Multi-channel digital video high-speed synchronous transmission equipment and video playing system

Abstract

A high-speed synchronous transmission device and a video playing system for multichannel digital videos, the device comprising: a plurality of high-speed synchronous transmission modules, each high-speed synchronous transmission module comprising a video input interface, a laser transmitting module, a laser receiving module, and a video output interface; the video input interface receives a high-bandwidth digital video signal from a video source; the laser transmitting module comprises a laser driver and a laser transmitter, the laser driver is connected with the video input interface so as to convert the video input interface into a laser driving signal, and the laser transmitter is connected with the laser driver so as to generate a laser signal corresponding to the high-bandwidth digital video signal under the driving of the laser driving signal; the laser receiving module comprises a laser receiver and a signal restoration circuit, the laser receiver is used for receiving the laser signal generated by the laser transmitter and converting the laser signal into a light current signal, and the signal restoration circuit is connected with the laser receiver so as to process the light current signal and restore a high-bandwidth digital video signal for playing.

Description

Technical Field

[0001] The present application relates to the field of video transmission technology, and in particular to a high-speed synchronous transmission device for multi-channel digital video and a video playback system. Background Art

[0002] In many multi-channel video systems that require synchronized video display across multiple channels, such as multi-channel video simulation systems and multi-channel dome display systems, the primary challenge facing video data transmission is transmission distance. In these systems, video source devices (such as servers and players) are typically installed in the equipment room, while display devices (such as monitors and projectors) may be located far away, tens or even hundreds of meters away. Traditional copper cable transmission lines, such as those based on DisplayPort, are unable to meet this requirement due to their limited transmission distance (typically only 3 meters). Therefore, long-distance transmitters based on optical fiber or Ethernet cables are the inevitable choice. However, while these transmitters extend transmission distance, they also introduce processing latency, which can affect the synchronized display of multi-channel systems.

[0003] Long-distance transmitters process video signals on a frame-by-frame basis through internal chips, including signal input, processing, packaging, transmission, reception, unpacking, reprocessing, and output. Due to variations in chip manufacturing, processing speeds can vary, leading to inconsistent signal arrival times between transmitters, impacting the synchronized display of multi-channel video systems. When the inter-channel arrival delay exceeds one frame, this asynchrony is perceived by the naked eye as "screen tearing." As video resolution and frame rates increase, the stability and lifespan of long-distance transmitters become increasingly prominent.

[0004] In multi-channel video systems, "zero latency" is crucial for ensuring the synchronous transmission of multiple video channels. Video delay in any channel can significantly impact the overall system's display quality. However, in practice, latency issues often occur during video signal transmission, becoming a significant factor affecting project quality and overall system performance.

[0005] To address the issue of "zero latency" requirements not being met, namely the asynchrony of video signals between different channels, current multi-channel video system projects often utilize highly integrated video fiber optic transmission cables. However, this approach also introduces new challenges. The high integration of laser devices and other related components leads to heat accumulation and poor heat dissipation, especially when transmitting high-bandwidth video. Furthermore, fiber optic cables are custom-made and fixed in length, lacking versatility. The "temperature drift" caused by poor heat dissipation can lead to unstable transmission and even component damage, thus affecting product lifespan and system stability. In practical applications, the service life of these fiber optic cables is often short, significantly increasing system maintenance costs. Summary of the Invention

[0006] In view of the above problems, an embodiment of the present application is proposed, which provides a high-speed synchronous transmission device for multi-channel digital video and a video playback system to at least solve the above problems.

[0007] An embodiment of the present application provides a high-speed synchronous transmission device for multi-channel digital video, comprising: a plurality of high-speed synchronous transmission modules, one high-speed synchronous transmission module being configured to transmit a high-bandwidth digital video signal from one video source, and a plurality of high-bandwidth digital video signals from multiple video sources being transmitted at high speed and synchronously;

[0008] Among them, each high-speed synchronous transmission module includes: video input interface, laser sending module, laser receiving module, video output interface;

[0009] The video input interface receives the high-bandwidth digital video signal from the video source;

[0010] The laser transmission module includes a laser driver and a laser emitter. The laser driver is connected to the video input interface to convert it into a laser driving signal. The laser emitter is connected to the laser driver to generate a laser signal corresponding to the high-bandwidth digital video signal under the drive of the laser driving signal.

[0011] The laser receiving module includes a laser receiver and a signal restoration circuit. The laser receiver is used to receive the laser signal generated by the laser transmitter and convert it into a photocurrent signal. The signal restoration circuit is connected to the laser receiver to process the photocurrent signal and restore the high-bandwidth digital video signal for playback.

[0012] An embodiment of the present application further provides a video playback system, characterized in that it includes the high-speed synchronous transmission device for multi-channel digital video as described in any one of the items of the present application.

[0013] In this application, the use of laser modules can meet the needs of long-distance transmission and overcome the limitations of traditional copper cables; modular settings and fine internal structures can reduce processing speed differences and reduce latency; no encoding and decoding processing is involved, which avoids related processing delays, effectively ensuring synchronous transmission and improving display effects; the signal restoration circuit ensures that the signal is complete and accurate to facilitate synchronous playback; it can also effectively avoid heat dissipation problems, and has both flexibility and versatility in system construction and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0015] Figure 1 This is a structural diagram of a high-speed synchronous transmission device for multi-channel digital video in this application.

[0016] Figure 2 This is a structural diagram of a high-speed synchronous transmission module of this application. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0018] For ease of understanding, before describing the specific embodiments of the present application in detail, an example description is given of the application scenarios of the high-speed synchronous transmission device for multi-channel digital video and the video playback system of the present application.

[0019] Figure 1 This is a structural diagram of a high-speed synchronous transmission device for multi-channel digital video in this application. Figure 2 This is a structural diagram of a high-speed synchronous transmission module for this application. Figure 1 、 2 As shown, the high-speed synchronous transmission device for multi-channel digital video includes: a plurality of high-speed synchronous transmission modules, one high-speed synchronous transmission module is used to transmit a high-bandwidth digital video signal of a video source, and the high-bandwidth digital video signals of multiple video sources are transmitted synchronously at high speed;

[0020] Among them, each high-speed synchronous transmission module includes: video input interface, laser sending module, laser receiving module, video output interface;

[0021] The video input interface receives the high-bandwidth digital video signal from the video source;

[0022] The laser transmission module includes a laser driver and a laser emitter. The laser driver is connected to the video input interface to convert it into a laser driving signal. The laser emitter is connected to the laser driver to generate a laser signal corresponding to the high-bandwidth digital video signal under the drive of the laser driving signal.

