Microwave bidirectional time comparison system based on general software radio

Abstract

The embodiment of the invention discloses a microwave bidirectional time comparison system based on general software radio. Comprising a first ground station and a second ground station; the first ground station is used for transmitting a first microwave time comparison signal by using the general software radio unit; the second ground station is used for receiving the first microwave time comparison signal by using the general software radio unit and processing the first microwave time comparison signal to obtain a first pseudo-range; the second ground station is also used for transmitting a second microwave time comparison signal by using the general software radio unit and transmitting the first pseudo-range to the first ground station; the first ground station is also used for receiving the second microwave time comparison signal by using a general software radio unit, processing the second microwave time comparison signal to obtain a second pseudo-range, and transmitting the second pseudo-range to the second ground station; and the first ground station or the second ground station is also used for calculating the clock difference between the first ground station and the second ground station according to the first pseudo-range and the second pseudo-range.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of time synchronization. More particularly, it relates to a microwave two-way time comparison system based on universal software radio. BACKGROUND

[0002] Traditional microwave two-way time comparison systems mostly use application-specific integrated circuit technology, which has excellent computing power, good real-time performance and high transmission rate. However, such a solution has poor algorithm upgrade capability, is difficult to modify and customize subsequently, has insufficient scalability, and has a long product iteration cycle. Unlike traditional hardware, software radio uses programmable general-purpose hardware platforms, based on digital signal processing technology, to define and implement system functions through software. The functions of the system can be upgraded through software download and update without replacing hardware devices. Universal software radio peripheral (USRP) has the characteristics of standardization, modularization and generalization, and is currently mainly used in the fields of communication and navigation. The functions can be flexibly defined through software, which is conducive to improving the upgradability of the system. SUMMARY

[0003] The present application relates to the field of time synchronization. More particularly, it relates to a microwave two-way time comparison system based on universal software radio.

[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0005] The first aspect of the present application provides a microwave two-way time comparison system based on universal software radio, which comprises a first ground station and a second ground station comprising a universal software radio unit.

[0006] The first ground station is configured to transmit a first microwave time comparison signal using the universal software radio unit.

[0007] The second ground station is configured to receive the first microwave time comparison signal using the universal software radio unit and process it to obtain a first pseudo-range.

[0008] The second ground station is further configured to transmit a second microwave time comparison signal using the universal software radio unit and transmit the first pseudo-range to the first ground station.

[0009] The first ground station is further configured to receive the second microwave time comparison signal using the universal software radio unit, process it to obtain a second pseudo-range, and transmit the second pseudo-range to the second ground station.

[0010] The first ground station or the second ground station is further configured to calculate a clock difference between the first ground station and the second ground station according to the first pseudo-range and the second pseudo-range.

[0011] Optionally, the first ground station comprises a first computer, a first universal software radio unit, and a first antenna.

[0012] The first computer is configured to send a first time comparison baseband signal.

[0013] The first universal software radio unit is configured to process the first time comparison baseband signal to obtain a first microwave time comparison signal.

[0014] The first antenna is configured to emit the first microwave time comparison signal.

[0015] Optionally, the first computer comprises a first spreading unit and a first modulation unit.

[0016] The first spreading unit is configured to spread a first time data frame to obtain a first spread signal.

[0017] The first modulation unit is configured to modulate the first spread signal to obtain the first time comparison baseband signal.

[0018] Optionally, the first universal software radio unit comprises a first digital-to-analog conversion unit and a first up-conversion unit.

[0019] The first digital-to-analog conversion unit is configured to process the first time comparison baseband signal to obtain a first analog signal.

[0020] The first up-conversion unit is configured to process the first analog signal to obtain the first microwave time comparison signal.

[0021] Optionally, the second ground station comprises a second computer, a second universal software radio unit, and a second antenna.

[0022] The second antenna is configured to receive the first microwave time comparison signal.

[0023] The second universal software radio unit is configured to process the first microwave time comparison signal to obtain a first digital signal.

[0024] The second computer is configured to obtain a first pseudo-range according to the first digital signal.

[0025] Optionally, the second universal software radio unit comprises a first down-conversion unit and a first analog-to-digital conversion unit.

[0026] The first down-conversion unit is configured to process the first microwave time comparison signal to obtain a first down-converted signal.

[0027] The first analog-digital conversion unit is configured to process the first down-converted signal to obtain a first digital signal.

[0028] Optionally, the second computer comprises a first demodulation module and a first resolving module.

[0029] The first demodulation module is configured to process the first digital signal to obtain a first demodulated signal.

[0030] The first resolving module is configured to process the first demodulated signal to obtain a first pseudo-range.

