Fire telephone system and signal transmission method between fire telephone main station and extension

Abstract

The application relates to a signal transmission method between a fire telephone main machine and a fire telephone extension and a fire telephone system, wherein a near-end optical transmission device is connected with the fire telephone main machine, a far-end optical transmission device is connected with the fire telephone extension, the near-end optical transmission device is connected with the far-end optical transmission device through an optical fiber; an electric signal of analog audio data on a first fire telephone bus is converted into an optical signal by the near-end optical transmission device, and the converted optical signal is transmitted through the optical fiber; the signal transmission method between the fire telephone main machine and the fire telephone extension and the fire telephone are ingeniously designed; the converted optical signal is transmitted through the optical fiber; the optical fiber has the advantages of low loss, high bandwidth, strong anti-electromagnetic interference capability and the like; the transmission distance of general optical signals can reach at least 20 kilometers; during the transmission process, the optical fiber is not conductive, is not interfered by electromagnetic waves, is less affected by resistance and voltage, and the stable transmission of signals in a complex electromagnetic environment is ensured.

Description

Technical Field

[0001] This invention relates to the technical field of fire communication, and more specifically, to a signal transmission method and a fire telephone system between a fire telephone switchboard and its extensions. Background Technology

[0002] A typical fire telephone system generally includes a main switchboard and extension telephone units. The main switchboard and extension telephone units are connected by a fire telephone bus, which provides power supply, message communication, and call functionality to the extension telephone units, working in conjunction with their respective circuits to realize the fire telephone function. my country's fire telephone systems should comply with the relevant requirements of GB16806-2006 "Fire Linkage Control System".

[0003] Fire telephone switchboards and extension units typically use twisted-pair cables for transmission, with a maximum transmission distance of 1 to 1.5 kilometers. However, with the increasing variety of fire telephone applications, distances exceeding 1.5 kilometers, even reaching tens of kilometers, are not uncommon. Furthermore, transmission using twisted-pair cables is significantly affected by factors such as terminal voltage drop, transmission distance, operating current, and the number of terminals. As the transmission distance increases, the signal gradually attenuates within the twisted-pair cable, leading to insufficient signal strength at the receiving end, potentially causing communication interruptions or degraded communication quality. Moreover, in long-distance transmission, the resistance of the twisted-pair wires causes voltage drops when current flows, potentially resulting in insufficient voltage for the terminal equipment to operate normally. Therefore, a new signal transmission method is needed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a signal transmission method and a fire telephone system between the main switchboard and extensions of the fire telephone system, in view of the above-mentioned defects of the prior art.

[0005] The technical solution adopted by this invention to solve its technical problem is as follows: On the one hand, this invention provides a signal transmission method between a fire telephone switchboard and its extensions, comprising the following steps:

[0006] The fire telephone switchboard is electrically connected to the near-end optical transmission equipment via the first fire telephone bus;

[0007] The remote fire telephone extension is electrically connected to the remote optical transmission equipment via the second fire telephone bus.

[0008] The near-end optical transmission equipment and the far-end optical transmission equipment are connected via optical fiber;

[0009] The fire telephone switchboard generates an electrical signal, and the first fire telephone bus transmits analog audio data to the near-end optical transmission device. The electrical signal of the analog audio data on the first fire telephone bus is converted into an optical signal by the near-end optical transmission device, and the converted optical signal is transmitted over a long distance through optical fiber. At the same time, the near-end optical transmission device combines communication messages and audio data into serial data frames according to a custom protocol to realize the audio mixing function.

[0010] The remote optical transmission equipment receives the optical signal and parses the data, separating the communication message and audio data, and then converts all the information back into an electrical signal. The converted electrical signal is amplified and filtered in the remote optical transmission equipment and then transmitted to the remote fire telephone extension through the second fire telephone bus. Conversely, the remote optical transmission equipment can also transmit to the fire switchboard telephone, thus completing the signal transmission process between the fire switchboard telephone and the tiered telephones.

[0011] In the signal transmission method of the present invention, the near-end optical transmission device, the far-end optical transmission device, and the far-end fire telephone branch constitute a group of signal transmission units; the fire telephone switchboard can connect multiple groups of signal transmission units through a first fire telephone bus.