[0023] The laser receiving module includes a laser receiver and a signal restoration circuit. The laser receiver is used to receive the laser signal generated by the laser transmitter and convert it into a photocurrent signal. The signal restoration circuit is connected to the laser receiver to process the photocurrent signal and restore the high-bandwidth digital video signal for playback.

[0024] The solution of the embodiment of the present application has at least the following technical advantages:

[0025] (1) Using high-speed synchronous transmission equipment for multi-channel digital video based on laser technology, the video signal transmission is completed using laser transmitting modules and laser receiving modules. Laser transmission loss in optical fiber is low. Compared with traditional copper cables (such as technology based on the DisplayPort interface, the transmission distance is generally only 3 meters), it can easily meet the long-distance transmission requirements of tens or even hundreds of meters between the video source device and the display device in the multi-channel video system, effectively overcoming the problem that traditional copper cables cannot meet system requirements due to transmission distance limitations.

[0026] (2) Each high-speed synchronous transmission module is dedicated to transmitting the high-bandwidth digital video signal of a video source. This modular setting can optimize the video signal processed by each module separately, reducing the processing speed inconsistency caused by chip manufacturing differences that may arise when multi-channel shared processing equipment.

[0027] The laser transmitter and receiver modules have sophisticated internal structures that facilitate precise signal processing to reduce latency. For example, when the laser driver converts the high-bandwidth digital video signal received by the video input interface into a laser drive signal, it undergoes meticulous steps such as impedance matching (the first input impedance network) and frequency equalization (equalization word) to ensure that the signal is stable and accurate in the early stages of conversion and transmission. This facilitates the subsequent generation and transmission of laser signals, reduces the "unsynchronized arrival" between different transmitters due to improper signal processing, and thus reduces the impact of processing delays on the synchronous display effects of multi-channel systems.

[0028] (3) Crucially, this clearly specifies the video data transmission process, not the encoding and decoding process of the video data frames. This ensures that the entire video data transmission will not experience any processing delays caused by encoding and decoding, further ensuring that the signal can be transmitted between channels more promptly and accurately, effectively guaranteeing the synchronous transmission of multi-channel video, and greatly improving the system's synchronous display effect.

[0029] (4) The system is equipped with multiple high-speed synchronous transmission modules, each of which is responsible for transmitting the high-bandwidth digital video signal of a video source, thus realizing the separate processing and transmission of multiple video source signals. This one-to-one correspondence enables more precise control of the transmission time and status of each video source signal during the transmission process. Compared with the previous situation where video signals between different channels interfere with each other and delays are not synchronized due to shared transmission lines or processing equipment, it can more effectively ensure the synchronous transmission of video signals in each channel, effectively approaching the goal of "zero delay", and effectively solving the problem of significant impact of inter-channel video delay on the display effect of the entire system.

[0030] (5) The signal restoration circuit in the laser receiving module uses components such as a multi-stage gain amplifier, a logic output buffer circuit, and a DC offset compensation circuit to perform multi-step processing on the photocurrent signal to restore a high-bandwidth digital video signal for playback. This series of sophisticated restoration processes ensures that the received laser signal can be accurately restored to the original video signal, ensuring the integrity and accuracy of the video signal after transmission, further facilitating the synchronous playback of video signals on each channel, and fully meeting the high requirements of multi-channel video systems for video display synchronization.

[0031] (6) Similarly, since the encoding and decoding process of the video data frame is not involved, there is no processing delay in this regard during the entire video data transmission process, so that the video signals of each channel can be transmitted more smoothly and synchronously, realizing the synchronous transmission function of multi-channel video, and providing high-quality transmission guarantee for multiple synchronous videos in the system.

[0032] (7) Unlike the previous background technology that uses a highly integrated video fiber transmission line, which causes heat accumulation and poor heat dissipation due to the high integration of laser devices, the high-speed synchronous transmission equipment of multi-channel digital video in this solution effectively avoids the problems of "temperature drift", unstable transmission and even device damage caused by heat dissipation problems, which affect the product life and system stability.

[0033] (8) This solution focuses on the module design and signal processing of high-speed synchronous transmission equipment for multi-channel digital video. It has certain flexibility and versatility in system construction and application, and will not affect the normal use and expansion of the system due to the inherent limitations of similar optical fiber lines.

[0034] Optionally, the laser driver includes a first input impedance network, an equalizer, a driving circuit, and an impedance bias network;

[0035] The first input impedance network is connected to the video input interface to receive one channel of video data and performs impedance matching on the received one channel of video data to generate a first differential signal;

[0036] The equalizer is connected to the first input impedance network to receive the first differential signal and perform frequency equalization processing on the received first differential signal to obtain a lossless signal;

[0037] The driving circuit is connected to the equalizer to receive the wireless lossless signal, and amplify and convert the received wireless lossless signal to generate the laser driving signal;

[0038] The impedance bias network is connected to the driving circuit to input bias parameters to the driving circuit, so that the driver amplifies and converts the received lossless signal and generates the laser driving signal accordingly.

[0039] To this end, the various components of the laser driver work together to effectively improve signal quality. The first input impedance network performs impedance matching to generate the first differential signal, laying a good foundation for subsequent processing. The equalizer's frequency equalization converts the signal into a lossless signal, reducing loss and distortion during signal transmission. The drive circuit amplifies and converts the lossless signal to generate the laser drive signal, ensuring sufficient driving power to operate the laser transmitter. Ultimately, the transmitted video signal can be transmitted over long distances in the form of a high-quality laser signal, maintaining signal accuracy and stability.

[0040] In addition, the impedance bias network inputs bias parameters to the driving circuit, allowing the driver to accurately amplify and convert the lossless signal to generate a suitable laser driving signal according to different input signal conditions (such as the characteristics of different video data). This achieves fine control of the signal processing process and ensures that the entire laser driving link can be well adapted to different video sources and transmission requirements.

