Protection Method and Protection Circuit for Preventing External Incoming Signals in an Optical Receiver

Abstract

The present invention discloses a protection method and a protection circuit for preventing external signals from being coupled into an optical receiver. The protection method for preventing external signals from being coupled into an optical receiver includes the following steps: Step S1: A disturbing signal externally coupled is accessed through the RF port F2 of the optical receiver; Step S2: The RF port F2 of the optical receiver outputs a first-stage input signal to the first-stage lightning and surge protection module; Step S3: The first-stage lightning and surge protection module processes the first-stage input signal and outputs a first-stage output signal; Step S4: The second-stage 220V electrical protection module processes the first-stage output signal and outputs a second-stage output signal. The protection method and the protection circuit for preventing external signals from being coupled into the optical receiver disclosed by the present invention help to specifically solve interferences such as the pulse voltage caused by lightning strikes, the AC leakage voltage of 220V, the low-frequency voltage of DC-DC conversion, and low-frequency signals.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical receiver protection, and particularly relates to a protection method for preventing external signals from being coupled into an optical receiver and a protection circuit for preventing external signals from being coupled into an optical receiver. Background Art

[0002] The utility model patent with the publication number CN2490764 and the theme name of an economical and practical fiber optic workstation discloses a technical solution including "a cable splicing box (3) connected to the two-way optical cable central computer room at its front end, an optical receiver (4) connected to the optical cable line led out from the splicing box (3), a power supply (2) for supplying power to the machine (4), and a device (1) for implementing power metering and security for the power supply, etc. The components are composed of; its characteristics are: ① At the output end of the optical receiver, there are connected: a power injection type 2-way splitter component (7) that can split one RF signal output by the optical receiver (4) into 2 downlink RF signals when only transmitting radio and television signals, and a two-way port component (6) that can split 2 downlink RF signals output by the optical receiver (4) into 4 downlink RF signals and at the same time synthesize 4 uplink RF signals into one return signal when upgraded to two-way communication. This component can be conveniently replaced with the power injection type 2-way splitter component (7) and directly connected to the downlink output end of the optical receiver (4). And between the uplink output end of the two-way port component (6) and the uplink input end of the cable splicing box (3), a return optical transmitter (5) is installed at the same time; ② All the above components; the power metering and security device (1), the power supply (2), the cable splicing box (3), the optical receiver (4), the return optical transmitter (5), and the 4-way output two-way port (6) are integrated in a box body (8)", "Its security circuit is composed of: two fuse tubes Bx1 and Bx2 and a leakage circuit breaker are installed at the 220V mains power supply incoming line end, and between the two output lines at the output end of the leakage circuit breaker, two varistors RV1 and RV2 grounded in the middle are connected in series. After the output line enters the power supply, first, two fuse tubes BX3 and BX4 are installed at its input end. Two varistors RV3 and RV4 grounded in the middle are connected in series in the primary circuit of the transformer of the power supply and are connected to the front-end fuse tubes BX3 and BX4. One end of the secondary circuit of the transformer, that is, the output end of the power supply, is grounded, and the other end is connected in series with a fuse tube BX5 and then has a 60V output."

[0003] Taking the above-mentioned utility model patent as an example, when we usually use a TV set, there may be a leakage problem (sometimes when we touch the TV set, we feel a tingling sensation in our hands, indicating that the TV set has a leakage), or there may be a potential difference problem between the TV set and the optical receiver. There are various leakage situations in the TV set. For example, the insulation is poor, leaking 220V alternating current, or there is a problem with the contact after DC-DC conversion, leaking direct current. The main reason for the above-mentioned leakage is that the voltage is transmitted from the video or radio frequency port to the optical receiver, causing the feedback voltage to burn out the optical receiver, which needs to be further improved. Summary of the Invention

[0004] In view of the current situation of the prior art, the present invention overcomes the above-mentioned defects and provides a protection method for preventing external signals from being coupled into an optical receiver and a protection circuit for preventing external signals from being coupled into an optical receiver.

[0005] The protection method for preventing external signals from being coupled into an optical receiver and its protection circuit disclosed in the present invention for patent application mainly aims to improve the product quality and effectively process interference signals such as those easily affected by the periphery in TVs.

