Orthogonal spread spectrum communication transceiver based on dual-drive Mach-Zehnder modulator and method

Abstract

This invention discloses an orthogonal spread spectrum communication transceiver device and method based on dual-drive Mach-Zehnder modulators, belonging to the field of photon-assisted spread spectrum communication technology. The device includes a transmitting module and a receiving module. Both the transmitting and receiving modules are equipped with two dual-drive Mach-Zehnder modulators. The transmitting module modulates the received information code and a cosine spread spectrum signal onto an optical wave, and modulates another received information code and a sine spread spectrum signal onto the optical wave, obtaining two optical signals, which are then processed to obtain an orthogonal broadband spread spectrum signal. The receiving module modulates the received spread spectrum signal and a delayed cosine despread signal onto the optical wave, and modulates the received spread spectrum signal and a delayed sine despread signal onto the optical wave, obtaining two optical signals, which are then processed to obtain two information codes. This invention can significantly improve the anti-interference capability, anti-interception capability, and user data transmission volume of spread spectrum communication.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photon-assisted spread spectrum communication technology, and in particular to a quadrature spread spectrum communication transceiver device and method based on a dual-drive Mach-Zehnder modulator. BACKGROUND

[0002] Spread spectrum communication technology has become one of the core technologies in the fields of wireless communication, satellite navigation and secure communication due to its good anti-interference ability, low probability of interception and multi-access capability. Traditional spread spectrum communication technology mainly includes direct sequence spread spectrum (DSSS) technology, frequency hopping spread spectrum (FHSS) technology and the hybrid of the two. The basic principle of direct sequence spread spectrum technology is to multiply a high-rate spread spectrum code with a low-rate original signal to achieve spectrum widening, so that the bandwidth of the spread spectrum signal is much larger than that of the original signal. The spread spectrum process greatly reduces the power spectral density of the original signal, and even can hide the spread spectrum signal under the environmental noise to achieve anti-interception. The interference part of the spread spectrum signal is widened and the original useful information becomes a narrowband signal after being despread at the receiving end, greatly improving the signal-to-noise ratio and achieving the effect of anti-interference. In order to further improve the anti-interference and anti-interception ability of the spread spectrum signal, a higher-rate spread spectrum code is generally used to obtain a larger spread spectrum bandwidth. However, in a conventional electrical spread spectrum communication system, a large spread spectrum bandwidth requires higher computing power of the digital electronic processing backend, which will significantly increase the processing time and reduce the real-time performance of the spread spectrum communication in the case of limited computing resources. In addition, the bandwidth bottleneck of electrical devices will limit the further increase of the spread spectrum bandwidth.

[0003] In order to alleviate the bandwidth limitation problem of the conventional electrical spread spectrum communication system, some researches have proposed photon-assisted spread spectrum technology. The photon-assisted spread spectrum technology relies on the characteristics of large bandwidth and high real-time performance of microwave photon devices, which can alleviate the bandwidth limitation of the electrical spread spectrum communication system and further improve the concealment of the spread spectrum communication. However, the current photon-assisted spread spectrum technology usually uses binary phase shift keying (BPSK) and other basic modulation methods, which can realize basic spread spectrum communication functions, but still have problems such as low spectrum efficiency and limited multi-user capacity in the modulation dimension and spread spectrum coordination. SUMMARY

[0004] To solve the above-mentioned technical problems in the prior art, the present application provides a quadrature spread spectrum communication transceiver device and method based on a dual-drive Mach-Zehnder modulator, which can realize efficient integration of ultra-wideband spread spectrum and quadrature modulation, solve the bandwidth limitation problem of the electrical spread spectrum communication system, and further improve the anti-interference ability, anti-interception ability and user data transmission amount of the spread spectrum communication.

[0005] The technical solution of the present invention is as follows:

[0006] In a first aspect, an orthogonal spread spectrum communication transceiver based on a dual-drive Mach-Zehnder modulator is provided, the device comprising:

[0007] The transmitting module is equipped with two dual-drive Mach-Zehnder modulators. The transmitting module uses one of the dual-drive Mach-Zehnder modulators to modulate the received information code and cosine spread spectrum signal onto the optical wave to obtain one optical signal, and uses the other dual-drive Mach-Zehnder modulator to modulate another received information code and sine spread spectrum signal onto the optical wave to obtain another optical signal. The two optical signals are processed to obtain an orthogonal broadband spread spectrum signal.

[0008] The receiving module is equipped with two dual-drive Mach-Zehnder modulators. The receiving module uses one of the dual-drive Mach-Zehnder modulators to modulate the received spread spectrum signal and the cosine despread signal with an additional delay onto the optical wave to obtain one optical signal, and uses the other dual-drive Mach-Zehnder modulator to modulate the received spread spectrum signal and the sine despread signal with an additional delay onto the optical wave to obtain another optical signal. The two optical signals are processed to obtain two information codes.

[0009] In some alternative implementations, the transmitting module includes:

[0010] The first laser has its output terminals connected to a first dual-drive Mach-Zehnder modulator and a second dual-drive Mach-Zehnder modulator, respectively. The first laser is used to generate a single-frequency laser and divide it into two equally distributed outputs.

[0011] The first dual-drive Mach-Zehnder modulator has its output terminal connected to the first signal conversion and processing unit. The first dual-drive Mach-Zehnder modulator is used to modulate the input information code and the input cosine spread spectrum signal including the spread spectrum code and the cosine carrier onto the optical wave to obtain and output the optical signal.

[0012] The second dual-drive Mach-Zehnder modulator has its output connected to the first signal conversion and processing unit. The second dual-drive Mach-Zehnder modulator is used to modulate the input information code and the input sinusoidal spread spectrum signal, which includes the spread spectrum code and the sinusoidal carrier, onto the optical wave to obtain and output the optical signal.

[0013] The first signal conversion and processing unit has its output end connected to the transmitting antenna. The first signal conversion and processing unit is used to convert the two input optical signals into electrical signals respectively, and then filter and synthesize them to obtain and output orthogonal broadband spread spectrum signals.

[0014] A transmitting antenna is used to receive and transmit orthogonal broadband spread spectrum signals.

[0015] In some optional implementations, the receiving module includes:

[0016] A receiving antenna, the output of which is connected to a first power divider, is used to receive and output spread spectrum signals.

[0017] The first power divider has its output terminals connected to the third dual-drive Mach-Zehnder modulator and the fourth dual-drive Mach-Zehnder modulator, respectively. The first power divider is used to divide the input spread spectrum signal into two output paths.

[0018] The second laser has its output terminals connected to the third dual-drive Mach-Zehnder modulator and the fourth dual-drive Mach-Zehnder modulator, respectively. The second laser is used to generate a single-frequency laser and divide it into two equally distributed outputs.

[0019] The first adjustable delay line is connected to the third dual-drive Mach-Zehnder modulator at its output end, and is used to output the input cosine despread signal, which includes despreading code and cosine carrier, after adding a delay.

[0020] The second adjustable delay line is connected to the fourth dual-drive Mach-Zehnder modulator at its output end, and is used to add a delay to the input sinusoidal despread signal, which includes despreading code and sinusoidal carrier, and output it.

[0021] The third dual-drive Mach-Zehnder modulator has its output connected to the second signal conversion and processing unit. The third dual-drive Mach-Zehnder modulator is used to modulate the input spread spectrum signal and cosine despread signal onto the optical wave to obtain and output an optical signal.

[0022] The fourth dual-drive Mach-Zehnder modulator has its output connected to the second signal conversion and processing unit. The fourth dual-drive Mach-Zehnder modulator is used to modulate the input spread spectrum signal and the sinusoidal despread signal onto the optical wave to obtain and output an optical signal.