[0041] In a specific implementation, the first input impedance network can utilize a circuit network composed of multiple resistors, capacitors, and other components to achieve impedance matching. For example, for the 50Ω single-ended impedance and 100Ω differential impedance networks, resistors of specific values ​​can be combined in series and parallel to construct circuit components that meet the 50Ω single-ended impedance and 100Ω differential impedance requirements, respectively. When video data is input from the video input interface, these carefully designed resistor-capacitor combination circuits process the input video data so that it meets the input signal impedance characteristics requirements of subsequent equalizer and other circuits, thereby generating a first differential signal.

[0042] For the equalizer, a combination of active or passive filter circuit elements can be used. For example, an LC filter circuit composed of an inductor and a capacitor or an active filter circuit composed of an operational amplifier combined with relevant capacitors and resistors can be used. These circuits can adjust the frequency component of the first differential signal input from the first input impedance network according to the set frequency characteristics, filter out unnecessary frequency components, or enhance certain key frequencies, thereby achieving frequency equalization and obtaining a lossless signal. The principle is to make the transmission characteristics of the signal more uniform in the entire frequency domain by processing different frequency signals in different ways (such as attenuation or amplification), thereby reducing the degradation of signal quality caused by frequency-related losses.

[0043] A power amplifier circuit can be used to implement the drive circuit. Common power amplifier circuit types include Class A, Class B, and Class AB power amplifiers. In this application, the appropriate power amplifier circuit type can be selected based on factors such as the required amplification factor, efficiency, and signal distortion requirements. For example, if a higher amplification factor is required and the distortion requirements are relatively less stringent, a Class B power amplifier may be selected. The power amplifier circuit generates the laser drive signal by amplifying the current or voltage of the lossless signal input from the equalizer and performing the necessary signal conversion operations (such as converting a small signal into a high current or high voltage signal suitable for driving the laser transmitter). Its core is to utilize the amplification characteristics of active components such as transistors (such as triodes and field-effect transistors) under appropriate bias conditions (partial bias parameters are provided by the impedance bias network) to effectively amplify and convert the input signal.

[0044] Finally, the impedance bias network can be composed of components such as resistors and capacitors. By reasonably setting the resistance and capacitance of these components, accurate bias parameters can be input to the drive circuit. For example, a resistor divider circuit can be used to divide the power supply voltage by connecting two resistors of different resistance values ​​in series to obtain a suitable bias voltage, which is then filtered by a capacitor and input into the drive circuit. Alternatively, a more complex network composed of multiple resistors and capacitors can be used to dynamically adjust parameters such as the bias current or bias voltage input to the drive circuit according to the specific drive circuit requirements and the operating characteristics of the entire laser driver, thereby ensuring that the drive circuit can amplify and convert the lossless signal as expected to generate a suitable laser drive signal.

[0045] Optionally, the first input impedance network includes a 50Ω single-ended impedance & a 100Ω differential impedance network, the 50Ω single-ended impedance is connected to the 100Ω differential impedance network, the 50Ω single-ended impedance is connected to the video input interface to receive one channel of video data, to perform 50Ω and 100Ω impedance matching on the received one channel of video data to generate a first differential signal, and the 100Ω differential impedance network is connected to the equalizer to transmit the first differential signal to the equalizer.

[0046] To this end, the first input impedance network adopts a 50Ω single-ended impedance and 100Ω differential impedance network structure, which has the following technical advantages:

[0047] (1) For the video data input from the video input interface, it is very critical to match the 50Ω single-ended impedance and the 100Ω differential impedance. In an electronic circuit system, when the signal source impedance, transmission line impedance, and load impedance match each other, maximum power transmission can be achieved and signal reflection can be effectively reduced. By connecting the 50Ω single-ended impedance to the video input interface, the input single-ended video data can adapt to the appropriate impedance environment when entering the network, avoiding signal reflection at the interface due to impedance mismatch, thereby ensuring that the video data can smoothly enter the subsequent processing links and reducing signal loss and distortion.

[0048] At the same time, a 100Ω differential impedance network is connected to the equalizer, providing a matching differential impedance environment for the first differential signal subsequently transmitted to the equalizer. Differential signal transmission offers advantages such as strong interference immunity in many situations, and proper 100Ω differential impedance matching can further optimize differential signal transmission characteristics, ensuring that the first differential signal maintains good signal integrity during transmission to the equalizer, reducing signal quality degradation caused by impedance mismatch.

[0049] (2) When processing the received video data, the impedance network structure can generate a first differential signal based on the synergistic effect of 50Ω single-ended impedance and 100Ω differential impedance. The differential signal is composed of two signals with equal amplitudes and opposite phases. Compared with single-ended signals, it has obvious advantages in anti-interference ability and common-mode noise suppression. The differential signal is generated by the specific processing method of the input video data through this impedance network, providing a signal form that is more suitable for high-precision processing for subsequent signal processing links (such as frequency equalization processing of the equalizer, etc.), which helps to improve the accuracy and stability of the entire system in video signal processing.

[0050] (3) Due to the good impedance matching and differential signal generation, the quality of the first differential signal generated and transmitted to the equalizer is significantly improved. It can not only effectively resist external interference, but also reduce signal distortion caused by factors such as reflection during transmission due to impedance matching, laying a solid foundation for subsequent processing into high-quality laser drive signals and ultimately achieving high-quality video signal transmission.

[0051] Optionally, the laser driver further includes an automatic optical power control loop, which is connected to the first input impedance network to monitor the power of the laser drive signal and control the configuration parameters of the drive circuit accordingly so that the power of the laser drive signal is constant.

[0052] Optionally, the automatic optical power control loop includes an optical power monitor, a comparator, a controller, and a drive circuit interface;

[0053] Wherein, the optical power monitor is used to monitor the optical power of the laser driving signal in real time;

[0054] The comparator compares the monitored optical power with a set optical power reference value to generate an error signal;

[0055] The controller is used to adjust the configuration parameters of the driving circuit according to the error signal, calculate the driving current or voltage value that needs to be adjusted, and generate an adjustment instruction;

[0056] The driving circuit interface is used to transmit the adjustment instruction to the driving circuit to adjust the driving current or voltage value of the driving circuit and thereby make the power of the laser driving signal constant.

