Space laser communication transceiving system and method with multi-wavelength self-loop test function

Abstract

The invention discloses a space laser communication transceiving system and method with a multi-wavelength self-loop test function, and solves the problem that after a laser communication load is launched into an orbit, rapid on-orbit self-inspection cannot be carried out on optical communication transceiving subsystem devices, modules, circuits and the like in the prior art. By switching the polarization state of the high-speed laser signal and utilizing the principle that the polarization beam splitter group reflects S light and transmits P light, a self-test loopback light path is formed for the emitted multi-band high-speed laser signal, the self-test test of the satellite can be realized before double-satellite link establishment is implemented, the emission light path is not influenced, and the measurement accuracy is improved. According to the method, the on-orbit state of the optical communication transceiving subsystem can be judged through single-byte telemetering data only by switching the laser polarization state, and on-orbit self-inspection testing can be rapidly and effectively completed under the urgent conditions that the transit time of a satellite is short and the number of testing steps is large.

Description

Technical Field

[0001] The 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 an important solution for achieving global network coverage in the 5G and even 6G eras, and is expected to become an important trend and strategic commanding height for the integrated development of aerospace, communications, and Internet industries. Satellite Internet refers to access to the Internet based on satellite communication technology, and its services can cover the world. By networking a certain number of satellites on a large scale and building a constellation system with real-time information transmission capabilities, satellite Internet can provide terminal users with communication services mainly based on broadband Internet access. It has the characteristics of high bandwidth, low latency, and wide coverage, and can provide technical support for the innovative development of broadband Internet access services.

[0003] A typical satellite Internet constellation is composed of low earth orbit (LEO) satellites, which are 500 to 2000 km from the ground and have an operating cycle of about 1.6 hours. Although the coverage of a single LEO satellite is limited, it can be compensated by launching a large number of low-orbit small satellites to build a satellite communication constellation system, thereby reducing latency, enhancing signals, and achieving global coverage. With the emergence of new multimedia technologies, the demand for data service throughput is increasing, requiring satellite communication systems to complement ground communication networks to achieve global coverage. There is no doubt that satellite communications will lead the new wave of next-generation wireless communications. Emerging LEO satellite communication systems include Telesat, Starlink, etc.

[0004] In this era of information explosion, the demand for data transmission with larger capacity, higher bandwidth and higher security is growing, and satellite laser communication technology has been born. As representatives of low-orbit constellations, both Telesat and Starlink are equipped with laser communication terminals to meet the future demand for more efficient and massive data transmission, providing important support for improving the performance of low-orbit 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 satellite communication payload. 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 communications for various types of 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 whether the payload can work normally as scheduled after launch is the most concerned issue for every participant in the space mission. After being transported and launched into orbit, the payload has been subjected to vibration, shock and space radiation, and the first power-on and self-test are key links. Laser communication payloads are equipped with various optoelectronic devices, passive optical devices, optical fibers and circuits, which form the path of optical signals. If a single point failure occurs, the laser signal will be cut off, resulting in the failure of the communication function in the sky and the failure of the mission. However, for different types of active and passive devices and modules in optical communication terminals, how to use unified methods and means to quickly and efficiently perform on-orbit detection has become a difficult problem. 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 on-orbit whether the optical communication transceiver subsystem is in a normal state.

[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 satellite self-test can be implemented without affecting the transmitting optical path. Only the laser polarization state needs to be switched and the on-orbit state of the optical communication transceiver subsystem can be determined through single-byte telemetry data. Under the urgent conditions of short satellite transit time and many test steps, the on-orbit self-test can be completed quickly and effectively.

[0010] In order to achieve the above purpose 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, and 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, the source communication optical signal is emitted outward; when receiving the source measurement optical signal, the source measurement optical signal is emitted 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 the plurality of 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 the plurality of wavelengths through 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 optical 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 amplify the power of the source communication optical signal or the source measurement optical signal and send it to the space relay optical path unit.

[0023] Further, the transmitting unit also 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] Further, the spatial relay optical path unit comprises 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, and 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 thereof is used to receive the external communication optical signal and transmit it to the receiving unit.

[0033] Furthermore, the space relay optical path unit further comprises 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 where the communication optical signal transmitted by the first polarization beam splitter is located;

[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] Further, the receiving unit includes a low-noise optical amplifier, a filter, an attenuator, and a photoelectric converter which are sequentially arranged 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 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, converting it into a source measurement electrical signal and then sending it to a 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 by the bit error rate:

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

[0058] If the bit error rate is non-zero bit error, the system fails and execute 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 by the bit error rate:

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

[0063] If the bit error rate is non-zero bit error, the system fails and no more communication is performed 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 to the outside, 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] Further, 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; 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 coefficient of the bit error rate, and the lower 4 bits represent the exponent of the bit error rate without the negative sign, wherein the coefficient of the bit error rate is rounded off.