[0006] Another object of the protection method for preventing external signals from being coupled into an optical receiver and its protection circuit disclosed in the present invention for patent application is to help specifically solve interferences such as impulse voltage caused by lightning strikes, 220V AC leakage voltage, low-frequency voltage of DC-DC conversion, and low-frequency signals.

[0007] Another object of the protection method for preventing external signals from being coupled into an optical receiver and its protection circuit disclosed in the present invention for patent application is to highlight the concept of hierarchical protection, skillfully set the purposes of each level of protection, so as to maximize the protection effect.

[0008] Another object of the protection method for preventing external signals from being coupled into an optical receiver and its protection circuit disclosed in the present invention for patent application is that the first-level protection uses a ceramic gas discharge tube, which has a small junction capacitance, does not affect high-frequency signals, and plays a lightning protection role to solve the lightning surge problem.

[0009] Another object of the protection method for preventing external signals from being coupled into an optical receiver and its protection circuit disclosed in the present invention for patent application is that the second-level protection uses a high-voltage capacitor to isolate the 220V current and prevent the 220V high-voltage from being fed back to the optical receiver.

[0010] Another object of the protection method for preventing external signals from being coupled into an optical receiver and its protection circuit disclosed in the present invention for patent application is that the third-level protection uses a fast-recovery diode with a small junction capacitance to filter out the DC voltage fed back by DC-DC.

[0011] The protection method and protection circuit for preventing external intrusion signals of an optical receiver disclosed in this invention patent application have another objective. The fourth-level protection uses a low-frequency filter to filter out the feedback low-frequency signals. Considering different interference signals from various aspects, different protection circuits are adopted to filter out other unnecessary signals and avoid damage to the active chips of the device.

[0012] The present invention adopts the following technical solutions. The protection method for preventing external intrusion signals of the optical receiver includes the following steps:

[0013] Step S1: The RF port F2 of the optical receiver accesses the externally intruded interference signal.

[0014] Step S2: The RF port F2 of the optical receiver outputs a first-stage input signal to the first-stage lightning and surge protection module.

[0015] Step S3: The first-stage lightning and surge protection module processes the first-stage input signal and outputs a first-stage output signal.

[0016] Step S4: The second-stage 220V power filtering protection module processes the first-stage output signal and outputs a second-stage output signal.

[0017] Step S5: The third-stage DC filtering protection module processes the second-stage output signal and outputs a third-stage output signal.

[0018] Step S6: The fourth-stage low-frequency signal filtering protection module processes the third-stage output signal and outputs a fourth-stage output signal.

[0019] Step S7: The active device U5 of the optical receiver processes the fourth-stage output signal and outputs an RF signal.

[0020] According to the above technical solutions, as a further preferred technical solution of the above technical solutions, the first-stage lightning and surge protection includes a ceramic gas discharge tube D8. One end of the ceramic gas discharge tube D8 is grounded, and the other end of the ceramic gas discharge tube D8 is connected to the RF port F2 of the optical receiver.

[0021] According to the above technical solutions, as a further preferred technical solution of the above technical solutions, the second-stage 220V power filtering protection module includes a high-voltage capacitor C37. One end of the high-voltage capacitor C37 is connected to the other end of the ceramic gas discharge tube D8.

[0022] According to the above technical solutions, as a further preferred technical solution of the above technical solutions, the third-stage DC filtering protection module includes an inductor L9 and two series-connected switch diodes D7 and D9 in the forward direction. One end of the inductor L9 is connected to the other end of the high-voltage capacitor C37.

[0023] According to the above technical solution, as a further preferred technical solution of the above technical solution, the fourth-stage low-frequency signal protection module includes a first low-frequency filter unit, a second low-frequency filter unit, a third low-frequency filter unit, and a fourth low-frequency filter unit connected in series in sequence. The first low-frequency filter unit is connected to the common terminal of the inductor L9 and the switching diode D9, and the fourth low-frequency filter unit is connected to the active device U5 of the optical receiver.

[0024] According to the above technical solution, as a further preferred technical solution of the above technical solution, the first low-frequency filter unit includes a capacitor C38 and a capacitor C42 and an inductor L10 connected in series in sequence. One end of the capacitor C38 is connected to the common terminal of the inductor L9 and the switching diode D7, the other end of the capacitor C38 is connected to one end of the capacitor C42, the other end of the capacitor C42 is connected to one end of the inductor L10, and the other end of the inductor L10 is grounded.

