CN113114378A - High-precision radio frequency phase stabilization system based on ROF link - Google Patents
High-precision radio frequency phase stabilization system based on ROF link Download PDFInfo
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- CN113114378A CN113114378A CN202110430621.3A CN202110430621A CN113114378A CN 113114378 A CN113114378 A CN 113114378A CN 202110430621 A CN202110430621 A CN 202110430621A CN 113114378 A CN113114378 A CN 113114378A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/58—Compensation for non-linear transmitter output
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
- H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
- H04B10/0795—Performance monitoring; Measurement of transmission parameters
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/25—Arrangements specific to fibre transmission
- H04B10/2575—Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
Abstract
The invention discloses a high-precision radio frequency phase stabilization system based on an ROF link, which comprises a radio frequency signal light emitting module, a measuring signal and a service signal enter an optical fiber to be transmitted to a receiving end after wavelength division multiplexing, the measuring signal returns to the emitting end from an original optical path after wavelength division demultiplexing, a time delay measuring unit measures the time delay of the received signal, calculates the variation of the time delay and provides the variation to a compensation control module, the compensation control module controls a time delay compensation unit to complete time delay compensation, and finally a radio frequency light receiving module demodulates and recovers the service radio frequency signal.
Description
Technical Field
The invention relates to the technical field of communication, in particular to a high-precision radio frequency phase stabilization system based on an ROF link.
Background
Radio-frequency on Fiber (Radio on Fiber), also known as ROF, is one of the important application directions of microwave photonics, is a communication mode combining optical communication technology and microwave technology, can utilize an optical Fiber link to transmit Radio-frequency signals in a long distance, has the advantages of long transmission distance, low loss, high cost performance, strong anti-interference capability, flexible mobile arrangement and the like, and has a very wide application prospect in various fields such as radar, satellite ground stations, electronic warfare, broadband wireless access, long-distance transmission and the like. In the ROF link, the optical cable transmission line is a long-distance optical fiber, and is easily affected by environmental factors, so that the equivalent length of the optical fiber changes, the transmission delay amount changes, and finally the phase of the radio frequency signal is unstable.
The existing phase stabilization research on the ROF link can be generally divided into two categories, one is to realize the phase stabilization of long-distance optical fiber transmission by performing conjugate delay compensation on the optical link, and the other is to realize the high-precision phase stabilization by using an optical fiber phase-locked loop, but these methods still cannot simultaneously consider the measurement of long-distance and high-precision delay and the phase stabilization.
Disclosure of Invention
The invention aims to provide a high-precision radio frequency phase stabilizing system based on an ROF link, and aims to solve the problem of insufficient stability of the existing radio frequency phase stabilizing technology.
In order to achieve the above purpose, the high-precision radio frequency phase stabilization system based on the ROF link adopted by the invention comprises a transmitting end and a receiving end, wherein the transmitting end is connected with the receiving end through an optical fiber; the transmitting terminal comprises a radio frequency light emitting module, a measuring module, a compensation control module, a time delay compensation unit and a first wavelength division multiplexer, the radio frequency light emitting module is connected with the first wavelength division multiplexer through optical fibers in sequence between the measuring module and the time delay compensation unit, and the measuring module is connected with the compensation control module and the time delay compensation unit through electrical connections in sequence.
The receiving end comprises a second wavelength division multiplexer, a radio frequency light receiving module and a measuring signal returning module, the second wavelength division multiplexer is connected with the radio frequency light receiving module through a one-way optical fiber, an optical signal flows to the radio frequency light receiving module from the second wavelength division multiplexer, and the second wavelength division multiplexer is connected with the measuring signal returning module through a two-way optical fiber.
The measurement module comprises a phase measurement unit and a time delay measurement unit, wherein the phase measurement unit measures the phase change of radio frequency signals of the ROF device link, and the time delay measurement unit measures the optical signal transmission time delay change of the ROF device link.