[0031] Optionally, the second computer comprises a second spreading unit and a second modulation unit.

[0032] The second spreading unit is configured to spread a second time data frame to obtain a second spread signal.

[0033] The second modulation unit is configured to modulate the second spread signal to obtain a second time comparison baseband signal.

[0034] The second universal software radio unit comprises a second digital-analog conversion unit and a second up-conversion unit.

[0035] The second digital-analog conversion unit is configured to process the second time comparison baseband signal to obtain a second analog signal.

[0036] The second up-conversion unit is configured to process the second analog signal to obtain a second microwave time comparison signal.

[0037] Optionally, the first universal software radio unit comprises a second down-conversion unit and a second analog-digital conversion unit.

[0038] The second down-conversion unit is configured to process the second microwave time comparison signal to obtain a second down-converted signal.

[0039] The second analog-digital conversion unit is configured to process the second down-converted signal to obtain a second digital signal.

[0040] The first computer comprises a second demodulation module and a second resolving module.

[0041] The second demodulation module is configured to process the second digital signal to obtain a second demodulated signal.

[0042] The second resolving module is configured to process the second demodulated signal to obtain a second pseudo-range.

[0043] Optionally, the first resolving module or the second resolving module is configured to obtain the clock difference between the first ground station and the second ground station according to a difference between the first pseudo-range and the second pseudo-range divided by 2.

[0044] The present application has the following advantages:

[0045] The technical scheme of the present application adopts a software radio device to construct a microwave two-way time comparison system, and the general hardware device can be controlled by a software program, and the modulation and demodulation of the time comparison signal are realized on the software program; compared with the traditional hardware microwave two-way comparison system, the software radio device combines the general hardware platform with flexible and reconfigurable software, and the signal processing can be realized by the software program; the microwave time comparison system based on the software radio device can improve the flexibility, upgradability and reconfigurability of the system, and the system function can be extended and reconfigured by only signal processing through software programming without replacing the hardware device; not only the equipment replacement cost is effectively reduced, but also the system integration is significantly improved, and the requirement of multiplexing of the time comparison device is fully met; the signal transmission and reception are realized by the software program control, and the new signal system can be flexibly, conveniently and efficiently adapted, and an efficient test and development platform is provided for researching the anti-multipath and anti-same-frequency interference algorithms in the time synchronization system; the system principle is clear and has realizability, and has important significance for the development of the industry. BRIEF DESCRIPTION OF DRAWINGS

[0046] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0047] Figure 1 A structure schematic diagram of the microwave two-way time comparison system based on the general software radio provided by the embodiment of the present application is shown.

[0048] Figure 2 A transmitting part principle diagram of the microwave two-way time comparison system based on the general software radio provided by the embodiment of the present application is shown.

[0049] Figure 3 A receiving part principle diagram of the microwave two-way time comparison system based on the general software radio provided by the embodiment of the present application is shown. DETAILED DESCRIPTION

[0050] In order to more clearly illustrate the present application, the present application will be further described below with reference to the embodiments and the accompanying drawings. Similar components are denoted by the same reference numerals in the drawings. Those skilled in the art should understand that the following specific description is illustrative rather than limiting, and should not limit the protection scope of the present application.

[0051] Traditional microwave two-way time comparison systems mostly use application specific integrated circuit technology, which has excellent computing ability, good real-time performance and high transmission rate. However, the algorithm upgrade ability of such scheme is poor, and it is difficult to modify and customize subsequently, has insufficient scalability and a long product iteration cycle. Traditional microwave two-way time comparison systems usually use the architecture of FPGA, select corresponding peripheral components, realize the radio frequency front-end module, and the frequency, bandwidth and other parameters of the system mainly depend on the design of the hardware circuit, which makes the reuse rate of the hardware device low.

[0052] Therefore, one embodiment of the present application provides a microwave two-way time comparison system based on a general software radio, which comprises a first ground station and a second ground station comprising a general software radio unit; the first ground station is configured to transmit a first microwave time comparison signal by using the general software radio unit; the second ground station is configured to receive the first microwave time comparison signal by using the general software radio unit, and process the first microwave time comparison signal to obtain a first pseudo-range; the second ground station is further configured to transmit a second microwave time comparison signal by using the general software radio unit, and transmit the first pseudo-range to the first ground station; the first ground station is further configured to receive the second microwave time comparison signal by using the general software radio unit, process the second microwave time comparison signal to obtain a second pseudo-range, and transmit the second pseudo-range to the second ground station; the first ground station or the second ground station is further configured to calculate a clock difference between the first ground station and the second ground station according to the first pseudo-range and the second pseudo-range.

