CN111756446A - A phase absolute synchronization system and method based on optical fiber transmission - Google Patents

Abstract

The invention discloses a phase absolute synchronization system and method based on optical fiber transmission. The system includes a phase distribution device, a phase reproduction device and at least one intermediate download device; the phase distribution device generates a radio frequency reference signal, and receives a signal from the phase reproduction device. The radio frequency auxiliary signal is subjected to phase conjugate mixing, and the output signal is transmitted to the phase reproduction device in the original way; the phase reproduction device generates the radio frequency auxiliary signal, transmits it to the phase distribution device, and simultaneously receives the phase conjugate signal from the phase distribution device. , perform up-mixing, and reproduce the RF reference signal; the intermediate download device receives and demodulates the RF auxiliary signal and the phase conjugate signal at any position of the optical fiber link, and performs up-mixing to reproduce the RF reference signal. The invention realizes the absolute synchronization of the phase of the off-site frequency signals, so that the phase difference between the off-site frequency signals has high stability and repeatability, and the phase difference will not change due to factors such as fiber link changes or system restarts.

Description

A system and method for absolute phase synchronization based on optical fiber transmission

technical field

The invention relates to the technical field of time-frequency signal transmission, in particular to a phase absolute synchronization system and method based on optical fiber transmission.

Background technique

The phase absolute synchronization technology is mainly used to make the phase difference between different frequency signals have the characteristics of high stability and high repeatability. With the rapid development of frequency reference, the technology of time-frequency signal transmission and synchronization has also made great progress. However, the requirement for absolute phase synchronization between different frequency signals has not been met for a long time. This technology can realize absolute phase synchronization of different frequency signals, and has broad application prospects in the fields of distributed phased array, dense aperture array, and radio astronomy observation.

At present, the frequency synchronization based on microwave signals only realizes the relative phase synchronization between the signals of the same frequency in different places, that is, after the frequency synchronization is completed, the phase difference between the microwave signals at the transmitter and the receiver will fluctuate slightly around a fixed value, but the phase difference does not Not fixed. If the link is interrupted or the frequency transmission system is restarted, the phase difference is not reproducible.

SUMMARY OF THE INVENTION

In view of this, in order to solve the above problems in the prior art, the present invention proposes a phase absolute synchronization system and method based on optical fiber transmission, which adopts passive transmission mode to avoid signal transmission that may be caused by factors such as system restart and optical fiber link change. Abrupt phase delay, using the phase conjugate mixing method to automatically cancel the phase delay of the microwave frequency signal during the transmission of the optical fiber link, and use the phase anti-correlation characteristic of the opposite transmission signal to achieve absolute phase synchronization at any position in the optical fiber link .

The present invention solves the above-mentioned problems through the following technical means:

The present invention proposes a phase absolute synchronization system based on optical fiber transmission, comprising:

The phase distribution device is used to receive the optical signal from the phase reproduction device, demodulate the radio frequency auxiliary signal with the transmission phase delay of the optical fiber link, and at the same time, the receiving and processing device generates the radio frequency reference signal, and the frequency of the signal is the frequency of the radio frequency auxiliary signal. 2 times. The RF reference signal is used as a local oscillator frequency signal and is down-mixed with the received RF auxiliary signal, and the obtained output signal has the same frequency and conjugate phase as the RF auxiliary signal. The phase-conjugated signal is modulated onto an optical signal with the same wavelength as that of the phase reproducing device, and is transmitted back to the transmitting device through an optical fiber link.

The phase reproduction device is used to generate a radio frequency auxiliary signal, modulate a part of the signal to the optical signal, and transmit it to the receiving and processing device through the optical fiber link; receive the optical signal from the phase distribution device, and demodulate the optical signal with the optical fiber link. The other part of the radio frequency auxiliary signal is up-mixed with the received phase conjugate signal, and the phase difference between the output signal and the radio frequency reference signal of the phase distribution device is highly stable and reproducible. present.