[0023] The second signal conversion and processing unit is also connected to the first adjustable delay line and the second adjustable delay line respectively. The second signal conversion and processing unit is used to convert the two input optical signals into electrical signals and filter them to obtain two information codes and output them. It is also used to calculate the signal energy of the two information codes respectively and feed it back to the first adjustable delay line and the second adjustable delay line respectively, so that the first adjustable delay line and the second adjustable delay line adjust the delay according to the signal energy.

[0024] In some optional embodiments, the first signal conversion processing unit includes:

[0025] The first photodetector has its input end connected to the output end of the first dual-drive Mach-Zehnder modulator. The first photodetector is used to convert the input optical signal into an electrical signal and output it.

[0026] The first electrical filter has its input end connected to the output end of the first photodetector. The first electrical filter is used to filter out noise components outside the center frequency band of the input electrical signal and output the filtered electrical signal.

[0027] The second photodetector has its input end connected to the output end of the second dual-drive Mach-Zehnder modulator. The second photodetector is used to convert the input optical signal into an electrical signal and output it.

[0028] The second electrical filter has its input end connected to the output end of the second photodetector. The second electrical filter is used to filter out noise components outside the center frequency band of the input electrical signal and output the filtered electrical signal.

[0029] The combiner has its input terminals connected to the output terminals of the first and second electrical filters, respectively, and is used to combine the two input electrical signals into one to obtain and output an orthogonal broadband spread spectrum signal.

[0030] In some optional embodiments, the second signal conversion processing unit includes:

[0031] The third photodetector has its input end connected to the output end of the third dual-drive Mach-Zehnder modulator. The third photodetector is used to convert the input optical signal into an electrical signal and output it.

[0032] The third electrical filter has its input end connected to the output end of the third photodetector. The third electrical filter is used to filter out high-frequency noise and DC signals in the input electrical signal to obtain and output the first information code.

[0033] The first energy calculation subunit has its input end connected to the output end of the third electrical filter. The first energy calculation subunit is also connected to the first adjustable delay line. The first energy calculation subunit is used to calculate the signal energy of the first information code and feed the signal energy calculation result back to the first adjustable delay line, and to output the first information code.

[0034] The fourth photodetector has its input end connected to the output end of the fourth dual-drive Mach-Zehnder modulator. The fourth photodetector is used to convert the input optical signal into an electrical signal and output it.

[0035] The fourth electrical filter, whose input terminal is connected to the output terminal of the fourth photodetector, is used to filter out high-frequency noise and DC signals in the input electrical signal to obtain and output the second information code.

[0036] The second energy calculation subunit has its input end connected to the output end of the fourth electrical filter. The second energy calculation subunit is also connected to the second adjustable delay line. The second energy calculation subunit is used to calculate the signal energy of the second information code and feed the signal energy calculation result back to the second adjustable delay line, and to output the second information code.

[0037] In some optional implementations, the first energy calculation subunit and the second energy calculation subunit calculate the signal energy in the following manner:

[0038] Squaring the information code signal;

[0039] The squared information code signal is integrated or accumulated within a set time window to obtain the signal energy value.

[0040] In some alternative implementations, the transmitting module further includes:

[0041] The first multiplier has its output connected to the input of the second power divider. The first multiplier is used to multiply the externally input spreading code and cosine carrier to obtain and output a cosine spread spectrum signal including the spreading code and cosine carrier.

[0042] The second power divider has its output terminals connected to the first dual-drive Mach-Zehnder modulator and the first 90° phase shifter, respectively. The second power divider is used to divide the input cosine spread spectrum signal into two output paths.

[0043] The first 90° phase shifter is connected to the second dual-drive Mach-Zehnder modulator at its output terminal. The first 90° phase shifter is used to perform a 90° phase shift on the input cosine spread spectrum signal to obtain and output a sine spread spectrum signal.

[0044] In some optional implementations, the receiving module further includes:

[0045] The second multiplier has its output connected to the input of the third power divider. The second multiplier is used to multiply the external input despreading code and cosine carrier to obtain and output a cosine despreading signal including the despreading code and cosine carrier.

[0046] The third power divider has its output terminals connected to the first adjustable delay line and the second 90° phase shifter, and is used to divide the input cosine despread signal into two output paths.

[0047] The second 90° phase shifter has its output terminal connected to the second adjustable delay line. The second 90° phase shifter is used to perform a 90° phase shift on the input cosine despread signal to obtain and output a sine despread signal.

[0048] Secondly, an orthogonal spread spectrum communication transceiver method based on a dual-drive Mach-Zehnder modulator is also provided. This method utilizes the aforementioned orthogonal spread spectrum communication transceiver device based on a dual-drive Mach-Zehnder modulator. The method includes:

[0049] A single-frequency laser is generated and divided into two equal paths, which are then output to the two dual-drive Mach-Zehnder modulators in the transmitting module. A first information code and a cosine spread spectrum signal including a spreading code and a cosine carrier are input to one of the dual-drive Mach-Zehnder modulators in the transmitting module. A second information code and a sine spread spectrum signal including a spreading code and a sine carrier are input to the other dual-drive Mach-Zehnder modulator in the transmitting module.

[0050] One optical signal is obtained by modulating the first information code and the cosine spread spectrum signal onto the optical wave through one of the dual-drive Mach-Zehnder modulators in the transmitting module, and another optical signal is obtained by modulating the second information code and the sine spread spectrum signal onto the optical wave through the other dual-drive Mach-Zehnder modulator in the transmitting module.

[0051] The two optical signals are converted into electrical signals, filtered, and synthesized to obtain and output orthogonal broadband spread spectrum signals.

[0052] Thirdly, an orthogonal spread spectrum communication transceiver method based on a dual-drive Mach-Zehnder modulator is also provided. This method utilizes the aforementioned orthogonal spread spectrum communication transceiver device based on a dual-drive Mach-Zehnder modulator. The method includes:

[0053] Receive spread spectrum signals from the outside;

[0054] The spread spectrum signal is divided into two equal paths and output to the two dual-drive Mach-Zehnder modulators in the receiving module respectively.

[0055] A single-frequency laser is generated and divided into two equal paths, which are then output to the two dual-drive Mach-Zehnder modulators in the receiving module.

[0056] The cosine despread signal with an added delay is input into one of the dual-drive Mach-Zehnder modulators in the receiving module;

[0057] The sinusoidal despread signal with an added delay is input into another dual-drive Mach-Zehnder modulator in the receiving module;

[0058] One optical signal is obtained by modulating the spread spectrum signal and the cosine despread signal onto the optical wave through one of the dual-drive Mach-Zehnder modulators in the receiving module, and another optical signal is obtained by modulating the spread spectrum signal and the sine despread signal onto the optical wave through the other dual-drive Mach-Zehnder modulator in the receiving module.

[0059] The two optical signals are converted into electrical signals and filtered to obtain two information codes. The signal energy of the two information codes is calculated. The delays added to the cosine despreading signal and the sine despreading signal are adjusted according to the signal energy until the calculated signal energy exceeds the set threshold.

[0060] Based on the adjusted delay, signal processing is performed to obtain two information codes, which are then output.

[0061] The main advantages of the technical solution of this invention are as follows:

[0062] The orthogonal spread spectrum communication transceiver device and method based on dual-drive Mach-Zehnder modulators of the present invention leverages the advantages of analog photonic devices, such as high bandwidth and high real-time performance, and utilizes a structure with two dual-drive Mach-Zehnder modulators for orthogonal modulation. This enables the efficient and organic integration of ultra-wideband spread spectrum and orthogonal modulation, significantly improving the anti-interference capability, anti-interception capability, and user data transmission volume of spread spectrum communication. Furthermore, by using dual-drive Mach-Zehnder modulators to achieve high real-time broadband spread spectrum and despreading in the optical domain, the spread spectrum bandwidth limitation of electronic devices can be overcome, avoiding the long processing time of complex digital signals and improving signal processing efficiency. In addition, by organically combining the photonic spread spectrum and despreading process with orthogonal modulation, and utilizing the orthogonality of sine and cosine carriers, information transmission between two users can be achieved using a single spread spectrum sequence, further increasing the data transmission volume. Attached Figure Description

[0063] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and constitute a part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0064] Figure 1 A schematic diagram of an orthogonal spread spectrum communication transceiver based on a dual-drive Mach-Zehnder modulator is provided for an embodiment of the present invention.