[0053] In one specific example, Figure 1 The structure of the microwave two-way time comparison system based on USRP N210 is shown in the figure. The two-way time comparison system comprises station 1 and station 2. Station 1 and station 2 each comprise a transmitting end and a receiving end. The transmitting end of station 1 spreads and modulates a frame of time signals, and transmits the signals by using USRP N210. The antenna of station 2 receives the microwave signals, down-converts the signals by using USRP N210, collects the intermediate frequency digital signals and transmits the signals to a software receiver, and obtains a pseudo-range Pd1. Station 2 performs corresponding signal transmission process to station 1, and obtains a pseudo-range Pd2. After data exchange between station 1 and station 2, the clock difference between the two stations is (Pd1-Pd2) / 2.

[0054] In one specific example, the USRP-based microwave two-way time comparison system mainly utilizes a USRP N210 device to implement the transmission and reception of the synchronization signal. The USRP N210 is a product of NI Company, and can connect a PC end with a radio frequency front end, and includes a motherboard and a daughterboard. The motherboard includes a clock generator, an FPGA, an ADC, a DAC, a power supply, etc., and mainly processes a baseband signal. The daughterboard includes an upconverter and a downconverter, a filter, etc., and mainly processes an analog signal. The USRP N210 is suitable for a fast processing speed scenario, adopts a modular design, and has a working frequency band range of 0-6 GHz.

[0055] Compared with the traditional hardware microwave two-way comparison system, the software radio device combines a general hardware platform with flexible and reconfigurable software, and can process a signal through a software program. The microwave time comparison system based on the software radio device can improve the flexibility, upgradability and reconfigurability of the system, and can realize the expansion and reconfiguration of the system function through software programming for signal processing without replacing hardware devices. Not only the equipment replacement cost is effectively reduced, but also the system integration is significantly improved, and the multiplexing requirement of the time comparison device is fully met. The transmission and reception of the signal are realized through the software program control, which can flexibly, conveniently and efficiently adapt to new signal systems, and provide an efficient test and development platform for researching algorithms such as anti-multipath and anti-co-frequency interference in the time synchronization system. The system has clear principles and is realizable, and has important significance for the development of the industry.

[0056] In one possible implementation, the first ground station includes a first computer, a first universal software radio unit and a first antenna; the first computer is configured to send a first time comparison baseband signal; the first universal software radio unit is configured to process the first time comparison baseband signal to obtain a first microwave time comparison signal; and the first antenna is configured to transmit the first microwave time comparison signal.

[0057] In one specific example, the USRP-based microwave two-way time comparison system is mainly divided into a microwave comparison signal transmission end and a microwave time comparison signal receiving end. The comparison signal transmission end mainly relies on a PC, a USRP N210 and a transmitting antenna to complete. First, a software code based on C language is used on the PC to spread and modulate a prepared comparison signal frame to generate a time comparison baseband signal. Then, the digital baseband signal is transmitted to the USRP N210 through a gigabit network cable, converted by a DA, processed by an upconverter, and changed into a radio frequency analog time comparison signal which is transmitted through the antenna.

[0058] In a possible implementation, the first computer comprises a first spreading unit and a first modulation unit; the first spreading unit is configured to spread the first time data frame to obtain a first spread spectrum signal; and the first modulation unit is configured to modulate the first spread spectrum signal to obtain a first time comparison baseband signal.

[0059] In a possible implementation, the first universal software radio unit comprises a first digital-to-analog conversion unit and a first up-conversion unit; the first digital-to-analog conversion unit is configured to process the first time comparison baseband signal to obtain a first analog signal; and the first up-conversion unit is configured to process the first analog signal to obtain a first microwave time comparison signal.

[0060] In a specific example, the working principle diagram of the transmitting end of the station 1 and the station 2 is as shown in FIG. 2. Figure 2 The spreading spectrum and the BPSK modulation of the time comparison signal source are implemented by using the C language on the PC, to generate a baseband digital signal. The signal stream is continuously transmitted to the USRP N210 through the gigabit network cable by controlling the USRP N210 through the GNU radio API interface. After the USRP N210 receives the baseband signal in real time, the baseband signal is converted into a radio frequency bidirectional time comparison signal through D / A conversion and up-conversion, and is transmitted through an antenna.

[0061] Further, the time data frame is spread by using a pseudo code generator, and is modulated by using cos(wt), wherein w is an angular frequency, and t is time.

[0062] In a possible implementation, the second ground station comprises a second computer, a second universal software radio unit and a second antenna; the second antenna is configured to receive the first microwave time comparison signal; the second universal software radio unit is configured to process the first microwave time comparison signal to obtain a first digital signal; and the second computer is configured to obtain a first pseudo-range according to the first digital signal.