[0025] According to the above technical solution, as a further preferred technical solution of the above technical solution, the second low-frequency filter unit includes a capacitor C39 and a capacitor C43 and an inductor L11 connected in series in sequence. One end of the capacitor C39 is connected to the common terminal of the capacitor C38 and the capacitor C42, the other end of the capacitor C39 is connected to one end of the capacitor C43, the other end of the capacitor C43 is connected to one end of the inductor L11, and the other end of the inductor L11 is grounded.

[0026] According to the above technical solution, as a further preferred technical solution of the above technical solution, the third low-frequency filter unit includes a capacitor C40 and a capacitor C44 and an inductor L12 connected in series in sequence. One end of the capacitor C40 is connected to the common terminal of the capacitor C39 and the capacitor C43, the other end of the capacitor C40 is connected to one end of the capacitor C44, the other end of the capacitor C44 is connected to one end of the inductor L12, and the other end of the inductor L12 is grounded.

[0027] According to the above technical solution, as a further preferred technical solution of the above technical solution, the fourth low-frequency filter unit includes a capacitor C41 and an inductor L13 and a resistor R37 connected in series in sequence. One end of the capacitor C41 is connected to the common terminal of the capacitor C40 and the capacitor C44, the other end of the capacitor C41 is connected to one end of the inductor L13, the other end of the inductor L13 is connected to one end of the resistor R37, and the other end of the resistor R37 is connected to a VCC power supply.

[0028] The present invention patent application also discloses a protection circuit for preventing external signals from being introduced into an optical receiver, which includes an RF port F2 of an optical receiver and an active device U5 of an optical receiver. The protection circuit for preventing external signals from being introduced into the optical receiver further includes:

[0029] A first-stage lightning and surge protection module. The first-stage lightning and surge protection includes a ceramic gas discharge tube D8. One end of the ceramic gas discharge tube D8 is grounded, and the other end of the ceramic gas discharge tube D8 is connected to the RF port F2 of the optical receiver;

[0030] A second-stage 220V power filter protection module. The second-stage 220V power filter protection module includes a high-voltage capacitor C37. One end of the high-voltage capacitor C37 is connected to the other end of the ceramic gas discharge tube D8;

[0031] A third-stage DC filter protection module. The third-stage DC filter protection module includes an inductor L9 and two switch diodes D7 and D9 connected in series in the forward direction. One end of the inductor L9 is connected to the other end of the high-voltage capacitor C37;

[0032] A fourth-stage low-frequency signal filter protection module. The fourth-stage low-frequency signal filter protection module includes a first low-frequency filter unit, a second low-frequency filter unit, a third low-frequency filter unit, and a fourth low-frequency filter unit connected in series in the forward direction. The first low-frequency filter unit is connected to the common end of the inductor L9 and the switch diode D9, and the fourth low-frequency filter unit is connected to the active device U5 of the optical receiver.

[0033] The protection method and protection circuit for preventing external signals from being introduced into the optical receiver disclosed by the present invention have the beneficial effect that they are helpful to specifically solve the interference of impulse voltage caused by lightning strikes, AC leakage voltage of 220V, low-frequency voltage of DC-DC conversion, low-frequency signals, etc. Description of the Drawings

[0034] Figure 1 is the circuit schematic diagram of the present invention.

[0035] Figure 2 is the system block diagram of the present invention. Detailed Embodiments

[0036] The present invention discloses a protection method for preventing external signals from being introduced into an optical receiver and a protection circuit for preventing external signals from being introduced into an optical receiver. The following further describes the specific embodiments of the present invention in conjunction with preferred embodiments.

[0037] Referring to the accompanying drawings of Figure 1 and Figure 2 , Figure 1Shows the circuit topology of a protection method and its protection circuit for a photoreceiver to prevent externally coupled-in signals. Figure 2 Shows the hierarchical protection concept of a protection method and its protection circuit for a photoreceiver to prevent externally coupled-in signals.

[0038] First embodiment.