[0012] In the signal transmission method of the present invention, each group of signal transmission units does not interfere with each other;

[0013] In the signal transmission method of the present invention, the fire telephone switchboard is further connected to at least one near-end fire telephone extension via a first fire telephone bus;

[0014] When a local fire telephone extension initiates a call, the local fire telephone sends an electrical signal to the first fire telephone bus; the electrical signal is transmitted to the fire telephone switchboard through the first fire telephone bus; the fire telephone switchboard receives the signal and processes it accordingly.

[0015] In another aspect, the present invention also provides a fire telephone system that uses any of the signal transmission methods described above, wherein the system includes a fire telephone switchboard, a near-end optical transmission device, a far-end optical transmission device, and a fire telephone extension.

[0016] The fire telephone switchboard is electrically connected to the near-end optical transmission equipment via a first fire telephone bus.

[0017] The remote fire telephone extension is electrically connected to the remote optical transmission equipment via a second fire telephone bus.

[0018] The near-end optical transmission device and the far-end optical transmission device are connected by optical fiber;

[0019] The fire telephone system of the present invention, wherein both the remote optical transmission device and the near-end optical transmission device include:

[0020] FPGA processing module, used for bridging and conversion between different hardware interfaces and communication protocols;

[0021] The CODEC conversion module is used to convert the analog audio signal transmitted on the fire telephone bus into a digital audio signal; the CODEC conversion module is connected to the FPGA processing module through a PCM interface;

[0022] Audio circuitry, used to connect the CODEC conversion module to the telephone bus driver circuitry;

[0023] The message transceiver circuit is used to connect the FPGA processing module and the telephone bus driver circuit.

[0024] An optical module is used to convert optical signals to electrical signals; the optical module is electrically connected to the FPGA.

[0025] The optical module of the remote optical transmission device and the optical module of the near-end optical transmission device are connected by optical fiber;

[0026] In the fire telephone system of the present invention, when data is transmitted, the FPGA processing module combines the PCM data of the CODEC conversion module into a serial code stream according to a certain frame format, and then sends it out through the transmission interface TD of the optical module.

[0027] During data reception, the FPGA processing module receives data from the optical module, first detects and locates the frame synchronization header, then finds the PCM data according to the data frame structure, and sends the PCM data to the CODEC conversion module after processing.

[0028] The beneficial effects of this invention are as follows:

[0029] (1) The signal transmission method between the fire telephone switchboard and the extension and the fire telephone design are ingenious. The near-end optical transmission equipment is connected to the fire telephone switchboard through the first fire telephone bus, and the far-end optical transmission equipment is connected to the fire telephone extension through the second fire telephone bus. The near-end optical transmission equipment is connected to the far-end optical transmission equipment through optical fiber, so as to realize the transparent transmission of communication messages and call data of the fire telephone.

[0030] (2) The analog audio data is transmitted from the first fire telephone bus to the near-end optical transmission equipment; the electrical signal of the analog audio data on the first fire telephone bus is converted into an optical signal by the near-end optical transmission equipment, and the converted optical signal is transmitted over a long distance through optical fiber. Generally, the transmission distance of optical signal can reach at least 20 kilometers; during the transmission process, the optical fiber is non-conductive, is not subject to electromagnetic interference, and its resistance and voltage are less affected, ensuring stable transmission of signal in complex electromagnetic environment.

[0031] (3) The near-end optical transmission equipment combines communication messages and audio data into serial data frames according to a custom protocol to realize audio mixing function;

[0032] (4) Data is received through remote optical module equipment, and communication messages and audio data are separated by data parsing. The data signals are then restored into data signals of the fire telephone bus interface by optical transmission equipment, so as to realize the normal communication function of the fire telephone switchboard and the fire telephone extension; the flexibility and efficiency of signal processing are improved.

