receiving unit of the present application on the signal received by the receiving unit from the transmitting unit.
Fig. 4 is a schematic flow chart of another example of the method of frequency response estimation of the present application.
Fig. 5 is a schematic diagram of an example of a processing system to which the frequency response estimation method and the spectrum measurement method of the present application are applied.
Fig. 6 is a schematic flow chart of still another example of the method of frequency response estimation of the present application.
Fig. 7 is a schematic flowchart of an example of the method of spectral measurement according to the present application.
Fig. 8 is a schematic flowchart of another example of the method of spectral measurement according to the present application.
Detailed Description
The technical solution in the present application will be described below with reference to the accompanying drawings.
The technical scheme of the application can be applied to the fields of optical communication, optical switching and the like. For example, the present technical solution can be used for the estimation process of the frequency responses of the optical transmitting unit and the optical receiving unit or the spectrum measurement process of the signal transmitted by the optical transmitting unit of these neighborhoods.
Fig. 1 is a schematic diagram of an example of an optical communication apparatus 100 according to the present application, and as shown in fig. 1, the optical communication apparatus 100 includes a transmitting unit 110, a receiving unit 120, and a processing unit 130.
The transmitting unit 110 may also be referred to as a transmitting end or a transmitter, and by way of example and not limitation, the transmitting unit 110 may include devices such as a Digital-to-Analog Converter (DAC), a modulator, an electrical signal driver, a laser, and the like.
The transmission unit 110 is configured to acquire a Digital Signal from a device or apparatus (e.g., a Digital Signal Processor (DSP) or the like) that generates the Digital Signal, and perform processes such as an analog-to-Digital conversion process (based on a DAC), an amplification process (based on an electric Signal driver), and a modulation process (based on a modulator and a laser) on the Digital Signal to generate and transmit an optical Signal.
The digital signal input to transmitting section 110 has a predetermined amplitude for each frequency bin in the frequency domain, and the digital signal is a symmetric signal, specifically, the amplitudes of two frequency bins which are located on both sides of the reference frequency bin in the frequency domain and are spaced apart from the reference frequency bin by the same distance are the same, and the reference frequency bin may be, by way of example and not limitation, a 0 frequency bin.
In the present application, the frequency of the laser of the transmission unit 110 may be changed, or the frequency (or the center frequency) of the optical signal generated by the transmission unit 110 may be changed, that is, the optical signals of a plurality of center frequencies that can be generated by the transmission unit 110. Alternatively, the frequency of the laser of the transmitting unit 110 may be fixed, or the frequency (or the center frequency) of the optical signal generated by the transmitting unit 110 may be fixed, that is, the transmitting unit 110 may generate only one optical signal with a center frequency, which is not particularly limited in the present application.
It should be understood that the above listed components and functions included in the transmitting unit 110 are only exemplary illustrations, the present application is not limited thereto, and the process of generating and transmitting the optical signal by the transmitting unit 110 may be similar to the prior art, and here, the detailed description thereof is omitted to avoid redundancy.
The receiving unit 120 may also be referred to as a receiving end or a receiver, and by way of example and not limitation, the receiving unit 120 may include a demodulator (or a coherent receiver or a coherent demodulator), a local oscillator light source, a Trans-Impedance Amplifier (TIA), an Analog-to-Digital Converter (ADC), and other devices.
The receiving unit 120 is configured to receive an optical signal, and perform demodulation processing (performed based on a coherent demodulator), amplification processing (performed based on TIA), and analog-to-digital conversion processing (performed based on ADC), for example, on the optical signal to generate a digital signal, and send the digital signal to a device or apparatus such as a DSP for processing a number signal.
In the present application, the frequency of the local light source of the receiving unit 120 may be changed, or the frequency (or the center frequency) of the local light generated by the receiving unit 120 may be changed, that is, the local light of a plurality of kinds of center frequencies that can be generated by the receiving unit 120. Alternatively, the frequency of the local oscillator light source of the receiving unit 120 may be fixed, or the frequency (or the center frequency) of the local oscillator light generated by the receiving unit 120 may be fixed, that is, the receiving unit 120 may generate only one local oscillator light with the center frequency, which is not particularly limited in this application.
It should be understood that the above-listed components and functions included in the receiving unit 120 are only exemplary, the present application is not limited thereto, and the process of the receiving unit 120 acquiring the digital signal according to the optical signal may be similar to the prior art, and the detailed description thereof is omitted here for avoiding redundancy.
When the frequency response estimation or spectrum measurement method of the present application is performed by the apparatus 100, the transmitting unit 110 and the receiving unit 120 are communicatively connected (for example, connected by an optical fiber or the like), that is, the receiving unit 120 can receive the optical signal transmitted from the transmitting unit 110.
In order to improve the accuracy of the frequency response and the spectrum measurement, it is preferable that the transmitting unit 110 and the receiving unit 120 are directly connected, that is, the optical signal transmitted between the transmitting unit 110 and the receiving unit 120 is not transferred via another device.
The processing unit 130 is configured to estimate a frequency response of the transmitting unit 110 or measure a spectrum of the optical signal, based on the optical signal transmitted from the transmitting unit 110 and received by the receiving unit 120.
By way of example and not limitation, the processing unit 130 includes but is not limited to a DSP.
