A transmission device, system and method for time-frequency signal

Abstract

The present invention provides a transmission device, system and method for time-frequency signals, wherein the transmission device includes an optical transmitter and an optical receiver; the optical transmitter is connected to a transmitting terminal device; the optical transmitter is connected to an optical receiver via an optical fiber line; the optical transmitter is used to perform "dark pulse" modulation on the time-frequency electrical signal sent by the transmitting terminal device, and perform electrical-optical conversion on the modulated time-frequency electrical signal to obtain a time-frequency optical signal; the optical receiver is connected to a receiving terminal device; the optical receiver performs photoelectric conversion on the time-frequency optical signal after transmission via the optical fiber line to obtain the transmitted time-frequency electrical signal, and transmits the transmitted time-frequency electrical signal to the receiving terminal device. The optical transmitter in the present invention performs "dark pulse" modulation on the time-frequency electrical signal sent by the transmitting terminal device, and has the advantages of resisting attenuation changes of the optical fiber line, stable transmission delay and low cost.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber transmission technology, and in particular to a transmission device, system and method for time-frequency signals. Background Art

[0002] In many large measurement networks, time and frequency equipment is required for time synchronization. A central device sends time synchronization pulses or measurement start pulses to other terminal devices, typically transmitting a pulse per second signal (PPS). The characteristic of this type of transmitted signal is that the duty cycle is extremely low. In some cases, a pulse signal with a width of tens of ns is sent within a time interval of one second, and the duty cycle can be as low as 10E-7. When optical fiber is used as the transmission medium for time and frequency signals, the length of the optical fiber ranges from several meters to tens of kilometers. Due to the influence of various environmental factors, the transmission delay of the signal changes. In order to solve this problem, the current practice is to automatically compensate for the transmission delay of the optical fiber line through reverse feedback on the same path to ensure that the delay of the time synchronization pulse signal remains stable during the optical fiber transmission process. This solution is appropriate when the optical fiber length is long, but for the close distance between devices, the optical fiber length is within several thousand meters, or even only tens of meters, the above solution is too complicated and costly. Summary of the invention

[0003] The object of the present invention is to provide a transmission device, system and method for time-frequency signals, which have the advantages of being resistant to attenuation changes of optical fiber lines, having stable transmission delay and low cost.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A transmission device for time-frequency signals, comprising:

[0006] Optical transmitters and optical receivers;

[0007] The optical transmitter is connected to the transmitting terminal device; the optical transmitter is connected to the optical receiver through an optical fiber line; the optical transmitter is used to perform "dark pulse" modulation on the time-frequency electrical signal sent by the transmitting terminal device, and perform electrical-optical conversion on the modulated time-frequency electrical signal to obtain a time-frequency optical signal;

[0008] The optical receiver is connected to a receiving terminal device; the optical receiver performs photoelectric conversion on the time-frequency optical signal transmitted through the optical fiber line to obtain a transmitted time-frequency electrical signal, and transmits the transmitted time-frequency electrical signal to the receiving terminal device.

[0009] Optionally, the optical transmitter specifically includes:

[0010] A pulse signal shaping circuit, a laser current driver, a laser, an automatic power controller and a first photodetector;

[0011] The input end of the pulse signal shaping circuit is connected to the transmitting terminal device; the pulse signal shaping circuit, the laser current driver and the laser are connected in sequence; the output end of the laser is connected to one end of the optical fiber line;

[0012] The first photodetector is connected to the automatic power controller; the first photodetector is used to detect the backlight signal of the laser;

[0013] The automatic power controller is used to amplify the backlight signal and control the current drive of the laser according to the amplified backlight signal to form a closed-loop control of automatic optical power.

[0014] Optionally, the optical receiver specifically includes:

[0015] A variable optical attenuator, a second photodetector, a preamplifier, a comparison amplifier, a DC signal amplification circuit and an optical attenuator controller;

[0016] The variable optical attenuator is connected to the other end of the optical fiber line; the variable optical attenuator, the second photodetector, the preamplifier, and the comparison amplifier are connected in sequence; the output end of the comparison amplifier is connected to the receiving terminal device;

[0017] The DC signal amplifying circuit is connected to the output end of the preamplifier and the input end of the optical attenuator controller respectively; the DC signal amplifying circuit is used to amplify the DC component of the output signal of the preamplifier;

[0018] The output end of the optical attenuator controller is connected to the attenuation control end of the variable optical attenuator. The optical attenuator controller is used to control the current drive of the variable optical attenuator according to the DC component of the output signal of the preamplifier after amplification, so as to form automatic gain closed-loop control.