[0039] Preferably, the protection circuit for the photoreceiver to prevent externally coupled-in signals includes an RF port F2 of a photoreceiver and an active device U5 of a photoreceiver. The protection circuit for the photoreceiver to prevent externally coupled-in signals further includes:

[0040] A first-stage lightning and surge protection module. The first-stage lightning and surge protection includes a ceramic gas discharge tube D8. One end of the ceramic gas discharge tube D8 is grounded, and the other end of the ceramic gas discharge tube D8 is connected to the RF port F2 of the photoreceiver.

[0041] A second-stage 220V power filter protection module. The second-stage 220V power filter protection module includes a high-voltage capacitor C37. One end of the high-voltage capacitor C37 is connected to the other end of the ceramic gas discharge tube D8.

[0042] A third-stage DC filter protection module. The third-stage DC filter protection module includes an inductor L9 and two switch diodes D7 and D9 connected in series in the forward direction. One end of the inductor L9 is connected to the other end of the high-voltage capacitor C37.

[0043] A fourth-stage low-frequency signal filter protection module. The fourth-stage low-frequency signal filter protection module includes a first low-frequency filter unit, a second low-frequency filter unit, a third low-frequency filter unit, and a fourth low-frequency filter unit connected in series in the forward direction. The first low-frequency filter unit is connected to the common end of the inductor L9 and the switch diode D9, and the fourth low-frequency filter unit is connected to the active device U5 of the photoreceiver.

[0044] Further, the other end of the ceramic gas discharge tube D8 is connected to the No. 1 terminal of the RF port F2 of the photoreceiver.

[0045] Further, the No. 2 terminal of the RF port F2 of the photoreceiver is grounded.

[0046] Further, the switch diode D7 is preferably a BAV99 (fast recovery diode with small junction capacitance).

[0047] Further, the switch diode D9 is preferably a BAV99 (fast recovery diode with small junction capacitance).

[0048] Further, the first low-frequency filter unit includes a capacitor C38, a capacitor C42 and an inductor L10 connected in series in sequence. One end of the capacitor C38 is connected to the common end of the inductor L9 and the switching diode D7. The other end of the capacitor C38 is connected to one end of the capacitor C42. The other end of the capacitor C42 is connected to one end of the inductor L10. The other end of the inductor L10 is grounded.

[0049] Further, the second low-frequency filter unit includes a capacitor C39, a capacitor C43 and an inductor L11 connected in series in sequence. One end of the capacitor C39 is connected to the common end of the capacitor C38 and the capacitor C42. The other end of the capacitor C39 is connected to one end of the capacitor C43. The other end of the capacitor C43 is connected to one end of the inductor L11. The other end of the inductor L11 is grounded.

[0050] Further, the third low-frequency filter unit includes a capacitor C40, a capacitor C44 and an inductor L12 connected in series in sequence. One end of the capacitor C40 is connected to the common end of the capacitor C39 and the capacitor C43. The other end of the capacitor C40 is connected to one end of the capacitor C44. The other end of the capacitor C44 is connected to one end of the inductor L12. The other end of the inductor L12 is grounded.

[0051] Further, the fourth low-frequency filter unit includes a capacitor C41, an inductor L13 and a resistor R37 connected in series in sequence. One end of the capacitor C41 is connected to the common end of the capacitor C40 and the capacitor C44. The other end of the capacitor C41 is connected to one end of the inductor L13. The other end of the inductor L13 is connected to one end of the resistor R37. The other end of the resistor R37 is connected to a VCC power supply.

[0052] Further, the fourth low-frequency filter unit further includes a capacitor C45. One end of the capacitor C45 is connected to the common end of the inductor L13 and the resistor R37. The other end of the capacitor C45 is grounded.

[0053] Further, the fourth low-frequency filter unit further includes a capacitor C46. One end of the capacitor C46 is connected to the common end of the resistor R37 and the VCC power supply. The other end of the capacitor C46 is grounded.

[0054] Further, the active device of the optical receiver includes an active chip U5. The 3rd terminal of the active chip U5 is connected to the common end of the capacitor C41 and the inductor L13. The 2nd terminal of the active chip U5 is grounded. The 1st terminal of the active chip U5 outputs an RF signal.

[0055] Preferred embodiment.