[0065] Figure 2 This is a schematic diagram of the structure of a transmitting module provided in an embodiment of the present invention;

[0066] Figure 3 This is a schematic diagram of the structure of a receiving module provided in an embodiment of the present invention;

[0067] Figure 4This is a schematic diagram of another transmitting module provided in an embodiment of the present invention;

[0068] Figure 5 This is a schematic diagram of another receiving module provided in an embodiment of the present invention;

[0069] Figure 6 A time-domain waveform diagram of a first information code provided in an embodiment of the present invention;

[0070] Figure 7 A time-domain waveform diagram of a second information code provided in an embodiment of the present invention;

[0071] Figure 8 The embodiments of the present invention are based on Figure 6 The first information code shown and Figure 7 The spectrum diagram of the orthogonal broadband spread spectrum signal obtained by the second information code is shown below;

[0072] Figure 9 According to the embodiments of the present invention Figure 8 The time-domain waveform of the first information code recovered from the orthogonal broadband spread spectrum signal is shown.

[0073] Figure 10 According to the embodiments of the present invention Figure 8 The time-domain waveform of the second information code recovered from the orthogonal broadband spread spectrum signal is shown. Detailed Implementation

[0074] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0075] The technical solutions provided by the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0076] Firstly, reference Figure 1 This invention provides an orthogonal spread spectrum communication transceiver based on a dual-drive Mach-Zehnder modulator, the device comprising:

[0077] The transmitting module is equipped with two dual-drive Mach-Zehnder modulators. The transmitting module uses one dual-drive Mach-Zehnder modulator to modulate the received information code and cosine spread spectrum signal onto the optical wave to obtain one optical signal, and uses the other dual-drive Mach-Zehnder modulator to modulate the received information code and sine spread spectrum signal onto the optical wave to obtain another optical signal. The two optical signals are processed to obtain an orthogonal broadband spread spectrum signal.

[0078] The receiving module is equipped with two dual-drive Mach-Zehnder modulators. One dual-drive Mach-Zehnder modulator modulates the received spread spectrum signal and the cosine despread signal with an additional delay onto the optical wave to obtain one optical signal. The other dual-drive Mach-Zehnder modulator modulates the received spread spectrum signal and the sine despread signal with an additional delay onto the optical wave to obtain another optical signal. The two optical signals are processed to obtain two information codes.

[0079] The working principle of the orthogonal spread spectrum communication transceiver based on a dual-drive Mach-Zehnder modulator provided in the embodiments of the present invention is explained below:

[0080] Specifically, in the orthogonal spread spectrum communication transceiver provided in this embodiment of the invention, when it is necessary to send a spread spectrum signal to the outside world, a single-frequency laser is generated and divided into two equal paths, which are output to two dual-drive Mach-Zehnder modulators in the transmitting module. A first information code and a cosine spread spectrum signal including the spread spectrum code and a cosine carrier are input to one of the dual-drive Mach-Zehnder modulators in the transmitting module. A second information code and a sine spread spectrum signal including the spread spectrum code and a sine carrier are input to the other dual-drive Mach-Zehnder modulator in the transmitting module. The first information code and the cosine spread spectrum signal are modulated onto the light wave by one of the dual-drive Mach-Zehnder modulators in the transmitting module to obtain one optical signal. The second information code and the sine spread spectrum signal are modulated onto the light wave by the other dual-drive Mach-Zehnder modulator in the transmitting module to obtain another optical signal. The two optical signals are converted into electrical signals and filtered and synthesized to obtain and output an orthogonal broadband spread spectrum signal.

[0081] When it is necessary to receive and process spread spectrum signals transmitted from the outside, the system receives the spread spectrum signal from the outside; it divides the spread spectrum signal into two equal paths and outputs them to two dual-drive Mach-Zehnder modulators in the receiving module respectively; it generates a single-frequency laser and divides it into two equal paths and outputs them to two dual-drive Mach-Zehnder modulators in the receiving module respectively; it inputs the cosine despread signal with an added delay into one of the dual-drive Mach-Zehnder modulators in the receiving module; it inputs the sine despread signal with an added delay into the other dual-drive Mach-Zehnder modulator in the receiving module; and it is then processed by one of the dual-drive Mach-Zehnder modulators in the receiving module. The modulator modulates the spread spectrum signal and the cosine despread signal onto the optical wave to obtain one optical signal. Another dual-drive Mach-Zehnder modulator in the receiving module modulates the spread spectrum signal and the sine despread signal onto the optical wave to obtain another optical signal. The two optical signals are converted into electrical signals and filtered to obtain two information codes. The signal energy of each information code is calculated, and the added delay of the cosine and sine despread signals is adjusted based on the signal energy until the calculated signal energy exceeds a set threshold. Based on the adjusted delay, signal processing is performed to obtain and output the two information codes.

[0082] The orthogonal spread spectrum communication transceiver based on dual-drive Mach-Zehnder modulators provided in this invention leverages the advantages of analog photonic devices—high bandwidth and high real-time performance—and utilizes a structure with two dual-drive Mach-Zehnder modulators for orthogonal modulation. This enables the efficient and organic integration of ultra-wideband spread spectrum and orthogonal modulation, significantly improving the anti-interference capability, anti-interception capability, and user data transmission volume of spread spectrum communication. Furthermore, by using dual-drive Mach-Zehnder modulators to achieve high real-time broadband spread spectrum and despreading in the optical domain, the spread spectrum bandwidth limitations of electronic devices can be overcome, avoiding the long processing time of complex digital signals and improving signal processing efficiency. In addition, by organically combining the photonic spread spectrum and despreading process with orthogonal modulation, and utilizing the orthogonality of sine and cosine carriers, information transmission between two users can be achieved using a single spread spectrum sequence, further increasing data transmission volume.

[0083] refer to Figure 2 In an optional embodiment of the present invention, in order to achieve the functions of the aforementioned transmitting module, the transmitting module includes:

[0084] The first laser has its output terminals connected to a first dual-drive Mach-Zehnder modulator and a second dual-drive Mach-Zehnder modulator, respectively. The first laser is used to generate a single-frequency laser and divide it into two equally distributed outputs.

[0085] The first dual-drive Mach-Zehnder modulator has its output connected to the first signal conversion and processing unit. The first dual-drive Mach-Zehnder modulator is used to modulate the input information code and the input cosine spread spectrum signal, which includes the spread spectrum code and the cosine carrier, onto the optical wave to obtain and output the optical signal.

[0086] The second dual-drive Mach-Zehnder modulator is connected to the first signal conversion and processing unit at its output end. The second dual-drive Mach-Zehnder modulator is used to modulate the input information code and the input sinusoidal spread spectrum signal, which includes the spread spectrum code and the sinusoidal carrier, onto the optical wave to obtain and output the optical signal.

[0087] The first signal conversion and processing unit has its output end connected to the transmitting antenna. The first signal conversion and processing unit is used to convert the two input optical signals into electrical signals respectively, and then filter and synthesize them to obtain and output orthogonal broadband spread spectrum signals.

[0088] A transmitting antenna is used to receive and transmit orthogonal broadband spread spectrum signals.