[0019] Optionally, the optical receiver further includes:

[0020] Filter circuit;

[0021] The input end of the filter circuit is connected to the output end of the preamplifier;

[0022] The output end of the filter circuit is connected to the input end of the DC signal amplifying circuit.

[0023] A time-frequency signal transmission system, comprising:

[0024] Transmitting terminal equipment, a plurality of transmission devices for the above-mentioned time-frequency signals, and a plurality of receiving terminal equipment;

[0025] The transmitting terminal equipment is connected to the plurality of transmission devices respectively; the plurality of transmission devices and the plurality of receiving terminal equipment are connected one-to-one.

[0026] A method for transmitting a time-frequency signal, optionally, the method is applied to the above-mentioned device for transmitting a time-frequency signal, the method comprising:

[0027] The optical transmitter performs a "dark pulse" modulation on the time-frequency electrical signal sent by the transmitting terminal device, and performs an electrical-optical conversion on the modulated time-frequency electrical signal to obtain a time-frequency optical signal;

[0028] The optical fiber line transmits the time-frequency optical signal;

[0029] The optical receiver performs photoelectric conversion on the time-frequency optical signal transmitted through the optical fiber line to obtain the transmitted time-frequency electrical signal;

[0030] The receiving terminal device receives the transmitted time-frequency electrical signal.

[0031] Optionally, the optical transmitter performs “dark pulse” modulation on the time-frequency electrical signal sent by the transmitting terminal device, and performs electrical-optical conversion on the modulated time-frequency electrical signal to obtain a time-frequency optical signal, specifically including:

[0032] Performing “dark pulse” modulation on the time-frequency electrical signal sent by the transmitting terminal device;

[0033] A first photodetector detects a backlight signal at the laser;

[0034] The automatic power controller amplifies the backlight signal and controls the current drive of the laser according to the amplified backlight signal, so that the pulse amplitude of the time-frequency optical signal output by the laser is maintained within a first preset range.

[0035] Optionally, the optical receiver performs photoelectric conversion on the time-frequency optical signal transmitted through the optical fiber line to obtain the transmitted time-frequency electrical signal, specifically including:

[0036] Acquiring a DC component of the time-frequency optical signal after transmission through the optical fiber line;

[0037] amplifying the DC component;

[0038] The optical attenuator controller controls the current drive of the variable optical attenuator according to the DC component of the output signal of the preamplifier after amplification processing, so that the signal amplitude of the input comparison amplifier is maintained within a second preset range.

[0039] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0040] The present invention provides a transmission device, system and method for time-frequency signals, wherein the transmission device includes an optical transmitter and an optical receiver; the optical transmitter is connected to a transmitting terminal device; the optical transmitter is connected to an optical receiver via an optical fiber line; the optical transmitter is used to perform "dark pulse" modulation on the time-frequency electrical signal sent by the transmitting terminal device, and perform electrical-optical conversion on the modulated time-frequency electrical signal to obtain a time-frequency optical signal; the optical receiver is connected to a receiving terminal device; the optical receiver performs photoelectric conversion on the time-frequency optical signal after transmission via the optical fiber line to obtain the transmitted time-frequency electrical signal, and transmits the transmitted time-frequency electrical signal to the receiving terminal device. The optical transmitter in the present invention performs "dark pulse" modulation on the time-frequency electrical signal sent by the transmitting terminal device, and has the advantages of resisting attenuation changes of the optical fiber line, stable transmission delay and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0042] Figure 1 It is a schematic diagram of the structure of a transmission device for modulating a time-frequency signal using a "bright pulse" in the prior art;

[0043] Figure 2 It is a schematic diagram of the change of the pulse signal amplitude output by the transmission device of the "bright pulse" modulated time-frequency signal in the prior art when the optical fiber attenuation changes;

[0044] Figure 3 It is a schematic diagram of the change of the pulse signal amplitude output by the transmission device of the "bright pulse" modulated time-frequency signal in the prior art when the optical fiber attenuation increases by 5dB;

[0045] Figure 4 It is a schematic diagram of the structure of a transmission device for modulating a time-frequency signal using a “dark pulse” in an embodiment of the present invention;

[0046] Figure 5 is a flow chart of a method for transmitting a time-frequency signal in an embodiment of the present invention;

[0047] Description of the drawings: 1-pulse signal shaping circuit; 2-laser current driver; 3-laser; 4-automatic power controller; 5-first photodetector; 6-variable optical attenuator; 7-optical attenuator controller; 8-second photodetector; 9-preamplifier; 10-comparison amplifier; 11-DC signal amplification circuit. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] The object of the present invention is to provide a transmission device, system and method for time-frequency signals, which have the advantages of being resistant to attenuation changes of optical fiber lines, having stable transmission delay and low cost.