[0033] (5) The MCU on the optical transmission device monitors the interactive messages between the fire telephone bus and controls the call channel. On the one hand, the call channel is connected when a call needs to be made through this device, and on the other hand, the call channel is disconnected when a call does not need to be made through this device. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort:

[0035] Figure 1 This is a schematic diagram of the signal transmission method between the fire telephone switchboard and extensions according to Embodiment 1 of the present invention;

[0036] Figure 2 This is a circuit diagram of a fire telephone system according to Embodiment 2 of the present invention;

[0037] Figure 3 yes Figure 2 Schematic diagram of external circuitry for FPGA;

[0038] Figure 4 yes Figure 2 Schematic diagram of the telephone interface of the first fire-fighting telephone bus in China;

[0039] Figure 5 yes Figure 2 The schematic diagram of the receiving circuit of the first fire telephone bus in China. Detailed Implementation

[0040] The terms "first," "second," "third," and "fourth," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0041] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0042] "Multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0043] Furthermore, the terms indicating orientation, such as "up, down, front, back, left, right, upper end, lower end, longitudinal," etc., are all based on the posture and position of the device or equipment described in this solution during normal use.

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, a clear and complete description will be provided below in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0045] Example 1:

[0046] The signal transmission method between the fire telephone switchboard and extensions in this embodiment of the invention, such as... Figure 1 As shown, it includes the following steps:

[0047] The fire telephone switchboard is electrically connected to the near-end optical transmission equipment via the first fire telephone bus;

[0048] The remote fire telephone extension is electrically connected to the remote optical transmission equipment via the second fire telephone bus.

[0049] The near-end optical transmission equipment and the far-end optical transmission equipment are connected via optical fiber;

[0050] The fire telephone switchboard generates an electrical signal, and analog audio data is transmitted to the near-end optical transmission equipment on the first fire telephone bus. The electrical signal of the analog audio data on the first fire telephone bus is converted into an optical signal by the near-end optical transmission equipment, and the converted optical signal is transmitted over long distances through optical fiber. Optical fiber has advantages such as low loss, high bandwidth, and strong resistance to electromagnetic interference. The transmission distance of optical signals can generally reach at least 20 kilometers. During transmission, optical fiber is non-conductive, unaffected by electromagnetic interference, and its resistance and voltage are minimally affected, ensuring stable signal transmission in complex electromagnetic environments.

[0051] Meanwhile, the near-end optical transmission device combines communication messages and audio data into serial data frames according to a custom protocol to realize audio mixing function; specifically, the implementation scheme of its audio mixing can refer to the prior patent application of our company entitled "A Method for Implementing Telephone Audio Mixing Using FPGA", or it can adopt common audio mixing processing schemes in the prior art, which will not be elaborated here.

[0052] The remote optical transmission equipment receives the optical signal and parses the data, separating the communication message and audio data. Then, it converts all the information back into an electrical signal. The converted electrical signal is amplified and filtered in the remote optical transmission equipment to further improve the signal quality and reduce noise and distortion. It is then transmitted to the remote fire telephone extension via the second fire telephone bus. Conversely, the remote optical transmission equipment can also transmit to the fire switchboard telephone, thus completing the signal transmission process between the fire switchboard telephone and the tiered telephones. This achieves two-way communication, making it more flexible and practical to use.

[0053] The signal transmission method between the fire telephone switchboard and extensions receives data through a remote optical module device, and separates the communication messages and audio data through data parsing. The optical transmission device then recovers the data signal of the fire telephone bus interface, realizing the normal communication function between the fire telephone switchboard and the fire telephone extensions; thus improving the flexibility and efficiency of signal processing.

[0054] The MCU on the optical transmission equipment monitors the interaction messages between the fire telephone buses, thereby controlling the call channel. On the one hand, the call channel is connected when a call needs to be made through this device, and on the other hand, the call channel is disconnected when a call does not need to be made through this device.

[0055] Furthermore, the near-end optical transmission device, the far-end optical transmission device, and the far-end fire telephone branch constitute a signal transmission unit; the fire telephone switchboard can connect multiple signal transmission units through the first fire telephone bus; each signal transmission unit is an independent module that can be installed, tested, and maintained separately, improving the modularity of the system; when a new communication point needs to be added, only a new signal transmission unit needs to be added, without reconfiguring the entire system, which greatly simplifies the expansion process;

[0056] Furthermore, each group of signal transmission units does not interfere with each other; therefore, a failure in one unit will not affect the normal operation of other units, which improves the overall reliability of the system and ensures communication quality.

