WO2020207181A1

WO2020207181A1 - Radiated emission positioning rectification method for multi-user unit of passive optical network

Info

Publication number: WO2020207181A1
Application number: PCT/CN2020/078941
Authority: WO
Inventors: 蔡云枝; 曹鹏; 王海波
Original assignee: 太仓市同维电子有限公司
Priority date: 2019-04-11
Filing date: 2020-03-12
Publication date: 2020-10-15
Also published as: KR20200127210A; CN109819641A; CN109819641B

Abstract

The present invention relates to the field of electronic communications, and specifically relates to a radiated emission positioning rectification method for a multi-user unit of a passive optical network. The method comprises the following steps: diagnosing an interference source and an interference propagation path; performing safe grounding and bonding on EMC in advance; removing an unnecessary frequency component from a frequency domain by means of filtering, thereby reducing electromagnetic disturbance in two aspects, i.e. conduction and radiation; suppressing, by means of shielding, various types of electromagnetic interference propagated in space; replacing a suspicious element with an element meeting an EMC requirement; and with regard to a crystal oscillator product, reducing output energy of a crystal oscillator and a harmonic wave thereof by means of a method of connecting resistors in series or in parallel. In the present invention, starting from the root, radiation energy is reduced from a source, a path of radiated interference is destroyed or changed, a gap is reduced, filtering is enhanced, and a radiation mechanism is destroyed by changing the position of a line, such that radiated emission positioning rectification of a multi-user unit of a passive optical network can be rapidly and accurately performed.

Description

Radiation emission positioning rectification method for passive optical network multi-user unit

Technical field

The invention relates to the field of electronic communication, in particular to a method for rectifying radiation emission positioning of a passive optical network multi-user unit.

Background technique

With the development of communication, light source optical network PON products are more and more widely used, and the MDU multi-user terminal unit is one of the more complicated ones. Meeting the electromagnetic compatibility and EMC requirements is a prerequisite for products to go global. The unqualified radiation emission of the MDU has become an important factor and difficult problem that plagues hardware R&D personnel and delays the project development schedule.

EMC rectification refers to the remedy measures taken after a product has a problem in the EMC test process. The purpose of the EMC rectification work is to reduce the interference generated by the EUT itself to meet the standard requirements, and at the same time to improve the anti-interference ability of the EUT itself, and also meet the requirements. Rectification is to use EMC techniques to suppress potential problems so that they no longer occur.

RE radiated emission and CE conducted emission are two major aspects of EMI. In view of this, we have summarized and refined a set of effective rectification methods on the basis of years of testing and rectification practices, which can be used for reference by hardware developers in product radiated emission RE testing and rectification.

Summary of the invention

The purpose of the present invention is to provide a method for rectifying radiation emission positioning of a passive optical network multi-user unit, which can quickly and accurately reduce EUT interference and improve its anti-interference ability.

To solve the above technical problems, the present invention adopts the following technical solutions:

A method for rectifying radiation emission positioning of a passive optical network multi-user unit includes the following steps:

Diagnose the source and propagation path of interference;

Carry out the safety ground connection of EMC in advance;

Remove unwanted frequency components from the frequency domain through filtering, reducing electromagnetic disturbance in both conduction and radiation;

Suppress various electromagnetic interference that propagate through space through shielding;

Replace suspicious components with components that meet EMC requirements;

For crystal products, reduce the output energy of the crystal oscillator and its harmonics by means of series resistance or parallel resistance.

A further technical solution is that the method for diagnosing the source and propagation path of interference is to find the maximum radiation direction first, remove the peripheral signal lines, and determine the strength of the EUT's own power line radiation interference to obtain the source and propagation path.

A further technical solution is that after removing the peripheral signal line, if the frequency of EUT Fail is still high, the magnetic field probe detects the intensity of the noise interference of the main components on the circuit board and finds the high point. The electric field probe Or probe the main part of the component pin connector to find the high point.

A further technical solution is that when diagnosing the source and propagation path of the interference, check whether the screws of the EUT metal casing are tightened, and check whether the grounding of the socket is good.

A further technical solution is that when the peripheral signal line is removed, the power line is reserved, and a core judgment is added to the unremovable signal line.

A further technical solution is that the specific method for determining the source and propagation path of the power line radiation interference of the EUT itself is as follows:

After unplugging all excess cables, if the radiation is qualified, eliminate the common mode current problem of the cable, and then connect all the cables to the equipment to determine whether the radiation is qualified, complete the judgment if it is qualified, and continue to eliminate the common mode current solution if it fails;

If the radiation is still unqualified after unplugging all the excess cables, add a magnetic ring to the power line. After adding the magnetic ring, the radiation is suppressed, then use a processing filter to eliminate the common mode current. After the elimination, it will be completed. If the radiation behind the loop is not suppressed or is unqualified, check the shielding effect of the chassis.

A further technical solution is to eliminate the common mode current of the cable by putting a ferrite magnetic ring on the cable. If it cannot be filtered, use or improve a shielded cable, and if it can filter, use circuit filtering;

If after putting on the ferrite magnetic ring, there is improvement but it is not qualified, then add the magnetic ring and use the circuit to filter until it is qualified.

