Optical fiber extender

Abstract

The utility model provides an optical fiber extender, which relates to the technical field of optical fiber extension equipment, comprises an SDI (Serial Digital Interface) line equalizer, an RECLOCK and line driver, a power supply module, an SDI video transmission channel, a single-fiber bidirectional optical module, an RS485 signal channel and a TALLY signal channel, and solves the problem that when a common cable is used for long-distance transmission of a higher-speed signal, the power supply module cannot be connected with the SDI video transmission channel. The phenomena of poor output signal quality, easy external interference and the like always occur; meanwhile, the transmission distance is short, the long-distance transmission requirement of occasions such as multimedia information issuing cannot be met, in practical application, a traditional cable is often difficult to support the integrity and stability of high-quality audio and video signals in long-distance transmission due to limitation of physical characteristics and transmission bandwidth of the traditional cable, and according to the research of Smitet al. (2020), the long-distance transmission requirement of the high-quality audio and video signals in the long-distance transmission process cannot be met, and the long-distance transmission requirement of the high-quality audio and video signals in the long-distance transmission process cannot be met. After the transmission distance of the traditional cable exceeds 100 meters, the signal attenuation can reach about 3dB, which has a significant influence on the image quality.

Description

Technical Field

[0001] This utility model relates to the field of optical fiber extension equipment technology, and in particular to optical fiber extenders. Background Technology

[0002] The rapid development of high-definition video transmission technology has brought great convenience to our lives and work. The demand for high-definition and long-distance transmission of video signals is increasing in urban road traffic monitoring systems, highway traffic monitoring systems, and monitoring systems for public security, confidentiality, and production. Modern digital studios all use transmission systems based on Serial Digital Interface (SDI). In digital video, to facilitate long-distance transmission of digital signals, parallel data is converted into serial data and transmitted to the receiving end via cable through a cable driver. SDI is short for this serial data interface.

[0003] In existing technologies, with the continuous advancement of science and technology and the ongoing updates to technology, high-definition multimedia interface technology has gradually evolved from HD-SDI (High-Definition Serial Digital Interface) to 3G-SDI, 6G-SDI, and 12G-SDI. In high-definition multimedia monitoring application systems, it is often necessary to transmit high-definition uncompressed digital audio and video signal sources over long distances. However, when using ordinary cables to transmit high-speed signals over long distances, phenomena such as poor output signal quality and susceptibility to external interference often occur. At the same time, the transmission distance is relatively short, which cannot meet the long-distance transmission requirements of multimedia information dissemination and other occasions. In practical applications, due to the limitations of its physical characteristics and transmission bandwidth, traditional cables often cannot support the integrity and stability of high-quality audio and video signals during long-distance transmission. For example, when using ordinary coaxial cables to transmit 3G-SDI or higher-specification high-definition signals, the signal attenuation and phase shift problems become particularly significant. According to the research of Smith et al. (2020), the signal attenuation of traditional cables can reach about 3dB after the transmission distance exceeds 100 meters, which has a significant impact on image quality. Utility Model Content

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing an optical fiber extender.

[0005] To achieve the above objectives, this utility model adopts the following technical solution: an optical fiber extender, including an SDI line equalizer, a RECLOCK and line driver, a power module, an SDI video transmission channel, a single-fiber bidirectional optical module, an RS485 signal channel, and a TALLY signal channel. The SDI video transmission channel includes input and output terminals, each fixed with a dedicated cable having a characteristic impedance of 75Ω. The input and output terminals are electrically connected to an SDI clock recovery cable equalizer. The SDI clock recovery cable equalizer has multiple output terminals internally. One output terminal is connected to a photoelectric conversion channel, and another output terminal is connected to a loop signal processing circuit. The input and output terminals are electrically connected to the photoelectric conversion channel, and the photoelectric conversion channel is electrically connected to a dual-output SDI clock recovery cable driver.