At least one intermediate download device is used to receive the optical signals transmitted in opposite directions in the optical fiber link at any position in the middle of the optical fiber link, and demodulate respectively to obtain the radio frequency auxiliary signal and the phase conjugate signal with a partial transmission phase delay of the optical fiber link. The phase difference between the output signal and the radio frequency reference signal of the phase distribution device has high stability and repeatability by using the phase anti-correlation characteristic between the two signals and up-mixing them.

Preferably, a passive transmission method is used to realize the reproducibility of the phase difference between the reference signal and the reproduced signal, that is, the phase-locked loop, active compensation, frequency division and frequency multiplication, etc. are not used in the signal transmission and processing links. Signal processing method; the phase conjugate mixing method is adopted, so that in the signal processing link, the phase delay of the radio frequency signal during the optical fiber link transmission process is automatically cancelled; at any position of the transmitted optical fiber link, the round-trip transmission is demodulated The radio frequency signal is up-mixed, so that the reproduced signal has a stable and reproducible phase difference with the reference signal.

Preferably, in the phase conjugate mixing link in the phase distribution device and the co-frequency up-mixing link between the phase reproduction device and the intermediate downloading device, methods including but not limited to double-shift frequency mixing are used to avoid radio frequency Nonlinear effects during direct mixing such as leakage and higher harmonic interference.

Preferably, it also includes performing band-pass filtering processing on the associated radio frequency signal, so as to extract the signal of the required frequency.

Optionally, the optical fiber link is a point-to-point transmission mode, the phase distribution device and the phase reproduction device are located in different places, and the phase absolute synchronization effect exists with any two or all three of the phase distribution device, the phase reproduction device, and the intermediate download device. between.

Optionally, the optical fiber link is in a ring transmission mode, the phase distribution device and the phase reproduction device are located at the same location, and the phase absolute synchronization effect exists between the phase distribution device and the intermediate download device.

The present invention provides a phase absolute synchronization method based on optical fiber transmission, comprising:

The phase distribution device generates a radio frequency reference signal, receives the radio frequency auxiliary signal from the phase reproduction device, performs phase conjugate mixing, and transmits the output signal to the phase reproduction device in the original way;

The phase reproduction device generates a radio frequency auxiliary signal, transmits it to the phase distribution device, and simultaneously receives the phase conjugate signal from the phase distribution device, performs up-mixing, and reproduces the radio frequency reference signal;

The intermediate download device receives and demodulates the radio frequency auxiliary signal and the phase conjugate signal at any position of the optical fiber link, performs up-mixing, and reproduces the radio frequency reference signal.

Compared with the prior art, the beneficial effects of the present invention at least include:

(1) Using the phase conjugate mixing method, the phase delay of the radio frequency signal in the transmission process of the optical fiber link is automatically canceled, and the principle is simple.

(2) Using the anti-correlation characteristic of the phase delay of the opposite transmission signal in the optical fiber link to achieve absolute phase synchronization at any position of the optical fiber link, breaking through the point-to-point limitation of the optical fiber link and expanding the application scope of absolute phase synchronization.

(3) The passive transmission method avoids the sudden change of signal transmission phase delay that may be caused by factors such as system restart and fiber link change, and ensures the high stability and reproducibility of the method.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

Fig. 1 is the structural representation of the phase absolute synchronization system based on optical fiber transmission of the present invention;

Fig. 2 is the structural representation of the phase reproduction device of the present invention;

Fig. 3 is the structural representation of the phase distribution device of the present invention;

FIG. 4 is a schematic structural diagram of an intermediate download device of the present invention.

Detailed ways

In order to make the above objects, features and advantages of the present invention more clearly understood, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be pointed out that the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, those of ordinary skill in the art can obtain all the Other embodiments fall within the protection scope of the present invention.

Example 1

FIG. 1 is a schematic structural diagram of a phase absolute synchronization system of the present invention.

