A spatial laser communication transceiver system and method with multi-wavelength self-loop test function

Abstract

The application discloses a kind of space laser communication transceiving systems and methods with multi-wavelength self-loop test function, solve the problem that after laser communication load is launched into orbit, existing technology cannot carry out fast on-orbit self-checking to optical communication transceiving subsystem device, module, circuit etc..The application forms self-test loop light path to the transmitted multi-waveband high-speed laser signal by switching the polarization state of high-speed laser signal, using the principle that polarization beamsplitter group reflects S light and transmits P light, before implementing double-star chain building, self-checking test of the star can be realized, and the transmitting light path is not affected, only need to switch laser polarization state, through single byte telemetry data, the on-orbit state of optical communication transceiving subsystem can be judged, under the urgent condition that satellite transit time is short and test steps are many, on-orbit self-checking test can be quickly and effectively completed.

Description

Technical Field

[0001] The present invention relates to a satellite laser communication transceiver system and method, and in particular to a space laser communication transceiver system and method with a multi-wavelength self-loop test function. Background Art

[0002] Satellite internet will become a key solution for achieving global network coverage in the 5G and even 6G eras, and is expected to become a key trend and strategic advantage in the integrated development of the aerospace, communications, and internet industries. Satellite internet refers to internet access based on satellite communications technology, with global coverage. By networking a critical mass of satellites to form a constellation system capable of real-time information transmission, satellite internet can provide end users with communication services primarily focused on broadband internet access. Featuring high bandwidth, low latency, and wide coverage, it provides technical support for the innovative development of broadband internet access services.

[0003] A typical satellite internet constellation consists of satellites in Low Earth Orbit (LEO), orbiting 500 to 2000 km above the Earth and with an operating cycle of approximately 1.6 hours. While the coverage of a single LEO satellite is limited, this limitation can be addressed by launching numerous small LEO satellites to form a satellite communications constellation, thereby reducing latency, enhancing signal quality, and achieving global coverage. With the emergence of new multimedia technologies, the demand for data throughput is increasing, requiring satellite communications systems to complement terrestrial communication networks to achieve global coverage. There is no doubt that satellite communications will lead the next generation of wireless communications. Emerging LEO satellite communications systems include Telesat and Starlink.

[0004] In this era of information explosion, the demand for greater capacity, higher bandwidth, and more secure data transmission is growing, giving rise to satellite laser communication technology. Both Telesat and Starlink, representatives of low-Earth orbit (LEO) constellations, are equipped with laser communication terminals to meet the future demand for more efficient and massive data transmission, providing crucial support for improving the performance of LEO satellite internet.

[0005] Satellite laser communication technology uses lasers instead of traditional microwaves as a carrier for communication. The communication terminal has the characteristics of wide bandwidth, small size, light weight, low power consumption, good confidentiality, and no spectrum restrictions. It is very suitable as a payload for satellite communication. It has become an effective means to solve the bandwidth bottleneck of satellite microwave communications and alleviate the shortage of satellite spectrum resources, and to achieve high-speed communication for various satellites. It has significant strategic needs and application value in both military and civilian fields, and can meet the growing communication needs of future space activities.

[0006] However, satellite laser communication payload technology is far from mature, and ensuring the payload functions as planned after launch is a paramount concern for every space mission participant. After transport and launch into orbit, the payload undergoes vibration, shock, and space radiation exposure. Initial power-up and self-testing are crucial steps. Laser communication payloads incorporate a variety of optoelectronic devices, passive optical components, optical fibers, and circuits, forming the optical signal pathway. A single point of failure can disrupt the laser signal, leading to inoperative communication and mission failure. However, for the diverse active and passive components and modules within optical communication terminals, achieving rapid and efficient on-orbit testing using unified methods and techniques presents a significant challenge. Summary of the Invention

[0007] In order to solve the technical problem that after the laser communication payload is launched into orbit, the existing technology is unable to perform rapid on-orbit self-inspection of the optical communication transceiver subsystem devices, modules, circuits, etc., the present invention provides a space laser communication transceiver system and method with a multi-wavelength self-loop test function, which can effectively confirm whether the optical communication transceiver subsystem is in a normal state on orbit.

[0008] The inventive concept of the present invention:

[0009] The present invention switches the polarization state of the high-speed laser signal and utilizes the principle of a polarization beam splitter group reflecting S light and transmitting P light to form a self-test loop optical path for the transmitted multi-band high-speed laser signal. Before implementing a dual-satellite link, the present invention can implement a self-test test on the satellite without affecting the transmitting optical path. Only the laser polarization state needs to be switched and the on-orbit status of the optical communication transceiver subsystem can be determined through single-byte telemetry data. Under the urgent conditions of short satellite transit time and multiple test steps, the on-orbit self-test test can be completed quickly and effectively.