The phase measurement unit comprises a pilot signal generator, a pilot signal light emitting module, a pilot signal light receiving module and a phase measurement module, wherein the pilot signal generator generates a measurement pilot signal, the pilot signal light emitting module modulates the measurement pilot signal onto an optical signal, the pilot signal light receiving module receives a returned optical signal and demodulates the returned optical signal into the pilot signal, and the phase measurement module measures a phase difference of the pilot signal after one round trip transmission.
The time delay measuring unit comprises a pulse generator, a pulse signal light emitting module, a pulse signal light receiving module and a time delay measuring module, wherein the pulse generator generates a measuring pulse signal, the pulse signal light emitting module modulates the measuring pulse signal into an optical signal, the pulse signal light receiving module receives a returned optical signal and restores the optical signal into the pulse signal, and the time delay measuring module measures the time delay difference of the pulse signal after one round trip transmission.
The high-precision radio frequency phase stabilization system based on the ROF link further comprises a first circulator, a second circulator, a third circulator and a fourth circulator, wherein the first circulator is arranged between the phase measurement unit and the first wavelength division multiplexer, the second circulator is arranged between the time delay measurement unit and the first wavelength division multiplexer, and the third circulator and the fourth circulator are arranged on the receiving end.
The high-precision radio frequency phase stabilization system based on the ROF link adopts optical wavelength division multiplexing transmission, radio frequency signals, pulse signals and pilot signals are respectively modulated onto the optical signals, and the signals are combined and transmitted in the same core optical fiber.
The invention relates to a high-precision radio frequency phase stabilization system based on an ROF link, which respectively modulates a radio frequency signal, a pilot frequency measuring signal and a pulse measuring signal onto an optical signal through a radio frequency signal light emitting module and a measuring module, enters an optical fiber after wavelength division multiplexing combination, is transmitted to a receiving end, returns a measuring signal to the transmitting end through an original optical path after wavelength division demultiplexing, measures the delay of the received signal by a delay measuring unit, measures the phase change of the received signal by phase measuring voltage, combines two measuring results, provides the two measuring results to a compensation control module, calculates the variation of the optical signal delay corresponding to the phase change of the radio frequency signal, controls a delay compensation unit to complete delay compensation by the compensation control module, and finally demodulates and recovers a service radio frequency signal by a radio frequency light receiving module, and adopts a method combining phase measurement and delay measurement, the problem of current radio frequency steady phase technique stability not enough is solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a high-precision radio frequency phase stabilization system based on an ROF link according to the present invention.
Fig. 2 is a schematic diagram of the phase measurement unit and the delay measurement unit according to the present invention.
Fig. 3 is a schematic view of the measurement process of the present invention.
Fig. 4 is a schematic diagram of the delay compensation process of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
In the description of the present invention, it is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships illustrated in the drawings, and are used merely for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention. Further, in the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
Referring to fig. 1 and fig. 2, the present invention provides a high-precision radio frequency phase stabilization system based on an ROF link, including a transmitting end and a receiving end, where the transmitting end is connected with the receiving end through an optical fiber; the transmitting terminal comprises a radio frequency light emitting module, a measuring module, a compensation control module, a time delay compensation unit and a first wavelength division multiplexer, the radio frequency light emitting module is connected with the first wavelength division multiplexer through optical fibers in sequence between the measuring module and the time delay compensation unit, and the measuring module is connected with the compensation control module and the time delay compensation unit through electrical connections in sequence.
The receiving end comprises a second wavelength division multiplexer, a radio frequency light receiving module and a measuring signal returning module, the second wavelength division multiplexer is connected with the radio frequency light receiving module through a one-way optical fiber, an optical signal flows to the radio frequency light receiving module from the second wavelength division multiplexer, and the second wavelength division multiplexer is connected with the measuring signal returning module through a two-way optical fiber.