As shown in FIG. 1 , the phase absolute synchronization system of the present invention includes: a phase distribution device 100 for generating a radio frequency reference signal, receiving a radio frequency auxiliary signal from the phase reproducing device 200, performing phase conjugate mixing, and outputting the signal The original path is transmitted to the phase reproduction device; the phase reproduction device is used to generate the radio frequency auxiliary signal, transmit it to the phase distribution device, and simultaneously receive the phase conjugate signal from the phase distribution device, perform up-mixing, and reproduce the radio frequency reference signal; The intermediate downloading device 300 is configured to receive and demodulate the radio frequency auxiliary signal and the phase conjugate signal at any position of the optical fiber link, perform up-mixing, and reproduce the radio frequency reference signal.

Referring to FIG. 1 , the phase absolute synchronization system of the present invention includes a phase distribution device, a phase reproduction device and multiple intermediate download devices. The transmission medium, ie, an optical fiber link, exemplarily adopts a point-to-point topology, but is not limited thereto. In practical applications, the phase distribution device and the phase reproduction device can be placed at the same location as required, and the optical fiber link adopts a topology structure such as a ring.

Each component of the phase absolute synchronization system of the present invention will be described in further detail below.

FIG. 2 is a schematic structural diagram of the phase reproducing apparatus of the present invention.

The phase reproduction device of the present invention mainly has the following functions: (1) generating a radio frequency auxiliary signal, modulating the optical signal and injecting it into the optical fiber link; (2) receiving the phase conjugate signal from the phase distribution device; (3) converting the above-mentioned The two radio frequency signals are up-mixed, and the output signal is band-pass filtered and provided to the user.

As shown in FIG. 2 , the phase reproduction apparatus 100 of the present invention includes a radio frequency auxiliary signal generator 101 , a first power division module 102 , a first optical modulation module 103 , a first optical fiber circulator 104 , and a first optical detector module 105 , a first mixer 106 and a first bandpass filter 107 .

In FIG. 2 , the radio frequency auxiliary signal is generated by the radio frequency auxiliary signal generator 101 , and the first power division module 102 is used to divide the signal into two paths according to a certain power ratio, one of which is modulated by the amplitude through the first optical modulation module 103 The method is loaded onto the optical signal, and the generated optical signal is injected into the optical fiber link through the first optical fiber circulator 104 . At the same time, the first optical fiber circulator 104 transmits the optical signal transmitted to the phase distribution device via the optical fiber link to the first optical detector module 105. Optionally, the demodulated signal can be appropriately power amplified according to actual needs. . The radio frequency signal demodulated by the first photodetector module 105 and the other signal output by the first power division module 102 are up-mixed by the first mixer 106, and the output signal is extracted by the first bandpass filter 107. The radio frequency signal of the target frequency is provided to the user. Preferably, the first mixer 106 can be replaced with other up-mixing modules to suppress nonlinear effects such as radio frequency leakage and high-order harmonic interference, such as high-performance up-mixers and double-shift frequency mixing modules, etc., not limited to this.

Let the RF auxiliary signal generated by the RF auxiliary signal generator 101 be:

V ₁ =A ₁ cos(ωt+φ ₁ )

Here, A ₁ represents the amplitude of the radio frequency auxiliary signal, ω is the frequency of the signal, t is the time instant, and φ ₁ is the phase of the signal. The RF auxiliary signal generator of the present invention can be any RF signal generator that generates a reference signal. Preferably, a high-stability frequency source such as a hydrogen bell, a cesium bell or a rubidium bell can be used to provide the RF auxiliary signal generator 101 with a frequency refer to.

FIG. 3 is a schematic structural diagram of the phase distribution device of the present invention.

The phase distribution device of the present invention mainly has the following functions: (1) generating a radio frequency reference signal; (2) receiving the radio frequency auxiliary signal from the phase reproducing device; (3) using the above two signals to carry out phase conjugate mixing, and combining The output signal is modulated onto the optical signal and injected into the fiber optic link.

As shown in FIG. 3 , the phase distribution device 200 of the present invention includes a radio frequency reference signal generator 201, a second power division module 202, a second fiber circulator 203, a second photodetector module 204, a second mixer 205, The second band pass filter 206 and the second light modulation module 207 .