[0057] Furthermore, the fire telephone switchboard is also connected to at least one local fire telephone extension via the first fire telephone bus. In this embodiment, the distance between the fire telephone switchboard and the local fire telephone extension is no greater than the distance between the fire telephone switchboard and the local optical transmission equipment. Since the connection between the local fire telephone extension and the switchboard is shorter, communication delay can be reduced and the real-time performance of the call can be improved. Connecting the local fire telephone extension via the bus can simplify the network structure and reduce the complexity of the system and potential points of failure. Secondly, when long-distance transmission is not required, using electrical signals to transmit via the first fire telephone bus can save the cost of optical fiber and optical transmission equipment.

[0058] Furthermore, when a local fire telephone extension initiates a call, the local fire telephone sends an electrical signal to the first fire telephone bus; the electrical signal is transmitted to the fire telephone switchboard through the first fire telephone bus; the fire telephone switchboard receives the signal and processes it accordingly.

[0059] Example 2:

[0060] The present invention also provides a fire telephone system, which adopts the signal transmission method as described in Embodiment 1. The system includes a fire telephone switchboard, a near-end optical transmission device, a far-end optical transmission device, and fire telephone extensions.

[0061] The fire telephone switchboard is electrically connected to the near-end optical transmission equipment via a first fire telephone bus.

[0062] The remote fire telephone extension is electrically connected to the remote optical transmission equipment via a second fire telephone bus.

[0063] The near-end optical transmission device and the far-end optical transmission device are connected by optical fiber;

[0064] Furthermore, such as Figure 2 As shown, both the far-end optical transmission device and the near-end optical transmission device include:

[0065] FPGA processing module, used for bridging and conversion between different hardware interfaces and communication protocols;

[0066] The CODEC conversion module is used to convert the analog audio signal transmitted on the fire telephone bus into a digital audio signal; the CODEC conversion module is connected to the FPGA processing module through a PCM interface;

[0067] The audio circuit is used to connect the CODEC conversion module and the telephone bus driver circuit; it is used to process audio signals by amplification and filtering, ensuring the quality and stability of audio signals during transmission.

[0068] The message transceiver circuit connects the FPGA processing module and the telephone bus driver circuit; it processes communication messages other than audio signals, such as on / off signals and status indicators. It connects the FPGA processing module and the telephone bus driver circuit to ensure that these messages are sent and received correctly.

[0069] An optical module is used to convert optical signals to electrical signals; the optical module is electrically connected to the FPGA; and it communicates with near-end optical transmission equipment via optical fiber. An optical module typically includes a transmitter (such as a laser) and a receiver (such as a photodiode).

[0070] In this embodiment, the FPGA processing module is the core of the remote optical transmission device, responsible for bridging and converting between different hardware interfaces and communication protocols. The FPGA can be programmed as needed to handle various signal formats and protocols, ensuring that signals can be correctly transmitted between different devices and networks; it is worth noting that the FPGA processing module is existing technology.

[0071] In digital form, audio signals can be transmitted more efficiently through optical fiber, with better anti-interference capabilities and longer transmission distances. The CODEC conversion module and the FPGA processing module are connected via a PCM (Pulse Code Modulation) interface to facilitate the processing and transmission of digital audio signals.

[0072] In this embodiment, the fire telephone switchboard and extensions transmit signals via optical fibers through near-end optical transmission equipment and far-end optical transmission equipment to achieve long-distance transmission of fire telephone signals without requiring any hardware modifications to the existing equipment (telephone switchboard and extensions); the cost is low.

[0073] When a call is initiated by the fire telephone switchboard or a local fire telephone extension, the analog audio signal of the first fire telephone bus is transmitted to the local optical transmission equipment. In the local optical transmission equipment, the CODEC conversion module converts the analog audio signal into a digital audio signal, which is then sent to the FPGA processing module via the PCM interface. The FPGA processing module processes the digital audio signal and other communication messages, and converts the electrical signal into an optical signal via the optical module, which is then sent to the remote optical transmission equipment via optical fiber. In the remote optical transmission equipment, the optical module converts the received optical signal back into an electrical signal, and the FPGA processing module processes these signals again. The processed digital audio signal is then sent to the CODEC conversion module via the PCM interface, converted into an analog audio signal, and then transmitted to the remote fire telephone extension via the second fire telephone bus through the audio circuit and the telephone bus drive circuit.