The method of frequency response estimation provided by the present application, which is applicable to the optical communication apparatus shown in fig. 1, is explained in detail below.
For ease of understanding and distinction, the following description will be given by taking as an example a case where it is necessary to estimate the frequency response of the transmission unit 110 in the frequency range of [0, f ]. As described above, since the digital signal is a symmetric signal having the reference frequency point (for example, the 0 frequency point) as the center of symmetry, the frequency response of the transmission unit 110 in the frequency range of [ -f, 0] corresponds to the frequency response in the frequency range of [0, f ].
Fig. 2 shows a schematic flow of the method 200 for frequency response estimation of the present application, wherein the method shown in fig. 2 is applicable to a case where the frequency of the local oscillation light source (or the center frequency of the local oscillation light generated by the local oscillation light source) of the receiving unit 120 can be changed.
As shown in fig. 2, in S210, the transmitting unit 110 acquires a digital signal (for easy understanding, signal # a) from the DSP, wherein the signal # a is a baseband signal, that is, the signal # a is a symmetrical signal with a reference frequency point (for example, a frequency point of 0) as a symmetrical center, and the bandwidth of the signal # a is [ -f, f ].
By way of example and not limitation, the amplitudes of the frequency bins of the signal # a may be the same, i.e., the signal # a may be a signal with a rectangular spectrum, thereby facilitating the calculation of the frequency response. That is, the amplitude of each frequency bin of signal # a is the same, and the phase of each frequency bin of signal # a is the same.
In addition, the signal # a may be a multicarrier signal in order to determine the phase of each frequency point in the frequency response.
The transmission unit 110 processes the signal # a, for example, the above-described digital-to-analog conversion process, amplification process, modulation process including up-conversion process by the laser, and the like, to generate an optical signal (hereinafter, referred to as a signal # B for ease of understanding). By way of example, and not limitation, the center frequency of the signal # B is denoted as f0
That is, this information # B is affected by the frequency response of the transmitting unit 110.
At S220, the receiving unit 120 receives the signal # B from the transmitting unit 110.
At S230, the receiving unit 120 subjects the signal # B to a signal based on the center frequency f0Specifically, the receiving unit 120 controls the local oscillation light source to generate a central frequency f0Is detected (note, signal # C). Receiving section 120 performs beat frequency (or down-conversion) on signal # B based on signal # C to obtain a signal having a center frequency of 0 (denoted as signal # D), and then performs demodulation, amplification, analog-to-digital conversion, and the like on signal # D to obtain a digital signal (denoted as signal # E)0)。
Thereafter, the receiving unit 120 controls the local oscillation light source to generate the center frequency f1And performs beat frequency on the signal # B according to the signal # F, and performs demodulation, amplification, analog-to-digital conversion, and the like on the resultant signal to obtain a digital signal (denoted as signal # E)1) The process and the above-mentioned receiving unit 120 acquire the signal # E based on the signal # C0Are similar, and detailed description thereof is omitted here for the sake of avoiding redundancy.
Similarly, the receiving unit 120 generates a plurality of center frequencies (e.g., f) by local oscillation light sources2~fN) And obtaining a plurality of (N-2) digital signals based on the plurality of (N-2) local oscillator signals.
It should be noted that transmitting section 110 may transmit signal # B a plurality of times (for example, N times), and receiving section 120 may beat signal # B received each time based on a plurality of local oscillation signals with center frequencies (for example, N) to obtain the plurality of digital signals (N).
Alternatively, the transmitting unit 110 may transmit the signal # B once, in which case the receiving unit 120 may store (or copy) the signal # B and obtain the plurality (N) of digital signals.
At S240, the processing unit 130 acquires the N digital signals from the transmitting unit 110 (e.g., an analog-to-digital converter of the transmitting unit).
At S250, the processing unit 130 determines the frequency response of the transmitting unit 110 (specifically, the components included in the transmitting unit 110) in the range of [0, f ] (or [ -f, 0]) based on the signal parameters of the N digital signals.
It should be noted that, in the present application, a certain digital signal parameter may include amplitudes of multiple frequency points within a bandwidth range of the digital signal, and/or phases of multiple frequency points within the bandwidth range of the digital signal.
Specifically, let f1And a reference frequency point f0(for ease of understanding, in f)0Illustrated as a 0 bin) is Δ f, i.e., f1-f0If Δ f, the receiving unit 120 is f based on the center frequency1The digital signal output after the beat frequency of the local oscillator signal can generate frequency spectrum shift.
Therefore, based on a center frequency of f1The amplitude (or phase) of the- Δ f frequency point of the signal input to the processing unit 130 after the beat frequency of the local oscillator signal of (B) is f in the signal # B transmitted by the transmitting unit 1100The amplitude (or phase) of the frequency point is influenced by the frequency response of the receiving unit 120 at- Δ f, or, in other words, f based on the center frequency1The amplitude (or phase) of the- Δ f bin of the signal input to the processing unit 130 after the beat frequency of the local oscillation signal # B is the amplitude (or phase) formed after the amplitude (or phase) of the signal # a at the 0 bin is affected by the frequency response of the transmitting unit 110 at the 0 bin and the frequency response of the receiving unit 120 at the- Δ f bin.
When the signal passes through the frequency response of the receiving unit, the signal is convolved and multiplied in the frequency domain in the time domain, and the amplitude-frequency characteristic and the phase-frequency characteristic are added.