[0006] Preferably, the single-fiber bidirectional optical module is equipped with an internal laser driver and a programmable limiting amplifier circuit. The limiting amplifier circuit contains an EEPROM, which is electrically connected to a microcontroller. The single-fiber bidirectional optical module has an internal optical signal path. The 12G SDI fiber extender uses an integrated programmable laser driver and limiting amplifier circuit to realize the optical module function in SDI signal transmission. The SDI optical module is used for video transmission. The encoding method of video data stream is different from that of telecommunication data. In addition to the difference in rate, it also needs to meet a "pathological code test" of the video standard. The programmable circuit's internal EEPROM allows for multiple recalibrations and can run the microcontroller with or without external control. The output voltage is controlled by an internal DAC. A temperature-based lookup table is stored in the EEPROM. The laser driver can be configured to control the laser with an open-loop lookup table or closed-loop control.

[0007] Preferably, the RS485 signal channel uses differential signal transmission. The RS485 signal channel has two fixed signal lines and an internal RS485 transceiver circuit. The RS485 transceiver circuit uses half-duplex communication. RS485 communication uses differential signal transmission, and normally only two signal lines are needed for normal communication. In RS485 signal transmission, the RS485 transceiver circuit is usually used to convert TTL level and RS485 level. When sending data, the TX signal of the serial port controller is converted into a differential signal by the transceiver and transmitted to the bus. When receiving data, the transceiver converts the differential signal on the bus into a TTL signal and transmits it to the serial port controller through the RX pin. The RS485 transceiver circuit is a half-duplex communication circuit. The TALLY signal transmits control / indication information, meets the specified control protocol, and can be used to send control commands and status information.

[0008] Preferably, the serialization of the RS485 signal channel signal and the TALLY signal channel signal is converted using a high-speed serializer-deserializer. The fiber optic extender includes a high-speed serializer-deserializer to realize the serial-to-parallel conversion of RS485 and TALLY signals, making it suitable for high-speed data communication transmission applications. This circuit, with its high-speed data transmission capability, low-power design, and flexible data interface options, meets the stringent requirements of high-speed data communication. At the signal transmitting end, parallel data or TTL data can be converted into a high-speed serial data stream with an embedded clock. At the signal receiving end, the serial data stream can be received and deserialized back into parallel data. The data conversion uses an embedded clock, which effectively solves the bottleneck problem of high-speed transmission caused by the lack of strict synchronization between the clock and data.

[0009] Preferably, the power module uses DC 5V power supply, which enables it to be widely used in professional SDI video signal application scenarios such as UHDTV / FHDTV / HDTV / SDTV, and is particularly suitable for long-distance fiber optic transmission and application of broadcast-grade high-definition digital signals.

[0010] Preferably, the dual-output SDI clock recovery cable driver transmits the retiming signal via a 75Ω coaxial cable. The signal received from the photoelectric conversion channel at the receiving end enters the dual-output SDI clock recovery cable driver. It is a low-power, multi-rate, heavy-timed cable driver that supports rates up to 12GSDI. It is designed to receive 100Ω differential input signals, automatically recover the embedded clock from the digital video signal and retiming the incoming data, and transmit the retiming signal via a 75Ω coaxial cable. The cable driver output has highly configurable pre-emphasis and slew rate control to compensate for long traces and connector losses. In addition, it provides automatic and user-selectable output slew rate control. The integrated 75Ω termination design of the two cable driver outputs meets the stringent SMPTE specification return loss requirements, enabling ultra-high-definition video transmission for 4K applications.

[0011] Preferably, the optical signal path employs wavelength division multiplexing (WDM) technology, which uses downlink and uplink data signals of different wavelengths to transmit in a single optical fiber, thereby achieving bidirectional transmission in a single optical fiber.