[0067] Beneficial effects of the present invention:

[0068] 1. The space laser communication transceiver system provided by the present invention realizes the self-loop mode in its internal optical path, and the entire internal optical communication link is fully tested, including the operation of the high-speed data processing circuit and the software can also be tested and verified. It only needs to judge the single byte of the bit error rate to realize on-orbit detection, and the detection accuracy is high. However, most existing satellite-borne space laser communication transceiver systems are only designed with electrical data self-loop test, and each optoelectronic module is self-checked separately, which increases the telemetry data volume overhead, and cannot judge the internal optical path situation, especially the on-orbit integrity of passive optical devices.

[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 precious time for the short and multi-step satellite tracking and control arc segment testing, and 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 loads in different ground environments, including thermal vacuum testing, vibration shock testing, electromagnetic compatibility testing, etc. It is not necessary to carry too many test equipment or need another laser communication product to test it, so as to verify the working status of optical signal transmission and reception, environmental adaptability, etc. The operation is simple and the testing is convenient, which increases the scope of application of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 It is a structural schematic 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 It is a method for representing bit error rate by a single byte and a data processing flow chart thereof in an embodiment of the present invention. DETAILED DESCRIPTION

[0074] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0075] An 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, and 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 is a digital circuit that can process serial high-speed data, which is composed of FPGA or DSP as the main control chip. It can be programmed to generate pseudo-random binary sequences (PRBS-7, PRBS-15, PRBS-31, etc.) with high-speed data streams (i.e. source communication electrical signals, source measurement electrical signals and external communication electrical signals), package the data streams according to the protocol, add frame synchronization headers and frame end words, and perform RS encoding (data error correction to reduce bit error rate) and interleaving encoding (improve error correction effect) at the same time to form a fixed format (equal frame length) data stream, and then perform 64B / 66B encoding and scrambling encoding in turn to ensure link DC balance and stable data transmission. Output from the transmitting end of the FPGA high-speed data transceiver I / O interface (GTX, GTH, etc.), and design the data stream rate according to demand (single port can support line rate: 500Mbps~25Gbps). The high-speed differential signal output of the FPGA is connected to the differential signal input on the electro-optical converter (Mach-Zehnder modulator, etc., data rate: ~10Gbps), and the differential signal uses CML level or other types of levels.

[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 the judgment through the telemetry data interface, which 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 is connected to the electrical signal output end of the high-speed data processing circuit through a high-speed data differential level, the RX+ and RX- of the electro-optical converter are respectively connected to the high-speed data processing circuit TX+ and TX-, 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 to the multi-band light source (i.e., a laser array or an optical frequency comb module, and the laser array is preferably used in this embodiment; the laser array or the optical frequency comb module is in the 1550nm band, and the wavelength is multi-wavelength (λ 0 ,λ 1 ......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 signal and send it 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 amplify the power of 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 enter 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 transmit it to the receiving unit, for a self-loop test 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 a transmitting branch of the space relay optical path unit, and the second ... The device is arranged on the receiving branch of the space relay optical path unit, and the coating film systems of the first polarization beam splitter and the second polarization beam splitter are both for reflecting S light and transmitting P light; and 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 for focusing light; the first polarization beam splitter corresponds to the output end of the high power amplifier, and is used for transmitting the source communication optical signal or reflecting the source measurement optical signal (S light); the second polarization beam splitter is arranged on the optical path where the reflected source measurement optical signal (S light) is located, and the reflection side of the second polarization beam splitter is used to reflect the source measurement optical signal (S light) to the receiving unit, and its transmission side is used to receive the external communication optical signal (P light) and transmit it to the receiving unit. 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 where the communication optical signal transmitted by the first polarization beam splitter is located; the third focusing lens group is arranged on the optical path between the second polarization beam splitter and the receiving unit; and the fourth focusing lens group is arranged on the transmission 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 after the low-noise optical amplification. 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 the 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 use the source communication optical signal (P light) for transmission, it enters the high-power amplifier output, 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~30dBm through automatic current control (ACC) or automatic power control (APC), and 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 space 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) of the self-loopback test is amplified to a fixed optical power (set the minimum power, generally 7dBm to 10dBm) by a low-noise optical amplifier through the ACC or APC mode, and then filtered out by a filter to remove noise and filter out the signal light. It is attenuated to below the saturation threshold of the photoelectric converter through an attenuator. The optical signal λ 1 The optical data is demodulated into electrical data by a photoelectric converter (avalanche photodiode detector (APD) or mixer + balanced detector), which is compatible with direct detection / coherent multiple demodulation methods (OOK / BPSK / 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 types of levels.

[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 descrambling, 64B / 66B decoding, deinterleaving, RS decoding, frame synchronization header and frame end word are removed, and finally the optical link data with 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 represented by 3C (H). The upper 4 bits are 0011 and the lower 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 the output power of the multi-band light source; the second monitor is connected to the high power amplifier to monitor the output power of the high power amplifier; the third monitor is connected to the low noise optical amplifier to monitor the output power of the low noise optical amplifier; the fourth monitor is connected to the photoelectric converter to monitor the output power of the photoelectric converter. 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 are the monitoring data that can be obtained by the monitoring unit.