The measurement module comprises a phase measurement unit and a time delay measurement unit, wherein the phase measurement unit measures the phase change of radio frequency signals of the ROF equipment link, and the time delay measurement unit measures the optical signal transmission time delay change of the ROF equipment link. The time delay measurement completes the coarse measurement of the signal phase, the phase measurement completes the fine measurement of the signal phase, and the two are combined together to complete the high-precision measurement of the radio frequency signal phase.
The phase measurement unit comprises a pilot signal generator, a pilot signal light emitting module, a pilot signal light receiving module and a phase measurement module, wherein the pilot signal generator generates a measurement pilot signal, the pilot signal light emitting module modulates the measurement pilot signal onto an optical signal, the pilot signal light receiving module receives a returned optical signal and demodulates the returned optical signal into the pilot signal, and the phase measurement module measures the phase difference of the pilot signal after one round trip transmission.
The time delay measuring unit comprises a pulse generator, a pulse signal light emitting module, a pulse signal light receiving module and a time delay measuring module, wherein the pulse generator generates a measuring pulse signal, the pulse signal light emitting module modulates the measuring pulse signal into an optical signal, the pulse signal light receiving module receives a returned optical signal and restores the optical signal into the pulse signal, and the time delay measuring module measures the time delay difference of the pulse signal after one round trip transmission.
The compensation control module calculates the phase measurement result and the time delay measurement result to obtain the phase variation of the radio frequency signal, controls the time delay of the time delay compensation unit in real time according to the calculated phase variation of the radio frequency signal, and compensates the phase of the radio frequency signal on the light path.
The high-precision radio frequency phase stabilization system based on the ROF link further comprises a first circulator, a second circulator, a third circulator and a fourth circulator, the first circulator is arranged between the phase measurement unit and the first wavelength division multiplexer, the second circulator is arranged between the time delay measurement unit and the first wavelength division multiplexer, and the third circulator and the fourth circulator are arranged on the receiving end.
The high-precision radio frequency phase stabilization system based on the ROF link adopts optical wavelength division multiplexing transmission, radio frequency signals, pulse signals and pilot signals are respectively modulated onto the optical signals, and the combined waves are transmitted in the same core optical fiber. The radio frequency signal is modulated to the optical signal through the radio frequency light emitting module, and passes through the optical wavelength division multiplexing wave with the pilot signal and the pulse signal which are modulated to the optical signal.
Furthermore, the core device of the delay compensation unit is an adjustable optical fiber delay line, and the delay compensation unit is composed of an electric adjustable optical fiber delay line, a delay line driving circuit and a microcontroller. The electric adjustable optical fiber delay line comprises a collimator with a tail fiber, a reflector, a motor and the like, and the distance between the reflector and the collimator is changed through the movement of the motor, so that the optical path is changed, and the purpose of changing time delay is achieved. The delay line driving circuit is used for driving motor operation and state feedback of the delay line, and comprises functions of delay amount change, stepping control, limit alarm and the like. The microcontroller is responsible for the calculation of time delay and phase measurement values, the control of a compensation system and the like.
In this embodiment, the basic process of transmitting the rf signal is as follows:
the radio frequency light emitting module generates an optical signal which modulates a service radio frequency signal, the optical signal sequentially enters the first wavelength division multiplexer, the time delay compensation module, the transmission optical fiber, the second wavelength division multiplexer and the radio frequency light receiving module, and the radio frequency light receiving module demodulates and recovers the service radio frequency signal.
The composition principle of the phase measurement unit and the time delay measurement unit is shown in fig. 2, the time delay measurement completes coarse measurement, the phase measurement realizes fine measurement, and the combination of the two can realize high-precision accurate measurement.
