Signal transmission method between fire-fighting telephone switchboard and fire-fighting telephone extensions and fire-fighting telephone system

Abstract

The invention relates to a signal transmission method between a fire-fighting telephone switchboard and a fire-fighting telephone extension and a fire-fighting telephone system, a near-end optical transmission device is connected with the fire-fighting telephone switchboard, a far-end optical transmission device is connected with the fire-fighting telephone extension, and 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 the first fire protection telephone bus is converted into an optical signal by the near-end optical transmission equipment, and the converted optical signal is remotely transmitted through an optical fiber; the signal transmission method between the fire-fighting telephone switchboard and the fire-fighting telephone extensions and the fire-fighting telephone are ingenious in design, and converted optical signals are transmitted remotely through optical fibers; 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 at least reach 20 kilometers, in the transmission process, the optical fibers are not conductive and not interfered by electromagnetic interference, the resistance and the voltage are slightly influenced, and stable transmission of the signals in a complex electromagnetic environment is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of firefighting communication, and more particularly to a signal transmission method between a firefighting telephone switchboard and extensions and a firefighting telephone system. Background Art

[0002] Commonly used fire telephone systems generally include telephone switchboards, telephone extensions and other equipment. The telephone switchboard and telephone extensions are connected by a fire telephone bus, which provides power supply, message communication and call circuits for fire telephone extensions, and cooperates with the relevant circuits of fire telephone extensions to realize the fire telephone function. my country's fire telephone system should comply with the relevant standard requirements of GB16806-2006 "Fire Linkage Control System".

[0003] Twisted pair cables are generally used for transmission between fire telephone switchboards and fire telephone extensions, and their maximum transmission distance is generally 1 to 1.5 kilometers. As the use scenarios of fire telephones become more and more diverse, it is not uncommon for the distance between the fire telephone host and the fire telephone extension to be greater than 1.5 kilometers or even tens of kilometers; however, the use of twisted pair cables for transmission is greatly affected by the terminal voltage drop, transmission distance, working current, number of terminals, etc. As the transmission distance increases, the signal will gradually attenuate when transmitted in the twisted pair cable, resulting in insufficient signal strength at the receiving end, which may cause communication interruption or degradation of communication quality; and in long-distance transmission, due to the resistance of the twisted pair cable, a voltage drop will be generated when the current passes through, resulting in the terminal equipment not receiving enough voltage to work 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 between a fire telephone switchboard and extensions and a fire telephone system in view of the above-mentioned defects of the prior art.

[0005] The technical solution adopted by the present invention to solve the technical problem is: on the one hand, the present invention provides a method for signal transmission between a fire telephone switchboard and an extension, which includes 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 device is connected to the far-end optical transmission device via an optical fiber;

[0009] The fire telephone switchboard generates an electrical signal, and transmits analog audio data to the near-end optical transmission device 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 device, and the converted optical signal is transmitted over a long distance through an optical fiber; at the same time, the near-end optical transmission device combines the communication message and the audio data into a serial data frame according to a custom protocol to realize an audio mixing function;

[0010] The remote optical transmission equipment receives the optical signal and analyzes the data, separates the communication message and audio data, and then converts all the information back into electrical signals; the converted electrical signals are 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, thereby completing the signal transmission process between the fire switchboard telephone and the hierarchical telephone;

[0011] The signal transmission method of the present invention, wherein 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 the first fire telephone bus;

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

[0013] The signal transmission method of the present invention, wherein the fire telephone switchboard is also connected to at least one proximal fire telephone extension via the first fire telephone bus;

[0014] When the proximal fire telephone extension initiates a call, the proximal 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 makes corresponding processing after receiving the signal;

[0015] In another aspect, the present invention further provides a fire telephone system, using any of the above-mentioned signal transmission methods, which 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 is connected to the far-end optical transmission device via an optical fiber;

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

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

[0021] A 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 via a PCM interface;

[0022] Audio circuit, used to connect the CODEC conversion module and the telephone bus driving circuit;

[0023] A message transceiver circuit, used to connect the FPGA processing module and the telephone bus driver circuit;

[0024] An optical module, used for converting optical signals into electrical signals; the optical module is electrically connected to the FPGA;

[0025] The optical module of the remote optical transmission device is connected to the optical module of the near-end optical transmission device via an optical fiber;

[0026] In the fire telephone system of the present invention, when data is sent, 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] When receiving data, 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 processed PCM data to the CODEC conversion module.