[0057] To this end, the automatic optical power control loop and its components have the following technical advantages:

[0058] (1) In high-speed synchronous transmission equipment for multi-channel digital video, the power stability of the laser drive signal is crucial. The automatic optical power control loop monitors the power of the laser drive signal in real time and dynamically adjusts the configuration parameters of the drive circuit based on the monitoring results, so that the power of the laser drive signal can always remain constant. This is critical to maintaining the stability and accuracy of the entire video signal transmission, because stable laser drive signal power can ensure that the laser transmitter outputs a stable laser signal, thereby ensuring that the video signal will not experience signal distortion, attenuation, etc. due to laser power fluctuations during long-distance transmission, thereby ensuring high-quality synchronous transmission of multi-channel video.

[0059] (2) The optical power monitor can monitor the optical power of the laser drive signal in real time, providing accurate feedback information for the entire control loop. By timely obtaining the current optical power status of the laser drive signal, subsequent comparisons, adjustments, and other operations can be performed based on the latest and most accurate data, effectively avoiding signal transmission problems caused by the inability to timely understand optical power changes, such as device damage caused by excessive power or insufficient signal strength caused by too low power.

[0060] (3) The comparator compares the optical power detected in real time by the optical power monitor with the set optical power reference value to generate an error signal. This error signal accurately reflects the degree of deviation between the current laser drive signal power and the desired power, providing a key basis for the controller to make precise adjustments. By clarifying this deviation, subsequent adjustment operations can be targeted to correct the power deviation of the laser drive signal, ensuring that it is as close as possible to and maintained at the set ideal power level.

[0061] (4) The controller can flexibly and intelligently adjust the configuration parameters of the drive circuit based on the error signal generated by the comparator. It calculates the drive current or voltage value that needs to be adjusted and generates corresponding adjustment instructions, thereby achieving fine control of the working state of the drive circuit. This intelligent adjustment method enables the drive circuit to respond promptly according to the actual power of the laser drive signal and dynamically change its drive current or voltage value, thereby effectively maintaining the constant power of the laser drive signal and ensuring that the entire system can maintain stable signal transmission performance under different working conditions (such as different video sources, different transmission distances, etc.).

[0062] (5) The drive circuit interface is responsible for accurately transmitting the adjustment instructions generated by the controller to the drive circuit. This ensures that the adjustment instructions can act on the drive circuit in a timely and effective manner, so that the drive circuit can adjust the drive current or voltage value as expected. Without this accurate transmission link, even if the controller generates the correct adjustment instructions, it will not be able to effectively control the drive circuit, and thus it will not be possible to ensure that the power of the laser drive signal is constant. Therefore, the drive circuit interface plays a crucial bridging role in the entire automatic optical power control loop, ensuring that the system can accurately control the power of the laser drive signal according to real-time monitoring conditions.

[0063] Optionally, the signal restoration circuit includes: a multi-stage gain amplifier, a logic output buffer circuit, a DC offset compensation circuit, a peak detection circuit, a signal loss output buffer, and a logic control circuit;

[0064] The multi-stage gain amplifier and the laser receiver receive the photocurrent signal and perform multi-stage gain amplification to obtain a multi-stage gain amplified signal;

[0065] The DC offset compensation circuit is connected to the multi-stage gain amplifier to perform DC offset compensation on the multi-stage gain amplified signal to obtain a compensated signal;

[0066] The logic output buffer circuit is connected to the DC offset compensation circuit to perform logic processing on the compensated signal to obtain a logic level signal;

[0067] The peak detection circuit is connected to the DC offset compensation circuit to detect the peak value of the compensated signal so as to control the multi-stage gain amplifier;

[0068] The signal loss output buffer is connected to the multi-stage gain amplifier to monitor the integrity of the multi-stage gain amplified signal and control the multi-stage gain amplifier when the multi-stage gain amplified signal is detected to be lost;

[0069] The logic control circuit is connected to the multi-stage gain amplifier, the DC offset compensation circuit, the peak detection circuit, and the signal loss output buffer to logically control the working processes of multiple pairs of the multi-stage gain amplifier, the logic output buffer circuit, the DC offset compensation circuit, the peak detection circuit, and the signal loss output buffer, so that the signal restoration circuit processes the photocurrent signal and restores the video data as one channel of playback data.

[0070] To this end, the signal restoration circuit and its components, through their respective functions and collaborative work, provide the following technical benefits to high-speed synchronous transmission equipment of multi-channel digital video in terms of signal amplification, DC offset compensation, logic processing, signal integrity monitoring, and overall logic coordination:

[0071] (1) The signal restoration circuit, through the coordinated work of a series of components such as a multi-stage gain amplifier, a logic output buffer circuit, and a DC offset compensation circuit, can perform multi-step fine processing on the photocurrent signal transmitted by the laser receiver, and ultimately restore the original video data as the playback data. This ensures that after a series of processes such as laser transmission, the video signal can be accurately restored to a state that can be played normally, ensuring the accuracy and integrity of video playback in multi-channel video systems and meeting the requirements for video display synchronization and high-quality transmission.

[0072] (2) The multi-stage gain amplifier receives the photocurrent signal and performs multi-stage gain amplification to obtain a multi-stage gain amplified signal. During the laser signal transmission process, the photocurrent signal may become relatively weak due to transmission loss and other reasons. The multi-stage gain amplifier effectively enhances the signal strength by amplifying it step by step, so that subsequent circuit components can better process it. This lays the foundation for the entire signal restoration process, ensuring that the subsequent processing links can receive signals of sufficient strength, avoiding inaccurate processing or unprocessable situations due to too weak signals.

[0073] (3) The DC offset compensation circuit connected to the multi-stage gain amplifier performs DC offset compensation on the multi-stage gain amplified signal to obtain a compensated signal. During the signal amplification process, a DC offset phenomenon may be introduced, that is, the DC component of the signal deviates from the normal level. The DC offset will affect the accuracy of the signal and the subsequent processing effect. Through the compensation effect of the DC offset compensation circuit, the influence of this DC offset can be effectively eliminated, so that the DC component of the compensated signal returns to a normal state, thereby improving the quality of the signal and ensuring that subsequent logic processing and other links can operate based on accurate signals.