In the phase measurement process, a pilot signal is divided into two paths, one path is used as a reference pilot signal, the other path is used as a measurement pilot signal, the reference pilot signal enters a phase measurement module, the measurement pilot signal enters a pilot signal light emitting module, the pilot signal is modulated onto an optical signal after passing through the pilot signal light emitting module, the modulated optical signal is marked as an optical signal 2, the optical signal 2 enters a first wavelength division multiplexer after passing through a first circulator, the multiplexed optical signal reaches a second wavelength division multiplexer after passing through an optical fiber, the optical signal is demultiplexed by the second wavelength division multiplexer, wherein the optical signal 2 returns along the original path after passing through a third circulator, the optical signal reaches a first circulator and then is output by a port to enter a pilot signal light receiving module, the pilot signal is recovered after being demodulated by the pilot signal light receiving module, and the recovered pilot signal enters the phase measurement module, the phase measurement module measures a phase difference between the reference pilot signal and the measurement pilot signal. The phase measurement method is to compare the phase difference of two pilot signals entering a phase measurement module, the measurement chip is an amplitude and phase discriminator chip AD8302 of AD company, the phase discrimination frequency of the AD8302 can reach 2.7GHz at most, the amplitude of an input signal ranges from-60 dBm to 0dBm, the characteristic impedance is 50 omega, the phase discrimination precision is better than 1 degree, and the phase measurement proportionality coefficient is 10 mv/degree.
In the time delay measurement process, a microcontroller generates two paths of pulse signals, namely a measurement pulse signal and a reference pulse signal, the measurement pulse signal modulates the pulse signal onto an optical signal through a pulse signal light emitting module, the modulated optical signal is marked as an optical signal 3, the modulated optical signal enters a first wavelength division multiplexer together with a modulated service optical signal 1 and an optical signal 2 modulated by a pilot signal after passing through a circulator, the modulated optical signal passes through the wavelength division multiplexer 1 and then reaches a second wavelength division multiplexer at the far end of an optical link through a transmission optical fiber, the wavelength division multiplexer 2 demultiplexes the optical signal 1, the optical signal 2 and the optical signal 3, the optical signal 3 returns along the original path after passing through a fourth circulator and reaches a pulse signal light receiving module, the pulse signal is demodulated and restored through a receiving module, the pulse signal enters a time delay measurement module and is compared with the reference pulse signal, and measuring the time delay difference, and finishing the time delay measuring process.
The time delay measuring method is characterized in that the time difference of two pulse signals entering a time delay measuring module is compared, a Time Digital Converter (TDC) chip AS6501 newly introduced by AMS company is selected AS a measuring chip, 2 measuring channels are provided, an LVDS interface, a CMOS interface and an SPI interface are supported, the highest measuring precision can reach 10ps, the pulse interval is less than 5ns, the sampling speed can reach 70MSPS, and the highest measuring range can reach 0-16 s. The TDC measurement process is as shown in fig. 3, the TDC is reset after initialization and related configuration, the configuration completes the production of the pulse signal, and when the measurement pulse signal returns, the read delay value is measured and stored. And the storage process is finished, the MCU generates a pilot signal, when the measured pilot signal returns, the phase difference value is measured and read, the interpolation is stored, and the single measurement process is finished.
The compensation process is performed after the measurement process, and the specific flow is as shown in fig. 4, the delay compensation program also first passes through the initialization process, after the delay and phase measurement process is finished after the initialization, the variation calculation and the compensation calculation are performed, then the delay and phase compensation are performed through the compensation control, after the compensation, whether the control is in place is judged through the check measurement, if the control is not in place, the variable calculation is returned, the cycle is performed again, and if the control is in place, the compensation program is ended.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (7)
1. A high-precision radio frequency phase stabilization system based on ROF link is characterized in that,
the optical fiber transmission device comprises a transmitting end and a receiving end, wherein the transmitting end is connected with the receiving end through an optical fiber; the transmitting terminal comprises a radio frequency light emitting module, a measuring module, a compensation control module, a time delay compensation unit and a first wavelength division multiplexer, the radio frequency light emitting module is connected with the first wavelength division multiplexer through optical fibers in sequence between the measuring module and the time delay compensation unit, and the measuring module is connected with the compensation control module and the time delay compensation unit through electrical connections in sequence.