That is, the signal # E is set1(i.e., based on a center frequency of f1Digital signal output after beat frequency of local oscillator signal) of which the amplitude (or phase) of the-delta f frequency point is HTX+RX(- Δ fGHz), and the frequency response of the transmitting unit 110 at frequency point 0 (or the amplitude (or phase) of frequency point 0 in the frequency response of the transmitting unit 110) is set as HTX(0GHz), the frequency response of the receiving unit 110 at the frequency point of- Δ f (or the amplitude (or phase) of the frequency point of- Δ f in the frequency response of the receiving unit 110) is set to HRX(- Δ fGHz), and assuming that the amplitude (or phase) of signal # A itself is β, the following equation 1 can be obtained:
HTX+RX(-Δf GHz)=HTX(0GHz)+HRX(. DELTA.fGHz) + beta formula 1
As shown in fig. 3, when Δ f is 20GHz, that is, f is based on the center frequency1=f0The local oscillation signal with +20GHz has the center frequency f0The value of the amplitude (or phase) of the-20 GHz frequency point in the digital signal obtained by beating the signal # B of (a) is equal to the sum of the amplitude (or phase) of the 0GHz frequency point in the frequency response of the transmitting unit 110 and the amplitude (or phase) of the-20 GHz frequency point in the frequency response of the receiving unit 120 and the amplitude (or phase) of the signal # a itself.
Similarly, let f2And f1Is Δ f, i.e., f2-f1=Δf,f2-f0When 2 Δ f is satisfied, the signal # E is shifted due to the spectrum shift1Middle delta f frequency point (i.e., f)2Frequency point) of the signals f transmitted by the transmitting unit 1100The magnitude (or phase) of the +2 Δ f bin is received by the receiving unit 120 at Δ f (i.e., f)1Frequency bins) of the frequency response.
Namely, let signal # E1In f2The frequency point has amplitude (or phase) of HTX+RX(Δ fGHz), and the amplitude (or phase) of the 2 Δ fGHz frequency point in the frequency response of the transmitting unit 110 is set to HTX(2. DELTA. fGHz), the frequency response of the receiving unit 110 is setIn f1The frequency point has amplitude (or phase) of HRX(Δ fGHz), the following equation 2 can be obtained:
HTX+RX(ΔfGHz)=HTX(2ΔfGHz)+HRX(Δ fGHz) + β formula 2
As shown in fig. 3, when Δ f is 20GHz, that is, f is based on the center frequency1=f0The local oscillation signal with +20GHz has the center frequency f0In the digital signal obtained by beating the signal # B of (2), the value of the amplitude (or phase) of the 20GHz frequency point is equal to the sum of the amplitude (or phase) of the 40GHz frequency point in the frequency response of the transmitting unit 110 and the amplitude (or phase) of the 20GHz frequency point in the frequency response of the receiving unit 120 and the amplitude (or phase) of the signal # a itself.
Furthermore, since the frequency response of the receiving unit 120 has symmetry with respect to the reference frequency point, the following equation 3 can be obtained:
HRX(-ΔfGHz)=HRX(Δ fGHz) formula 3
Therefore, based on the above formulas 1 to 3, the following formula 4 can be obtained:
HTX+RX(ΔfGHz)-HTX+RX(-ΔfGHz)=HTX(2ΔfGHz)+HRX(ΔfGHz)+β-(HTX(0GHz)+HRX(-ΔfGHz)+β)=HTX(2ΔfGHz)-HTX(0GHz) formula 4
That is, as shown in equation 4, the difference between the amplitude (or phase) at the frequency 2 Δ f and the amplitude (or phase) at the frequency 0 bin (i.e., an example of the reference bin) in the frequency response of transmitting section 110 is the difference between the amplitude (or phase) at- Δ f and the amplitude (or phase) at- Δ f in the digital signal obtained by beating signal # B based on the local oscillation signal having the center frequency Δ f.
Further, since the amplitude (or phase) of the 0-bin in the frequency response of the transmitting unit 110 is 0, the amplitude at 2 Δ f in the frequency response of the transmitting unit 110 is: based on the centre frequency f0And the difference between the amplitude at- Δ f and the amplitude at- Δ f in the digital signal obtained after the beat frequency of the signal # B is performed by the local oscillator signal of + Δ f.
In addition, in the present application, the processing unit 130 obtains the center frequency-based data from the receiving unit 120f0The local oscillator signal of + Δ f may beat the signal # B to obtain a digital signal, frequency shift may be performed on the digital signal (where the frequency shift corresponds to the offset between the center frequency of the local oscillator signal and the center frequency of the signal # B, for example, the frequency shift is- Δ f), and the phase at 2 Δ f in the frequency response of the transmitting unit 110 may be determined based on the difference between the phase after frequency shift and the phase of the signal # a.
It should be understood that the above-listed determination method of the phase in the frequency response is only an exemplary one, and the present application is not limited thereto, for example, the digital signal may be down-sampled before the frequency shift of the digital signal, and the signal after the frequency shift may be processed by frequency offset compensation (to compensate the frequency offset of the laser or the local oscillator light source) and framing. Hereinafter, the description of the same or similar cases will be omitted in order to avoid redundancy.