[0056] Preferably, the protection method for the optical receiver to prevent external intrusion signals includes the following steps:

[0057] Step S1: The RF port F2 of the optical receiver accesses the externally intruded interference signal;

[0058] Step S2: The RF port F2 of the optical receiver outputs a first-stage input signal to the first-stage lightning and surge protection module;

[0059] Step S3: The first-stage lightning and surge protection module (obtains the first-stage input signal and) processes the first-stage input signal and outputs a first-stage output signal;

[0060] Step S4: The second-stage 220V power filter protection module (obtains the first-stage output signal and) processes the first-stage output signal and outputs a second-stage output signal;

[0061] Step S5: The third-stage DC filter protection module (obtains the second-stage output signal and) processes the second-stage output signal and outputs a third-stage output signal;

[0062] Step S6: The fourth-stage low-frequency signal filter protection module (obtains the third-stage output signal and) processes the third-stage output signal and outputs a fourth-stage output signal;

[0063] Step S7: The active device U5 of the optical receiver processes the fourth-stage output signal and outputs an RF signal.

[0064] Furthermore, the first-stage lightning and surge protection includes a ceramic gas discharge tube D8. One end of the ceramic gas discharge tube D8 is grounded, and the other end of the ceramic gas discharge tube D8 is connected to the RF port F2 of the optical receiver.

[0065] It is worth mentioning that the first-stage protection uses a ceramic gas discharge tube, which has a small junction capacitance, does not affect high-frequency signals, and plays a role in lightning protection, solving the problem of lightning surges.

[0066] Furthermore, the second-stage 220V power filter protection module includes a high-voltage capacitor C37. One end of the high-voltage capacitor C37 is connected to the other end of the ceramic gas discharge tube D8.

[0067] It is worth mentioning that the second-stage protection uses a high-voltage capacitor, which plays a role in isolating the 220V current and preventing the 220V high voltage from being fed back to the optical receiver.

[0068] Furthermore, the third-stage DC filter protection module includes an inductor L9 and two series-connected switching diodes D7 and D9 in the forward direction. One end of the inductor L9 is connected to the other end of the high-voltage capacitor C37.

[0069] It is worth mentioning that the third-level protection uses fast-recovery diodes with small junction capacitance to filter out the DC voltage of the DC-DC feedback.

[0070] Further, the fourth-level low-frequency signal filtering protection module includes a first low-frequency filter unit, a second low-frequency filter unit, a third low-frequency filter unit, and a fourth low-frequency filter unit connected in series in sequence. The first low-frequency filter unit is connected to the common terminal of the inductor L9 and the switching diode D9, and the fourth low-frequency filter unit is connected to the active device U5 of the optical receiver.

[0071] Further, the other end of the ceramic gas discharge tube D8 is connected to the 1st terminal of the RF port F2 of the optical receiver.

[0072] Further, the 2nd terminal of the RF port F2 of the optical receiver is grounded.

[0073] Further, the switching diode D7 is preferably a BAV99 (fast-recovery diode with small junction capacitance).

[0074] Further, the switching diode D9 is preferably a BAV99 (fast-recovery diode with small junction capacitance).

[0075] Further, the first low-frequency filter unit includes a capacitor C38 and a capacitor C42 and an inductor L10 connected in series in sequence. One end of the capacitor C38 is connected to the common terminal of the inductor L9 and the switching diode D7, the other end of the capacitor C38 is connected to one end of the capacitor C42, the other end of the capacitor C42 is connected to one end of the inductor L10, and the other end of the inductor L10 is grounded.

[0076] Further, the second low-frequency filter unit includes a capacitor C39 and a capacitor C43 and an inductor L11 connected in series in sequence. One end of the capacitor C39 is connected to the common terminal of the capacitor C38 and the capacitor C42, the other end of the capacitor C39 is connected to one end of the capacitor C43, the other end of the capacitor C43 is connected to one end of the inductor L11, and the other end of the inductor L11 is grounded.

[0077] Further, the third low-frequency filter unit includes a capacitor C40 and a capacitor C44 and an inductor L12 connected in series in sequence. One end of the capacitor C40 is connected to the common terminal of the capacitor C39 and the capacitor C43, the other end of the capacitor C40 is connected to one end of the capacitor C44, the other end of the capacitor C44 is connected to one end of the inductor L12, and the other end of the inductor L12 is grounded.