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

[0029] (1) The signal transmission method between the fire telephone switchboard and the extension and the fire telephone are cleverly designed. The near-end optical transmission device is connected to the fire telephone switchboard via the first fire telephone bus, the far-end optical transmission device is connected to the fire telephone extension via the second fire telephone bus, and the near-end optical transmission device is connected to the far-end optical transmission device via an optical fiber, thereby realizing 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 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 an optical fiber. Generally, the transmission distance of the optical signal can reach at least 20 kilometers; during the transmission process, the optical fiber is non-conductive and not affected by electromagnetic interference, and the resistance and voltage are less affected, thereby ensuring the stable transmission of the signal in a complex electromagnetic environment;

[0031] (3) The near-end optical transmission device combines the communication message and audio data into a serial data frame according to a custom protocol to implement the audio mixing function;

[0032] (4) The remote optical module device receives data, analyzes the data, separates the communication message and audio data, and restores the data signal of the fire telephone bus interface by the optical transmission device, so as to realize the normal communication function of the fire telephone switchboard and the fire telephone extension; thus, the flexibility and efficiency of signal processing are improved;

[0033] (5) The interactive messages between the fire telephone buses are monitored by the MCU on the optical transmission device to control the call channel. On the one hand, the call channel is connected when a call needs to pass through this device. On the other hand, the call channel is disconnected when a call does not need to pass through this device. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in 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 of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work:

[0035] Figure 1 It is a principle block diagram of a signal transmission method between a fire telephone switchboard and extensions according to a first embodiment of the present invention;

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

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

[0038] Figure 4 yes Figure 2 The telephone interface schematic diagram of the first fire telephone bus in China;

[0039] Figure 5 yes Figure 2 The schematic diagram of the code receiving circuit of the first fire telephone bus. DETAILED DESCRIPTION

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

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

[0042] "Multiple" means two or more. "And / or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the related objects are in an "or" relationship.

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

[0044] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be described clearly and completely in combination with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are partial embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0045] Embodiment 1:

[0046] The signal transmission method between the fire telephone switchboard and the extension in the embodiment of the present invention is as follows: Figure 1 As shown, the following steps are included:

[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 device is connected to the far-end optical transmission device via an optical fiber;

[0050] The fire telephone switchboard generates an electrical signal, and the analog audio data is transmitted to the near-end optical transmission device 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 device, and the converted optical signal is transmitted over a long distance through an optical fiber; the optical fiber has the advantages of low loss, high bandwidth, and strong anti-electromagnetic interference ability; the transmission distance of a general optical signal can reach at least 20 kilometers. During the transmission process, the optical fiber is non-conductive and not subject to electromagnetic interference, and the resistance and voltage are less affected, which ensures the stable transmission of the signal in a complex electromagnetic environment;

[0051] At the same time, the near-end optical transmission equipment combines the communication messages and audio data into serial data frames according to the custom protocol to realize the audio mixing function; specifically, the implementation scheme of its sound mixing can refer to the company's prior patent application entitled "A method for realizing telephone audio mixing using FPGA", or the common audio mixing processing scheme in the prior art can be adopted, which will not be repeated here.

[0052] The remote optical transmission equipment receives the optical signal and analyzes the data, separates the communication message and audio data, and then converts all the information back into electrical signals; the converted electrical signals are amplified and filtered in the remote optical transmission equipment to further improve the signal quality and reduce noise and distortion; they are transmitted to the remote fire telephone extension through the second fire telephone bus, and vice versa, the remote optical transmission equipment can also transmit to the fire switchboard telephone, thereby completing the signal transmission process between the fire switchboard telephone and the hierarchical telephone; two-way communication is realized, which is more flexible and practical to use.

[0053] The signal transmission method between the fire telephone switchboard and the extension receives data through the remote optical module device, separates the communication message and the audio data through the data analysis, and restores the data signal of the fire telephone bus interface by the optical transmission device, so as to realize the normal communication function of the fire telephone switchboard and the fire telephone extension; and improves the flexibility and efficiency of signal processing;

[0054] The interactive messages between the fire telephone buses are monitored by the MCU on the optical transmission equipment to control the call channel. On the one hand, the call channel is connected when a call needs to pass through this device. On the other hand, the call channel is disconnected when a call does not need to pass 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 group of signal transmission units; the fire telephone switchboard can connect multiple groups of signal transmission units through the first fire telephone bus; each group of signal transmission units is an independent module and can be installed, tested and maintained separately, which improves 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, the failure of a certain unit will not affect the normal operation of other units, which improves the overall reliability of the system and ensures the communication quality.