[0074] (4) The logic output buffer circuit performs logic processing on the compensated signal to obtain a logic level signal. It converts the previously processed signal into a logic level form suitable for subsequent devices (such as displays) to receive and process. This logic processing makes the signal more consistent with the requirements of the playback device, facilitating subsequent video playback operations. At the same time, it also further standardizes and organizes the signal to a certain extent, improving the signal's playability and compatibility.

[0075] (5) The peak monitoring circuit is connected to the DC offset compensation circuit, and the multi-stage gain amplifier is controlled by monitoring the peak value of the compensated signal. During the signal processing process, the peak value of the signal can reflect the strength and change of the signal. By monitoring the peak value in real time, when the signal peak value is found to be abnormal (such as too high or too low), the gain and other parameters of the multi-stage gain amplifier can be adjusted in time to achieve dynamic control of the signal strength. This helps to maintain the stability of the signal throughout the processing process and avoid problems such as signal distortion or processing difficulties caused by excessive fluctuations in signal strength.

[0076] (6) The signal loss output buffer is connected to the multi-stage gain amplifier to monitor the integrity of the multi-stage gain amplified signal. When the multi-stage gain amplified signal loss is detected, the multi-stage gain amplifier can be controlled in a timely manner. This ensures that possible signal loss can be discovered in a timely manner during the signal processing process, and the signal can be restored or other corresponding measures can be taken by controlling the multi-stage gain amplifier (such as adjusting its working state, etc.), thereby ensuring the integrity of the signal and avoiding problems such as video playback interruption or errors caused by signal loss.

[0077] (7) The logic control circuit is connected to the multi-stage gain amplifier, DC offset compensation circuit, peak monitoring circuit, and signal loss output buffer to perform logical control on the working process of each component. It ensures that the components can work together in the correct order and logical relationship, so that the entire signal restoration circuit can process the photocurrent signal efficiently and accurately. Through the coordination of the logic control circuit, problems such as signal processing errors or low efficiency caused by the lack of coordination between components can be avoided, thereby improving the working performance and reliability of the entire signal restoration circuit.

[0078] Optionally, the high-speed synchronous transmission device for multi-channel digital video further includes a power supply network, which includes multiple power supply modules, different power supply modules are assigned different identifiers, and one power supply module supplies power to one high-speed synchronous transmission module.

[0079] Therefore, the above-mentioned power supply network is provided in the high-speed synchronous transmission equipment of multi-channel digital video, which has the following technical advantages:

[0080] (1) Each high-speed synchronous transmission module is powered by a separate power module, achieving independence in power supply for each transmission module. This effectively avoids the mutual interference that may occur when multiple modules share a single power supply. For example, when the power demand of one module fluctuates significantly (such as a momentary increase in current), it will not affect the normal power supply of other modules. This ensures that each module can operate under stable power conditions, thereby maintaining the stable operation of the entire multi-channel digital video transmission equipment.

[0081] (2) A stable power supply is crucial for the high-speed synchronous transmission module to accurately process and transmit video signals. A separate power supply module can provide continuous and stable power to the corresponding transmission module, so that components such as the laser transmitter module and the laser receiver module will not experience signal distortion or processing errors due to power fluctuations when performing signal conversion, transmission, and processing operations, effectively ensuring the high-quality synchronous transmission of video signals in each channel.

[0082] (3) Different power modules are assigned different identifiers. When a power supply-related fault occurs in the system, the power module identifier can be used to quickly and accurately locate the specific power module with the problem, thereby narrowing the scope of troubleshooting. This fault isolation mechanism makes it possible to more efficiently identify the power supply fault point when facing complex multi-channel digital video transmission equipment, reducing the time and workload of troubleshooting and improving the maintainability of the system.

[0083] (4) Because each high-speed synchronous transmission module is powered by an independent power module, when maintaining or replacing a transmission module, the corresponding power module can be operated independently without affecting other normally operating modules. For example, when a faulty high-speed synchronous transmission module needs to be replaced, it is only necessary to disconnect the corresponding power module, replace the module, and then reconnect the power supply. The operation process is simple and does not cause unnecessary interference to other parts of the system, facilitating daily maintenance and upgrades of the system.

[0084] (5) With the development of multi-channel digital video systems, it may be necessary to add new high-speed synchronous transmission modules to meet the transmission needs of more video sources. The existing power supply network structure is convenient for system expansion. It only needs to add new power supply modules with labels and connect them to the newly added high-speed synchronous transmission modules. There is no need for large-scale redesign and transformation of the entire power supply system, which provides convenient conditions for system scalability.

[0085] (6) Power modules with different markings can be flexibly configured according to the specific requirements of different high-speed synchronous transmission modules (such as power requirements, voltage requirements, etc.). For example, for transmission modules that process high-bandwidth video signals and have higher requirements for power supply stability, power modules with better performance can be configured; while for some relatively conventional transmission modules, power modules with ordinary specifications can be selected. This flexible configuration method can better adapt to the diverse requirements of different modules in multi-channel digital video systems and improve the overall flexibility of the system.

[0086] Optionally, the laser emitter includes a vertical resonant cavity, which includes: two upper and lower reflectors and one or more active layers clamped between the two reflectors. When the driving signal passes through the active layer, the electrons in the laser driving signal recombine with the active layer, releasing energy and generating photons. The photons are repeatedly reflected by the upper and lower reflectors in the resonant cavity to enhance light interference and thereby form the laser signal.

[0087] To this end, the laser transmitter adopts this vertical resonant cavity structure, which brings many technical benefits to high-speed synchronous transmission equipment of multi-channel digital video in terms of efficient generation of high-quality laser signals and stable laser signal output characteristics:

[0088] (1) When the driving signal passes through the active layer, the electrons in the laser driving signal recombine with the substances in the active layer, thereby releasing energy and generating photons. This electron recombination process based on the specific active layer can achieve relatively efficient energy conversion, so that photons can be generated stably and effectively after the input of the driving signal, providing a sufficient photon source for the subsequent formation of the laser signal.