[0010] In order to achieve the above objectives and complete the above invention concept, the present invention adopts the following technical solutions:

[0011] A space laser communication transceiver system with a multi-wavelength self-loop test function, which is special in that it includes a high-speed data processing circuit, a transmitting unit, a space relay optical path unit, a receiving unit and a monitoring unit;

[0012] The high-speed data processing circuit is used to send a source communication electrical signal to the transmitting unit, and receive a source measurement electrical signal and an external communication electrical signal from the receiving unit, then compare the source measurement electrical signal with the source communication electrical signal bit by bit, and output a bit error rate after statistical calculation; the source communication electrical signal and the external communication electrical signal are used for communication;

[0013] The transmitting unit is used to receive the source communication electrical signal, then convert it into a corresponding source laser signal, then split the source laser signal into a source measurement optical signal and a source communication optical signal, and switch between the source measurement optical signal and the source communication optical signal;

[0014] The spatial relay optical path unit is used to receive the source measurement optical signal or the source communication optical signal; when receiving the source communication optical signal, it transmits the source communication optical signal outward; when receiving the source measurement optical signal, it transmits the source measurement optical signal to the receiving unit, and is also used to receive the external communication optical signal and send it to the receiving unit;

[0015] The receiving unit is used to receive the source measurement optical signal and the external communication optical signal from the space relay optical path, and convert the two into the source measurement electrical signal and the external communication electrical signal respectively, and then send them to the high-speed data processing circuit;

[0016] The monitoring unit is used to monitor the transmitting unit and the receiving unit to obtain monitoring data that can be used to judge the system status.

[0017] Furthermore, the transmitting unit includes a multi-band light source, an electro-optical converter, an optical path combiner, a tunable polarizer and a high power amplifier;

[0018] The multi-band light source is used to emit laser beams of multiple wavelengths;

[0019] The electrical signal input end of the electro-optical converter is connected to the electrical signal output end of the high-speed data processing circuit, the optical detection end thereof is used to receive the laser beams of multiple wavelengths, and the output end thereof corresponds to the input end of the optical path combiner, and is used to modulate the laser beams of multiple wavelengths by the source communication electrical signal output by the high-speed data processing circuit to form the source laser signal;

[0020] The output end of the optical path combiner corresponds to the light input side of the tunable polarizer, and is used to combine the source laser signals and send them to the tunable polarizer;

[0021] The tunable polarizer is used to split the source laser signal into a source communication optical signal or a source measurement optical signal;

[0022] The input end of the high power amplifier corresponds to the optical output side of the tunable polarizer, and its output end corresponds to the input end of the space relay optical path unit, and is used to power amplify the source communication optical signal or the source measurement optical signal and send it to the space relay optical path unit.

[0023] Furthermore, the transmitting unit further includes a first spatial optical coupler and a second spatial optical coupler;

[0024] The first spatial optical coupler is arranged on the optical path between the optical path combiner and the tunable polarizer, and is used to couple the combined source laser signal into the tunable polarizer;

[0025] The second spatial optical coupler is arranged on an optical path between the tunable polarizer and the high power amplifier, and is used to couple the source communication optical signal or the source measurement optical signal into the high power amplifier.

[0026] Furthermore, the multi-band light source is a multi-band laser source array or an optical frequency comb module;

[0027] The optical path combining unit is a wavelength division multiplexer;

[0028] The electro-optical converter is a Mach-Zehnder modulator;

[0029] The high power amplifier is an erbium-doped fiber amplifier or an erbium-yttrium-doped fiber amplifier.

[0030] Furthermore, the spatial relay optical path unit includes a first polarization beam splitter and a second polarization beam splitter, both of which have the same polarization state as the tunable polarizer;

[0031] The first polarization beam splitter corresponds to the output end of the high power amplifier and is used to transmit the source communication optical signal or reflect the source measurement optical signal;

[0032] The second polarization beam splitter is arranged on the optical path where the reflected source measurement optical signal is located. The reflection side of the second polarization beam splitter is used to reflect the source measurement optical signal to the receiving unit, and the transmission side is used to receive the external communication optical signal and transmit it to the receiving unit.

[0033] Furthermore, the spatial relay optical path unit further includes a first focusing lens group, a second focusing lens group, a third focusing lens group and a fourth focusing lens group, all of which are used for focusing light;

[0034] The first focusing lens group is arranged on the optical path between the high power amplifier and the first polarization beam splitter;

[0035] The second focusing lens group is arranged on the optical path of the communication optical signal transmitted by the first polarization beam splitter;

[0036] The third focusing lens group is arranged on the optical path between the second polarization beam splitter and the receiving unit;

[0037] The fourth focusing lens group is arranged on the transmission side of the second polarization beam splitter.

[0038] Furthermore, the receiving unit includes a low-noise optical amplifier, a filter, an attenuator, and a photoelectric converter arranged in sequence along the optical path where the source measurement optical signal reflected by the second polarization beam splitter is located;

[0039] The low-noise optical amplifier is used to perform low-noise optical amplification on the source measurement optical signal or the external communication optical signal;

[0040] The filter is used to filter the source measurement optical signal or the external communication optical signal after low-noise optical amplification to eliminate stray light;

[0041] The attenuator is used to attenuate the power of the filtered source measurement optical signal or the external communication optical signal;

[0042] The photoelectric converter is used to convert the power-attenuated source measurement optical signal or the external communication optical signal into the source measurement electrical signal or the external communication electrical signal.