[0089] refer to Figure 3 In an optional embodiment of the present invention, in order to achieve the functions of the receiving module as defined above, the receiving module includes:

[0090] The receiving antenna is connected to the first power divider at its output end. The receiving antenna is used to receive and output spread spectrum signals.

[0091] The first power divider has its output terminals connected to the third and fourth dual-drive Mach-Zehnder modulators, respectively. The first power divider is used to divide the input spread spectrum signal into two output paths.

[0092] The second laser is connected to the third and fourth dual-drive Mach-Zehnder modulators at its output end. The second laser is used to generate a single-frequency laser and divide it into two equal outputs.

[0093] The first adjustable delay line is connected to the third dual-drive Mach-Zehnder modulator at its output end. It is used to add a delay to the input cosine despread signal, which includes despreading code and cosine carrier, and output it.

[0094] The second adjustable delay line is connected to the fourth dual-drive Mach-Zehnder modulator at its output end. It is used to add a delay to the input sinusoidal despread signal, which includes despreading code and sinusoidal carrier, and then output it.

[0095] The third dual-drive Mach-Zehnder modulator is connected to the second signal conversion and processing unit at its output end. The third dual-drive Mach-Zehnder modulator is used to modulate the input spread spectrum signal and cosine despread signal onto the optical wave respectively, so as to obtain and output the optical signal.

[0096] The fourth dual-drive Mach-Zehnder modulator is connected to the second signal conversion and processing unit at its output end. The fourth dual-drive Mach-Zehnder modulator is used to modulate the input spread spectrum signal and the sinusoidal despread signal onto the optical wave respectively, so as to obtain and output the optical signal.

[0097] The second signal conversion and processing unit is also connected to the first adjustable delay line and the second adjustable delay line respectively. The second signal conversion and processing unit is used to convert the two input optical signals into electrical signals and filter them to obtain two information codes and output them. It is also used to calculate the signal energy of the two information codes respectively and feed it back to the first adjustable delay line and the second adjustable delay line respectively, so that the first adjustable delay line and the second adjustable delay line adjust the delay according to the signal energy.

[0098] Based on the aforementioned defined structures of the transmitting and receiving modules, in the orthogonal spread spectrum communication transceiver provided in this embodiment of the invention, when a spread spectrum signal needs to be transmitted to the outside world, a single-frequency laser is generated by a first laser and divided into two equal paths. The two laser paths are output to a first dual-drive Mach-Zehnder modulator and a second dual-drive Mach-Zehnder modulator, respectively. Simultaneously, a first information code to be transmitted and a cosine spread spectrum signal including a spread spectrum code and a cosine carrier are input to the first dual-drive Mach-Zehnder modulator. A second information code to be transmitted and a sine spread spectrum signal including a spread spectrum code and a sine carrier are input to the second dual-drive Mach-Zehnder modulator, wherein the sine spread spectrum signal can be obtained by 90° phase shifting of the cosine spread spectrum signal. Then, the first dual-drive Mach-Zehnder modulator modulates the first information code and the cosine spread spectrum signal onto the light wave, respectively, to realize the transmission of the first information code and the cosine spread spectrum signal. The cosine spread spectrum signal is multiplied in the optical domain to obtain and output a corresponding optical signal. The second dual-drive Mach-Zehnder modulator modulates the second information code and the sinusoidal spread spectrum signal onto the optical wave, thereby realizing the multiplication of the second information code and the sinusoidal spread spectrum signal in the optical domain to obtain and output a corresponding optical signal. Then, the optical signal output from the first dual-drive Mach-Zehnder modulator is converted into an electrical signal by the first signal conversion processing unit to obtain the corresponding cosine spread spectrum signal, and the optical signal output from the second dual-drive Mach-Zehnder modulator is converted into an electrical signal to obtain the corresponding sinusoidal spread spectrum signal. The obtained cosine spread spectrum signal and sinusoidal spread spectrum signal are filtered to remove noise components outside the signal center frequency band. The filtered cosine spread spectrum signal and sinusoidal spread spectrum signal are combined into an orthogonal broadband spread spectrum signal and output to the transmitting antenna. The orthogonal broadband spread spectrum signal is transmitted to the outside world using the transmitting antenna.

[0099] When it is necessary to receive and process spread spectrum signals transmitted from the outside, the spread spectrum signal is received through the receiving antenna and output to the first power divider. The first power divider divides the spread spectrum signal received by the receiving antenna into two equal paths and outputs the two spread spectrum signals to the third and fourth dual-drive Mach-Zehnder modulators, respectively. At the same time, a single-frequency laser is generated by the second laser and divided into two equal paths, which are output to the third and fourth dual-drive Mach-Zehnder modulators, respectively. A cosine despreading signal including despreading code and cosine carrier is input to the first adjustable delay line. The first adjustable delay line adds a delay to the cosine despreading signal, and the delayed cosine despreading signal is input to the third dual-drive Mach-Zehnder modulator. A sinusoidal despreading signal including despreading code and sinusoidal carrier is input to the second adjustable delay line. The second adjustable delay line adds a delay to the sinusoidal despreading signal, and the delayed sinusoidal despreading signal is input to the third dual-drive Mach-Zehnder modulator. The optical signal is fed into a fourth dual-drive Mach-Zehnder modulator, where the sinusoidal despread signal is obtained by 90° phase shifting of the cosine despread signal. Then, a third dual-drive Mach-Zehnder modulator modulates the spreading signal and the cosine despread signal onto the optical wave, achieving multiplication of the spreading signal and the cosine despread signal in the optical domain to obtain and output the corresponding optical signal. The fourth dual-drive Mach-Zehnder modulator modulates the spreading signal and the sinusoidal despread signal onto the optical wave, achieving multiplication of the spreading signal and the sinusoidal despread signal in the optical domain to obtain and output the corresponding optical signal. Next, a second signal conversion processing unit converts the optical signal output from the third dual-drive Mach-Zehnder modulator into an electrical signal to obtain the corresponding despread signal, and also converts the optical signal output from the fourth dual-drive Mach-Zehnder modulator into an electrical signal to obtain the corresponding despread signal. The obtained despread signals are then filtered to remove high-frequency noise and DC signals, resulting in two corresponding information codes. Each time an information code is obtained, the signal energy of the information code is calculated, and it is determined whether the signal energy exceeds a set threshold. If the signal energy exceeds the set threshold, it is determined that the despreading signal and the spreading signal are synchronized, the delay settings of the first adjustable delay line and the second adjustable delay line are correct, and the current information code is output as the final result. If the signal energy does not exceed the set threshold, it is determined that the despreading signal and the spreading signal are not synchronized, the delay settings of the first adjustable delay line and the second adjustable delay line are adjusted, and based on the adjusted delay, the signal processing is performed again according to the received spreading signal and the input despreading signal to obtain the information code, and the signal energy of the information code is calculated, until the signal energy of the calculated information code exceeds the set threshold.

[0100] refer to Figure 4 In an optional embodiment of the present invention, in order to achieve the function of the first signal conversion processing unit as defined above, the first signal conversion processing unit includes:

[0101] The first photodetector has its input end connected to the output end of the first dual-drive Mach-Zehnder modulator. The first photodetector is used to convert the input optical signal into an electrical signal and output it.

[0102] The first electrical filter has its input end connected to the output end of the first photodetector. The first electrical filter is used to filter out noise components outside the center frequency band of the input electrical signal and output the filtered electrical signal.

[0103] The second photodetector has its input end connected to the output end of the second dual-drive Mach-Zehnder modulator. The second photodetector is used to convert the input optical signal into an electrical signal and output it.

[0104] The second electrical filter has its input end connected to the output end of the second photodetector. The second electrical filter is used to filter out noise components outside the center frequency band of the input electrical signal and output the filtered electrical signal.