[0050] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Figure 4 FIG. 1 is a schematic diagram of the structure of a transmission device for modulating a time-frequency signal using a “dark pulse” in an embodiment of the present invention. Figure 4 The present invention provides a transmission device for time-frequency signals, comprising:

[0052] Optical transmitters and optical receivers;

[0053] The optical transmitter is connected to the transmitting terminal device; the optical transmitter is connected to the optical receiver through an optical fiber line; the optical transmitter is used to perform "dark pulse" modulation on the time-frequency electrical signal sent by the transmitting terminal device, and perform electrical-optical conversion on the modulated time-frequency electrical signal to obtain a time-frequency optical signal;

[0054] The optical receiver is connected to the receiving terminal device; the optical receiver performs photoelectric conversion on the time-frequency optical signal transmitted through the optical fiber line to obtain the transmitted time-frequency electrical signal, and transmits the transmitted time-frequency electrical signal to the receiving terminal device.

[0055] Specifically, the optical transmitter includes:

[0056] A pulse signal shaping circuit 1, a laser current driver 2, a laser 3, an automatic power controller 4 and a first photodetector 5;

[0057] The input end of the pulse signal shaping circuit is connected to the transmitting terminal device; the pulse signal shaping circuit, the laser current driver and the laser are connected in sequence; the output end of the laser is connected to one end of the optical fiber line;

[0058] The first photoelectric detector is connected to the automatic power controller; the first photoelectric detector is used to detect the backlight signal of the laser;

[0059] The automatic power controller is used to amplify the backlight signal and control the current drive of the laser according to the amplified backlight signal to form a closed-loop control of automatic optical power.

[0060] Specifically, the optical receiver includes:

[0061] A variable optical attenuator 6, a second photodetector 8, a preamplifier 9, a comparison amplifier 10, a DC signal amplifying circuit 11 and an optical attenuator controller 7;

[0062] The variable optical attenuator is connected to the other end of the optical fiber line; the variable optical attenuator, the second photodetector, the preamplifier, and the comparison amplifier are connected in sequence; the output end of the comparison amplifier is connected to the receiving terminal device;

[0063] The DC signal amplifying circuit is connected to the output end of the preamplifier and the input end of the optical attenuator controller respectively; the DC signal amplifying circuit is used to amplify the DC component of the output signal of the preamplifier;

[0064] The output end of the optical attenuator controller is connected to the attenuation control end of the variable optical attenuator. The optical attenuator controller is used to control the current drive of the variable optical attenuator according to the DC component of the output signal of the preamplifier after amplification, so as to form automatic gain closed-loop control.

[0065] In addition, the optical receiver also includes:

[0066] Filter circuit (not shown);

[0067] The input end of the filter circuit is connected to the output end of the preamplifier;

[0068] The output end of the filter circuit is connected to the input end of the DC signal amplifying circuit.

[0069] like Figure 1 As shown in the figure, the current pulse fiber transceiver technology solution includes two parts: an optical transmitter composed of a pulse signal shaping circuit and a laser current driving circuit; and an optical receiver composed of a preamplifier and a comparison amplifier. The optical transmitter completes the electrical-optical conversion, and the optical receiver completes the optical-electrical conversion and pulse regeneration.

[0070] The current fiber optic transceiver technology adopts the optical signal modulation method of "bright pulse", that is, when a pulse appears, it corresponds to the "1" logic signal, corresponding to the "high optical power level"; when no pulse appears, it corresponds to the "0" logic signal, corresponding to "no optical power level or extremely low optical power level". In the optical transmitter, when a pulse signal - "1" signal appears at the input end, the pulse signal shaping circuit generates a "1" signal, so that the laser current driving circuit generates a pulse current to drive the laser to emit light, and generates an optical pulse signal corresponding to the pulse signal; when no pulse signal - "0" signal appears at the input end, the pulse signal shaping circuit generates a "0" signal, so that the laser current driving circuit does not output current to drive the laser, the laser does not emit light, and the output optical power is 0 or an extremely low optical power level.