[0057] Furthermore, the fire telephone switchboard is also connected to at least one proximal fire telephone extension through the first fire telephone bus; in this embodiment, the distance between the fire telephone switchboard and the proximal fire telephone extension is not greater than the distance between the fire telephone main office and the proximal optical transmission equipment; since the connection between the proximal fire telephone extension and the switchboard is shorter, communication delays can be reduced and the real-time nature of calls can be improved; connecting the proximal fire telephone extensions through the bus can simplify the network structure, reduce the complexity of the system and potential failure points; secondly, when long-distance transmission is not required, using electrical signals to transmit through the first fire telephone bus can save the cost of optical fiber and optical transmission equipment.

[0058] Furthermore, when the proximal fire telephone extension initiates a call, the proximal 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 makes corresponding processing after receiving the signal.

[0059] Embodiment 2:

[0060] The present invention also provides a fire telephone system, which adopts the signal transmission method of the first embodiment, and the system includes a fire telephone switchboard, a near-end optical transmission device, a far-end optical transmission device and a fire telephone extension;

[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 is connected to the far-end optical transmission device via an optical fiber;

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

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

[0066] A 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 via a PCM interface;

[0067] Audio circuit, used to connect the CODEC conversion module and the telephone bus driving circuit; used to process the amplification and filtering of audio signals to ensure the quality and stability of audio signals during transmission;

[0068] The message transceiver circuit is used to connect the FPGA processing module and the telephone bus driver circuit; it is used to process other communication messages besides audio signals, such as telephone on / off signals, status indications, etc. It connects the FPGA processing module and the telephone bus driver circuit to ensure that these messages can be sent and received correctly;

[0069] An optical module is used to convert optical signals into electrical signals; the optical module is electrically connected to the FPGA; and communicates with a near-end optical transmission device via an optical fiber. An optical module generally 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, which is responsible for bridging and converting between different hardware interfaces and communication protocols. The FPGA can be programmed as needed to process various signal formats and protocols to ensure that the signal can be correctly transmitted between different devices and networks; it is worth noting that the FPGA processing module is a prior art.

[0071] In digital form, audio signals can be transmitted more efficiently through optical fiber, and have better anti-interference ability and longer transmission distance. The CODEC conversion module is connected to the FPGA processing module through 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 the extension transmit signals through the optical fiber of the near-end optical transmission device and the far-end optical transmission device to realize the long-distance transmission of the fire telephone signal without any hardware modification of the existing equipment (telephone host and telephone extension); the cost is low;

[0073] When the fire telephone switchboard or the near-end fire telephone extension initiates a call, the analog audio signal of the first fire telephone bus is transmitted to the near-end optical transmission equipment; in the near-end optical transmission equipment, the CODEC conversion module converts the analog audio signal into a digital audio signal, and then sends it to the FPGA processing module through 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 through the optical module, and sends it to the far-end optical transmission equipment through the optical fiber; in the far-end 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 sent to the CODEC conversion module through the PCM interface, converted into an analog audio signal, and then transmitted to the far-end fire telephone extension through the second fire telephone bus through the audio circuit and the telephone bus driving circuit.

[0074] In this embodiment, combined with Figure 2 and Figure 3 Explain the data flow. The CODEC conversion module realizes the analog-to-digital conversion of the audio signal. Since the audio signal transmitted on the fire telephone bus is analog data, it is necessary to convert the analog audio signal into a digital audio signal before connecting to the optical module for digital signal transmission. Therefore, the CEDEC chip is required. The digital signal of the CODEC conversion module is directly connected to the FPGA interface, including:

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

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

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

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

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

[0080] Data reception: The FPGA processing module receives the RD port data of 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 processed PCM data 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 an optical fiber; long-distance signal transmission can be achieved; and the transmission is stable.

[0082] The circuit diagram of the first fire telephone bus is the same as the circuit diagram of the second fire telephone bus, for example, Figure 4 The figure shows the telephone interface schematic diagram of the first fire telephone bus, including bus power supply and code sending.