[0089] (2) The generated photons will be repeatedly reflected by the upper and lower mirrors in the vertical resonant cavity, and the laser signal will be formed through the interference of light. The interference phenomenon of light allows the light of a specific frequency to be continuously superimposed and enhanced in the resonant cavity, while the light of other frequencies cancel each other out, thereby achieving frequency screening and energy concentration of light, and ultimately forming a laser signal with high coherence, high directionality and high intensity. This high-quality laser signal is crucial for high-speed synchronous transmission equipment of multi-channel digital video. It can achieve longer distance and lower loss transmission in transmission media such as optical fiber, and can be more accurately restored to the original video signal at the receiving end, ensuring the accuracy and stability of video signal transmission.

[0090] (3) The structure of the vertical resonant cavity itself provides a relatively stable physical environment for the generation of laser signals. The upper and lower reflectors and the active layer sandwiched between them together form a closed and adjustable space, so that the reflection, interference and other processes of photons in it can proceed according to relatively fixed rules. This stability helps to maintain the consistency of the laser signal output, that is, the laser signal generated each time can remain relatively stable in terms of frequency, intensity, phase, etc., avoiding large changes in the laser signal due to external factors (such as slight temperature changes, small fluctuations in the drive signal, etc.), thereby providing a reliable signal source for multi-channel digital video transmission equipment and ensuring the synchronization and stability of the video signal transmission of each channel.

[0091] (3) The vertical resonant cavity structure is adjustable to a certain extent. For example, the resonant frequency and other optical properties of the resonant cavity can be adjusted by changing parameters such as the spacing between the reflectors, the material or thickness of the active layer, etc. This adjustability enables the laser transmitter to be optimized and adjusted according to the specific needs of the multi-channel digital video system (such as different laser signal requirements corresponding to different video resolutions and frame rates), thereby better adapting to different transmission scenarios and video signal characteristics, further improving the flexibility and adaptability of the system.

[0092] Optionally, the laser receiver includes a photosensor and a signal processing circuit, the photosensor receives the laser signal generated by the laser transmitter and converts it into an initial photocurrent signal, the signal processing circuit processes the initial photocurrent signal to obtain the photocurrent signal, and the processing includes at least one of amplification, shaping, and compensation processing.

[0093] To this end, the laser receiver, a structure consisting of a photosensitive element and signal processing circuit, brings the following technical benefits to high-speed synchronous transmission equipment of multi-channel digital video in terms of effective signal conversion, improved signal quality, and enhanced adaptability:

[0094] (1) The photosensitive element is able to receive the laser signal generated by the laser transmitter and accurately convert it into the initial photocurrent signal. This conversion process is the basis of the entire receiving link, allowing the laser signal in the form of an optical signal to be converted into a photocurrent signal in the form of an electrical signal, thereby facilitating further processing by subsequent electronic circuits. This light-to-electricity conversion capability ensures that the information transmitted by the laser can be obtained in a manner suitable for processing by electronic equipment, laying the foundation for restoring the original video signal.

[0095] (2) The signal processing circuit amplifies the initial photocurrent signal, which can effectively enhance the signal strength. During the laser signal transmission process, due to transmission loss and other reasons, the laser signal reaching the laser receiver may be relatively weak, and the converted initial photocurrent signal is also relatively weak. Through amplification processing, the weak initial photocurrent signal can be enhanced to an appropriate intensity, so that subsequent circuit components (such as subsequent components at all levels in the signal recovery circuit) can better process it, avoiding inaccurate or unprocessable processing due to too weak signals, and ensuring that the signal can be smoothly transmitted throughout the entire receiving and recovery link.

[0096] (3) Shaping the initial photocurrent signal can make the signal waveform more regular, meeting the requirements of subsequent circuit processing and the final restoration of the video signal. For example, during the laser transmission process, the signal waveform may be distorted due to various interference factors. Shaping can correct these distortions and restore the signal to a more standard waveform state, improving the signal's processability and adaptability to subsequent circuits, and helping to more accurately restore the original video signal.

[0097] (4) Compensation processing can compensate for some characteristic changes that occur during the transmission of laser signals (such as changes in signal characteristics caused by factors such as temperature changes). By performing corresponding compensation processing on the initial photocurrent signal, the relevant parameters of the signal (such as amplitude, phase, etc.) can be adjusted to restore it to a state closer to the original transmission state, thereby improving the signal quality and reducing signal distortion caused by external factors during the transmission process, further ensuring the accuracy of the final restored video signal.

[0098] To this end, the specific circuits of the photosensitive element and signal processing circuit can effectively convert the laser signal generated by the laser transmitter into a suitable photocurrent signal, and amplify, shape, compensate and process it to meet the signal processing requirements of the receiving end of the high-speed synchronous transmission equipment of multi-channel digital video.

[0099] Photosensitive elements, such as photodiodes, operate based on the semiconductor's photoelectric effect. When a laser signal generated by a laser emitter strikes the photodiode's PN junction, the photon's energy is absorbed by the semiconductor, allowing electrons in the valence band to gain sufficient energy to transition to the conduction band, generating electron-hole pairs. Under the influence of the electric field within the PN junction, electrons migrate to the N region and holes to the P region, forming a photocurrent that is related to the light intensity. This converts the laser signal into the initial photocurrent signal.

[0100] Alternatively, a photomultiplier tube (PMT) can be used. It consists of a photocathode, several dynodes, and an anode. When a laser signal strikes the photocathode, electrons are generated based on the photoelectric effect. These electrons are accelerated by the electric field and collide with the dynodes. Each time they collide with a dynode, the number of electrons multiplies. After multiple multiplications by multiple dynodes, a large number of electrons are ultimately collected at the anode, forming a detectable photocurrent. The advantage of a PMT is its extremely high sensitivity, which allows it to detect very weak laser signals. However, it is also relatively expensive and has a more complex structure.

[0101] Whether it's a photodiode or a photomultiplier tube, they're typically reverse-biased in their circuits. For example, in a photodiode, its P region is connected to the negative terminal of the power supply, and its N region is connected to the positive terminal (via a suitable resistor). This connection ensures that when there's no light, only a small reverse leakage current flows. However, when a laser signal is applied, the generated photocurrent creates a noticeable current change in the reverse-biased circuit, facilitating detection and processing by subsequent circuits.