In FIG. 3 , the RF reference signal is generated by the RF reference signal generator 201 , and the frequency of the signal is twice the frequency of the RF auxiliary signal in the phase reproducing apparatus 100 . The RF reference signal is divided into two channels by the second power division module 202 , one of which is provided to the user, and the other is used as the local oscillator signal of the second mixer 205 to participate in the phase conjugate mixing process. The second optical fiber circulator 203 transmits the optical signal from the optical fiber link to the second optical detector module 204, and demodulates the radio frequency auxiliary signal from the phase reproduction device 100. The resulting signal undergoes appropriate power amplification. The radio frequency signal enters the second mixer 205 and participates in the phase conjugate mixing process. Preferably, the second mixer 205 can be replaced with other mixing modules to suppress nonlinear effects such as radio frequency leakage and high-order harmonic interference, such as high-performance dedicated phase conjugate mixers and double-shift frequency mixing modules, etc., Not limited to this. The output signal of the second mixer 205 is connected to the second bandpass filter 206 to extract the required phase conjugate signal, and is loaded onto the optical signal by the amplitude modulation method through the second optical modulation module 207, and the generated optical signal passes through the second optical fiber Circulator 203 is injected into the fiber link. Wherein, the center wavelength of the laser source of the second optical modulation module 207 is the same as the center wavelength of the laser source of the first optical modulation module 103, then: optionally, the center of the laser source of the first optical modulation module 103 and the second optical modulation module 207 The wavelengths are adjusted to be the same in advance; optionally, when the phase reproducing device 100 and the phase distribution device 200 are located in different places, the laser sources of the first optical modulation module 103 and the second optical modulation module 207 realize the same center by means of optical frequency synchronization Wavelength; Optionally, when the phase reproduction device 100 and the phase distribution device 200 are located at the same location, the optical signals to be modulated by the first optical modulation module 103 and the second optical modulation module 207 may come from the same laser source.

Specifically, the radio frequency signal demodulated by the second photodetector module 204 is:

V ₂ =A ₂ cos[ω(t-τ)+φ ₁ ]

Among them, A ₂ represents the amplitude of the radio frequency signal obtained by demodulation, and τ is the one-way transmission time of the radio frequency modulated optical signal in the optical fiber link.

The RF reference signal generated by the RF reference signal generator 201 can be expressed as:

V ₃ =A ₃ cos(2ωt+φ ₂ )

Among them, A ₃ represents the amplitude of the radio frequency reference signal, φ ₂ is the phase of the signal, and the frequency of the signal is 2ω.

After the above two radio frequency signals are subjected to the phase conjugate mixing operation of the second mixer 205, the output signal can be expressed as:

V ₄ =A ₄ cos[ω(t+τ)+φ ₂ -φ ₁ ]

where A ₄ represents the amplitude of the phase conjugate signal.

The output signal of the second mixer 205 is transmitted to the second band-pass filter 206 to extract a phase conjugate signal with a frequency of ω, and the signal is loaded onto the second photodetector module 207 . The optical signal modulated by the phase conjugate signal is transmitted to the phase reproduction device 100 through the optical fiber link, and after being demodulated by the first optical detector module 105, it can be expressed as:

V ₅ =A ₅ cos(ωt+φ ₂ -φ ₁ )

Among them, A ₅ represents the amplitude of the phase conjugate signal obtained by demodulation.

The up-mixing operation is performed on the phase conjugate signal obtained by demodulation and the other radio frequency auxiliary signal output by the first power division module 102, and the obtained output signal after being extracted by the first bandpass filter 107 can be expressed as:

V ₆ =A ₆ cos(2ωt+φ ₂ +φ ₃ )

Here, A ₆ represents the amplitude of the up-mixed output radio frequency signal, and φ ₃ is the phase delay accumulated in the non-common mode transmission paths other than the optical fiber link during the signal synchronization process.