[0071] The optical pulse light signal is transmitted through the optical fiber to the photodetector in the optical receiver to complete the optical-electrical conversion, and is converted into a photocurrent and amplified by the preamplifier to obtain a pulse signal V p It is regenerated by the comparison amplifier circuit and finally a regenerated pulse output is obtained.

[0072] In the above process, when the pulse duty cycle of the optical pulse signal modulated by the "bright pulse" method is low, it is not easy to detect the pulse amplitude level in the output optical signal in the optical transmitter to implement automatic optical power control; in the optical receiver, it is not easy to implement automatic gain control to control the pulse amplitude stability, nor is it easy to detect the pulse amplitude level well to automatically adjust the comparison threshold level of the comparison amplifier. Therefore, when regenerating the pulse, the comparison amplifier can only use a fixed comparison threshold level for comparison amplification to regenerate the pulse signal, such as Figure 2 and Figure 3 shown.

[0073] exist Figure 2 In the example, the comparison threshold level V th The value is a fixed value, such as the pulse signal V p When the fiber attenuation changes, the amplitude of the pulse signal output by the preamplifier changes accordingly, such as Figure 3 In this example, when the fiber attenuation increases by 5dB, the pulse signal amplitude changes from V p Drop to V' p , V' p =V p / 3. Since the comparison threshold level V this a fixed value, the rising edge time position of the regenerated pulse signal obtained by the comparison amplifier will change, the change is Δt, and the size of Δt is related to the change in the pulse signal amplitude and the pulse signal rising edge rate. When the pulse signal amplitude changes greatly, such as 10dB, and the pulse signal rising edge rate is low, such as 1ns, in the above example, the value of Δt can reach more than 600ps. In some applications, the transmission delay change of hundreds of ps exceeds the tolerance.

[0074] like Figure 4 The technical solution of the optical fiber transmission device includes two parts: an optical transmitter and an optical receiver. The optical transmitter completes the electrical-optical conversion, and the optical receiver completes the optical-electrical conversion and pulse regeneration.

[0075] The optical transmitter includes: pulse signal shaping, laser current driving, automatic power control, laser and a first photodetector; the pulse signal shaping, laser current driving and laser are connected in sequence, the first photodetector detects the backlight signal of the laser, and after being amplified by the automatic power control circuit, the pulse current driving is controlled to form an automatic optical power closed-loop control to stabilize the output optical power.

[0076] The optical receiver comprises: a variable optical attenuator, an optical attenuator controller, a second photodetector, a preamplifier, a comparison amplifier, and a DC signal amplifier; the variable optical attenuator, the second photodetector, the preamplifier, and the comparison amplifier are connected in sequence, the DC signal amplification circuit filters the output signal of the preamplifier, amplifies the obtained DC component signal, and then outputs it to the attenuation control end of the optical attenuator controller to form an automatic gain closed-loop control, so that the output signal of the preamplifier is stable and unchanged, and the comparison amplifier uses a fixed comparison threshold for pulse regeneration.

[0077] In the device of the present invention, a "dark pulse" optical signal modulation method is adopted. When a pulse signal appears, it corresponds to a "1" logic signal, corresponding to "no optical power level or extremely low optical power level"; when no pulse signal appears, it corresponds to a "0" logic signal, corresponding to "high optical power level". When a pulse signal - "1" signal appears at the input end, the pulse signal shaping circuit generates a "1" signal, the laser current driving circuit does not generate a pulse current to drive the laser, the laser does not emit light or only emits very low-power light, and the output optical power is 0 or an extremely low optical power level; when no pulse signal - "0" signal appears at the input end, the pulse signal shaping circuit generates a "0" signal, the laser current driving circuit outputs current to drive the laser to emit light, and the output optical power is high optical power.

[0078] After adopting the optical signal modulation method of "dark pulse", due to the low pulse duty cycle, less than 10E-3, at the optical transmitter end, the optical signal output by the optical transmitter is a high-power optical signal close to DC for most of the time; when a pulse signal appears, the optical power output by the optical transmitter is a lower value, such as less than -30dBm. In this way, it is easy to use the back-light signal DC signal amplification circuit to form an automatic optical power control circuit, so that the average optical power level of the optical signal output by the optical transmitter tends to a stable value, such as 0dBm, and the amplitude level value of the optical pulse signal is also approximately equal to the average power level value of the optical signal. Since the amplitude level of the optical pulse is approximately equal to the average output optical power of the laser, the amplitude of the pulse signal in the optical signal can be stabilized by controlling the average output optical power of the optical transmitter.