[0012] Beneficial effects:

[0013] 1. In existing technologies, with the continuous advancement of science and technology and ongoing technological updates, high-definition multimedia interface technology has gradually evolved from HD-SDI (High-Definition Serial Digital Interface) to 3G-SDI, 6G-SDI, and 12G-SDI. In high-definition multimedia monitoring application systems, it is often necessary to transmit high-definition uncompressed digital audio and video signal sources over long distances. However, when using ordinary cables to transmit high-speed signals over long distances, issues such as poor output signal quality and susceptibility to external interference often arise. Furthermore, the transmission distance is relatively short, failing to meet the long-distance transmission requirements of multimedia information dissemination and other applications. In practical applications, traditional cables, due to their physical characteristics and bandwidth limitations, often struggle to support the integrity and stability of high-quality audio and video signals during long-distance transmission. For example, when using ordinary coaxial cables to transmit 3G-SDI or higher-specification high-definition signals, signal attenuation and phase shift become particularly significant, according to Smith et al. A study (2020) found that traditional cables experience signal attenuation of approximately 3dB over transmission distances exceeding 100 meters, significantly impacting image quality. To address this issue, this utility model utilizes a paired SDI fiber optic extender. Through an optical signal channel, it simultaneously supports one SDI signal input and one SDI loop-out at the transmitter, and two SDI signal outputs at the receiver. It also supports one channel of reverse RS485 and SDI tally transmission control information. The extender's transmitter sends the SDI video signal input from the BNC cable connector to the receiver over a long distance via optical cable. Without any signal compression, it outputs a high-fidelity "original" video signal. The "control protocol" varies depending on the specific application and equipment, meeting RS485 protocol requirements and providing tally control and status information. The reverse 5M bandwidth data channel uses DoC (data on...)... The technology is modulated onto the video cable. RS485 control signals can be transmitted from the monitoring room via coaxial cable to the front-end camera. SDI signal transmission at both input and output must use a dedicated 75Ω characteristic impedance cable with low high-frequency attenuation. At the transmitting end, the signal is received via cable to a low-power, multi-rate SDI clock recovery cable equalizer, supporting rates up to 12G SDI. The equalizer is used to equalize and repair signals received from the signal source via coaxial cable, compensate for the DC content of SMPTE pathological signals, and perform clock recovery on the input data. Optimized for excellent performance at 11.88 Gbps, it features programmable start-up swing compensation for incompatible sources, automatic mute or disable upon signal loss, and wide loop bandwidth control. This dual-output equalizer operates with extremely low power consumption and has two outputs, eliminating the need for an external 1:2 buffer.One output connects to the optoelectronic conversion channel, enabling the next stage of fiber optic repeater transmission. The other output connects to the loop signal processing circuit, including the signal re-equalization cable driver output circuit, completing a loop output of a signal from the coaxial cable. The signal received from the optoelectronic conversion channel at the receiving end enters the dual-output SDI clock recovery cable driver, a low-power, multi-rate, heavily timed cable driver supporting rates up to 12G SDI. It is designed to receive 100Ω differential input signals, automatically recover the embedded clock from the digital video signal and re-time the incoming data, transmitting the re-timed signal over a 75Ω coaxial cable. The cable driver output features highly configurable pre-emphasis and slew rate control to compensate for long traces and connector losses. Furthermore, automatic and user-selectable output slew rate control is provided. The integrated 75Ω termination design at both cable driver outputs meets stringent SMPTE specification return loss requirements, enabling ultra-high-definition video transmission for 4K applications.

[0014] 2. The 2G SDI fiber optic extender uses an integrated programmable laser driver and limiting amplifier circuit to realize the optical module function in SDI signal transmission. The SDI optical module is used for video transmission. The encoding method of video data stream is different from that of telecommunication data. In addition to the difference in rate, it also needs to meet a "pathological code test" of the video standard. The programmable circuit's internal EEPROM allows for multiple recalibrations and can run the microcontroller with or without external control. The output voltage is controlled by the internal DAC. The temperature-based lookup table is stored in the EEPROM. The laser driver can be configured to control the laser with open-loop lookup table or closed-loop control.