[0043] Further, the monitoring unit includes a first monitor, a second monitor, a third monitor and a fourth monitor;

[0044] The first monitor is connected to the multi-band light source and is used to monitor the output power of the multi-band light source;

[0045] The second monitor is connected to the high power amplifier and is used to monitor the output power of the high power amplifier;

[0046] The third monitor is connected to the low-noise optical amplifier and is used to monitor the output power of the low-noise optical amplifier;

[0047] The fourth monitor is connected to the photoelectric converter and is used to monitor the output power of the photoelectric converter;

[0048] The low-noise optical amplifier is an erbium-doped fiber amplifier (EDFA) or a phase-sensitive amplifier (PSA);

[0049] The photoelectric converter adopts an avalanche photodiode detector or a mixer + balanced detector.

[0050] A space laser communication transceiver method with a multi-wavelength self-loop test function adopts the above-mentioned space laser communication transceiver system with a multi-wavelength self-loop test function, and its special feature is that it includes the following steps:

[0051] Step 1: Using a high-speed data processing circuit to send a source communication electrical signal to a transmitting unit;

[0052] Step 2: Using a transmitting unit to receive the source communication electrical signal and convert it into a corresponding source laser signal, then splitting the source laser signal into a source measurement optical signal and a source communication optical signal, and then switching the source measurement optical signal to send it to the space relay optical path unit;

[0053] Step 3: Using a spatial relay optical path unit to receive the source measurement optical signal, and transmitting the source measurement optical signal to a receiving unit;

[0054] Step 4: Using a receiving unit to receive the source measurement optical signal from the space relay optical path, convert it into a source measurement electrical signal and then send it to the high-speed data processing circuit;

[0055] Step 5: Use a high-speed data processing circuit to compare the source communication electrical signal with the source measurement electrical signal bit by bit, and output the bit error rate after statistical calculation; at the same time, the monitoring unit monitors the transmitting unit and the receiving unit to obtain corresponding monitoring data;

[0056] Step 6: Determine the system status based on the bit error rate:

[0057] If the bit error rate is zero, the system is normal and proceed to step 9;

[0058] If the bit error rate is non-zero, the system fails and proceed to step 7;

[0059] Step 7: Determine whether the monitoring data is normal:

[0060] If the monitoring data is abnormal, the transmitting unit and / or the receiving unit are corrected accordingly until the monitoring data is normal, and step 8 is executed;

[0061] Step 8: Determine the system status based on the bit error rate:

[0062] If the bit error rate is zero, the system is normal and proceed to step 9;

[0063] If the bit error rate is non-zero error, the system fails and no further communication is possible through the system;

[0064] Step 9: Use the transmitting unit to switch the source communication optical signal and send it to the space relay optical path unit; the space relay optical path unit transmits the source communication optical signal outward, and receives the external communication optical signal and sends it to the receiving unit; the receiving unit converts the external communication optical signal into an external communication electrical signal and sends it to the high-speed data processing circuit to realize communication.

[0065] Furthermore, step 5 is specifically to use a high-speed data processing circuit to compare the source communication electrical signal with the source measurement electrical signal bit by bit, and output a bit error rate when the comparison process accumulates to a preset statistical time length; at the same time, the monitoring unit monitors the transmitting unit and the receiving unit to obtain corresponding monitoring data;

[0066] The bit error rate value is represented by one byte; the upper 4 bits of the byte represent the bit error rate coefficient, and the lower 4 bits represent the exponent of the bit error rate without the negative sign, wherein the bit error rate coefficient is rounded off.

[0067] Beneficial effects of the present invention:

[0068] 1. The space laser communication transceiver system provided by the present invention implements a self-looping mode within its internal optical path, fully testing the entire internal optical communication link. This includes the high-speed data processing circuits and software, which can also be tested and verified. On-orbit detection can be achieved by simply interpreting the bit error rate (BER) in a single byte, with high detection accuracy. Most existing satellite-borne space laser communication transceiver systems, on the other hand, only feature self-looping testing for electrical data, with each optoelectronic module undergoing independent self-testing. This increases telemetry data overhead and makes it impossible to determine the internal optical path status, especially the on-orbit integrity of passive optical components.

[0069] 2. The present invention simplifies the optical link test in the development of laser communication payloads and can support wavelength division optical communication systems with multi-wavelength laser arrays, greatly reducing the on-orbit self-test steps of space laser communication transceiver systems, saving valuable time for the short but multi-step satellite tracking and control arc test. In addition, the implementation method and system design are simple and reliable, which can provide new ideas and methods for the aerospace product design of laser communication terminals.

[0070] 3. The single-byte bit error rate representation method provided by the present invention is simple, efficient and accurate.