[0089] In this embodiment, it is only necessary to set the laser as the receiving wavelength in the remote control command, turn on the low noise amplifier at the lowest power, and read the bit error rate byte of the telemetry parameter. When the bit error rate shows 00 (H), it means that the optical signal is zero error after being resolved by the self-loop optical path, indicating that the electro-optical converter (modulator, etc.), laser array, high power amplifier, photoelectric converter (detector, mixer, etc.), and digital circuit and software in the space laser communication transceiver system can work normally, and it also means that the passive components such as DWDM, the first polarization beam splitter, the second polarization beam splitter, the tunable polarizer, the filter, the attenuator, and the optical fiber are not damaged and the path is normal. When the bit error rate shows FF (H), it means that the optical signal is not detected and demodulated normally, the optical path is blocked, and the cause needs to be checked. If the bit error rate shows FF (H), but the four power monitoring data are normal, the clock problem in the high-speed data processing circuit can be checked. In the absence of a normal clock, the FPGA does not process the data stream correctly. Since the self-loop optical path belongs to a closed optical signal channel, the four power monitoring data should all be a stable and fixed value. When the stable fixed value read is significantly lower than the normal value, it indicates that the properties of a 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 a transmitting unit;

[0092] Step 2, using a transmitting unit to receive a source communication electrical signal, turning on the laser array, and rotating and switching the tunable polarizer to the S light polarization state; in the automatic current control ACC mode, setting the high-power optical amplifier to have an output power of 20±0.5dBm (minimum output optical power), 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 a wavelength division multiplexer, and 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 a 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, the output optical power of the low noise amplifier is 7±0.5dbm (minimum output optical power), and the source measurement optical signal (S light) enters the photoelectric converter after filtering and attenuation. The photoelectric converter 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, and output a bit error rate when the comparison process accumulates to a preset statistical time; 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, wherein the bit error rate coefficient is rounded off.

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

[0098] If the bit error rate is zero bit error (00(H)), it proves that the self-loop path is normal, and it 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 working normally on track, that is, the system is normal, and go to step 9;

[0099] If the bit error rate is non-zero bit error (FF(H)), it indicates that the system is faulty, and go 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 the receiving unit are corrected accordingly until the 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 bit error (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 working normally on track, that is, the system is normal, and go to step 9;

[0104] If the bit error rate is non-zero error (FF(H)), it proves that the system is faulty and no more 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 to the outside, 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 is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A space laser communication transceiver system with a multi-wavelength self-loop test function, characterized 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; 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, and 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, the source communication optical signal is emitted outward; when receiving the source measurement optical signal, the source measurement optical signal is emitted 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.

2. The space laser communication transceiver system with multi-wavelength self-loop test function according to claim 1, characterized in that: 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 the plurality of 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 the plurality of wavelengths through 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 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; 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 amplify the power of the source communication optical signal or the source measurement optical signal and send it to the space relay optical path unit.

3. The space laser communication transceiver system with multi-wavelength self-loop test function according to claim 2 is 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.

4. The space laser communication transceiver system with multi-wavelength self-loop test function according to claim 3 is 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.

5. The space laser communication transceiver system with multi-wavelength self-loop test function according to claim 3 or 4, characterized in that: The spatial relay optical path unit comprises 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, and 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 thereof is used to receive the external communication optical signal and transmit it to the receiving unit.

6. The space laser communication transceiver system with multi-wavelength self-loop test function according to claim 5, 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 where the communication optical signal transmitted by the first polarization beam splitter is located; 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.

7. The space laser communication transceiver system with multi-wavelength self-loop test function according to claim 6, characterized in that: The receiving unit includes a low-noise optical amplifier, a filter, an attenuator, and a photoelectric converter which are sequentially arranged 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.

8. The space laser communication transceiver system with multi-wavelength self-loop test function according to claim 7, 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.

9. 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 8, 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 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, converting it into a source measurement electrical signal and then sending it to a 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 by the bit error rate: If the bit error rate is zero, the system is normal, and go to step 9; If the bit error rate is non-zero bit error, the system fails and execute step 7; Step 7: Determine whether the monitoring data is normal: 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; Step 8: Determine the system status by the bit error rate: If the bit error rate is zero, the system is normal, and go to step 9; If the bit error rate is non-zero bit error, the system fails and no more communication is performed 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 to the outside, 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.

10. The space laser communication transceiver method with multi-wavelength self-loop test function according to claim 9, characterized in that: Step 5 specifically comprises: using a high-speed data processing circuit to compare the source communication electrical signal with the source measurement electrical signal bit by bit, and outputting a bit error rate when the comparison process accumulates to a preset statistical time; 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 coefficient of the bit error rate, and the lower 4 bits represent the exponent of the bit error rate without the negative sign, wherein the coefficient of the bit error rate is rounded off.

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