[0063] In a specific example, the microwave time comparison signal receiving end comprises a receiving antenna, a USRP N210 and a PC. The receiving antenna receives the radio frequency time comparison signal and transmits the radio frequency time comparison signal to the USRP N210. The USRP N210 first converts the signal to an intermediate frequency through a radio frequency front end, and then converts the analog signal into a digital signal through AD conversion. The digital signal is transmitted to the software receiver on the PC through the gigabit network cable for demodulation and analysis. After the pseudo-range is resolved, the clock difference value is calculated, so that the microwave bidirectional time comparison is completed.

[0064] In a possible implementation, the second universal software radio unit comprises a first down-conversion unit and a first analog-to-digital conversion unit; the first down-conversion unit is configured to process the first microwave time comparison signal to obtain a first down-converted signal; and the first analog-to-digital conversion unit is configured to process the first down-converted signal to obtain a first digital signal.

[0065] In a possible implementation, the second computer comprises a first demodulation module and a first resolution module; the first demodulation module is configured to process the first digital signal to obtain a first demodulated signal; and the first resolution module is configured to process the first demodulated signal to obtain a first pseudo-range.

[0066] In a specific example, the working principle block diagram of the receiving end in the station 1 and the station 2 is as shown in Figure 3 First, the antenna receives the microwave two-way time comparison signal, which is transmitted to the USRP N210 for down-conversion to an intermediate frequency signal, and then converted to an intermediate frequency digital signal through A / D conversion. The signal at the i th moment can be expressed as:

[0067]

[0068] In the formula, A n represents the signal amplitude of the station n that transmits the signal; T s represents the s th sampling period; C n,i (iT s -τ n represents that the code phase of the station n at the i th moment is delayed by τ n , and τ n is the code phase delay amount; ω n represents the carrier frequency of the station n; represents the carrier phase of the station n; w i represents the additive noise sampled at the i th moment; n = 1, 2, …, M, and M is the maximum station number.

[0069] Further, the intermediate frequency digital signal stream is transmitted to the PC through the gigabit network cable, and the digital signal is captured, tracked, frame-synchronized, demodulated and resolved by the software receiver written by the C language on the PC to obtain the pseudo-range.

[0070] In a possible implementation, the second computer comprises a second spreading unit and a second modulation unit; the second spreading unit is configured to spread the second time data frame to obtain a second spread spectrum signal; the second modulation unit is configured to modulate the second spread spectrum signal to obtain a second time comparison baseband signal; the second universal software radio unit comprises a second digital-to-analog conversion unit and a second up-conversion unit; the second digital-to-analog conversion unit is configured to process the second time comparison baseband signal to obtain a second analog signal; and the second up-conversion unit is configured to process the second analog signal to obtain a second microwave time comparison signal.

[0071] In a possible implementation, the first universal software radio unit comprises a second down-conversion unit and a second analog-to-digital conversion unit; the second down-conversion unit is configured to process the second microwave time comparison signal to obtain a second down-converted signal; and the second analog-to-digital conversion unit is configured to process the second down-converted signal to obtain a second digital signal. The first computer comprises a second demodulation module and a second resolving module; the second demodulation module is configured to process the second digital signal to obtain a second demodulated signal; and the second resolving module is configured to process the second demodulated signal to obtain a second pseudo-range.

[0072] In a possible implementation, the first resolving module or the second resolving module is configured to obtain a clock difference between the first ground station and the second ground station according to a difference between the first pseudo-range and the second pseudo-range divided by 2.

[0073] The USRP N210-based microwave two-way time comparison scheme of the embodiment adopts the software radio idea, relies on a universal hardware platform, and realizes microwave two-way time comparison through software programming. The system can flexibly configure corresponding spreading pseudo-codes, modulation strategies and the like according to different environments. Meanwhile, the system can set any frequency point and bandwidth for two-way comparison according to the frequency point range and bandwidth range supported by the equipment, and solves the problem that different versions of the current microwave two-way time comparison system cannot be compatible.

[0074] The file transmission between the PC and the USRP N210 adopts a buffer mechanism. The traditional file transmission has a relatively serious bit error rate and packet loss rate. The application adopts a double-buffer mechanism in the system to realize real-time transmission of signal streams and reduce the bit error rate and the packet loss rate.