[0102] For the signal processing circuit, for example, an amplifier circuit may be included, which may be an amplifier composed of a transistor or a field-effect transistor. For example, a common-emitter transistor amplifier circuit is used to input the initial photocurrent signal output by a photosensitive element (such as a photodiode) into the base of the transistor through a coupling capacitor. The collector of the transistor is connected to a higher power supply voltage, and the emitter is grounded through an emitter resistor. When the input initial photocurrent signal changes, it will cause a change in the base current of the transistor, and then through the amplification effect of the transistor, an amplified current signal is output at the collector, thereby amplifying the initial photocurrent signal.

[0103] To achieve higher amplification, multiple amplifier circuits may be connected in series. For example, after the common-emitter transistor amplifier circuit described above, a similar amplifier circuit or another type of amplifier circuit, such as a differential amplifier, may be connected as a second stage of amplification. This multi-stage amplification can gradually boost the weak initial photocurrent signal to sufficient intensity to meet the requirements of subsequent circuit processing.

[0104] Furthermore, the shaping circuit utilizes a comparator. The initial photocurrent signal is divided by a suitable resistor divider network and then fed into one input of the comparator. A fixed reference voltage is set at the other input. When the input signal is higher than the reference voltage, the comparator outputs a high level; when the input signal is lower than the reference voltage, the comparator outputs a low level. This comparison and output switching process can shape the irregular initial photocurrent signal waveform into a square wave or other regular waveform, making it more suitable for subsequent circuit processing.

[0105] Alternatively, shaping can be achieved using a Schmitt trigger, a commonly used shaping circuit component. It exhibits hysteresis: when the input signal rises from a low level to a certain threshold, the output level changes from a low level to a high level; when the input signal falls from a high level to another threshold, the output level changes from a high level to a low level. By inputting the initial photocurrent signal into a Schmitt trigger, its hysteresis characteristic can effectively shape the signal waveform, removing small fluctuations and distortions and making the waveform more regular.

[0106] Furthermore, regarding the implementation of a compensation circuit, since the laser signal may be affected by temperature changes during transmission, causing the initial photocurrent signal characteristics of the photosensitive element to change, a temperature compensation circuit can be used to address this issue. For example, a thermistor and a fixed resistor form a voltage divider. The initial photocurrent signal output by the photosensitive element is compared with the voltage output of the voltage divider. A difference amplifier composed of an operational amplifier adjusts parameters such as the signal amplitude to compensate for changes in signal characteristics caused by temperature changes.

[0107] Finally, if phase shifts occur during laser signal transmission, a phase compensation circuit can be employed. A simple phase compensation circuit can consist of an LC circuit consisting of a capacitor and an inductor. The initial photocurrent signal is passed through the LC circuit, and the resonant characteristics of the LC circuit adjust the signal's phase to a value closer to the original transmitted state, thereby compensating for the phase shift.

[0108] An embodiment of the present application further provides a video playback system, which includes the high-speed synchronous transmission device for multi-channel digital video as described in any one of the embodiments of the present application.

[0109] In addition to being a multi-channel video simulation system and a multi-channel dome display system, the video playback system may also be applicable to the following systems:

[0110] 1. Multi-channel video surveillance system

[0111] In video surveillance applications in large venues (such as shopping malls, airports, industrial parks, etc.), it is often necessary to monitor multiple areas at the same time, and each area can be used as a channel. These surveillance cameras serve as video sources, and the video data generated needs to be transmitted to the display device of the monitoring center for real-time playback and viewing. There are high requirements for the synchronization of the video display of each channel to ensure that the monitoring personnel can accurately and coherently observe the situation in different areas. The high-speed synchronous transmission equipment of the multi-channel digital video of this application can meet the needs of long-distance transmission (surveillance cameras may be distributed in a wide area and far away from the monitoring center), while ensuring the synchronous transmission and high-quality playback of the videos of each channel, so it can be applied to this system.

[0112] 2. Multi-channel virtual reality (VR) / augmented reality (AR) display system

[0113] In a VR / AR experience scenario, there may be multiple perspectives or scene elements that require video data to be transmitted through different channels to build a complete virtual or augmented reality environment. For example, in some high-end VR games or immersive experience projects, in order to provide users with a more realistic and coherent visual experience, video content such as scene images and character actions in different directions need to be displayed synchronously on the VR device. The high-speed synchronous transmission equipment of this application can ensure zero-delay synchronous transmission of multi-channel videos, avoid problems such as screen tearing or asynchrony that affect immersion, and thus improve the quality of the VR / AR experience.

[0114] 3. Multi-channel digital cinema playback system

[0115] In order to provide a more shocking and diverse viewing experience, modern digital cinemas sometimes use multi-channel video playback technology. For example, in some giant screen theaters or special format movies (such as 3D, IMAX, etc.), in addition to the main picture channel, there may be an auxiliary picture channel for displaying special effects, supplementary scenes and other content. These multi-channel videos need to be played back accurately and synchronously to ensure that the audience sees a complete, coherent and visually impactful film content. The high-speed synchronous transmission equipment of the multi-channel digital video of the present application can meet the long-distance transmission requirements between the video source (such as a server) and the projection equipment (such as a projector) in the theater environment, and ensure the synchronization of the videos of each channel, so it can be applied to the digital cinema playback system.

[0116] 4. Multi-channel video conferencing system

[0117] In a remote video conferencing scenario, when multiple participants are presenting videos at the same time (such as each participant's camera image as a channel), in order for each party to be able to see the situation of other participants clearly and synchronously, the synchronous transmission and display of each channel video are required to be high. In addition, the participants may be distributed in different locations, and there may be a long distance between the video source equipment (such as the participant's computer, camera, etc.) and the display equipment (such as the large screen in the conference room, the participant's personal monitor, etc.). The high-speed synchronous transmission equipment of multi-channel digital video in this application can effectively solve the problems of transmission distance and synchronization, and ensure the smooth progress of video conferencing.