[0071] 4. The present invention can also be conveniently applied to anytime and anywhere testing of payloads in different ground environments, including thermal vacuum testing, vibration shock testing, and electromagnetic compatibility testing. This eliminates the need to carry excessive testing equipment or require another laser communication product for comparison, thereby verifying the operating status of optical signal transmission and reception, environmental adaptability, and other aspects. The simple operation and convenient testing expand the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 This is a schematic structural diagram of an embodiment of a space laser communication transceiver system with a multi-wavelength self-loop test function according to the present invention;

[0073] Figure 2 This is a flowchart of a method for representing bit error rate by a single byte and its data processing in an embodiment of the present invention. DETAILED DESCRIPTION

[0074] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the accompanying drawings and embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0075] The embodiment of the present invention provides a space laser communication transceiver system with a multi-wavelength self-loop test function, such as Figure 1As shown, it includes a high-speed data processing circuit, a transmitting unit, a space relay optical path unit, a receiving unit and a monitoring unit;

[0076] The high-speed data processing circuit is used to send the source communication electrical signal to the transmitting unit, and receive the source measurement electrical signal and the external communication electrical signal from the receiving unit, then compare the source measurement electrical signal with the source communication electrical signal bit by bit, and output the bit error rate after statistical calculation; the source communication electrical signal and the external communication electrical signal are used for communication.

[0077] The high-speed data processing circuit, comprised of an FPGA or DSP as the main control chip, is a digital circuit capable of processing serial high-speed data. It can be programmed to generate high-speed data streams (i.e., source communication signals, source measurement signals, and external communication signals) in a formatted pseudo-random binary sequence (PRBS-7, PRBS-15, PRBS-31, etc.). It then packages the data streams according to the protocol, adds a frame synchronization header and end-of-frame word, and simultaneously performs RS encoding (to correct data errors and reduce bit error rates) and interleaving (to improve error correction) to form a fixed-format (equal frame length) data stream. 64B / 66B encoding and scrambling are then performed sequentially to ensure DC link balance and stable data transmission. Output is transmitted from the transmitting end of the FPGA's high-speed data transceiver I / O interface (GTX, GTH, etc.), with a data rate designed to meet the requirements (a single port can support line rates from 500Mbps to 25Gbps). The high-speed differential signal output of the FPGA is connected to the differential signal input of an electro-optical converter (Mach-Zehnder modulator, etc., data rate: ~10Gbps), and the differential signal uses CML level or other types of level.

[0078] The high-speed data processing circuit can calculate the bit error rate of the high-speed data stream through time window comparison statistics, express the bit error rate with one byte, and output it through the telemetry data interface. The telemetry data interface can be LVDS or RS422, etc.

[0079] The transmitting unit is used to receive the source communication electrical signal, then convert it into a corresponding source laser signal, and then split the source laser signal into a source measurement optical signal and a source communication optical signal, and switch between the source measurement optical signal and the source communication optical signal; specifically, the transmitting unit includes a multi-band light source, an electro-optical converter, an optical path combiner, a first spatial optical coupler, a tunable polarizer, a second spatial optical coupler and a high-power amplifier; the multi-band light source is used to emit laser beams of multiple wavelengths; the electrical signal input end of the electro-optical converter and the electrical signal output end of the high-speed data processing circuit are connected through a high The high-speed data is connected at a differential level, and the RX+ and RX- of the electro-optical converter are respectively connected to the TX+ and TX- of the high-speed data processing circuit. The optical detection end of the electro-optical converter is used to receive laser beams of multiple wavelengths. The output end of the electro-optical converter corresponds to the input end of the optical path combiner, and is used to load the parallel source communication electrical signal output by the high-speed data processing circuit into a multi-band light source (i.e., a laser array or an optical frequency comb module. In this embodiment, a laser array is preferred; the laser array or optical frequency comb module is in the 1550nm band, and the wavelength is multiple wavelengths (λ0, λ1...λ n , n≥3)), thereby modulating the laser beams of multiple wavelengths emitted by the laser array into source laser signals of multiple wavelengths, and the electro-optical converter is compatible with direct detection / coherent multiple modulation modes (OOK / BPSK / DPSK); the output end of the optical path combiner (preferably a wavelength division multiplexer in this embodiment) corresponds to the optical input side of the tunable polarizer, and is used to combine the source laser signals and send them to the tunable polarizer; the tunable polarizer is used to split the source laser signal into a source communication optical signal or a source measurement optical signal, and the tunable polarizer is preferably an electrically controlled rotatable polarizer, and the spatial laser signal is switched between the source communication optical signal and the source measurement optical signal by rotating the polarizer; in this embodiment, the source measurement optical signal is S light, and the source communication optical signal is P light, so the tunable polarizer is actually used for switching between S light and P light; the input end of the high power amplifier corresponds to the optical output side of the tunable polarizer, and its output end corresponds to the input end of the space relay optical path unit, and is used to power amplify the source communication optical signal or the source measurement optical signal and send it to the space relay optical path unit. The first spatial optical coupler is arranged on the optical path between the optical path combiner and the tunable polarizer, and is used to couple the combined source laser signal from the optical fiber into space and then into the tunable polarizer; the second spatial optical coupler is arranged on the optical path between the tunable polarizer and the high-power amplifier, and is used to couple the source communication optical signal or the source measurement optical signal into the polarization-maintaining optical fiber, and then send it to the high-power amplifier through the polarization-maintaining optical fiber.