Comparing the phases of the radio frequency signal V ₆ and the radio frequency reference signal V ₃ , it can be known that their phase difference is φ ₃ , that is, the accumulated phase delay in the non-common mode paths other than the optical fiber link. Since the phase absolute synchronization scheme of the present invention adopts a passive transmission scheme, for a selected frequency ω, the device is placed in a certain environmental condition (such as room temperature condition, not limited thereto), the accumulated phase delay _φ3 is highly stable, and It will not change due to factors such as system restart and fiber link changes, which means that it is highly reproducible. By pre _- calibrating the phase delay φ3, the phase difference between the radio frequency signals used by the phase reproducing apparatus 100 and the phase distributing apparatus 200 for the user can be obtained, thereby realizing absolute phase synchronization.

FIG. 4 is a schematic structural diagram of an intermediate download device of the present invention.

The intermediate download device of the present invention mainly has the following functions: (1) coupling out a part of the radio frequency auxiliary signal modulated optical signal from the optical fiber link, and detecting and demodulating the radio frequency auxiliary signal; (2) coupling out a part of the phase common signal from the optical fiber link The conjugate signal modulates the optical signal, and demodulates the phase conjugate signal; (3) uses the above two radio frequency signals to perform up-mixing, and provides the output signal to the user for use.

As shown in FIG. 4 , the intermediate download device 300 of the present invention includes a fiber coupler 301 , a third photodetector module 302 , a fourth photodetector module 303 , a third mixer 304 and a third bandpass filter 305 .

In FIG. 4 , a part of the RF modulated signals transmitted in the opposite direction in the optical fiber link are respectively coupled out by the optical fiber coupler 301 , and are detected and demodulated by the third photodetector module 302 and the fourth photodetector module 303 respectively. For the required radio frequency signal, optionally, the demodulated signal can be appropriately power amplified according to actual needs. The two radio frequency signals detected and demodulated by the third photodetector module 302 and the fourth photodetector module 303 are transmitted to the third mixer 304 for up-mixing operation. Preferably, the third mixer 304 can be replaced with other up-mixing modules to suppress nonlinear effects such as radio frequency leakage and high-order harmonic interference, such as high-performance up-mixers and double-shift frequency mixing modules, etc., not limited to this. The output signal of the third mixer 304 is connected to the third band-pass filter 305 to extract the required up-mixed signal and provide it to the user.

In FIG. 4 , the radio frequency signal detected and demodulated by the third photodetector module 302 can be expressed as:

V ₇ =A ₇ cos[ω(t+τ-τ ₂ )+φ ₂ -φ ₁ ]

Among them, A ₇ represents the amplitude of the demodulated radio frequency signal, and τ ₂ is the one-way transmission time of the phase-conjugated signal-modulated optical signal from the phase distribution device to the intermediate download device in the optical fiber link.

The radio frequency signal detected and demodulated by the fourth photodetector module 303 can be expressed as:

V ₈ =A ₈ cos[ω(t-τ ₁ )+φ ₁ ]

Among them, A ₈ represents the amplitude of the demodulated radio frequency signal, τ ₁ is the one-way transmission time of the optical signal modulated by the radio frequency auxiliary signal from the phase reproduction device to the intermediate download device in the optical fiber link, here, by the transmission structure of the system It can be obtained that τ ₁ +τ ₂ =τ.

The above two radio frequency signals are transmitted to the third mixer 304 for up-mixing operation, and the obtained output signal after being extracted by the third bandpass filter 305 can be expressed as:

V ₉ =A ₉ cos(2ωt+φ ₂ +φ ₄ )

Here, _A9 represents the amplitude of the up-mixed radio frequency signal, and φ4 is the phase delay accumulated in the non _- common mode transmission paths other than the optical fiber link during the signal synchronization process.

Comparing the phases of the radio frequency signal V ₉ and the radio frequency reference signal V ₃ , it can be known that their phase difference is φ ₄ , that is, the accumulated phase delay in the non-common mode paths other than the optical fiber link. Similarly, since the phase absolute synchronization scheme of the present invention adopts a passive transmission scheme, for the selected frequency ω, the device is placed in a certain environmental condition (such as room temperature condition, not limited to this), and the accumulated phase delay is _φ4 height. It is stable and will not change due to factors such as system restarts and fiber link changes, which means it is highly reproducible. By pre _- calibrating the phase delay φ4, the phase difference between the radio frequency signals used by the intermediate downloading device 300 and the phase distribution device 200 for the user can be obtained, thereby realizing absolute phase synchronization.