[0079] After adopting the optical signal modulation method of the "dark pulse" mode, in the embodiment, the preamplifier in the optical receiver simultaneously amplifies the DC signal and the pulse signal contained in the optical signal, the pulse signal level is approximately equal to the DC signal level, and the amplitude level of the pulse signal is obtained by detecting the DC level of the received optical signal; the DC signal amplification circuit filters the output signal of the preamplifier, amplifies the obtained DC component signal, and then outputs it to the attenuation control end of the optical attenuator, forming an automatic gain closed-loop control, so that the output signal of the preamplifier is stable and unchanged, even if the comparison amplifier uses a fixed comparison threshold, the ratio of the amplitude level of the pulse input signal to the comparison threshold level can still remain almost unchanged, and the rising edge time position of the regenerated pulse signal obtained by the comparison amplifier regeneration does not change with the change of the input pulse signal level, which greatly reduces the influence of the amplitude level change of the pulse input signal on the transmission delay. Even if a device with a lower rate and a smaller bandwidth is used, when the optical fiber line loss changes, it can ensure that the transmission delay hardly changes with the change of the optical fiber line loss.

[0080] In addition, the present invention also provides a time-frequency signal transmission system, comprising:

[0081] Transmitting terminal equipment, a plurality of transmission devices for the above-mentioned time-frequency signals, and a plurality of receiving terminal equipment;

[0082] The transmitting terminal equipment is connected to the multiple transmission devices respectively; the multiple transmission devices and the multiple receiving terminal equipment are connected one by one.

[0083] Figure 5 FIG. 1 is a flow chart of a method for transmitting a time-frequency signal in an embodiment of the present invention. Figure 5 The present invention provides a method for transmitting a time-frequency signal. The method is applied to the above-mentioned device for transmitting the time-frequency signal. The method comprises:

[0084] Step 501: The optical transmitter performs “dark pulse” modulation on the time-frequency electrical signal sent by the transmitting terminal device, and performs electrical-optical conversion on the modulated time-frequency electrical signal to obtain a time-frequency optical signal;

[0085] Step 502: The optical fiber line transmits the time-frequency optical signal;

[0086] Step 503: the optical receiver performs photoelectric conversion on the time-frequency optical signal transmitted through the optical fiber line to obtain the transmitted time-frequency electrical signal;

[0087] Step 504: The receiving terminal device receives the transmitted time-frequency electrical signal.

[0088] Step 501 specifically includes:

[0089] Performing “dark pulse” modulation on the time-frequency electrical signal sent by the transmitting terminal device;

[0090] A first photodetector detects a backlight signal at the laser;

[0091] The automatic power controller amplifies the backlight signal and controls the current drive of the laser according to the amplified backlight signal, so that the pulse amplitude of the time-frequency optical signal output by the laser is maintained within a first preset range.

[0092] Step 503 specifically includes:

[0093] Obtaining a DC component of a time-frequency optical signal after transmission through an optical fiber line;

[0094] Amplifying the DC component;

[0095] The optical attenuator controller controls the current drive of the variable optical attenuator according to the DC component of the output signal of the preamplifier after amplification processing, so that the signal amplitude of the input comparison amplifier is maintained within a second preset range.