[0080] The space relay optical path unit is used to receive a source measurement optical signal (S light) or a source communication optical signal (P light); when receiving a source communication optical signal (P light), the source communication optical signal (P light) is transmitted outward through an optical antenna; when receiving a source measurement optical signal (S light), the source measurement optical signal (S light) is transmitted to a receiving unit, and is also used to receive an external communication optical signal and send it to the receiving unit for self-loop testing of a communication transceiver system; specifically, the space relay optical path unit includes a first polarization beam splitter and a second polarization beam splitter, both of which have the same polarization state as the polarization state of the tunable polarizer, wherein the first polarization beam splitter is arranged on the transmitting branch of the space relay optical path unit, and the second polarization beam splitter is arranged on the transmitting branch of the space relay optical path unit. The device is disposed on the receiving branch of the spatial relay optical path unit. The coating systems of the first polarization beam splitter and the second polarization beam splitter both reflect S light and transmit P light. The device also includes a first focusing lens group, a second focusing lens group, a third focusing lens group, and a fourth focusing lens group, all of which are used to focus light. The first polarization beam splitter corresponds to the output end of the high-power amplifier and is used to transmit the source communication optical signal or reflect the source measurement optical signal (S light). The second polarization beam splitter is disposed on the optical path of the reflected source measurement optical signal (S light). The reflective side of the second polarization beam splitter is used to reflect the source measurement optical signal (S light) to the receiving unit, and the transmissive side of the second polarization beam splitter is used to receive the external communication optical signal (P light) and transmit it to the receiving unit. The first focusing lens group is disposed on the optical path between the high-power amplifier and the first polarization beam splitter. The second focusing lens group is disposed on the optical path of the communication optical signal transmitted by the first polarization beam splitter. The third focusing lens group is disposed on the optical path between the second polarization beam splitter and the receiving unit. The fourth focusing lens group is disposed on the transmissive side of the second polarization beam splitter.

[0081] The receiving unit is used to receive the source measurement optical signal (S light) and the external communication optical signal (P light) from the space relay optical path, and convert the two into the source measurement electrical signal and the external communication electrical signal respectively, and then send them to the high-speed data processing circuit; specifically, the receiving unit includes a low-noise optical amplifier, a filter, an attenuator, and a photoelectric converter arranged in sequence along the optical path where the source measurement optical signal (S light) reflected by the second polarization beam splitter is located; the low-noise optical amplifier is used to perform low-noise optical amplification on the source measurement optical signal (S light) or the external communication optical signal (P light); the filter is used to perform low-noise optical amplification on the low-noise optical signal. The source measurement optical signal (S light) or the external communication optical signal (P light) is filtered to eliminate stray light; the attenuator is used to attenuate the power of the filtered source measurement optical signal (S light) or the external communication optical signal (P light); the photoelectric converter is connected to the high-speed data processing circuit through a high-speed data differential level, the TX+ and TX- of the photoelectric converter are correspondingly connected to the TX+ and TX- of the high-speed data processing circuit, and the photoelectric converter is used to convert the power-attenuated source measurement optical signal (S light) or the external communication optical signal (P light) into a source measurement electrical signal or an external communication electrical signal.

[0082] When the transmitting unit switches to using the source communication optical signal (P light), it enters the high-power amplifier output, then passes through the space relay optical path unit and is transmitted into space through the optical antenna. Here, the high-power amplifier can be an erbium-doped fiber amplifier (EDFA) or an erbium-yttrium-doped fiber amplifier (EYDFA). The high-power amplifier can amplify the source communication optical signal (P light) to 20dBm to 30dBm through automatic current control (ACC) or automatic power control (APC), and then transmit it from the optical antenna to another satellite or ground station.

[0083] When the transmitting unit switches to use the source measurement optical signal (S light) for transmission, the source measurement optical signal (S light) passes through the spatial relay optical path unit and enters the low-noise optical amplifier after two reflections. Here, the low-noise amplifier uses an erbium-doped fiber amplifier (EDFA) or a phase-sensitive amplifier (PSA).

[0084] The source measurement optical signal (S light) in the self-loopback test is amplified to a fixed optical power (set to a minimum power of 7dBm to 10dBm) by a low-noise optical amplifier using the ACC or APC mode. A filter then removes noise and filters out the signal light. The signal is then attenuated by an attenuator to below the saturation threshold of the optoelectronic converter. The optical signal λ1 is then demodulated into electrical data by the optoelectronic converter (an avalanche photodiode detector (APD) or a mixer + balanced detector), ensuring compatibility with direct detection and coherent demodulation methods (OOK, BPSK, and DPSK).

[0085] The differential signal output terminal on the photoelectric converter is connected to the high-speed differential signal input terminal of the FPGA, and the differential signal uses a CML level or other type of level.

[0086] The electrical data stream is input into the receiving end of the FPGA high-speed data transceiver I / O interface (GTX, GTH, etc.). The data stream is processed by the FPGA according to the clock cycle, and descrambled, 64B / 66B decoded, deinterleaved, RS decoded, and the frame synchronization header and frame end word are removed. Finally, the optical link data with the protocol format is restored to the original bare PRBS data stream.