Optionally, the phase difference between the radio frequency signal _V6 and the radio frequency signal _V9 is compared in advance, so that the phase difference between the radio frequency signals used by the phase reproduction device 100 and the intermediate download device 300 for the user can be obtained, and the absolute phase can be realized. Synchronize.

Example 2

The present invention also provides a phase absolute synchronization method based on optical fiber transmission, comprising:

The phase distribution device generates a radio frequency reference signal, receives the radio frequency auxiliary signal from the phase reproduction device, performs phase conjugate mixing, and transmits the output signal to the phase reproduction device in the original way;

The phase reproduction device generates a radio frequency auxiliary signal, transmits it to the phase distribution device, and simultaneously receives the phase conjugate signal from the phase distribution device, performs up-mixing, and reproduces the radio frequency reference signal;

The intermediate download device receives and demodulates the radio frequency auxiliary signal and the phase conjugate signal at any position of the optical fiber link, performs up-mixing, and reproduces the radio frequency reference signal.

In the present invention, the radio frequency auxiliary signal is transmitted through the transmission medium, and the radio frequency reference signal is subjected to phase conjugate mixing and reverse transmission through the same transmission medium. The delay is automatically cancelled, and the RF reference signal is stably reproduced to the phase reproduction device and the intermediate download device. The passive transmission method ensures that the phase difference between the reproduced signal and the RF reference signal is stable and unchanged.

The invention realizes the absolute synchronization of the phases between the frequency signals in different places, and can achieve the effect at any position in the optical fiber link. The principle of this technology is simple, and the scope of application is wide, and the optical fiber link can be matched in various topological structures, including but not limited to point-to-point, ring and so on.

The invention can realize the absolute synchronization of the phase of the different frequency signals, so that the phase difference between the different frequency signals has high stability and repeatability. That is to say, the phase difference of frequency signals transmitted based on this technology will not change due to factors such as fiber link changes or system restarts.

With the scheme of the present invention, for the absolute phase synchronization requirement, since the scheme adopts the passive transmission mode and the phase conjugate mixing mode, there are only two optical signals transmitted in opposite directions in the optical fiber link. The downloading device can realize the phase absolute synchronization function at any position of the optical fiber link, that is, the phase difference between the recurring signal and the reference signal is stable, and will not change due to factors such as system restart and changes in the optical fiber link.

Compared with the prior art, the present invention has the following advantages and technical effects:

(1) Using the phase conjugate mixing method, the phase delay of the radio frequency signal in the transmission process of the optical fiber link is automatically canceled, and the principle is simple.

(2) Using the anti-correlation characteristic of the phase delay of the opposite transmission signal in the optical fiber link to achieve absolute phase synchronization at any position of the optical fiber link, breaking through the point-to-point limitation of the optical fiber link and expanding the application scope of absolute phase synchronization.

(3) The passive transmission method avoids the sudden change of signal transmission phase delay that may be caused by factors such as system restart and fiber link change, and ensures the high stability and reproducibility of the method.

The above-mentioned embodiments only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the patent of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims (10)

1. A phase absolute synchronization system based on optical fiber transmission, comprising:

the phase distribution device is used for generating a radio frequency reference signal, receiving a radio frequency auxiliary signal from the phase reproduction device, carrying out phase conjugate mixing and transmitting an output signal to the phase reproduction device in an original path;

the phase reproduction device is used for generating a radio frequency auxiliary signal, transmitting the radio frequency auxiliary signal to the phase distribution device, receiving a phase conjugate signal from the phase distribution device at the same time, performing up-mixing and reproducing a radio frequency reference signal;

and the intermediate downloading device is used for receiving and demodulating at any position of the optical fiber link to obtain a radio frequency auxiliary signal and a phase conjugate signal, performing up-mixing and reproducing the radio frequency reference signal.