Similarly, the processing unit 130 can determine the frequency response of the transmitting unit 110 at the 2X frequency point according to the digital signal obtained after the beat frequency of the local oscillation signal with the center frequency of X.
That is, the frequency response of the transmitting unit 110 at N bins within the range of [0, f ] (or [ -f, 0]) can be determined from the digital signal obtained by the beat frequency based on N local oscillation signals (different center frequencies), and the frequency response of the transmitting unit 110 can be estimated (or reconstructed) from the frequency responses of the N bins (referred to as frequency response # a).
In one implementation, the frequency interval between two adjacent frequency points in the N frequency points may be the same, for example, Δ f, so that the processing unit 130 may control the receiving unit 120 (or the local oscillator light source of the receiving unit) to generate N local oscillator signals, where the central frequency differences between the N local oscillator signals and the signal # B are Δ f, 2 Δ f, 3 Δ f, … …, and N Δ f, respectively, where N Δ f is f/2.
Alternatively, in S260, the processing unit 130 may further determine a frequency response # B from the signal transmitted by the transmitting unit 110 and received by the receiving unit 120, where the frequency response # B includes both the frequency response of the transmitting unit 110 and the frequency response of the receiving unit 120, for example, the transmitting unit 110 may generate an optical signal # Y based on the digital signal # X, the receiving unit 120 may receive the optical signal # Y and process the optical signal # Y to generate a digital signal # Z, and the processing unit 130 may determine the frequency response # B from the amplitude difference (or phase difference) between the digital signal # Z and the digital signal # X at the frequency points. In addition, the process may be similar to the prior art, and the present application is not particularly limited.
Further, at S270, the processing unit 130 may determine the frequency response of the receiving unit 120 based on the frequency response # B and the frequency response # a. For example, the amplitude (or phase) of the frequency bin # a in the frequency response of the receiving unit 120 is equal to the difference between the amplitude (or phase) of the frequency bin # a in the frequency response # B and the amplitude (or phase) of the frequency bin # a in the frequency response # a.
Fig. 4 shows a schematic flow of the method 300 for frequency response estimation of the present application, wherein the method shown in fig. 4 is applicable to a case where the frequency of the laser of the transmitting unit 110 (or the center frequency of the beam generated by the laser) can be changed.
Unlike the process shown in fig. 2, in the method 300, the transmitting units 110 respectively generate the center frequencies f0~fNBased on the same center frequency (e.g., f) of the receiving unit 1200) The local oscillator light performs beat frequency on the N optical signals respectively, and then determines N digital signals.
Thus, the frequency response of the transmitting unit 110 is determined from the N digital signals, i.e. the amplitude (or phase) at 2 Δ f in the frequency response of the transmitting unit 110 can be determined as: based on the center frequency being f0The local oscillator signal has a center frequency of f0And the difference value between the amplitude (or phase) at the position of-delta f and the amplitude (or phase) at the frequency point of delta f in the digital signal obtained after the optical signal of + delta f is subjected to beat frequency.
Other processes and principles are similar to the method 200 described above, and a detailed description thereof is omitted here to avoid redundancy.
Fig. 5 is a schematic diagram of an example of a processing system 400 to which the method of frequency response estimation of the present application is applied. As shown in fig. 5, the processing system 400 includes: a measurement device 410 and a device under test 420.
Wherein the measurement device 410 comprises a receiving unit 415 and a processing unit 417.
The device under test 420 includes a sending unit 425.
Here, the structure and function of the transmitting unit 425 are similar to those of the transmitting unit 110 described above, and here, detailed description thereof is omitted to avoid redundancy, and the frequency of the laser of the transmitting unit 425 may be fixed, that is, the frequency of the optical signal transmitted by the transmitting unit 425 is fixed.
The structure and function of the receiving unit 415 are similar to those of the receiving unit 120, and detailed description thereof is omitted here for avoiding redundancy, and the frequency of the local oscillation light source of the receiving unit 415 may be changed, that is, the center frequency of the local oscillation signal may be changed.
Fig. 6 shows a schematic flow diagram of a method 500 of frequency response estimation suitable for use in the processing system 400 described above. Unlike the process shown in fig. 2, in the method 500, the receiving unit 415 of the measuring device 410 beats the optical signals received from the transmitting unit 425 of the device under test 420 based on N local oscillator lights with different center frequencies, respectively, to obtain N digital signals, so as to determine the frequency response of the transmitting unit 110 according to the N digital signals, that is, the amplitude (or phase) at 2 Δ f in the frequency response of the transmitting unit 110 may be determined as: based on the centre frequency f0The local oscillator signal of + delta f has a received central frequency of f0The amplitude (or phase) at- Δ f and the amplitude (or phase) at Δ f in the digital signal obtained after the beat frequency of the optical signal of (a).
Other processes and principles are similar to the method 200 described above, and a detailed description thereof is omitted here to avoid redundancy.
In one possible implementation, the device under test 420 may further include a receiving unit 427 and a processing unit 429.
The structure and function of the receiving unit 427 are similar to those of the receiving unit 120, and a detailed description thereof is omitted here for the sake of avoiding redundancy, and the frequency of the local oscillation light source of the receiving unit 427 may be fixed, that is, the center frequency of the local oscillation light of the receiving unit 427 is fixed.
Also, the measurement device 410 may further include a transmitting unit 419.