[0087] By programming and developing software function modules, the FPGA compares the received data stream (source measurement electrical signal) with the generated source data stream (source communication electrical signal) bit by bit. When the comparison process accumulates to the preset statistical length (10s), a bit error rate is output; the output bit error rate is represented by one byte, as shown in the attached figure. Figure 2 As shown in the figure, in this byte, the upper 4 bits represent the coefficient of the bit error rate, and the lower 4 bits represent the exponent of the bit error rate without the negative sign. For example, ① the bit error rate is 1×10 -7, the coefficient is 1, the exponent without the negative sign is 7, expressed as 17 (H), the upper 4 bits are 0001, and the lower 4 bits are 0111; ② Bit error rate 3.4×10 -12 The coefficient 3.4 is rounded to 3, and the exponent without the negative sign is 12, which is expressed as 3C(H). The high 4 bits are 0011 and the low 4 bits are 1100.

[0088] The monitoring unit includes a first monitor, a second monitor, a third monitor, and a fourth monitor. The first monitor is connected to the multi-band light source to monitor its output power. The second monitor is connected to the high-power amplifier to monitor its output power. The third monitor is connected to the low-noise optical amplifier to monitor its output power. The fourth monitor is connected to the photoelectric converter to monitor its output power. The monitoring data that the monitoring unit can obtain includes the output power of the multi-band light source, the output power of the high-power amplifier, the output power of the low-noise optical amplifier, and the output power of the photoelectric converter.

[0089] In this embodiment, all that is required is to set the laser to the receiving wavelength in the remote control command, enable the low-noise amplifier at its lowest power, and read the bit error rate byte of the telemetry parameters. A bit error rate of 00 (H) indicates that the optical signal is error-free after being resolved through the self-loop optical path. This indicates that the electro-optical converter (modulator, etc.), laser array, high-power amplifier, opto-electrical converter (detector, mixer, etc.), digital circuits, and software in the space laser communication transceiver system are functioning properly. This also indicates that passive components such as the DWDM, first polarization beam splitter, second polarization beam splitter, tunable polarizer, filter, attenuator, and optical fiber are intact and functioning properly. A bit error rate of FF (H) indicates that the optical signal is not being properly detected and demodulated, and the optical path is blocked, requiring investigation. If the bit error rate is FF (H) but the four power monitoring data are normal, investigate the clock problem in the high-speed data processing circuitry. Without a normal clock, the FPGA is not processing the data stream correctly. Because the self-loop optical path is a closed optical signal channel, the four power monitoring data should all be stable and fixed values. When the stable fixed value read is significantly lower than the normal value, it indicates that the properties of a certain device have deteriorated due to factors such as vibration, impact, and radiation.

[0090] After the laser communication payload is launched into orbit, it is powered on for the first time to prepare for the self-test of the optical communication transceiver subsystem. The on-orbit self-test operation process is as follows:

[0091] Step 1: Use a high-speed data processing circuit to send a source communication electrical signal (PRBS-15 data stream, packaged in a fixed data protocol format, at a rate of 2.8 Gbps) to the transmitting unit;

[0092] Step 2: Use the transmitting unit to receive the source communication electrical signal, turn on the laser array, and rotate the tunable polarizer to switch to the S light polarization state; in the automatic current control ACC mode, set the high-power optical amplifier to have an output power of 20±0.5dBm (minimum output optical power), and the laser array emits laser beams of multiple wavelengths; the electro-optical converter converts the laser beams of multiple wavelengths into corresponding source laser signals through the source communication electrical signal, and then combines the source laser signals through the wavelength division multiplexer. The tunable polarizer splits the combined source laser signal into a source measurement optical signal (S light) and a source communication optical signal (P light), and then rotates the tunable polarizer to switch to the source measurement optical signal (S light), which is then amplified by the high-power amplifier and sent to the space relay optical path unit;

[0093] Step 3: Using a spatial relay optical path unit to receive the source measurement optical signal (S light), the source measurement optical signal (S light) enters the receiving unit after two reflections;

[0094] Step 4: Use a receiving unit to receive the source measurement optical signal (S light) from the space relay optical path, turn on the low-noise optical amplifier through the automatic power control APC mode, and the output optical power of the low-noise amplifier is 7±0.5dBm (minimum output optical power). After filtering and attenuation, the source measurement optical signal (S light) enters the photoelectric converter, which converts it into a source measurement electrical signal and then sends it to the high-speed data processing circuit;

[0095] Step 5: Use a high-speed data processing circuit to compare the source communication electrical signal with the source measurement electrical signal bit by bit. When the comparison process accumulates to a preset statistical length, a bit error rate is output; at the same time, the monitoring unit monitors the transmitting unit and the receiving unit to obtain corresponding monitoring data;

[0096] The bit error rate value is represented by one byte; the upper 4 bits of the byte represent the bit error rate coefficient, and the lower 4 bits represent the exponent of the bit error rate without the negative sign. The bit error rate coefficient is rounded to the nearest integer.