[0015] 3. RS485 communication uses differential signal transmission. Normally, only two signal lines are needed for normal communication. In RS485 signal transmission, an RS485 transceiver circuit is usually used to convert TTL level and RS485 level. When sending data, the TX signal of the serial port controller is converted into a differential signal by the transceiver and transmitted to the bus. When receiving data, the transceiver converts the differential signal on the bus into a TTL signal and transmits it to the serial port controller through the RX pin. The RS485 transceiver circuit is half-duplex communication. The TALLY signal transmits control / indication information, meets the specified control protocol, and can be used to send control commands and status information. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the application connection of the fiber optic extender of this utility model;

[0017] Figure 2 This is a block diagram illustrating the transmission principle of the SDI extender of this utility model;

[0018] Figure 3This is a block diagram illustrating the receiving principle of the SDI extender of this utility model.

[0019] Figure 4 These are the front view and side view of the present invention.

[0020] Figure 5 This is a rear view of the exterior of this utility model;

[0021] Figure 6 This is a test access block diagram of this utility model. Detailed Implementation

[0022] To make the technical means, creative features, and achieved objectives and effects of this utility model easier to understand, the present utility model is further described below with reference to specific embodiments and accompanying drawings. However, the following embodiments are merely preferred embodiments of this utility model and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments described in the implementation plan without creative effort are all within the protection scope of this utility model.

[0023] The specific embodiments of this utility model are described below with reference to the accompanying drawings. Specific implementation examples:

[0025] Reference Figure 1-6The fiber optic extender includes an SDI line equalizer, a RECLOCK and line driver, a power module, an SDI video transmission channel, a single-fiber bidirectional optical module, an RS485 signal channel, and a TALLY signal channel. The SDI video transmission channel includes input and output terminals, each fixed with a dedicated cable with a characteristic impedance of 75Ω. The input and output terminals are electrically connected to an SDI clock recovery cable equalizer. The SDI clock recovery cable equalizer has multiple output terminals; one output terminal is connected to a photoelectric conversion channel, and another output terminal is connected to a loop signal processing circuit. The input and output terminals are electrically connected to the photoelectric conversion channel, and the photoelectric conversion channel is electrically connected to a dual-output SDI clock recovery cable driver. The single-fiber bidirectional optical module has an internal laser driver and a programmable limiting amplifier circuit. The limiting amplifier circuit has an internal EEPROM, which is electrically connected to a microcontroller. The single-fiber bidirectional optical module has an internal optical signal path. The 12G SDI fiber extender uses an integrated programmable laser driver and limiting amplifier circuit to realize the optical module function in SDI signal transmission. The SDI optical module is used for video transmission. The encoding method of video data stream is different from that of telecommunication data. In addition to the difference in rate, it also needs to meet a "pathological code test" of the video standard. The programmable circuit's internal EEPROM allows for multiple recalibrations and can run the microcontroller with or without external control. The output voltage is controlled by an internal DAC. A temperature-based lookup table is stored in the EEPROM. The laser driver can be configured to control the laser with an open-loop lookup table or closed-loop control. The RS485 signal channel uses differential signal transmission. It has two fixed signal lines and an internal RS485 transceiver circuit. This circuit uses half-duplex communication. Since RS485 communication uses differential signal transmission, normally only two signal lines are needed for normal communication. In RS485 signal transmission, the transceiver circuit is typically used to convert TTL and RS485 levels. When sending data, the serial port controller's TX signal is converted into a differential signal by the transceiver and transmitted to the bus. When receiving data, the transceiver converts the differential signal on the bus back into a TTL signal and transmits it to the serial port controller via the RX pin. The RS485 transceiver circuit uses half-duplex communication; the TALLY signal transmits control / indication information, conforming to the specified control protocol, and can be used to send control commands and status information.