[0075] In the description of the present application, it needs to be explained that the terms "upper", "lower" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise expressly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication between two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0076] It also needs to be explained that in the description of the present application, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without more limitation, the element defined by the sentence "including a…" does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0077] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not a limitation on the embodiments of the present application. For those skilled in the art, on the basis of the above description, other different forms of changes or variations can also be made, and it is impossible to enumerate all the embodiments here. Any obvious changes or variations derived from the technical solutions of the present application are still within the protection scope of the present application.

Claims

1. A microwave two-way time comparison system based on general-purpose software radio, characterized in that, The system includes a first ground station and a second ground station; The first ground station is used to transmit a first microwave time comparison signal using a general-purpose software radio unit; The second ground station is used to receive the first microwave time comparison signal using a general-purpose software radio unit and process it to obtain the first pseudorange. The second ground station is also used to transmit a second microwave time comparison signal using a general-purpose software radio unit, and to transmit the first pseudorange to the first ground station; The first ground station is also configured to receive the second microwave time comparison signal using a general-purpose software radio unit, process it to obtain the second pseudorange, and transmit the second pseudorange to the second ground station. The first ground station or the second ground station is further configured to calculate the clock difference between the first ground station and the second ground station based on the first pseudorange and the second pseudorange.

2. The microwave two-way time comparison system based on general-purpose software radio according to claim 1, characterized in that, The first ground station includes a first computer, a first general-purpose software radio unit, and a first antenna; The first computer is used to send a first-time comparison baseband signal; The first general-purpose software radio unit is used to process the first time comparison baseband signal to obtain a first microwave time comparison signal; The first antenna is used to transmit the first microwave time comparison signal.

3. The microwave two-way time comparison system based on general-purpose software radio according to claim 2, characterized in that, The first computer includes a first spread spectrum unit and a first modulation unit; The first spreading unit is used to spread the first time data frame to obtain a first spreading signal; The first modulation unit is used to modulate the first spread spectrum signal to obtain a first time comparison baseband signal.

4. The microwave two-way time comparison system based on general-purpose software radio according to claim 3, characterized in that, The first general-purpose software radio unit includes a first digital-to-analog converter and a first up-conversion unit; The first digital-to-analog converter is used to process the first time-comparison baseband signal to obtain a first analog signal; The first upconversion unit is used to process the first analog signal to obtain a first microwave time comparison signal.

5. The microwave two-way time comparison system based on general-purpose software radio according to claim 4, characterized in that, The second ground station includes a second computer, a second general-purpose software radio unit, and a second antenna; The second antenna is used to receive the first microwave time comparison signal; The second general-purpose software radio unit is used to process the first microwave time comparison signal to obtain a first digital signal; The second computer is used to obtain a first pseudorange based on the first digital signal.

6. The microwave two-way time comparison system based on general-purpose software radio according to claim 5, characterized in that, The second general-purpose software radio unit includes a first down-conversion unit and a first analog-to-digital converter unit; The first down-conversion unit is used to process the first microwave time comparison signal to obtain the first down-conversion signal; The first analog-to-digital converter is used to process the first down-converted signal to obtain a first digital signal.

7. The microwave bidirectional time comparison system according to claim 6, characterized in that, The second computer includes a first demodulation module and a first parsing module; The first demodulation module is used to process the first digital signal to obtain a first demodulated signal; The first parsing module is used to process the first demodulated signal to obtain the first pseudorange.

8. The microwave two-way time comparison system based on general-purpose software radio according to claim 7, characterized in that, The second computer includes a second spread spectrum unit and a second modulation unit; The second spreading unit is used to spread the second time data frame to obtain a second spreading signal; The second modulation unit is used to modulate the second spread spectrum signal to obtain a second time comparison baseband signal; The second general-purpose software radio unit includes a second digital-to-analog converter and a second up-conversion unit; The second digital-to-analog converter is used to process the second time-comparison baseband signal to obtain a second analog signal; The second upconversion unit is used to process the second analog signal to obtain the second microwave time comparison signal.

9. The microwave two-way time comparison system based on general-purpose software radio according to claim 8, characterized in that, The first general-purpose software radio unit includes a second down-conversion unit and a second analog-to-digital converter unit; The second down-conversion unit is used to process the second microwave time comparison signal to obtain the second down-conversion signal; The second analog-to-digital conversion unit is used to process the second down-converted signal to obtain a second digital signal; The first computer includes a second demodulation module and a second parsing module; The second demodulation module is used to process the second digital signal to obtain a second demodulated signal; The second parsing module is used to process the second demodulated signal to obtain the second pseudorange.

10. The microwave two-way time comparison system based on general-purpose software radio according to claim 9, characterized in that, The first parsing module or the second parsing module is used to obtain the clock difference between the first ground station and the second ground station by dividing the difference between the first pseudorange and the second pseudorange by 2.

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