[0097] Step 6: Determine the system status by the bit error rate:

[0098] If the bit error rate is zero (00(H)), it proves that the self-loop path is normal, and that the laser array, electro-optical converter, wavelength division multiplexer, high-power optical amplifier, low-noise optical amplifier and other optoelectronic devices, filters and other passive optical devices, signal processing circuits and software in the laser communication transceiver subsystem are all in orbit and working normally. In other words, the system is normal, and go to step 9;

[0099] If the bit error rate is non-zero (FF(H)), it indicates a system failure and proceed to step 7.

[0100] Step 7: Determine whether the monitoring data is normal:

[0101] If the monitoring data is abnormal, the corresponding components in the transmitting unit and / or receiving unit are corrected accordingly until all four monitoring data are normal, and then step 8 is executed;

[0102] Step 8: Determine the system status by bit error rate:

[0103] If the bit error rate is zero (00(H)), it proves that the self-loop path is normal, which proves that the laser array, electro-optical converter, wavelength division multiplexer, high-power optical amplifier, low-noise optical amplifier and other optoelectronic devices, filters and other passive optical devices, signal processing circuits and software in the laser communication transceiver subsystem are all in orbit and working normally, that is, the system is normal, and go to step 9;

[0104] If the bit error rate is non-zero error (FF(H)), it indicates a system failure and no further communication will be conducted through the system;

[0105] Step 9: Use the transmitting unit to switch the source communication optical signal and send it to the space relay optical path unit; the space relay optical path unit transmits the source communication optical signal outward, and receives the external communication optical signal and sends it to the receiving unit; the receiving unit converts the external communication optical signal into an external communication electrical signal and sends it to the high-speed data processing circuit to realize communication.

[0106] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention shall be covered by the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A space laser communication transceiver system with a multi-wavelength self-loop test function, characterized by: It includes a high-speed data processing circuit, a transmitting unit, a space relay optical path unit, a receiving unit and a monitoring unit; The high-speed data processing circuit is used to send a source communication electrical signal to the transmitting unit, and receive a source measurement electrical signal and an external communication electrical signal from the receiving unit, then compare the source measurement electrical signal with the source communication electrical signal bit by bit, and output a bit error rate after statistical calculation; the source communication electrical signal and the external communication electrical signal are used for communication; The transmitting unit is used to receive the source communication electrical signal, then convert it into a corresponding source laser signal, then split the source laser signal into a source measurement optical signal and a source communication optical signal, and switch between the source measurement optical signal and the source communication optical signal; The spatial relay optical path unit is used to receive the source measurement optical signal or the source communication optical signal; when receiving the source communication optical signal, it transmits the source communication optical signal outward; when receiving the source measurement optical signal, it transmits the source measurement optical signal to the receiving unit, and is also used to receive the external communication optical signal and send it to the receiving unit; The receiving unit is used to receive the source measurement optical signal and the external communication optical signal from the space relay optical path, and convert the two into the source measurement electrical signal and the external communication electrical signal respectively, and then send them to the high-speed data processing circuit; The monitoring unit is used to monitor the transmitting unit and the receiving unit to obtain monitoring data that can be used to judge the system status; The transmitting unit includes a multi-band light source, an electro-optical converter, an optical path combiner, a tunable polarizer and a high power amplifier; The multi-band light source is used to emit laser beams of multiple wavelengths; The electrical signal input end of the electro-optical converter is connected to the electrical signal output end of the high-speed data processing circuit, the optical detection end thereof is used to receive the laser beams of multiple wavelengths, and the output end thereof corresponds to the input end of the optical path combiner, and is used to modulate the laser beams of multiple wavelengths by the source communication electrical signal output by the high-speed data processing circuit to form the source laser signal; The output end of the optical path combiner corresponds to the light input side of the tunable polarizer, and is used to combine the source laser signals and send them to the tunable polarizer; The tunable polarizer is used to split the source laser signal into a source communication optical signal or a source measurement optical signal; The input end of the high power amplifier corresponds to the optical output side of the tunable polarizer, and its output end corresponds to the input end of the space relay optical path unit, and is used to power amplify the source communication optical signal or the source measurement optical signal and send it to the space relay optical path unit.

2. The space laser communication transceiver system with multi-wavelength self-loop test function according to claim 1, characterized in that: The transmitting unit further includes a first spatial optical coupler and a second spatial optical coupler; The first spatial optical coupler is arranged on the optical path between the optical path combiner and the tunable polarizer, and is used to couple the combined source laser signal into the tunable polarizer; The second spatial optical coupler is arranged on an optical path between the tunable polarizer and the high power amplifier, and is used to couple the source communication optical signal or the source measurement optical signal into the high power amplifier.

3. The space laser communication transceiver system with multi-wavelength self-loop test function according to claim 2, characterized in that: The multi-band light source is a multi-band laser source array or an optical frequency comb module; The optical path combining unit is a wavelength division multiplexer; The electro-optical converter is a Mach-Zehnder modulator; The high power amplifier is an erbium-doped fiber amplifier or an erbium-yttrium-doped fiber amplifier.