[0026] The RS485 and TALLY signal channels utilize a high-speed serializer-deserializer for serial-to-parallel conversion. The fiber optic extender includes a high-speed serializer-deserializer to achieve serial-to-parallel conversion of RS485 and TALLY signals, suitable for high-speed data communication applications. This circuit, with its high-speed data transmission capability, low-power design, and flexible data interface options, meets the stringent requirements of high-speed data communication. At the signal transmitting end, it converts parallel or TTL data into a high-speed serial data stream with an embedded clock. At the signal receiving end, it receives this serial data stream and deserializes it back into parallel data. The data conversion uses an embedded clock, effectively solving the bottleneck problem of high-speed transmission caused by the lack of strict synchronization between the clock and data. The power module uses DC 5V power, enabling wide application in professional SDI video signal application scenarios such as UHDTV / FHDTV / HDTV / SDTV, and is particularly suitable for long-distance fiber optic transmission and applications of broadcast-grade high-definition digital signals. The dual-output SDI clock recovery cable driver transmits the retiming signal via a 75Ω coaxial cable. The signal received from the optoelectronic conversion channel at the receiving end enters the dual-output SDI clock recovery cable driver. This low-power, multi-rate, time-critical cable driver supports rates up to 12GSDI. It is designed to receive 100Ω differential input signals, automatically recover the embedded clock from the digital video signal, and retiming the incoming data. The retiming signal is transmitted via a 75Ω coaxial cable. The cable driver output features highly configurable pre-emphasis and slew rate control to compensate for long traces and connector losses. Furthermore, it provides automatic and user-selectable output slew rate control. The integrated 75Ω termination design at both cable driver outputs meets stringent SMPTE specification return loss requirements, enabling ultra-high-definition video transmission for 4K applications. The optical signal path employs wavelength division multiplexing (WDM) technology, using downlink and uplink data signals of different wavelengths transmitted in a single optical fiber, thus achieving bidirectional transmission over a single fiber.

[0027] The working principle of this utility model is as follows: For paired testing of the 12G SDI fiber optic extender, a dedicated SDI cable is used to connect the signal source to the BNC interface of the transmitter, and a corresponding dedicated SDI cable is used to connect the receiver to the display at the BNC interface of the receiver. During loop output testing, the display is connected to the loop output port of the transmitter via the dedicated SDI cable. The TALLY control and indication RS485 serial signal is connected via a 4P connector, with one end connected to the input port of the receiver and the other end connected to the output port of the transmitter. The LC fiber optic interface is then connected. Upon power-on, the system enters the test environment. The status of the "POWERN," "LINK," "TALLY," and "VIDEO OUT" indicator lights determines whether the system power supply, fiber optic link connection, and TALLY control information are in normal working mode. The status of the "SDI IN," "LOOP OUT," "SDI OUT1," and "SDI OUT1" indicator lights determines whether the cable SDI signal input and output status is normal. Repeated plugging and unplugging tests of the fiber optic interface are performed, and if the test standards are met, the transmitter and receiver are individually or simultaneously powered off and restarted, and if the test standards are met.

[0028] Currently, our standard optical modules support overclocking to 12Gbps, and 16G / 25Gbps downscaling can also meet rate matching requirements. However, without special design testing, they cannot be directly compatible with pathological code transmission. Our actual tests show that our standard modules have no signal at the receiving end on a 12G 3840x2160p 30Hz line; in a 10Gbps environment using a Blu-ray DAD line, the video image appears, but with jitter. Therefore, in high-definition video transmission environments, a professional 12G SDI optical module circuit is still needed to complete the data signal transmission and transmission to ensure video clarity and stability.