[0078] Further, the fourth low-frequency filter unit includes a capacitor C41, an inductor L13 and a resistor R37 connected in series in sequence. One end of the capacitor C41 is connected to the common end of the capacitor C40 and the capacitor C44. The other end of the capacitor C41 is connected to one end of the inductor L13. The other end of the inductor L13 is connected to one end of the resistor R37. The other end of the resistor R37 is connected to a VCC power supply.

[0079] Further, the fourth low-frequency filter unit further includes a capacitor C45. One end of the capacitor C45 is connected to the common end of the inductor L13 and the resistor R37. The other end of the capacitor C45 is grounded.

[0080] Further, the fourth low-frequency filter unit further includes a capacitor C46. One end of the capacitor C46 is connected to the common end of the resistor R37 and the VCC power supply. The other end of the capacitor C46 is grounded.

[0081] It is worth mentioning that the fourth-level protection adopts a low-frequency filter to filter out the feedback low-frequency signals. Considering different interference signals from all aspects, different protection circuits are adopted to filter out other unnecessary signals to avoid damage to the active chips of the device.

[0082] Further, the active device of the optical receiver includes an active chip U5. The 3rd terminal of the active chip U5 is connected to the common end of the capacitor C41 and the inductor L13. The 2nd terminal of the active chip U5 is grounded. The 1st terminal of the active chip U5 outputs an RF signal.

[0083] It is worth mentioning that through the above hierarchical protection, the concept of hierarchical protection is highlighted, which helps to specifically solve the interference of lightning impulse voltage, 220V AC leakage voltage, low-frequency voltage of DC-DC conversion, low-frequency signals, etc., so as to maximize the protection effect.

[0084] It is worth mentioning that the specific selection and other technical features of the active chip U5 involved in this invention patent application should be regarded as the prior art. The specific structures, working principles, and possible control methods and spatial arrangement methods of these technical features can be selected conventionally in the art, and should not be regarded as the invention points of this invention patent. This invention patent will not be further specifically elaborated.

[0085] For those skilled in the art, it is still possible to modify the technical solutions recorded in the foregoing embodiments, or equivalently replace some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A protection method for a photoreceiver to prevent externally infiltrating signals, characterized in that, Including the following steps: Step S1: The RF port F2 of the optical receiver accesses the externally injected interference signal; Step S2: The RF port F2 of the optical receiver outputs a first-stage input signal to the first-stage lightning and surge protection module; Step S3: The first-stage lightning and surge protection module processes the first-stage input signal and outputs a first-stage output signal; Step S4: The second-stage 220V power filter protection module processes the first-stage output signal and outputs a second-stage output signal; Step S5: The third-stage DC filter protection module processes the second-stage output signal and outputs a third-stage output signal; Step S6: The fourth-stage low-frequency signal filter protection module processes the third-stage output signal and outputs a fourth-stage output signal; Step S7: The active device U5 of the optical receiver processes the fourth-stage output signal and outputs an RF signal; The fourth-stage low-frequency signal filter protection module includes a first low-frequency filter unit, a second low-frequency filter unit, a third low-frequency filter unit, and a fourth low-frequency filter unit connected in series in sequence; The fourth low-frequency filter unit includes a capacitor C41 and an inductor L13 and a resistor R37 connected in series in sequence. One end of the capacitor C41 accesses the third low-frequency filter unit. The other end of the capacitor C41 accesses one end of the inductor L13. The other end of the inductor L13 is connected to one end of the resistor R37. The other end of the resistor R37 is connected to a VCC power supply; The fourth low-frequency filter unit further includes a capacitor C45. One end of the capacitor C45 accesses the common end of the inductor L13 and the resistor R37. The other end of the capacitor C45 is grounded; The fourth low-frequency filter unit further includes a capacitor C46. One end of the capacitor C46 accesses the common end of the resistor R37 and the VCC power supply. The other end of the capacitor C46 is grounded.