[0083] In the figure, Q1 is a high-power transistor that can provide a maximum bus current of 5A;

[0084] In the figure, PHONE_BUS is the bus signal, which is fed back to Q2 through C22 for amplification, and then amplified through Q1 to achieve the amplification of the bus audio signal;

[0085] LN_DOUT is connected to the bus controller. When a message needs to be sent, the bus controller controls LN_DOUT to generate a sending signal waveform, and then forms a strong protection communication waveform on the bus through the relatively large current pulling capability of transistor Q3 to clearly distinguish the amplitude of the audio signal change;

[0086] In the figure, the LNTEST_A signal is connected to the I / O port of the bus controller, and the real-time monitoring of the bus voltage is achieved through the AD conversion function.

[0087] The circuit diagram of the first fire telephone bus is the same as the circuit diagram of the second fire telephone bus, for example, Figure 5 As shown, what is shown is the schematic diagram of the code receiving circuit of the first fire telephone bus;

[0088] In the figure, R18, C16, R75, R35, and C20 constitute a bus communication waveform shaping circuit, which shapes the 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 realize level conversion function and generate 3.3V level signal suitable for microcontroller recognition;

[0090] Q12 further shapes the signal and finally generates a received code signal LN_DIN, which is sent to the bus controller for processing.

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

[0092] Furthermore, when data is sent, 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;

[0093] When receiving data, 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 processed PCM data to the CODEC conversion module.

[0094] The fire telephone system receives data through the remote optical module equipment, separates the communication message and audio data through data analysis, and restores the data signal of the fire telephone bus interface by the optical transmission equipment, so as to realize the normal communication function of the fire telephone switchboard and the fire telephone extension; and improves the flexibility and efficiency of signal processing;

[0095] The interactive messages between the fire telephone buses are monitored by the MCU on the optical transmission equipment to control the call channel. On the one hand, the call channel is connected when a call needs to pass through this device. On the other hand, the call channel is disconnected when a call does not need to pass through this device.

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

Claims

1. A method for transmitting signals between a fire telephone switchboard and an extension, characterized in that: The following steps are involved: 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 device is connected to the far-end optical transmission device via an optical fiber; The fire telephone switchboard generates an electrical signal, and transmits analog audio data to the near-end optical transmission device 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 device, and the converted optical signal is transmitted over a long distance through an optical fiber; at the same time, the near-end optical transmission device combines the communication message and the audio data into a serial data frame according to a custom protocol to realize an audio mixing function; The remote optical transmission equipment receives the optical signal and analyzes the data, separates the communication message and audio data, and then converts all the information back into electrical signals; the converted electrical signals are 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, thereby completing the signal transmission process between the fire switchboard telephone and the hierarchical telephone.

2. The signal transmission method according to claim 1, characterized in that: The near-end optical transmission equipment, the far-end optical transmission equipment 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 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 each other.

4. The signal transmission method according to any one of claims 1 to 3, characterized in that: The fire telephone switchboard is also connected to at least one proximal fire telephone extension via a first fire telephone bus; When the proximal fire telephone extension initiates a call, the proximal 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 makes corresponding processing after receiving the signal.

5. A fire telephone system, using the signal transmission method according to any one of claims 1 to 4, characterized in that: Including fire telephone switchboard, near-end optical transmission equipment, far-end optical transmission equipment and fire telephone extension; 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 is connected to the far-end optical transmission device via an optical fiber.

6. The fire telephone system according to claim 5, characterized in that: The remote optical transmission device and the near-end optical transmission device both include: FPGA processing module for bridging and conversion between different hardware interfaces and communication protocols; A CODEC conversion module, used for converting the analog audio signal transmitted on the first fire telephone bus or the second fire telephone bus into a digital audio signal; the CODEC conversion module is connected to the FPGA processing module via a PCM interface; Audio circuit, used to connect the CODEC conversion module and the telephone bus driving circuit; A message transceiver circuit, used to connect the FPGA processing module and the telephone bus driver circuit; An optical module, used for converting optical signals into electrical signals; the optical module is electrically connected to the FPGA; The optical module of the remote optical transmission device is connected to the optical module of the near-end optical transmission device through an optical fiber.

7. The fire telephone system according to claim 6, characterized in that: When data is sent, 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; When receiving data, 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 processed PCM data to the CODEC conversion module.

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