In this case, the method 500 may further include the transmitting unit 419 generating N optical signals with different center frequencies and transmitting the N optical signals to the receiving unit 427, so that the processing unit 429 may determine the frequency response of the receiving unit 427 according to the N optical signals with different center frequencies, and the process is similar to that of the method 300 shown in fig. 4, and a detailed description thereof is omitted here for avoiding redundancy.
Fig. 7 shows a schematic flow of the method 600 for spectrum measurement according to the present application, where the method shown in fig. 7 is applicable to a case where the frequency of the local oscillation light source of the receiving unit 120 (or the center frequency of the local oscillation light generated by the local oscillation light source) can be changed.
As shown in fig. 7, in S610, the transmitting unit 110 acquires a digital signal (for easy understanding, signal #1) from the DSP, where the signal #1 is a baseband signal, that is, the signal #1 is a symmetrical signal with a reference frequency point (for example, a frequency point of 0) as a symmetrical center, and a bandwidth of the signal #1 is [ -f, f ].
In the present application, the signal #1 may be a multicarrier signal, and the present application is not particularly limited.
The transmission unit 110 processes the signal #1, for example, the above-described digital-to-analog conversion process, amplification process, modulation process including up-conversion process by the laser, and the like, to generate an optical signal (hereinafter, referred to as a signal #2 for ease of understanding). By way of example, and not limitation, the center frequency of the signal #2 is denoted as f0
At S620, the receiving unit 120 receives the signal #2 from the transmitting unit 110.
At S630, the receiving unit 120 subjects the signal #2 to a process based on the center frequency f0In particular, the receiving unit 120 controls the local oscillator light source to generate the central frequency f0Is detected (note, signal # 3). The receiving unit 120 beats (or down-converts) the signal #2 based on the signal #3 to obtain an optical signal (denoted as signal #4) having a center frequency of 0, and then advances the signal #4Line demodulation, amplification and A/D conversion to obtain f0Digital signals corresponding to frequency points (note, signal # 5)0)。
Thereafter, the receiving unit 120 controls the local oscillation light source to generate the center frequency f1And f is obtained from the signal #6, and1digital signal corresponding to frequency point (note as signal # 5)1) The process and the above-mentioned receiving unit 120 acquire the signal #5 based on the signal #30Are similar, and detailed description thereof is omitted here for the sake of avoiding redundancy.
Similarly, the receiving unit 120 generates a plurality of center frequencies (e.g., f) by local oscillation light sources2~fN) And obtaining a plurality of (N-2) digital signals based on the plurality of (N-2) local oscillator signals.
It should be noted that transmitting section 110 may transmit signal #2 a plurality of times (for example, N times), and receiving section 120 may beat signal #2 received each time based on a plurality of local oscillation signals with center frequencies (for example, N) to obtain the plurality of digital signals (N).
Alternatively, the transmitting unit 110 may transmit the signal #2 once, in which case the receiving unit 120 may store (or copy) the signal #2, and further obtain the plurality (N) of digital signals.
At S640, the processing unit 130 acquires the N digital signals from the transmitting unit 110 (e.g., an analog-to-digital converter of the transmitting unit).
At S650, the processing unit 130 determines the spectrum of the signal #2 based on the signal parameters of the N digital signals.
Specifically, let f1And a reference frequency point f0(for ease of understanding, in f)0Illustrated as a 0 bin) is Δ f, i.e., f1-f0If Δ f, the receiving unit 120 is f based on the center frequency1The digital signal output after the beat frequency of the local oscillator signal can generate frequency spectrum shift.
Therefore, based on a center frequency of f1The amplitude of the- Δ f frequency point of the signal input to the processing unit 130 after the beat frequency of the local oscillation signal #2 isSignal #2 transmitted from transmission section 1100The magnitude of the frequency bins is affected by the frequency response of the receiving unit 120 at- Δ f, or f based on the center frequency1The amplitude of the- Δ f frequency point of the signal input to the processing unit 130 after the beat frequency of the local oscillation signal #2 is the amplitude formed after the amplitude of the signal #1 at the frequency point 0 is affected by the frequency response of the transmitting unit 110 at the frequency point 0 and the frequency response of the receiving unit 120 at the- Δ f.
When the signal passes through the frequency response of the receiving unit, the signal is convolved and multiplied in the frequency domain in the time domain, and the amplitude-frequency characteristic and the phase-frequency characteristic are added.
That is, the signal #5 is set1(i.e., based on a center frequency of f1Digital signal output after beat frequency of local oscillator signal) of-delta f frequency point is HTX+RX(- Δ fGHz), and the frequency response of the transmitting unit 110 at frequency point 0 (or the amplitude of frequency point 0 in the frequency response of the transmitting unit 110) is set as HTX(0GHz), the frequency response of the receiving unit 110 at the frequency point of- Δ f (or the amplitude of the frequency point of- Δ f in the frequency response of the receiving unit 110) is set to HRX(- Δ fGHz), and assuming that the amplitude of signal #1 itself is β, the following equation 1 can be obtained:
HTX+RX(-Δf GHz)=HTX(0GHz)+HRX(. DELTA.fGHz) + beta formula 1
Similarly, let f2And f1Is Δ f, i.e., f2-f1=Δf,f2-f0When the frequency spectrum shifts to 2 Δ f, signal #5 is output1Middle delta f frequency point (i.e., f)2Frequency point) of the signal f transmitted by the transmitting unit 1100The magnitude of the +2 Δ f bin is received by the receiving unit 120 at Δ f (i.e., f)1Frequency bins) of the frequency response.