2. The protection method for preventing external intrusion signals in an optical receiver according to claim 1, characterized in that, The first-stage lightning and surge protection includes a ceramic gas discharge tube D8. One end of the ceramic gas discharge tube D8 is grounded. The other end of the ceramic gas discharge tube D8 accesses the RF port F2 of the optical receiver; 3. The protection method for preventing externally intruding signals in an optical receiver according to claim 2, characterized in that The second-stage 220V power filter protection module includes a high-voltage capacitor C37. One end of the high-voltage capacitor C37 is connected to the other end of the ceramic gas discharge tube D8; 4. The protection method for preventing external intrusion signals in an optical receiver according to claim 3, characterized in that, The third-stage DC filter protection module includes an inductor L9 and two switching diodes D7 and D9 connected in series in sequence. One end of the inductor L9 is connected to the other end of the high-voltage capacitor C37; 5. The protection method for preventing external interfering signals in an optical receiver according to claim 4, characterized in that, The first low-frequency filter unit accesses the common end of the inductor L9 and the switching diode D9. The fourth low-frequency filter unit accesses the active device U5 of the optical receiver; 6. The protection method for preventing external intrusion signals in an optical receiver according to claim 5, characterized in that, The first low-frequency filter unit includes a capacitor C38 and a capacitor C42 and an inductor L10 connected in series in sequence. One end of the capacitor C38 accesses the common end of the inductor L9 and the switching diode D7. The other end of the capacitor C38 is connected to one end of the capacitor C42. The other end of the capacitor C42 accesses one end of the inductor L10. The other end of the inductor L10 is grounded.

7. The protection method for preventing external interfering signals in an optical receiver according to claim 6, characterized in that, The second low-frequency filter unit includes a capacitor C39, a capacitor C43 and an inductor L11 connected in series in sequence. One end of the capacitor C39 is connected to the common end of the capacitor C38 and the capacitor C42. The other end of the capacitor C39 is connected to one end of the capacitor C43. The other end of the capacitor C43 is connected to one end of the inductor L11. The other end of the inductor L11 is grounded.

8. The protection method for preventing external intrusion signals in an optical receiver according to claim 7, characterized in that, The third low-frequency filter unit includes a capacitor C40, a capacitor C44 and an inductor L12 connected in series in sequence. One end of the capacitor C40 is connected to the common end of the capacitor C39 and the capacitor C43. The other end of the capacitor C40 is connected to one end of the capacitor C44. The other end of the capacitor C44 is connected to one end of the inductor L12. The other end of the inductor L12 is grounded.

9. A protection circuit for a photoreceiver to prevent external signal intrusion, characterized in that, It includes an RF port F2 of an optical receiver and an active device U5 of an optical receiver. It is characterized in that the protection circuit for preventing external signals from being connected in series to the optical receiver further includes: A first-stage lightning and surge protection module. The first-stage lightning and surge protection includes a ceramic gas discharge tube D8. One end of the ceramic gas discharge tube D8 is grounded. The other end of the ceramic gas discharge tube D8 is connected to the RF port F2 of the optical receiver. A second-stage 220V power filter protection module. The second-stage 220V power filter protection module includes a high-voltage capacitor C37. One end of the high-voltage capacitor C37 is connected to the other end of the ceramic gas discharge tube D8. A third-stage DC filter protection module. The third-stage DC filter protection module includes an inductor L9 and two switching diodes D7 and D9 connected in series in sequence. One end of the inductor L9 is connected to the other end of the high-voltage capacitor C37. A fourth-stage low-frequency signal filter protection module. The fourth-stage low-frequency signal filter protection module includes a first low-frequency filter unit, a second low-frequency filter unit, a third low-frequency filter unit and a fourth low-frequency filter unit connected in series in sequence. The first low-frequency filter unit is connected to the common end of the inductor L9 and the switching diode D9. The fourth low-frequency filter unit is connected to the active device U5 of the optical receiver. The fourth low-frequency filter unit includes a capacitor C41, an inductor L13 and a resistor R37 connected in series in sequence. One end of the capacitor C41 is connected to the third low-frequency filter unit. The other end of the capacitor C41 is connected to one end of the inductor L13. The other end of the inductor L13 is connected to one end of the resistor R37. The other end of the resistor R37 is connected to a VCC power supply. The fourth low-frequency filter unit further includes a capacitor C45. One end of the capacitor C45 is connected to the common end of the inductor L13 and the resistor R37. The other end of the capacitor C45 is grounded. The fourth low-frequency filter unit further includes a capacitor C46. One end of the capacitor C46 is connected to the common end of the resistor R37 and the VCC power supply. The other end of the capacitor C46 is grounded.

Images