2. The ROF link-based high precision radio frequency phase stabilization system of claim 1,
the receiving end comprises a second wavelength division multiplexer, a radio frequency light receiving module and a measuring signal returning module, the second wavelength division multiplexer is connected with the radio frequency light receiving module through a one-way optical fiber, an optical signal flows to the radio frequency light receiving module from the second wavelength division multiplexer, and the second wavelength division multiplexer is connected with the measuring signal returning module through a two-way optical fiber.
3. The ROF link based high precision radio frequency phase stabilization system of claim 2,
the measurement module comprises a phase measurement unit and a time delay measurement unit, wherein the phase measurement unit measures the phase change of radio frequency signals of the ROF equipment link, and the time delay measurement unit measures the optical signal transmission time delay change of the ROF equipment link.
4. The ROF link based high precision radio frequency phase stabilization system of claim 3,
the phase measurement unit comprises a pilot signal generator, a pilot signal light emitting module, a pilot signal light receiving module and a phase measurement module, wherein the pilot signal generator generates a measurement pilot signal, the pilot signal light emitting module modulates the measurement pilot signal onto an optical signal, the pilot signal light receiving module receives a returned optical signal and demodulates the returned optical signal into the pilot signal, and the phase measurement module measures the phase difference of the pilot signal after one round trip transmission.
5. The ROF link-based high precision radio frequency phase stabilization system of claim 4,
the time delay measuring unit comprises a pulse generator, a pulse signal light emitting module, a pulse signal light receiving module and a time delay measuring module, wherein the pulse generator generates a measuring pulse signal, the pulse signal light emitting module modulates the measuring pulse signal into an optical signal, the pulse signal light receiving module receives a returned optical signal and restores the optical signal into the pulse signal, and the time delay measuring module measures the time delay difference of the pulse signal after one round trip transmission.
6. The ROF link-based high precision radio frequency phase stabilization system of claim 5,
the high-precision radio frequency phase stabilization system based on the ROF link further comprises a first circulator, a second circulator, a third circulator and a fourth circulator, the first circulator is arranged between the phase measurement unit and the first wavelength division multiplexer, the second circulator is arranged between the time delay measurement unit and the first wavelength division multiplexer, and the third circulator and the fourth circulator are arranged on the receiving end.
7. The ROF link-based high precision radio frequency phase stabilization system of claim 6,
the high-precision radio frequency phase stabilization system based on the ROF link adopts optical wavelength division multiplexing transmission, radio frequency signals, pulse signals and pilot signals are respectively modulated onto the optical signals, and the combined waves are transmitted in the same core optical fiber.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113612541A (en) * | 2021-09-09 | 2021-11-05 | 北京电子工程总体研究所 | TDOA-based target analog signal photon link transmission delay measuring device |
| CN114726443A (en) * | 2022-02-25 | 2022-07-08 | 中国电子科技集团公司第二十九研究所 | Microwave photon bidirectional time-frequency transmission system, device and method |
| WO2023040763A1 (en) * | 2021-09-17 | 2023-03-23 | 中兴通讯股份有限公司 | Delay ripple detection method and delay ripple detection circuit |
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2021
- 2021-04-21 CN CN202110430621.3A patent/CN113114378A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113612541A (en) * | 2021-09-09 | 2021-11-05 | 北京电子工程总体研究所 | TDOA-based target analog signal photon link transmission delay measuring device |
| WO2023040763A1 (en) * | 2021-09-17 | 2023-03-23 | 中兴通讯股份有限公司 | Delay ripple detection method and delay ripple detection circuit |
| CN114726443A (en) * | 2022-02-25 | 2022-07-08 | 中国电子科技集团公司第二十九研究所 | Microwave photon bidirectional time-frequency transmission system, device and method |
| CN114726443B (en) * | 2022-02-25 | 2023-09-19 | 中国电子科技集团公司第二十九研究所 | Microwave photon bidirectional time-frequency transmission system, device and method |
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