[0074] In this embodiment, combined with Figure 2 and Figure 3 The data flow is described below. The CODEC conversion module performs analog-to-digital conversion of the audio signal. Since the audio signal transmitted on the fire telephone bus is analog data, it needs to be converted to a digital audio signal before being transmitted to the optical module. Therefore, a CEDEC chip is required. The digital signal of the CODEC conversion module directly interfaces with the FPGA, including:

[0075] The I2C communication signals SCLK and SDIO are controlled by the software of the M3 core within the FPGA processing module.

[0076] PCM interface signals include bit clock signal BCLK, frame synchronization signal FS, and PCM signals ADCOUT and ADCIN.

[0077] The data interface of the optical module is connected to the FPGA processing module, including the receive data signal RD, the transmit data signal TD, and the optical module status signal SD.

[0078] The audio data transmission process is as follows:

[0079] Data transmission: Inside the FPGA processing module, the PCM data from the CODEC is combined into a serial code stream according to a certain frame format, and then sent out through the optical module's transmit interface TD.

[0080] Data reception: The FPGA processing module receives data from the RD port of the optical module. First, it detects and locates the frame synchronization header, and then finds the PCM data according to the data frame structure. After processing, the PCM data is sent to the CODEC conversion module.

[0081] The optical module of the remote optical transmission device is connected to the optical module of the near-end optical transmission device via optical fiber; this enables long-distance signal transmission and ensures stable transmission.

[0082] The circuit diagrams for the first and second fire telephone buses are the same, for example, as follows: Figure 4 The diagram shown is the schematic of the telephone interface of the first fire telephone bus, including bus power supply and code transmission.

[0083] Q1 in the diagram is a high-power transistor that can provide a maximum bus current of 5A.

[0084] In the diagram, PHONE_BUS is the bus signal. This signal is fed back to Q2 for amplification via C22, and then amplified again via Q1 to realize the amplification of the bus audio signal.

[0085] LN_DOUT is connected to the bus controller. When there is a message to be sent, the bus controller controls LN_DOUT to generate a transmission signal waveform. Then, through the relatively large current-pull capability of transistor Q3, a strong protection communication waveform is formed on the bus to clearly distinguish the change amplitude of the audio signal.

[0086] In the diagram, the LNTEST_A signal is connected to the I / O port of the bus controller, and the bus voltage is monitored in real time through the AD conversion function.

[0087] The circuit diagrams for the first and second fire telephone buses are the same, for example, as follows: Figure 5 The diagram shown is the schematic of the receiving circuit of the first fire telephone bus.

[0088] In the diagram, R18, C16, R75, R35, and C20 constitute a bus communication waveform shaping circuit, which shapes a continuous square wave of a certain frequency and amplitude on the bus into a low-level pulse signal with a corresponding width.

[0089] Q9 and Q10 are used as comparators to perform level conversion and generate a 3.3V level signal suitable for microcontroller recognition.

[0090] Q12 further shapes the signal, ultimately generating the received code signal LN_DIN, which is then sent to the bus controller for processing.

[0091] The communication mechanism of the telephone bus is divided into two parts: code transmission control and code reception detection.

[0092] Furthermore, during data transmission, the FPGA processing module combines the PCM data from the CODEC conversion module into a serial code stream according to a certain frame format, and then sends it out through the optical module's transmit interface TD.

[0093] During data reception, the FPGA processing module receives data from the optical module, first detects and locates the frame synchronization header, then finds the PCM data according to the data frame structure, and sends the PCM data to the CODEC conversion module after processing.

[0094] This fire telephone system receives data through a remote optical module device, and through data parsing, separates communication messages and audio data. The optical transmission device then recovers the data signal of the fire telephone bus interface, enabling normal communication between the fire telephone switchboard and fire telephone extensions; thus improving the flexibility and efficiency of signal processing.

[0095] The MCU on the optical transmission equipment monitors the interaction messages between the fire telephone buses, thereby controlling the call channel. On the one hand, the call channel is connected when a call needs to be made through this device, and on the other hand, the call channel is disconnected when a call does not need to be made through this device.