[0118] 5. Multi-channel stage performance video display system

[0119] In large-scale stage performances, multi-channel video technology is often used to cooperate with stage performances to create more colorful stage effects. For example, in some musicals, concerts and other performances, display screens in different positions (as display devices) may need to synchronously play videos related to the performance content (the video source may come from a server or player in the background), such as stage background videos, actor close-up videos, etc. These multi-channel videos need to be strictly synchronized to ensure that the visual effects of the entire stage performance are coherent and unified. The high-speed synchronous transmission equipment of the multi-channel digital video of this application can meet the long-distance transmission requirements in the stage performance environment and ensure the synchronization of the videos of each channel, so it can be applied to such systems.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A high-speed synchronous transmission device for multi-channel digital video, characterized in that: include: A plurality of high-speed synchronous transmission modules, one high-speed synchronous transmission module is used to transmit a high-bandwidth digital video signal of a video source, and to transmit high-bandwidth digital video signals of multiple video sources synchronously at a high speed; Among them, each high-speed synchronous transmission module includes: a video input interface, a laser sending module, a laser receiving module, and a video output interface; The video input interface receives the high-bandwidth digital video signal from the video source; The laser sending module includes a laser driver and a laser emitter, wherein the laser driver is connected to the video input interface to convert the video input interface into a laser driving signal, and the laser emitter is connected to the laser driver to generate a laser signal corresponding to the high-bandwidth digital video signal under the drive of the laser driving signal; The laser receiving module includes a laser receiver and a signal restoration circuit. The laser receiver is used to receive the laser signal generated by the laser transmitter and convert it into a photocurrent signal. The signal restoration circuit is connected to the laser receiver to process the photocurrent signal and restore the high-bandwidth digital video signal for playback.

2. A multi-channel digital video high-speed synchronous transmission device according to claim 1, characterized in that: The laser driver includes a first input impedance network, an equalizer, a driving circuit, and an impedance bias network; The first input impedance network is connected to the video input interface to receive one channel of video data, and performs impedance matching on the received one channel of video data to generate a first differential signal; The equalizer is connected to the first input impedance network to receive the first differential signal, and performs frequency equalization processing on the received first differential signal to obtain a wireless lossless signal; The driving circuit is connected to the equalizer to receive the wireless lossless signal, and amplify and convert the received wireless lossless signal to generate the laser driving signal; The impedance bias network is connected to the driving circuit to input bias parameters to the driving circuit, so that the driver amplifies and converts the received lossless signal and generates the laser driving signal accordingly.

3. A multi-channel digital video high-speed synchronous transmission device according to claim 2, characterized in that: The first input impedance network includes a 50Ω single-ended impedance & a 100Ω differential impedance network, the 50Ω single-ended impedance is connected to the 100Ω differential impedance network, the 50Ω single-ended impedance is connected to the video input interface to receive one channel of video data, so as to perform 50Ω and 100Ω impedance matching on the received one channel of video data to generate a first differential signal, and the 100Ω differential impedance network is connected to the equalizer to transmit the first differential signal to the equalizer.

4. The high-speed synchronous transmission device for multi-channel digital video according to claim 2, characterized in that: The laser driver also includes an automatic optical power control loop, which is connected to the first input impedance network to monitor the power of the laser drive signal and control the configuration parameters of the drive circuit accordingly so that the power of the laser drive signal is constant.

5. The high-speed synchronous transmission device for multi-channel digital video according to claim 4, characterized in that: The automatic optical power control loop includes an optical power monitor, a comparator, a controller, and a drive circuit interface; Wherein, the optical power monitor is used to monitor the optical power of the laser driving signal in real time; The comparator compares the monitored optical power with a set optical power reference value to generate an error signal; The controller is used to adjust the configuration parameters of the driving circuit according to the error signal, calculate the driving current or voltage value that needs to be adjusted, and generate an adjustment instruction; The driving circuit interface is used to transmit the adjustment instruction to the driving circuit to adjust the driving current or voltage value of the driving circuit and thereby make the power of the laser driving signal constant.

6. The high-speed synchronous transmission device for multi-channel digital video according to claim 1, characterized in that: The signal restoration circuit includes: a multi-stage gain amplifier, a logic output buffer circuit, a DC offset compensation circuit, a peak monitoring circuit, a signal loss output buffer, and a logic control circuit; The multi-stage gain amplifier and the laser receiver receive the photocurrent signal and perform multi-stage gain amplification to obtain a multi-stage gain amplified signal; The DC offset compensation circuit is connected to the multi-stage gain amplifier to perform DC offset compensation on the multi-stage gain amplified signal to obtain a compensated signal; The logic output buffer circuit is connected to the DC offset compensation circuit to perform logic processing on the compensated signal to obtain a logic level signal; The peak monitoring circuit is connected to the DC offset compensation circuit to perform peak detection on the compensated signal to control the multi-stage gain amplifier; The signal loss output buffer is connected to the multi-stage gain amplifier to monitor the integrity of the multi-stage gain amplified signal, and when the multi-stage gain amplified signal is detected to be lost, the multi-stage gain amplifier is controlled; The logic control circuit is connected to the multi-stage gain amplifier, the DC offset compensation circuit, the peak monitoring circuit and the signal loss output buffer to perform logic control on the working processes of the multi-stage gain amplifier, the logic output buffer circuit, the DC offset compensation circuit, the peak monitoring circuit and the signal loss output buffer, so that the signal restoration circuit processes the photocurrent signal and restores the video data as one channel of playback data.

7. The high-speed synchronous transmission device for multi-channel digital video according to claim 1, characterized in that: The high-speed synchronous transmission device for multi-channel digital video also includes a power supply network, which includes a plurality of power supply modules. Different power supply modules are assigned different identifiers, and one power supply module supplies power to one high-speed synchronous transmission module.

8. The high-speed synchronous transmission device for multi-channel digital video according to claim 1, characterized in that: The laser transmitter includes a vertical resonant cavity, which includes: two reflectors arranged upper and lower and one or more active layers clamped between the two reflectors. When the driving signal passes through the active layer, the electrons in the laser driving signal recombine with the active layer, release energy and generate photons. The photons are repeatedly reflected by the upper and lower reflectors in the resonant cavity to enhance light interference and form the laser signal accordingly.

9. The high-speed synchronous transmission device for multi-channel digital video according to claim 1, characterized in that: The laser receiver includes a photosensitive element and a signal processing circuit. The photosensitive element receives the laser signal generated by the laser transmitter and converts it into an initial photocurrent signal. The signal processing circuit processes the initial photocurrent signal to obtain the photocurrent signal. The processing includes at least one of amplification, shaping, and compensation.

10. A video playback system, characterized in that: A high-speed synchronous transmission device for multi-channel digital video comprising any one of claims 1-9.

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