[0105] The combiner has its input terminals connected to the output terminals of the first and second electrical filters, respectively, and is used to combine the two input electrical signals into one to obtain and output an orthogonal broadband spread spectrum signal.

[0106] In this embodiment of the invention, the first photodetector converts the optical signal output from the first dual-drive Mach-Zehnder modulator into an electrical signal, obtains the corresponding cosine spread spectrum signal, and outputs it; the second photodetector converts the optical signal output from the second dual-drive Mach-Zehnder modulator into an electrical signal, obtains the corresponding sine spread spectrum signal, and outputs it; the combiner combines the filtered cosine spread spectrum signal and the sine spread spectrum signal into an orthogonal broadband spread spectrum signal and outputs it to the transmitting antenna.

[0107] refer to Figure 5 In an optional embodiment of the present invention, in order to achieve the function of the second signal conversion processing unit as defined above, the second signal conversion processing unit includes:

[0108] The third photodetector has its input end connected to the output end of the third dual-drive Mach-Zehnder modulator. The third photodetector is used to convert the input optical signal into an electrical signal and output it.

[0109] The third electrical filter has its input end connected to the output end of the third photodetector. The third electrical filter is used to filter out high-frequency noise and DC signals in the input electrical signal, and obtain and output the first information code.

[0110] The first energy calculation subunit has its input terminal connected to the output terminal of the third electrical filter. The first energy calculation subunit is also connected to the first adjustable delay line. The first energy calculation subunit is used to calculate the signal energy of the first information code and feed the signal energy calculation result back to the first adjustable delay line, and to output the first information code.

[0111] The fourth photodetector has its input end connected to the output end of the fourth dual-drive Mach-Zehnder modulator. The fourth photodetector is used to convert the input optical signal into an electrical signal and output it.

[0112] The fourth electrical filter, whose input is connected to the output of the fourth photodetector, is used to filter out high-frequency noise and DC signals in the input electrical signal, and to obtain and output the second information code.

[0113] The second energy calculation subunit has its input terminal connected to the output terminal of the fourth electrical filter. The second energy calculation subunit is also connected to the second adjustable delay line. The second energy calculation subunit is used to calculate the signal energy of the second information code and feed the signal energy calculation result back to the second adjustable delay line, as well as to output the second information code.

[0114] In this embodiment of the invention, the third photodetector converts the optical signal output from the third dual-drive Mach-Zehnder modulator into an electrical signal, obtains the corresponding despread signal, and outputs it; the fourth photodetector converts the optical signal output from the fourth dual-drive Mach-Zehnder modulator into an electrical signal, obtains the corresponding despread signal, and outputs it; the first energy calculation subunit feeds back the calculated signal energy of the first information code to the first adjustable delay line, and outputs the first information code when the signal energy exceeds a set threshold; the second energy calculation subunit feeds back the calculated signal energy of the second information code to the second adjustable delay line, and outputs the second information code when the signal energy exceeds a set threshold.

[0115] In this embodiment of the invention, the threshold is dynamically adjusted based on the actual signal-to-noise ratio (SNR) of the orthogonal spread spectrum communication transceiver, and the threshold is set higher than the noise floor but lower than the theoretical signal energy in the fully synchronized state.

[0116] Furthermore, in this embodiment of the invention, the first energy calculation subunit and the second energy calculation subunit calculate the signal energy in the following manner:

[0117] Squaring the information code signal;

[0118] The squared information code signal is integrated or accumulated within a set time window to obtain the signal energy value.

[0119] The time window is set according to the actual situation. The time window is set to be longer than the spreading code period to ensure complete coverage of the despreading code correlation peaks.

[0120] Furthermore, in this embodiment of the invention, during the delay adjustment process, half the time length of a single symbol of the spreading code is used as the time step, and the delay is increased or decreased by one time step. After the delay is adjusted, if the obtained signal energy increases, the delay is adjusted in the current direction; if the obtained signal energy decreases, the delay is adjusted in the opposite direction until the obtained signal energy exceeds the set threshold.

[0121] refer to Figure 4 In an optional embodiment of the present invention, the transmitting module further includes:

[0122] The first multiplier has its output connected to the input of the second power divider. The first multiplier is used to multiply the externally input spreading code and cosine carrier to obtain and output a cosine spread spectrum signal including the spreading code and cosine carrier.

[0123] The second power divider has its output terminals connected to the first dual-drive Mach-Zehnder modulator and the first 90° phase shifter, respectively. The second power divider is used to divide the input cosine spread spectrum signal into two outputs.

[0124] The first 90° phase shifter is connected to the output of the second dual-drive Mach-Zehnder modulator. The first 90° phase shifter is used to shift the input cosine spread spectrum signal by 90° to obtain and output a sine spread spectrum signal.

[0125] With this configuration, when performing spread spectrum communication, only the spreading code and cosine carrier need to be input to the first multiplier. There is no need to obtain the cosine spread spectrum signal and the sine spread spectrum signal in advance and input the corresponding signals to the first dual-drive Mach-Zehnder modulator and the second dual-drive Mach-Zehnder modulator respectively, which can facilitate operation and improve efficiency.

[0126] refer to Figure 5 In an optional embodiment of the present invention, the receiving module further includes:

[0127] The second multiplier, whose output is connected to the input of the third power divider, is used to multiply the external input despreading code and cosine carrier to obtain and output a cosine despreading signal including the despreading code and cosine carrier.

[0128] The third power divider is connected to the first adjustable delay line and the second 90° phase shifter at its output terminals. The third power divider is used to divide the input cosine despread signal into two outputs.

[0129] The second 90° phase shifter is connected to the second adjustable delay line at its output terminal. The second 90° phase shifter is used to perform a 90° phase shift on the input cosine despread signal to obtain and output a sine despread signal.

[0130] With this configuration, when performing spread spectrum communication, only the despreading code and cosine carrier need to be input to the second multiplier. There is no need to obtain the cosine despreading signal and sine despreading signal in advance and input the corresponding signals to the first and second adjustable delay lines respectively, which can facilitate operation and improve efficiency.

[0131] Based on the structure of the orthogonal spread spectrum communication transceiver defined above, the principle of the orthogonal spread spectrum communication transceiver is analyzed as follows:

[0132] The first laser emits a single-frequency laser beam, which is then split into two identical beams by a beam splitter inside the first laser. These beams then enter a first dual-drive Mach-Zehnder modulator and a second dual-drive Mach-Zehnder modulator, respectively. The photoelectric field entering a single dual-drive Mach-Zehnder modulator can be represented as:

[0133] ;

[0134] in, Represents the photoelectric field. Indicates field strength. Indicates the center frequency of the laser. Represents the imaginary unit. Represents a time variable. Represents an exponential function, laser intensity .

[0135] Assume the dual-drive Mach-Zehnder modulator is an ideal modulator, i.e., perfectly symmetrical at both ports and neglecting insertion loss. Assume the output photoelectric field of the first dual-drive Mach-Zehnder modulator is... ,but It can be represented as:

[0136] ;

[0137] in, and These represent the DC bias voltages of the upper and lower arms of the first dual-drive Mach-Zehnder modulator, respectively. This represents the half-wave voltage of the radio frequency modulated signal. This represents the half-wave voltage under DC bias. and These represent the electrical signals input to the two arms of the first dual-drive Mach-Zehnder modulator, respectively.

[0138] Furthermore, by setting the operating point of the first dual-drive Mach-Zehnder modulator to its minimum, we obtain: , At the same time, define Then the output photoelectric field It can be represented as:

[0139] ;

[0140] Therefore, the light intensity output by the first dual-drive Mach-Zehnder modulator can be expressed as:

[0141] ;

[0142] in, This indicates the light intensity output by the first dual-drive Mach-Zehnder modulator. express The complex conjugate, This indicates the intensity of the laser light entering the first dual-drive Mach-Zehnder modulator. This indicates the calculation of the cosine function;

[0143] When the small-signal approximation is satisfied, i.e. and When both signals are small, the light intensity output of the first dual-drive Mach-Zehnder modulator can be approximated as:

[0144] .