2. The system according to claim 1, wherein the phase reproduction apparatus comprises a radio frequency auxiliary signal generator, a first power division module, a first optical modulation module, a first optical fiber circulator, a first optical detector module, a first mixer, and a first band-pass filter;

the radio frequency auxiliary signal generator generates a radio frequency auxiliary signal, the signal is divided into two paths according to a certain power ratio by using a first power division module, wherein one path is loaded on an optical signal in an amplitude modulation mode through a first optical modulation module, and the generated optical signal is injected into an optical fiber link through a first optical fiber circulator; meanwhile, the first optical fiber circulator transmits the optical signal transmitted to the phase distribution device through the optical fiber link to the first optical detector module, the radio-frequency signal obtained by demodulation of the first optical detector module and the other path of signal output by the first power division module are subjected to up-mixing operation through the first mixer, and the output signal passes through the first band-pass filter, extracts the radio-frequency signal of the target frequency and provides the radio-frequency signal for a user.

3. The fiber optic transmission-based phase absolute synchronization system of claim 2 wherein the rf auxiliary signal generator generates the rf auxiliary signal as:

V₁＝A₁cos(ωt+φ₁)

wherein A is₁Is the amplitude of the RF auxiliary signal, omega is the frequency of the signal, t is the time, phi₁Is the phase of the signal.

4. The system according to claim 1, wherein the phase distribution apparatus comprises a radio frequency reference signal generator, a second power division module, a second fiber circulator, a second optical detector module, a second mixer, a second band-pass filter, and a second optical modulation module;

a radio frequency reference signal generator generates a radio frequency reference signal, the radio frequency reference signal is divided into two paths through a second power division module, one path is provided for a user, and the other path is used as a local oscillation signal of a second frequency mixer and participates in the phase conjugation frequency mixing process; the second optical fiber circulator transmits the optical signal from the optical fiber link to the second optical detector module, the radio frequency auxiliary signal from the phase reproduction device is obtained through demodulation, and the radio frequency signal enters the second frequency mixer to participate in the phase conjugation frequency mixing process; the output signal of the second mixer is connected with a second band-pass filter to extract a required phase conjugate signal, the phase conjugate signal is loaded on an optical signal in an amplitude modulation mode through a second optical modulation module, and the generated optical signal is injected into an optical fiber link through a second optical fiber circulator.

5. The fiber optic transmission-based phase absolute synchronization system of claim 4 wherein the frequency of the RF reference signal is 2 times the frequency of the RF auxiliary signal in the phase replication device; the central wavelengths of the laser sources of the first light modulation module and the second light modulation module are adjusted to be the same in advance; when the phase reproduction device and the phase distribution device are in different places, the laser sources of the first light modulation module and the second light modulation module realize the same central wavelength in a light frequency synchronization mode; when the phase reproduction device and the phase distribution device are located at the same place, the optical signals to be modulated of the first optical modulation module and the second optical modulation module come from the same laser source.

6. The fiber optic transmission-based phase absolute synchronization system of claim 4, wherein the radio frequency signal demodulated by the second photo-detector module is:

V₂＝A₂cos[ω(t-τ)+φ₁]

wherein A is₂To solveModulating the amplitude of the obtained radio frequency signal, wherein tau is the one-way transmission time of the radio frequency modulated optical signal in the optical fiber link;

the radio frequency reference signal generated by the radio frequency reference signal generator is expressed as:

V₃＝A₃cos(2ωt+φ₂)

wherein A is₃Is the amplitude of the radio frequency reference signal, phi₂The frequency of the signal is 2 ω, which is the phase of the signal;

after the radio frequency signal demodulated by the second optical detector module and the radio frequency reference signal generated by the radio frequency reference signal generator are subjected to phase conjugate mixing operation by the second mixer, the output signal is expressed as:

V₄＝A₄cos[ω(t+τ)+φ₂-φ₁]

wherein A is₄Representing the amplitude of the phase conjugate signal.