Namely, let signal #51In f2The frequency point amplitude is HTX+RX(Δ fGHz), and the amplitude of the 2 Δ fGHz frequency point in the frequency response of the transmitting unit 110 is set to HTX(2. DELTA. fGHz) in the frequency response of the receiving unit 1101The frequency point amplitude is HRX(Δ fGHz), thenThe following formula 2 can be obtained:
HTX+RX(ΔfGHz)=HTX(2ΔfGHz)+HRX(Δ fGHz) + β formula 2
Furthermore, since the frequency response of the receiving unit 120 has symmetry with respect to the reference frequency point, the following equation 3 can be obtained:
HRX(-ΔfGHz)=HRX(Δ fGHz) formula 3
Therefore, based on the above formulas 1 to 3, the following formula 4 can be obtained:
HTX+RX(ΔfGHz)-HTX+RX(-ΔfGHz)=HTX(2ΔfGHz)+HRX(ΔfGHz)+β-(HTX(0GHz)+HRX(-ΔfGHz)+β)=HTX(2ΔfGHz)-HTX(0GHz) formula 4
That is, as shown in equation 4, the difference between the amplitude at frequency 2 Δ f and the amplitude at the 0 bin (i.e., an example of the reference bin) in the frequency response of transmitting section 110 is the difference between the amplitude at- Δ f and the amplitude at- Δ f in the digital signal obtained by beating signal #2 based on the local oscillation signal having center frequency Δ f.
Further, since the amplitude (or phase) of the 0-bin in the frequency response of the transmitting unit 110 is 0, the amplitude at 2 Δ f in the signal transmitted by the transmitting unit 110 is: based on the centre frequency f0The difference between the amplitude at- Δ f and the amplitude at- Δ f in the digital signal obtained after the beat frequency of the local oscillator signal of + Δ f on the signal # 2.
Similarly, the processing unit 130 can determine the amplitude at the 2X frequency point in the optical signal #2 from the digital signal obtained after the beat frequency based on the local oscillation signal having the center frequency X.
That is, the amplitudes of N frequency points of the optical signal #2 in the range of [0, f ] (or [ -f, 0]) can be determined from the digital signals obtained by the beat frequency based on N local oscillation signals (having different center frequencies), and the spectrum of the optical signal #2 can be estimated (or reconstructed) according to the amplitudes of the N frequency points.
In one implementation, the frequency interval between two adjacent frequency points in the N frequency points may be the same, for example, Δ f, so that the processing unit 130 may control the receiving unit 120 (or the local oscillator light source of the receiving unit) to generate N local oscillator signals, where the central frequency differences between the N local oscillator signals and the signal # B are Δ f, 2 Δ f, 3 Δ f, and an ellipsis N Δ f, respectively, where N Δ f is f/2.
Fig. 8 shows a schematic flow diagram of a method 700 of spectral measurement suitable for use in the processing system 400 described above. In contrast to the process shown in fig. 7, in the method 700, the optical signals received from the transmitting unit 425 of the device under test 420 are respectively beat-frequency-modulated by the receiving unit 415 of the measuring apparatus 410 based on N local oscillator lights with different center frequencies, so as to obtain N digital signals, and thus, the spectrum of the optical signal transmitted by the transmitting unit 110 is determined according to the N digital signals, that is, the amplitude (or phase) at 2 Δ f in the frequency response of the transmitting unit 110 can be determined as: and performing beat frequency on the received optical signal based on the local oscillator signal with the central frequency of delta f to obtain the difference value between the amplitude at 2 delta f and the amplitude at 0 frequency point in the digital signal.
Other processes and principles are similar to the method 600 described above, and a detailed description thereof is omitted here to avoid redundancy.
In this application, the processing unit 130 may be a processing device. The functions of the processing device may be implemented by hardware, or may be implemented by hardware executing corresponding software. For example, the processing device may include at least one processor and at least one memory, wherein the at least one memory is used for storing a computer program, and the at least one processor reads and executes the computer program stored in the at least one memory, so that the processing unit 130 performs the operations and/or processes performed by the processing unit in the method embodiments.
Alternatively, the processing unit 130 may comprise only a processor, the memory for storing the computer program being located outside the processing means. The processor is connected to the memory through the circuit/wire to read and execute the computer program stored in the memory.
In some examples, the processing unit 130 may also be a chip or an integrated circuit. For example, the processing means comprise processing/logic circuits and interface circuits for receiving and transmitting signals and/or data to said processing circuits, which process said signals and/or data to implement the functions of the processing unit in the respective method embodiments.
In one implementation, the processing unit 130 includes: one or more processors, one or more memories, and one or more communication interfaces. The processor is used for controlling the communication interface to send and receive information, the memory is used for storing a computer program, and the processor is used for calling and running the computer program from the memory so as to enable the processing unit 130 to execute the processing and/or operations executed by the processing unit 130 in the method embodiments of the present application.
Optionally, the memory and the processor in the foregoing device embodiments may be physically separate units, or the memory and the processor may be integrated together, which is not limited herein.