[0145] Furthermore, assume that the conversion efficiency of the first photodetector and the second photodetector in the transmitting module is... Then, after the optical signal passes through the first photodetector, the current output by the first photodetector can be expressed as:

[0146] ;

[0147] in, This represents the current output by the first photodetector.

[0148] Furthermore, assume that the signal loaded on one arm of the first dual-drive Mach-Zehnder modulator... First information code The signal loaded on the other arm of the first dual-drive Mach-Zehnder modulator For spreading code The cosine spread spectrum signal multiplied by a cosine carrier, and with all signals normalized, is as follows:

[0149] ;

[0150] ;

[0151] in, Indicates the carrier frequency.

[0152] Furthermore, due to and If both are bipolar signals with amplitudes of ±1, then we have , Then the current output by the first photodetector can be expressed as:

[0153] ;

[0154] Among them, due to For terms that do not include the DC term and carrier frequency multiplication term of the spread spectrum signal, after passing through the center frequency of The signal can be filtered out after the first electrical filter; therefore, the relevant terms of the electrical signal output by the first electrical filter can be expressed as:

[0155] ;

[0156] in, This represents the electrical signal output by the first electrical filter.

[0157] The electrical signal output by the first electrical filter contains the first information code, as well as the product of the spreading code and the cosine carrier, thus generating a cosine spread spectrum signal.

[0158] Similarly, suppose the signals loaded on the two arms of the second dual-drive Mach-Zehnder modulator are the second information codes. Spreading code Sinusoidal spread spectrum signal multiplied by a sinusoidal carrier And since all signals are normalized, the electrical signal generated by the spread spectrum optical signal modulated by the second dual-drive Mach-Zehnder modulator, after being detected by the second photodetector and filtered by the second electrical filter, can be expressed as:

[0159] ;

[0160] in, This represents the electrical signal output by the second electrical filter. This indicates the calculation of the sine function.

[0161] Based on the electrical signals output by the first and second electrical filters (i.e., the cosine spread spectrum signal output by the first filter and the sine spread spectrum signal output by the second filter), an orthogonal broadband spread spectrum signal is obtained by combining the cosine and sine spread spectrum signals. It can be represented as:

[0162] ;

[0163] in, and These represent the amplitudes of the cosine spread spectrum signal and the sine spread spectrum signal, respectively.

[0164] Furthermore, assuming orthogonal broadband spread spectrum signals After being transmitted through the transmitting antenna, the orthogonal broadband spread spectrum signal will not be distorted or attenuated during transmission. After being received by the receiving antenna, the signal is split into two identical signals by the first power divider and loaded onto the third and fourth dual-drive Mach-Zehnder modulators of the receiving module, respectively.

[0165] For the third dual-drive Mach-Zehnder modulator, assume the total delay of the spread spectrum signal from the antenna to the third dual-drive Mach-Zehnder modulator is... The spread spectrum signal loaded on the third dual-drive Mach-Zehnder modulator It can be represented as .

[0166] Assuming the despreading code is loaded on the third dual-drive Mach-Zehnder modulator The cosine despread signal multiplied by the cosine carrier is Delay of cosine despread signal Controlled by the first adjustable delay line, the cosine despread signal It can be represented as:

[0167] .

[0168] Referring to the aforementioned expression for the light intensity output of the first dual-drive Mach-Zehnder modulator and the expression for the current output of the first photodetector, when At that time, the cosine despreading is completely synchronized with the received spread spectrum signal. After detection by the third photodetector and low-pass filtering and DC blocking by the third electrical filter, the harmonic and DC terms in the signal are filtered out, and the first information code is recovered, specifically as follows:

[0169] ;

[0170] in, This represents the electrical signal output by the third electrical filter.

[0171] Similarly, for the fourth dual-drive Mach-Zehnder modulator, assuming the total delay of the spread spectrum signal from the antenna to the fourth dual-drive Mach-Zehnder modulator is... The spread spectrum signal loaded on the fourth dual-drive Mach-Zehnder modulator It can be represented as .

[0172] Assuming the despreading code is loaded on the fourth dual-drive Mach-Zehnder modulator The sinusoidal despread signal multiplied by the sinusoidal carrier is Delay of sinusoidal despread signal Controlled by the second adjustable delay line, the sinusoidal despread signal It can be represented as:

[0173] .

[0174] Referring to the aforementioned expression for the light intensity output of the first dual-drive Mach-Zehnder modulator and the expression for the current output of the first photodetector, when At that time, the sinusoidal despreading code is completely synchronized with the received spread spectrum signal. After detection by the fourth photodetector and low-pass filtering and DC blocking by the fourth electrical filter, the frequency multiplication term and DC term in the signal are filtered out, and the second information code is recovered, specifically as follows:

[0175] ;

[0176] in, This represents the electrical signal output by the fourth electrical filter.

[0177] Secondly, embodiments of the present invention also provide an orthogonal spread spectrum communication transceiver method based on a dual-drive Mach-Zehnder modulator. This method is implemented using the aforementioned orthogonal spread spectrum communication transceiver device based on a dual-drive Mach-Zehnder modulator, and includes the following steps:

[0178] A single-frequency laser is generated and divided into two equal paths, which are output to two dual-drive Mach-Zehnder modulators in the transmitting module. A first information code and a cosine spread spectrum signal including a spreading code and a cosine carrier are input to one of the dual-drive Mach-Zehnder modulators in the transmitting module. A second information code and a sine spread spectrum signal including a spreading code and a sine carrier are input to the other dual-drive Mach-Zehnder modulator in the transmitting module.

[0179] One optical signal is obtained by modulating the first information code and the cosine spread spectrum signal onto the optical wave through a dual-drive Mach-Zehnder modulator in the transmission module, and another optical signal is obtained by modulating the second information code and the sine spread spectrum signal onto the optical wave through another dual-drive Mach-Zehnder modulator in the transmission module.

[0180] The two optical signals are converted into electrical signals, filtered, and synthesized to obtain and output orthogonal broadband spread spectrum signals.

[0181] Furthermore, in this embodiment of the invention, based on the structure of the transmitting module specifically defined above, a single-frequency laser is generated by a first laser and equally divided into two paths, which are output to a first dual-drive Mach-Zehnder modulator and a second dual-drive Mach-Zehnder modulator, respectively. A first information code and a cosine spread spectrum signal including a spreading code and a cosine carrier are input to the first dual-drive Mach-Zehnder modulator, and a second information code and a sine spread spectrum signal including a spreading code and a sine carrier are input to the second dual-drive Mach-Zehnder modulator; the first dual-drive Mach-Zehnder modulator... The device modulates the first information code and the cosine spread spectrum signal onto the light wave respectively to obtain and output an optical signal. It also modulates the second information code and the sine spread spectrum signal onto the light wave respectively through the second dual-drive Mach-Zehnder modulator to obtain and output an optical signal. The first signal conversion and processing unit converts the optical signals output by the first dual-drive Mach-Zehnder modulator and the optical signals output by the second dual-drive Mach-Zehnder modulator into electrical signals respectively, and performs filtering and synthesis to obtain and output an orthogonal broadband spread spectrum signal. The orthogonal broadband spread spectrum signal is transmitted outward through the transmitting antenna.

[0182] Thirdly, embodiments of the present invention also provide an orthogonal spread spectrum communication transceiver method based on a dual-drive Mach-Zehnder modulator. This method is implemented using the aforementioned orthogonal spread spectrum communication transceiver device based on a dual-drive Mach-Zehnder modulator, and includes the following steps:

[0183] Receive spread spectrum signals from the outside;

[0184] The spread spectrum signal is divided into two equal paths and output to two dual-drive Mach-Zehnder modulators in the receiving module.