4. The space laser communication transceiver system with multi-wavelength self-loop test function according to claim 2 or 3, characterized in that: The spatial relay optical path unit includes a first polarization beam splitter and a second polarization beam splitter, both of which have the same polarization state as the tunable polarizer; The first polarization beam splitter corresponds to the output end of the high power amplifier and is used to transmit the source communication optical signal or reflect the source measurement optical signal; The second polarization beam splitter is arranged on the optical path where the reflected source measurement optical signal is located. The reflection side of the second polarization beam splitter is used to reflect the source measurement optical signal to the receiving unit, and the transmission side is used to receive the external communication optical signal and transmit it to the receiving unit.

5. The space laser communication transceiver system with multi-wavelength self-loop test function according to claim 4, characterized in that: The spatial relay optical path unit further includes a first focusing lens group, a second focusing lens group, a third focusing lens group and a fourth focusing lens group, all of which are used for focusing light; The first focusing lens group is arranged on the optical path between the high power amplifier and the first polarization beam splitter; The second focusing lens group is arranged on the optical path of the communication optical signal transmitted by the first polarization beam splitter; The third focusing lens group is arranged on the optical path between the second polarization beam splitter and the receiving unit; The fourth focusing lens group is arranged on the transmission side of the second polarization beam splitter.

6. The space laser communication transceiver system with multi-wavelength self-loop test function according to claim 5, characterized in that: The receiving unit includes a low-noise optical amplifier, a filter, an attenuator, and a photoelectric converter arranged in sequence along the optical path where the source measurement optical signal reflected by the second polarization beam splitter is located; The low-noise optical amplifier is used to perform low-noise optical amplification on the source measurement optical signal or the external communication optical signal; The filter is used to filter the source measurement optical signal or the external communication optical signal after low-noise optical amplification to eliminate stray light; The attenuator is used to attenuate the power of the filtered source measurement optical signal or the external communication optical signal; The photoelectric converter is used to convert the power-attenuated source measurement optical signal or the external communication optical signal into the source measurement electrical signal or the external communication electrical signal.

7. The space laser communication transceiver system with multi-wavelength self-loop test function according to claim 6, characterized in that: The monitoring unit includes a first monitor, a second monitor, a third monitor and a fourth monitor; The first monitor is connected to the multi-band light source and is used to monitor the output power of the multi-band light source; The second monitor is connected to the high power amplifier and is used to monitor the output power of the high power amplifier; The third monitor is connected to the low-noise optical amplifier and is used to monitor the output power of the low-noise optical amplifier; The fourth monitor is connected to the photoelectric converter and is used to monitor the output power of the photoelectric converter; The low-noise optical amplifier is an erbium-doped fiber amplifier (EDFA) or a phase-sensitive amplifier (PSA); The photoelectric converter adopts an avalanche photodiode detector or a mixer + balanced detector.

8. A space laser communication transceiver method with a multi-wavelength self-loop test function, using the space laser communication transceiver system with a multi-wavelength self-loop test function according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Using a high-speed data processing circuit to send a source communication electrical signal to a transmitting unit; Step 2: Using a transmitting unit to receive the source communication electrical signal and convert it into a corresponding source laser signal, then splitting the source laser signal into a source measurement optical signal and a source communication optical signal, and then switching the source measurement optical signal to send it to the space relay optical path unit; Step 3: Using a spatial relay optical path unit to receive the source measurement optical signal, and transmitting the source measurement optical signal to a receiving unit; Step 4: Using a receiving unit to receive the source measurement optical signal from the space relay optical path, convert it into a source measurement electrical signal and then send it to the high-speed data processing circuit; Step 5: Use a high-speed data processing circuit to compare the source communication electrical signal with the source measurement electrical signal bit by bit, and output the bit error rate after statistical calculation; at the same time, the monitoring unit monitors the transmitting unit and the receiving unit to obtain corresponding monitoring data; Step 6: Determine the system status based on the bit error rate: If the bit error rate is zero, the system is normal and proceed to step 9; If the bit error rate is non-zero, the system fails and proceed to step 7; Step 7: Determine whether the monitoring data is normal: If the monitoring data is abnormal, the transmitting unit and / or receiving unit are corrected accordingly until the monitoring data is normal, and step 8 is executed; Step 8: Determine the system status based on the bit error rate: If the bit error rate is zero, the system is normal and proceed to step 9; If the bit error rate is non-zero error, the system fails and no further communication is possible through the system; Step 9: Use the transmitting unit to switch the source communication optical signal and send it to the space relay optical path unit; the space relay optical path unit transmits the source communication optical signal outward, and receives the external communication optical signal and sends it to the receiving unit; the receiving unit converts the external communication optical signal into an external communication electrical signal and sends it to the high-speed data processing circuit to realize communication.

9. The space laser communication transceiver method with multi-wavelength self-loop test function according to claim 8, characterized in that: Specifically, step 5 uses a high-speed data processing circuit to compare the source communication electrical signal with the source measurement electrical signal bit by bit. When the comparison process accumulates to a preset statistical time, a bit error rate is output; at the same time, the monitoring unit monitors the transmitting unit and the receiving unit to obtain corresponding monitoring data; The bit error rate value is represented by one byte; the upper 4 bits of the byte represent the bit error rate coefficient, and the lower 4 bits represent the exponent of the bit error rate without the negative sign, wherein the bit error rate coefficient is rounded off.

Images