In addition, the present application also provides a computer-readable storage medium, in which computer instructions are stored, and when the computer instructions are executed on a computer, the computer is caused to execute the operations and/or processes executed by the control device in the method embodiments of the present application.
Furthermore, the present application also provides a computer program product, which includes computer program code or instructions, when the computer program code or instructions runs on a computer, the operations and/or processes executed by the control device in the method embodiments of the present application are executed.
In addition, the present application also provides a chip, where the chip includes a processor, and a memory for storing a computer program is provided separately from the chip, and the processor is configured to execute the computer program stored in the memory, so that a controller in which the chip is installed performs the operations and/or processes performed by the controller in any one of the method embodiments.
Further, the chip may also include a communication interface. The communication interface may be an input/output interface, an interface circuit, or the like. Further, the chip may further include the memory.
Furthermore, the present application also provides a communication device (which may be a chip, for example) comprising a processor and a communication interface for receiving and transmitting signals to the processor, the processor processing the signals such that the operations and/or processes performed by the processing unit 130 in any of the method embodiments are performed.
The processor in the embodiments of the present application may be an integrated circuit chip having the capability of processing signals. In implementation, the steps of the above method embodiments may be performed by integrated logic circuits of hardware in a processor or instructions in the form of software. The processor may be a general purpose processor, a Digital Signal Processor (DSP), an application-specific integrated circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, or discrete hardware components. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of the method disclosed in the embodiments of the present application may be directly implemented by a hardware encoding processor, or implemented by a combination of hardware and software modules in the encoding processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in a memory, and a processor reads information in the memory and completes the steps of the method in combination with hardware of the processor.
The memory in the embodiments of the present application may be either volatile memory or nonvolatile memory, or may include both volatile and nonvolatile memory. The non-volatile memory may be a read-only memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an electrically Erasable EPROM (EEPROM), or a flash memory. Volatile memory can be Random Access Memory (RAM), which acts as external cache memory. By way of example, but not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), Synchronous Dynamic Random Access Memory (SDRAM), double data rate SDRAM, enhanced SDRAM, SLDRAM, Synchronous Link DRAM (SLDRAM), and Direct Rambus RAM (DRRAM). It should be noted that the memory of the systems and methods described herein is intended to comprise, without being limited to, these and any other suitable types of memory.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
It can be clearly understood by those skilled in the art that, for convenience and simplicity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described device embodiments are merely illustrative, and the division of the unit is only one division of logic functions, and other division ways may be available in actual implementation. For example, multiple units or components may be combined or may be integrated into another system, or some features may be omitted, or not implemented. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as the separate parts may or may not be physically separate, and the parts displayed as the units may or may not be physical units, that is, may be located in one place, or may also be distributed on a plurality of network units, and some or all of the units may be selected according to actual needs to achieve the purpose of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application.
The above description is only for the specific embodiments of the present application, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present disclosure, and all the changes or substitutions should be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (26)

1. A method of frequency response estimation, performed in a communication device configured with a receiving unit, the method comprising:
acquiring N first optical signals, wherein the N first optical signals correspond to N frequency points in a target frequency range one by one, N is an integer greater than or equal to 2, and the first optical signals are determined based on optical signals sent by a sending unit and received by a receiving unit;
and determining a first frequency response according to the signal parameters of the N first optical signals, where the first frequency response includes the frequency response of the sending unit in the target frequency range, and a first response value corresponding to a first frequency point in the first frequency response is determined according to the signal parameters of the first optical signals corresponding to a second frequency point, and the signal parameters include at least one of amplitude or phase.
2. The method of claim 1 wherein the frequency values of the first frequency points are 2 times the frequency values of the second frequency points.
3. The method according to claim 1 or 2, characterized in that the method further comprises:
receiving, by the receiving unit, a second optical signal transmitted by the transmitting unit, a bandwidth of the second optical signal corresponding to the target frequency range;
determining a second frequency response according to the signal parameters of the second optical signal, the second frequency response comprising a frequency response of the transmitting unit within a target frequency range and a frequency response of the receiving unit within the target frequency range;
determining a third frequency response from the first frequency response and the second frequency response, the third frequency response comprising a frequency response of the receiving unit within the target frequency range.
4. The method of any one of claims 1 to 3, wherein the acquiring N first optical signals comprises:
receiving, by the receiving unit, a third optical signal transmitted by the transmitting unit, a bandwidth of the third optical signal corresponding to the target frequency range;
performing beat frequency on the first optical signals respectively based on N first local oscillator signals to obtain the N first optical signals, where center frequencies of the N first local oscillator signals correspond to the N frequencies one to one.
5. The method of any one of claims 1 to 3, wherein the acquiring N first optical signals comprises:
receiving, by the receiving unit, N fourth optical signals sent by the sending unit, where center frequencies of the N fourth optical signals correspond to the N frequencies one to one;
and performing beat frequency on the N fourth optical signals respectively based on a second local oscillator signal to acquire the N first optical signals.
6. The method of any of claims 1 to 5, wherein determining a first frequency response from the signal parameters of the N first optical signals comprises:
and determining the first response value according to a first parameter value in the signal parameters of the first optical signal corresponding to the second frequency point, wherein the first parameter value is a parameter value corresponding to the first frequency point.