[0096] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A signal transmission method between a fire telephone switchboard and its extensions, characterized in that, Includes the following steps: The fire telephone switchboard is electrically connected to the near-end optical transmission equipment via the first fire telephone bus; The remote fire telephone extension is electrically connected to the remote optical transmission equipment via the second fire telephone bus. The near-end optical transmission equipment and the far-end optical transmission equipment are connected via optical fiber; The fire telephone switchboard generates an electrical signal, and the first fire telephone bus transmits analog audio data to the near-end optical transmission device. The electrical signal of the analog audio data on the first fire telephone bus is converted into an optical signal by the near-end optical transmission device, and the converted optical signal is transmitted over a long distance through optical fiber. At the same time, the near-end optical transmission device combines communication messages and audio data into serial data frames according to a custom protocol to realize the audio mixing function. The remote optical transmission equipment receives the optical signal and parses the data, separating the communication message and audio data, and then converts all the information back into an electrical signal. The converted electrical signal is amplified and filtered in the remote optical transmission equipment and then transmitted to the remote fire telephone extension through the second fire telephone bus. Conversely, the remote optical transmission equipment can also transmit to the fire switchboard telephone, thus completing the signal transmission process between the fire switchboard telephone and the tiered telephones. Both the near-end optical transmission device and the far-end optical transmission device include an FPGA processing module, a CODEC conversion module, an audio circuit, a message transceiver circuit, and an optical module. During data transmission, the FPGA processing module combines the PCM data from the CODEC conversion module into a serial code stream according to a custom frame format and sends it out through the optical module's transmit interface TD. During data reception, the FPGA processing module receives data from the optical module, performs frame synchronization header detection and positioning, finds the PCM data according to the data frame structure, and sends the PCM data to the CODEC conversion module after processing.

2. The signal transmission method according to claim 1, characterized in that, The near-end optical transmission device, the far-end optical transmission device, and the far-end fire telephone branch constitute a signal transmission unit; the fire telephone switchboard can connect to multiple signal transmission units through the first fire telephone bus.

3. The signal transmission method according to claim 2, characterized in that, Each group of signal transmission units does not interfere with the others.

4. The signal transmission method according to any one of claims 1-3, characterized in that, The fire telephone switchboard is also connected to at least one local fire telephone extension via the first fire telephone bus; When a local fire telephone extension initiates a call, the local fire telephone sends an electrical signal to the first fire telephone bus; the electrical signal is transmitted to the fire telephone switchboard through the first fire telephone bus; the fire telephone switchboard receives the signal and processes it accordingly.

5. A fire telephone system, employing the signal transmission method as described in any one of claims 1-4, characterized in that, This includes a fire telephone switchboard, near-end optical transmission equipment, far-end optical transmission equipment, and fire telephone extensions; The fire telephone switchboard is electrically connected to the near-end optical transmission equipment via a first fire telephone bus. The remote fire telephone extension is electrically connected to the remote optical transmission equipment via a second fire telephone bus. The near-end optical transmission device and the far-end optical transmission device are connected by optical fiber; Both the far-end optical transmission device and the near-end optical transmission device include: FPGA processing module, used for bridging and conversion between different hardware interfaces and communication protocols; The CODEC conversion module is used to convert analog audio signals transmitted on the first or second fire telephone bus into digital audio signals; the CODEC conversion module is connected to the FPGA processing module through a PCM interface; Audio circuitry, used to connect the CODEC conversion module to the telephone bus driver circuitry; The message transceiver circuit is used to connect the FPGA processing module and the telephone bus driver circuit. An optical module is used to convert optical signals to electrical signals; the optical module is electrically connected to the FPGA. The optical module of the remote optical transmission device and the optical module of the near-end optical transmission device are connected by optical fiber; When transmitting data, the FPGA processing module combines the PCM data from the CODEC conversion module into a serial code stream according to a certain frame format, and then sends it out through the optical module's transmit interface TD. During data reception, the FPGA processing module receives data from the optical module, first detects and locates the frame synchronization header, then finds the PCM data according to the data frame structure, and sends the PCM data to the CODEC conversion module after processing.

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