7. The fiber optic transmission-based phase absolute synchronization system of claim 4 wherein the second mixer output signal is transmitted to a second bandpass filter, a phase conjugate signal at frequency ω is extracted and loaded onto a second photodetector module; the phase conjugate signal modulated optical signal is transmitted to the phase reproduction device through the original path of the optical fiber link, and after being demodulated by the first optical detector module, the phase conjugate signal modulated optical signal is expressed as:

V₅＝A₅cos(ωt+φ₂-φ₁)

wherein A is₅Representing the amplitude of the demodulated phase conjugate signal;

and performing up-mixing operation on the demodulated phase conjugate signal and the other path of radio frequency auxiliary signal output by the first power division module, wherein the obtained output signal is extracted by a first band-pass filter and is represented as:

V₆＝A₆cos(2ωt+φ₂+φ₃)

wherein A is₆Amplitude of the RF signal output for up-mixing₃For non-common mode transmission during signal synchronization, except for optical fibre linksThe accumulated phase delay within the path.

8. The fiber optic transmission-based phase absolute synchronization system of claim 1, wherein the intermediate download apparatus comprises a fiber coupler, a third photo-detector module, a fourth photo-detector module, a third mixer, and a third band-pass filter;

the optical fiber coupler respectively couples out a part of radio frequency modulation signals which are transmitted oppositely in the optical fiber link, the third optical detector module and the fourth optical detector module respectively detect and demodulate to obtain required radio frequency signals, and the third optical detector module and the fourth optical detector module detect and demodulate the two radio frequency signals and transmit the two radio frequency signals to the third mixer for up-mixing operation; the output signal of the third mixer is connected with a third band-pass filter to extract the required up-mixing signal and provide the up-mixing signal for users.

9. The fiber optic transmission-based phase absolute synchronization system of claim 8, wherein the third photo-detector module detects the demodulated rf signal as:

V₇＝A₇cos[ω(t+τ-τ₂)+φ₂-φ₁]

wherein A is₇For demodulating the amplitude, tau, of the resulting radio-frequency signal₂The unidirectional transmission time of the optical signal from the phase distribution device to the intermediate download device in the optical fiber link is modulated for the phase conjugate signal;

the radio frequency signal obtained by the detection and demodulation of the fourth optical detector module is represented as:

V₈＝A₈cos[ω(t-τ₁)+φ₁]

wherein A is₈For demodulating the amplitude, tau, of the resulting radio-frequency signal₁Modulating the unidirectional transmission time of an optical signal from a phase reproduction device to an intermediate download device in an optical fiber link for a radio frequency auxiliary signal, where τ is derived from the transmission structure of the system₁+τ₂＝τ；

The radio frequency signal obtained by the detection and demodulation of the third optical detector module and the radio frequency signal obtained by the detection and demodulation of the fourth optical detector module are transmitted to a third mixer for up-mixing operation, and the obtained output signal is extracted by a third band-pass filter and expressed as:

V₉＝A₉cos(2ωt+φ₂+φ₄)

wherein A is₉For amplitude of up-mixed radio-frequency signals, phi₄Is the accumulated phase delay in the non-common mode transmission path except the optical fiber link during the signal synchronization process.

10. A phase absolute synchronization method based on optical fiber transmission is characterized by comprising the following steps:

the phase distribution device generates a radio frequency reference signal, receives a radio frequency auxiliary signal from the phase reproduction device, performs phase conjugate mixing, and transmits an output signal to the phase reproduction device in an original path;

the phase reproduction device generates a radio frequency auxiliary signal, transmits the radio frequency auxiliary signal to the phase distribution device, receives a phase conjugate signal from the phase distribution device at the same time, performs up-mixing and reproduces a radio frequency reference signal;

the intermediate downloading device receives and demodulates the radio frequency auxiliary signal and the phase conjugate signal at any position of the optical fiber link, performs up-mixing and reproduces the radio frequency reference signal.

Images