7. The method according to claim 6, wherein the determining the first response value according to the first parameter value in the signal parameter of the first optical signal corresponding to the second frequency point includes:
determining a first difference value between the first response value and a second response value according to the first parameter value, wherein the second response value is a response value corresponding to the reference frequency point;
and determining the first response value according to the first difference value and the second response value.
8. The method of claim 7, wherein the reference frequency point is a 0 frequency point.
9. The method according to any one of claims 1 to 8, wherein the frequency intervals between two adjacent frequency points in the N frequency points are the same.
10. The method according to any of claims 1 to 9, wherein the communication device further comprises the transmitting unit.
11. An apparatus for frequency response estimation, the apparatus comprising:
the receiving unit is used for acquiring N first optical signals, the N first optical signals correspond to N frequency points in a target frequency range one by one, N is an integer greater than or equal to 2, and the first optical signals are determined based on the optical signals sent by the sending unit and received by the receiving unit;
and the processing unit is configured to determine a first frequency response according to the signal parameters of the N first optical signals, where the first frequency response includes a frequency response of the transmitting unit in the target frequency range, a first response value corresponding to a first frequency point in the first frequency response is determined according to a signal parameter of a second optical signal corresponding to a second frequency point, the signal parameter includes at least one of an amplitude or a phase, and the first frequency point is any one of the N frequency points.
12. The apparatus of claim 11 wherein the frequency value of the first frequency point is 2 times the frequency value of the second frequency point.
13. The apparatus according to claim 11 or 12, wherein the receiving unit is further configured to receive a second optical signal transmitted by the transmitting unit, and a bandwidth of the second optical signal corresponds to the target frequency range;
the processing unit is further configured to determine a second frequency response according to the signal parameter of the second optical signal, where the second frequency response includes a frequency response of the transmitting unit in a target frequency range and a frequency response of the receiving unit in the target frequency range, and determine a third frequency response according to the first frequency response and the second frequency response, where the third frequency response includes a frequency response of the receiving unit in the target frequency range.
14. The apparatus according to any one of claims 11 to 13, wherein the receiving unit is specifically configured to receive a third optical signal sent by the sending unit, a bandwidth of the third optical signal corresponds to the target frequency range, and perform beat frequency on the first optical signal based on N first local oscillation signals respectively to obtain the N first optical signals, where center frequencies of the N first local oscillation signals correspond to the N frequencies one to one.
15. The apparatus according to any one of claims 11 to 13, wherein the receiving unit is specifically configured to receive N fourth optical signals sent by the sending unit, center frequencies of the N fourth optical signals correspond to the N frequencies in a one-to-one manner, and perform beat frequency on the N fourth optical signals respectively based on a second local oscillation signal to obtain the N first optical signals.
16. The apparatus according to any one of claims 11 to 15, wherein the processing unit is specifically configured to determine the first response value according to a first parameter value in a signal parameter of a first optical signal corresponding to the second frequency point, where the first parameter value is a parameter value corresponding to the first frequency point.
17. The apparatus according to claim 16, wherein the processing unit is specifically configured to determine a first difference between the first response value and a second response value according to the first parameter value, where the second response value is a response value corresponding to a reference frequency point, and determine the first response value according to the first difference and the second response value.
18. The apparatus of claim 17, wherein the reference frequency point is a 0 frequency point.
19. The apparatus according to any of claims 11 to 18, wherein the frequency intervals between two adjacent frequency points of the N frequency points are the same.
20. The apparatus according to any of claims 11 to 19, wherein the communication apparatus further comprises the transmitting unit.
21. A method of spectral measurement, performed in a communication device configured with a receiving unit, the method comprising:
acquiring N first optical signals, wherein the N first optical signals correspond to N frequency points in a target frequency range one by one, N is an integer greater than or equal to 2, and the first optical signals are determined based on optical signals sent by a sending unit and received by a receiving unit;
and determining a first spectrum according to the amplitudes of the N first optical signals, wherein the first spectrum comprises the spectrum of the optical signal sent by the sending unit in the target frequency range, and the first amplitude corresponding to the first frequency point in the first spectrum is determined according to the amplitude of the first optical signal corresponding to the second frequency point.
22. An apparatus for spectral measurement, comprising:
the receiving unit is used for acquiring N first optical signals, the N first optical signals correspond to N frequency points in a target frequency range one by one, N is an integer greater than or equal to 2, and the first optical signals are determined based on the optical signals sent by the sending unit and received by the receiving unit;
and the processing unit is configured to determine a first spectrum according to the amplitudes of the N first optical signals, where the first spectrum includes a spectrum of the optical signal sent by the sending unit in the target frequency range, and a first amplitude corresponding to a first frequency point in the first spectrum is determined according to an amplitude of the first optical signal corresponding to a second frequency point.
23. An optical signal processing apparatus comprising a processor coupled with a memory for storing a computer program or instructions, the processor being configured to execute the computer program or instructions in the memory such that the method of any of claims 1 to 8, 21 is performed.
24. The apparatus of claim 23, wherein the optical signal processing device is a chip.
25. A computer-readable storage medium, in which a computer program or instructions for implementing the method according to any one of claims 1 to 8, 21 is stored.
26. A computer program product comprising a computer program which, when executed, causes a computer to perform the method of any one of claims 1 to 8, 21.
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