[0029] 12G SDI fiber optic extenders are used in pairs, simultaneously supporting one SDI signal input and one SDI loop-out at the transmitter, and two SDI signal outputs at the receiver via optical signal channels; they also support one reverse RS485 and SDI tally transmission control information. Their main functions are reflected in "signal transmission" and "control protocol," achieving zero latency, high quality, support for single-mode and multi-mode compatibility, ease of use, no debugging required, and ultra-high definition. In "signal transmission," the fiber optic extender's transmitter sends the SDI video signal input from the BNC cable connector to the receiver over long distances via optical fiber, outputting a high-fidelity "original" video signal without any signal compression. It supports 12G / 4096*2160 60p resolution SDI signal transmission and is backward compatible. Depending on the specific application and equipment, the "control protocol" meets the requirements of the RS485 protocol and provides tally control and status information. A reverse 5M bandwidth data channel is modulated onto the video cable using DoC (data on cable) technology. The RS485 control signal can be controlled from the monitoring room via a coaxial cable to the front-end camera.

[0030] The 12G SDI fiber optic extender can also function as a high-definition SDI repeater to extend transmission distance. Its internal design includes an SDI line equalizer, RECLOCK, and line driver, meeting all SMPT standards and broadcast television transmission requirements. Furthermore, at the electrical interface, it can simultaneously provide 12G SDI high-definition image, remote power supply, and line-mounted remote control (one-way RS485) signal over a single 75-ohm coaxial cable. For further extension, another repeater can be connected and power supplied; no separate power supply is required for any intermediate repeater sections.

[0031] The 12G SDI fiber optic extender is an optical signal transmission system designed for broadcast-grade 12G SDI signals. It features adaptive input SDI signal and selectable outputs (2160 / 1080P60 / 30, etc.). The output is synchronized with the input and supports ReClock functionality. It can transmit RS485 signals simultaneously with 12G SDI. The device incorporates SDI signal equalization, SDI serial clock recovery, and line drive, ensuring signal quality meets broadcast standards. It supports RS485 data transmission simultaneously with SDI. Employing a single-mode, single-fiber design, the standard transmission distance is 20km, and different optical components can be used to adjust the distance for various applications. Powered by DC 5V, it is widely applicable to professional SDI video signal applications such as UHDTV / FHDTV / HDTV / SDTV. It is particularly suitable for long-distance fiber optic transmission and applications of broadcast-grade high-definition digital signals.

[0032] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. An optical fiber extender, comprising an SDI line equalizer, a RECLOCK and line driver, a power module, an SDI video transmission channel, a single-fiber bidirectional optical module, an RS485 signal channel, and a TALLY signal channel, characterized in that: The SDI video transmission channel includes input and output terminals. Each input and output terminal is fixed with a dedicated cable having a characteristic impedance of 75Ω. The input and output terminals are electrically connected to an SDI clock recovery cable equalizer. The SDI clock recovery cable equalizer has multiple output terminals. One output terminal is connected to a photoelectric conversion channel, and another output terminal is connected to a loop signal processing circuit. The input and output terminals are electrically connected to the photoelectric conversion channel, and the photoelectric conversion channel is electrically connected to a dual-output SDI clock recovery cable driver.

2. The fiber optic extender according to claim 1, characterized in that: The single-fiber bidirectional optical module is equipped with an internal laser driver, a programmable limiting amplifier circuit, an EEPROM, and a microcontroller electrically connected to the EEPROM. The single-fiber bidirectional optical module also has an internal optical signal path.

3. The fiber optic extender according to claim 1, characterized in that: The RS485 signal channel uses differential signal transmission. The RS485 signal channel has two fixed signal lines. The RS485 signal channel is equipped with an RS485 transceiver circuit, which uses half-duplex communication.

4. The fiber optic extender according to claim 1, characterized in that: The serialization of the RS485 signal channel signal and the TALLY signal channel signal is converted using a high-speed serializer-deserializer.

5. The fiber optic extender according to claim 2, characterized in that: The power module is powered by DC 5V.

6. The fiber optic extender according to claim 1, characterized in that: The dual-output SDI clock recovery cable driver transmits the re-timing signal via a 75Ω coaxial cable.

7. The fiber optic extender according to claim 2, characterized in that: The optical signal path employs wavelength division multiplexing (WDM) technology.

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