[0185] A single-frequency laser is generated and split into two equal paths, which are then output to two dual-drive Mach-Zehnder modulators in the receiving module.

[0186] The cosine despread signal with added delay is input into a dual-drive Mach-Zehnder modulator in the receiving module;

[0187] The sinusoidal despread signal with added delay is input into another dual-drive Mach-Zehnder modulator in the receiving module;

[0188] One optical signal is obtained by modulating the spread spectrum signal and the cosine despread signal onto the optical wave through a dual-drive Mach-Zehnder modulator in the receiving module, and another optical signal is obtained by modulating the spread spectrum signal and the sine despread signal onto the optical wave through another dual-drive Mach-Zehnder modulator in the receiving module.

[0189] The two optical signals are converted into electrical signals and filtered to obtain two information codes. The signal energy of the two information codes is calculated. The delays added to the cosine despreading signal and the sine despreading signal are adjusted according to the signal energy until the calculated signal energy exceeds the set threshold.

[0190] Based on the adjusted delay, signal processing is performed to obtain two information codes, which are then output.

[0191] Further, in this embodiment of the invention, based on the structure of the receiving module specifically defined above, a spread spectrum signal from the outside is received through a receiving antenna; the spread spectrum signal received by the receiving antenna is divided into two equal paths by a first power divider and output to a third dual-drive Mach-Zehnder modulator and a fourth dual-drive Mach-Zehnder modulator, respectively; a single-frequency laser is generated by a second laser and divided into two equal paths and output to a third dual-drive Mach-Zehnder modulator and a fourth dual-drive Mach-Zehnder modulator, respectively; a cosine despreading signal including a despreading code and a cosine carrier is input to a first adjustable delay line, and a delay is added to the cosine despreading signal through the first adjustable delay line, and the cosine despreading signal with the added delay is input to the third dual-drive Mach-Zehnder modulator; a sinusoidal despreading signal including a despreading code and a sinusoidal carrier is input to a second adjustable delay line, and a delay is added to the sinusoidal despreading signal through the second adjustable delay line, and the cosine despreading signal with the added delay is input to the third dual-drive Mach-Zehnder modulator; a sinusoidal despreading signal including a despreading code and a sinusoidal carrier is input to a second adjustable delay line, and a delay is added to the sinusoidal despreading signal through the second adjustable delay line, and the cosine despreading signal with the added delay is input to the third dual-drive Mach-Zehnder modulator. The sinusoidal despread signal is input to the fourth dual-drive Mach-Zehnder modulator; the spread spectrum signal and the cosine despread signal are modulated onto the optical wave by the third dual-drive Mach-Zehnder modulator to obtain and output an optical signal; the spread spectrum signal and the sinusoidal despread signal are modulated onto the optical wave by the fourth dual-drive Mach-Zehnder modulator to obtain and output an optical signal; the optical signals output by the third dual-drive Mach-Zehnder modulator and the fourth dual-drive Mach-Zehnder modulator are converted into electrical signals by the second signal conversion and processing unit and filtered to obtain two information codes; the signal energy of the two information codes is calculated and fed back to the first adjustable delay line and the second adjustable delay line respectively, so that the first adjustable delay line and the second adjustable delay line adjust the delay according to the signal energy until the calculated signal energy exceeds a set threshold; based on the adjusted delay, signal processing is performed to obtain and output the two information codes.

[0192] refer to Figures 6-10 , Figure 6 A time-domain waveform diagram of a first information code provided in an embodiment of the present invention; Figure 7 A time-domain waveform diagram of a second information code provided in an embodiment of the present invention; Figure 8 The embodiments of the present invention are based on Figure 6 The first information code shown and Figure 7 The spectrum diagram of the orthogonal broadband spread spectrum signal obtained by the second information code is shown below; Figure 9 According to the embodiments of the present inventionFigure 8 The time-domain waveform of the first information code recovered from the orthogonal broadband spread spectrum signal is shown. Figure 10 According to the embodiments of the present invention Figure 8 The diagram shows the time-domain waveform of the second information code recovered from the orthogonal wideband spread spectrum signal. It can be seen that the orthogonal spread spectrum communication transceiver device and method based on a dual-drive Mach-Zehnder modulator provided in this embodiment of the invention can achieve efficient and organic integration of ultra-wideband spread spectrum and orthogonal modulation, significantly improving the anti-interference capability, anti-interception capability, and user data transmission volume of spread spectrum communication. It can utilize a single spread spectrum sequence to achieve information transmission between two users, further increasing the data transmission volume.

[0193] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Additionally, the terms "front," "back," "left," "right," "upper," and "lower" in this document refer to the placement shown in the accompanying drawings.

[0194] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A quadrature spread spectrum communication transceiver based on a dual drive Mach-Zehnder modulator, characterized by The application relates to a quadrature wideband spread spectrum signal transmission and receiving system, which comprises a transmitting module and a receiving module. The transmitting module is provided with two double-drive Mach-Zehnder modulators, one of which is used to modulate received information code and cosine spread spectrum signals onto light waves to obtain one light signal, and the other of which is used to modulate received another information code and sine spread spectrum signals onto light waves to obtain one light signal, and the two light signals are processed to obtain quadrature wideband spread spectrum signals. The receiving module is provided with two double-drive Mach-Zehnder modulators, one of which is used to modulate received spread spectrum signals and cosine despread spectrum signals with additional delay onto light waves to obtain one light signal, and the other of which is used to modulate received spread spectrum signals and sine despread spectrum signals with additional delay onto light waves to obtain one light signal, and the two light signals are processed to obtain two information codes.

2. The dual-drive Mach-Zehnder modulator based quadrature spread spectrum communication transceiver of claim 1, wherein, The transmitting module comprises a first laser, a first double-drive Mach-Zehnder modulator and a second double-drive Mach-Zehnder modulator. The first laser is used to generate single-frequency laser and divide the laser into two paths. The first double-drive Mach-Zehnder modulator is connected with a first signal conversion processing unit and used to modulate input information code and input cosine spread spectrum signals including spread spectrum code and cosine carrier onto light waves to obtain and output light signals. The second double-drive Mach-Zehnder modulator is connected with the first signal conversion processing unit and used to modulate input information code and input sine spread spectrum signals including spread spectrum code and sine carrier onto light waves to obtain and output light signals. The first signal conversion processing unit is connected with a transmitting antenna and used to convert input two-path light signals into electric signals, filter and synthesize the electric signals to obtain and output quadrature wideband spread spectrum signals. The transmitting antenna is used to receive and transmit quadrature wideband spread spectrum signals.

3. The dual-drive Mach-Zehnder modulator based quadrature spread spectrum communication transceiver of claim 1, wherein, The receiving module comprises a receiving antenna, a first power divider, a second laser, a third double-drive Mach-Zehnder modulator, a fourth double-drive Mach-Zehnder modulator and a first adjustable delay line. The receiving antenna is connected with the first power divider and used to receive and output spread spectrum signals. The first power divider is connected with the third double-drive Mach-Zehnder modulator and the fourth double-drive Mach-Zehnder modulator and used to divide input spread spectrum signals into two paths. The second laser is used to generate single-frequency laser and divide the laser into two paths. The first adjustable delay line is connected with the third double-drive Mach-Zehnder modulator and used to output cosine despread spectrum signals including despread spectrum code and cosine carrier after additional delay. A second adjustable delay line, an output end of which is connected with the fourth dual-drive Mach-Zehnder modulator, is used for outputting the input sine despreading signal including the despreading code and the sine carrier after additional delay; The third dual-drive Mach-Zehnder modulator, an output end of which is connected with the second signal conversion processing unit, is used for modulating the input spread spectrum signal and the cosine despreading signal onto light waves respectively to obtain and output optical signals; The fourth dual-drive Mach-Zehnder modulator, an output end of which is connected with the second signal conversion processing unit, is used for modulating the input spread spectrum signal and the sine despreading signal onto light waves respectively to obtain and output optical signals; The second signal conversion processing unit is also connected with the first adjustable delay line and the second adjustable delay line respectively, and is used for converting the input two-way optical signals into electrical signals respectively and filtering to obtain and output two-way information codes, and for calculating the signal energy of the two-way information codes respectively and feeding back to the first adjustable delay line and the second adjustable delay line respectively so that the first adjustable delay line and the second adjustable delay line adjust the delay according to the signal energy.