[0096] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0097] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A transmission device for time-frequency signals, characterized in that: The transmission device comprises: Optical transmitters and optical receivers; The optical transmitter is connected to the transmitting terminal device; the optical transmitter is connected to the optical receiver through an optical fiber line; the optical transmitter is used to perform "dark pulse" modulation on the time-frequency electrical signal sent by the transmitting terminal device, and perform electrical-optical conversion on the modulated time-frequency electrical signal to obtain a time-frequency optical signal; The optical receiver is connected to a receiving terminal device; the optical receiver performs photoelectric conversion on the time-frequency optical signal transmitted through the optical fiber line to obtain a transmitted time-frequency electrical signal, and transmits the transmitted time-frequency electrical signal to the receiving terminal device; The optical transmitter specifically comprises: A pulse signal shaping circuit, a laser current driver, a laser, an automatic power controller and a first photodetector; The input end of the pulse signal shaping circuit is connected to the transmitting terminal device; the pulse signal shaping circuit, the laser current driver and the laser are connected in sequence; the output end of the laser is connected to one end of the optical fiber line; The first photodetector is connected to the automatic power controller; the first photodetector is used to detect the backlight signal of the laser; The automatic power controller is used to amplify the backlight signal and control the current drive of the laser according to the amplified backlight signal to form a closed-loop control of automatic optical power; The optical receiver specifically comprises: A variable optical attenuator, a second photodetector, a preamplifier, a comparison amplifier, a filter circuit, a DC signal amplification circuit and an optical attenuator controller; The variable optical attenuator is connected to the other end of the optical fiber line; the variable optical attenuator, the second photodetector, the preamplifier, and the comparison amplifier are connected in sequence; the output end of the comparison amplifier is connected to the receiving terminal device; The DC signal amplifying circuit is connected to the output end of the preamplifier and the input end of the optical attenuator controller respectively; the DC signal amplifying circuit is used to amplify the DC component of the output signal of the preamplifier; The output end of the optical attenuator controller is connected to the attenuation control end of the variable optical attenuator, and the optical attenuator controller is used to control the current drive of the variable optical attenuator according to the DC component of the output signal of the preamplifier after amplification, so as to form an automatic gain closed-loop control; The input end of the filter circuit is connected to the output end of the preamplifier; The output end of the filter circuit is connected to the input end of the DC signal amplifying circuit; The optical transmitter performs "dark pulse" modulation on the time-frequency electrical signal sent by the transmitting terminal device, and performs electrical-optical conversion on the modulated time-frequency electrical signal to obtain a time-frequency optical signal; the optical fiber line transmits the time-frequency optical signal; the optical receiver performs photoelectric conversion on the time-frequency optical signal transmitted through the optical fiber line to obtain a transmitted time-frequency electrical signal; the receiving terminal device receives the transmitted time-frequency electrical signal; The optical transmitter performs "dark pulse" modulation on the time-frequency electrical signal sent by the transmitting terminal device, and performs electro-optical conversion on the modulated time-frequency electrical signal to obtain a time-frequency optical signal, specifically including: performing "dark pulse" modulation on the time-frequency electrical signal sent by the transmitting terminal device; a first photodetector detects a backlight signal at the laser; an automatic power controller amplifies the backlight signal, and controls the current drive of the laser according to the amplified backlight signal, so that the pulse amplitude of the time-frequency optical signal output by the laser is maintained within a first preset range; The optical receiver performs photoelectric conversion on the time-frequency optical signal transmitted through the optical fiber line to obtain the time-frequency electrical signal after transmission, specifically including: obtaining the DC component of the time-frequency optical signal transmitted through the optical fiber line; amplifying the DC component; and the optical attenuator controller controls the current drive of the variable optical attenuator according to the DC component of the output signal of the preamplifier after the amplification process, so that the signal amplitude of the input comparison amplifier is maintained within a second preset range.

2. A time-frequency signal transmission system, characterized in that: The transmission system comprises: A transmitting terminal device, a plurality of time-frequency signal transmission devices according to any one of claims 1, and a plurality of receiving terminal devices; The transmitting terminal equipment is connected to the plurality of transmission devices respectively; the plurality of transmission devices and the plurality of receiving terminal equipment are connected one-to-one.

3. A method for transmitting a time-frequency signal, characterized in that: The transmission method is applied to the transmission device of the time-frequency signal according to any one of claims 1, and the transmission method comprises: The optical transmitter performs "dark pulse" modulation on the time-frequency electrical signal sent by the transmitting terminal device, and performs electro-optical conversion on the modulated time-frequency electrical signal to obtain a time-frequency optical signal; The optical fiber line transmits the time-frequency optical signal; The optical receiver performs photoelectric conversion on the time-frequency optical signal transmitted through the optical fiber line to obtain the transmitted time-frequency electrical signal; The receiving terminal device receives the transmitted time-frequency electrical signal; The optical transmitter performs "dark pulse" modulation on the time-frequency electrical signal sent by the transmitting terminal device, and performs electro-optical conversion on the modulated time-frequency electrical signal to obtain a time-frequency optical signal, specifically including: performing "dark pulse" modulation on the time-frequency electrical signal sent by the transmitting terminal device; a first photodetector detects a backlight signal at the laser; an automatic power controller amplifies the backlight signal, and controls the current drive of the laser according to the amplified backlight signal, so that the pulse amplitude of the time-frequency optical signal output by the laser is maintained within a first preset range; The optical receiver performs photoelectric conversion on the time-frequency optical signal transmitted through the optical fiber line to obtain the time-frequency electrical signal after transmission, specifically including: obtaining the DC component of the time-frequency optical signal transmitted through the optical fiber line; amplifying the DC component; and the optical attenuator controller controls the current drive of the variable optical attenuator according to the DC component of the output signal of the preamplifier after the amplification process, so that the signal amplitude of the input comparison amplifier is maintained within a second preset range.

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