4. The dual-drive Mach-Zehnder modulator based quadrature spread spectrum communication transceiver of claim 2, wherein, The first signal conversion processing unit comprises: A first photoelectric detector, an input end of which is connected with an output end of the first dual-drive Mach-Zehnder modulator, is used for converting the input optical signal into an electrical signal and outputting; A first electrical filter, an input end of which is connected with an output end of the first photoelectric detector, is used for filtering out the noise components outside the center frequency band of the input electrical signal and outputting the filtered electrical signal; A second photoelectric detector, an input end of which is connected with an output end of the second dual-drive Mach-Zehnder modulator, is used for converting the input optical signal into an electrical signal and outputting; A second electrical filter, an input end of which is connected with an output end of the second photoelectric detector, is used for filtering out the noise components outside the center frequency band of the input electrical signal and outputting the filtered electrical signal; A combiner, input ends of which are connected with an output end of the first electrical filter and an output end of the second electrical filter respectively, is used for combining the input two-way electrical signals into one way to obtain and output the quadrature wideband spread spectrum signal.

5. The dual-drive Mach-Zehnder modulator based quadrature spread spectrum communication transceiver of claim 3, wherein, The second signal conversion processing unit comprises: A third photoelectric detector, an input end of which is connected with an output end of the third dual-drive Mach-Zehnder modulator, is used for converting the input optical signal into an electrical signal and outputting; A third electrical filter, an input end of which is connected with an output end of the third photoelectric detector, is used for filtering out the high-frequency noise and direct current signal in the input electrical signal to obtain and output the first information code; a first energy calculation subunit, an input end of which is connected with an output end of the third electric filter, the first energy calculation subunit is also connected with the first adjustable delay line, the first energy calculation subunit is used for calculating signal energy of the first information code and feeding back the signal energy calculation result to the first adjustable delay line, and is used for outputting the first information code; a fourth photoelectric detector, an input end of which is connected with an output end of the fourth double-drive Mach-Zehnder modulator, the fourth photoelectric detector is used for converting an input optical signal into an electrical signal and outputting; a fourth electric filter, an input end of which is connected with an output end of the fourth photoelectric detector, the fourth electric filter is used for filtering high-frequency noise and direct current signals in the input electrical signal, obtaining and outputting the second information code; a second energy calculation subunit, an input end of which is connected with an output end of the fourth electric filter, the second energy calculation subunit is also connected with the second adjustable delay line, the second energy calculation subunit is used for calculating signal energy of the second information code and feeding back the signal energy calculation result to the second adjustable delay line, and is used for outputting the second information code.

6. The dual-drive Mach-Zehnder modulator based quadrature spread spectrum communication transceiver of claim 5, wherein, The first energy calculation subunit and the second energy calculation subunit calculate the signal energy in the following manner: performing square operation on the information code signal; integrating or accumulating the squared information code signal in a set time window to obtain a signal energy value.

7. The dual-drive Mach-Zehnder modulator based quadrature spread spectrum communication transceiver of claim 2, wherein, The transmitting module further comprises: a first multiplier, an output end of which is connected with an input end of the second power divider, the first multiplier is used for multiplying an externally input spread spectrum code and a cosine carrier to obtain and output a cosine spread spectrum signal comprising the spread spectrum code and the cosine carrier; The second power divider, the output end of which is connected with the first double-drive Mach-Zehnder modulator and the first 90° phase shifter respectively, the second power divider is used for equally dividing the input cosine spread spectrum signal into two paths for output; The first 90° phase shifter, the output end of which is connected with the second double-drive Mach-Zehnder modulator, the first 90° phase shifter is used for performing 90° phase shift on the input cosine spread spectrum signal to obtain and output a sine spread spectrum signal.

8. The dual-drive Mach-Zehnder modulator based quadrature spread spectrum communication transceiver of claim 3, wherein, The receiving module further comprises: a second multiplier, an output end of which is connected with an input end of the third power divider, the second multiplier is used for multiplying an externally input despread code and a cosine carrier to obtain and output a cosine despread signal comprising the despread code and the cosine carrier; The third power divider, the output end of which is connected with the first adjustable delay line and the second 90° phase shifter respectively, the third power divider is used for equally dividing the input cosine despread signal into two paths for output; The second 90° phase shifter, the output end of which is connected with the second adjustable delay line, the second 90° phase shifter is used for performing 90° phase shift on the input cosine despread signal to obtain and output a sine despread signal.

9. A quadrature spread spectrum communication transceiving method based on a dual drive Mach-Zehnder modulator, characterized by, The method is implemented by using the double-drive Mach-Zehnder modulator-based quadrature spread spectrum communication transceiver device according to any one of claims 1-8, and the method comprises: The single-frequency laser is generated and equally divided into two paths and output to the two double-drive Mach-Zehnder modulators in the transmitting module, the first information code and the cosine spread spectrum signal including the spread spectrum code and the cosine carrier are input to one of the double-drive Mach-Zehnder modulators in the transmitting module, and the second information code and the sine spread spectrum signal including the spread spectrum code and the sine carrier are input to the other of the double-drive Mach-Zehnder modulators in the transmitting module; The first information code and the cosine spread spectrum signal are modulated onto the light wave by one of the double-drive Mach-Zehnder modulators in the transmitting module to obtain one path of light signal, and the second information code and the sine spread spectrum signal are modulated onto the light wave by the other of the double-drive Mach-Zehnder modulators in the transmitting module to obtain one path of light signal; The two paths of light signal are respectively converted into electrical signals, filtered and synthesized to obtain and output the quadrature wideband spread spectrum signal.

10. A quadrature spread spectrum communication transceiving method based on a dual drive Mach-Zehnder modulator, characterized by, The method is implemented by using the quadrature spread spectrum communication transceiver based on the double-drive Mach-Zehnder modulator according to any one of claims 1-8, and the method comprises: receiving the spread spectrum signal from outside; equally dividing the spread spectrum signal into two paths and outputting to the two double-drive Mach-Zehnder modulators in the receiving module; generating a single-frequency laser and equally dividing it into two paths and outputting to the two double-drive Mach-Zehnder modulators in the receiving module; inputting the cosine despread signal with additional delay to one of the double-drive Mach-Zehnder modulators in the receiving module; inputting the sine despread signal with additional delay to the other of the double-drive Mach-Zehnder modulators in the receiving module; modulating the spread spectrum signal and the cosine despread signal onto the light wave by one of the double-drive Mach-Zehnder modulators in the receiving module to obtain one path of light signal, and modulating the spread spectrum signal and the sine despread signal onto the light wave by the other of the double-drive Mach-Zehnder modulators in the receiving module to obtain one path of light signal; filtering the two paths of light signal converted into electrical signals to obtain two paths of information code, calculating the signal energy of the two paths of information code, adjusting the delay of the cosine despread signal and the sine despread signal according to the signal energy until the calculated signal energy exceeds the set threshold value; based on the adjusted delay, performing signal processing to obtain and output the two paths of information code.

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