Compared with the prior art, the beneficial effects of the present invention are: starting from the source, the present invention reduces the radiation energy from the source, destroys or changes the path of radiation interference, reduces gaps, strengthens filtering, and changes the position of the line to perform the radiation mechanism. It can quickly and accurately carry out the rectification of the radiation emission of the passive optical network multi-user unit.

Description of the drawings

Figure 1 is a schematic diagram of the position of the steps of the present invention in product testing.

Fig. 2 is a schematic diagram of the process of judging the intensity of the radiation interference from the power line of the EUT itself and obtaining the source and propagation path according to the present invention.

Fig. 3 is a schematic diagram of a method for eliminating common mode currents for eliminating cables according to the present invention.

detailed description

In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not to limit the present invention.

Principle of EMI generation:

The electric field and magnetic field are produced by the action of voltage and current, which are mainly affected by the change rate of voltage and current per unit time dI/dt and dv/dt. If the higher dI/dt, dv/dt, the corresponding electric and magnetic field interference will be The stronger.

EMI (Electromagnetic Interference) radiation propagation path: Noise is transmitted by the characteristics of electric waves, electric and magnetic fields.

In terms of EMI test rectification, it is necessary to determine the EMI source and coupling propagation path

EMI countermeasures

(1) Start from the source and reduce the radiation energy from the source

For example: the clock crystal pin is serially connected to the resistor, and the clock line is serially connected to the resistor.

(2) Destroy or change the path of radiation interference

Reduce the coupling mechanism, usually when the trace is λ/4 of the interference signal frequency, the interference is the strongest, you can change the wiring or strengthen the filtering.

(3) Destruction of radiation mechanism

Reduce the gap, strengthen the filtering, and change the position of the line.

Therefore, the present invention provides the following embodiments:

According to an embodiment of the method for rectifying radiation emission positioning of a passive optical network multi-user unit of the present invention: a method for rectifying radiation emission positioning of a passive optical network multi-user unit includes the following steps: diagnosing the source and propagation path of interference; Safe ground connection in advance; remove unwanted frequency components from the frequency domain through filtering, reduce electromagnetic disturbance in both conduction and radiation; suppress various electromagnetic interference propagating through space through shielding; replace with EMC-compliant components Suspicious components: For crystal products, reduce the output energy of the crystal oscillator and its harmonics by means of series resistance or parallel resistance.

For an MDU, we first confirm the EMI radiation interference according to the standard test method, find the frequency point of the test Fail, and then judge from the actual characteristics of the EUT, the influence of the equivalent radiation antenna, the influence of the path and the influence of the Source, and then Take corresponding measures according to the influence of various factors.

Figure 2 shows a preferred embodiment of the present invention. The method of diagnosing the source and propagation path of interference is to first find the maximum radiation direction, remove the peripheral signal lines, and determine the strength of the EUT's own power line radiation interference. Source and propagation path.

As a preferred solution of the above embodiment, after removing the peripheral signal lines, if the frequency of EUT Fail is still high, the magnetic field probe detects the intensity of the noise interference of the main components on the circuit board and finds the high point. The pin connector of the main part of the rod or probe probes the components and finds the high point. You can use the spectrum analyzer and the electric field and magnetic field probe.

As a preferred solution of the foregoing embodiment, when diagnosing the source and propagation path of the interference, check whether the screws of the EUT metal casing are tightened, and check whether the grounding of the socket is good.

As a preferred solution of the foregoing embodiment, when the peripheral signal line is removed, the power line is reserved, and the core judgment is added to the unremovable signal line.

Figure 2 also specifically shows a specific embodiment of the present invention. The specific method for determining the source and propagation path of the power line radiation interference of the EUT itself is as follows:

As shown in Figure 3, the method of the present invention to eliminate the common mode current of the cable is to put a ferrite magnetic ring on the cable, if it cannot be filtered, use or improve the shielded cable, if it can filter, use the circuit filter;

Although the present invention has been described with reference to a number of explanatory embodiments of the present invention, it should be understood that many other modifications and embodiments can be devised by those skilled in the art, and these modifications and embodiments will fall into the disclosure of this application. Within the scope and spirit of principles. More specifically, within the scope of the disclosure, drawings and claims of the present application, various modifications and improvements can be made to the component parts and/or layout of the theme combination layout. In addition to the deformation and improvement of the component parts and/or the layout, other uses will also be obvious to those skilled in the art.

Claims

A method for rectifying radiation emission positioning of a passive optical network multi-user unit is characterized by comprising the following steps:

Diagnose the source and propagation path of interference;

Carry out the safety ground connection of EMC in advance;

Remove unwanted frequency components from the frequency domain through filtering, reducing electromagnetic disturbance in both conduction and radiation;

Suppress various electromagnetic interference that propagate through space through shielding;

Replace suspicious components with components that meet EMC requirements;

For crystal products, reduce the output energy of the crystal oscillator and its harmonics by means of series resistance or parallel resistance.
The method for positioning and rectifying radiation emission of a passive optical network multi-user unit according to claim 1, wherein the method for diagnosing the source and propagation path of interference is to first find the maximum radiation direction and remove the peripheral signal lines, Judge the strength of the EUT's own power line radiation interference to get the source and propagation path.
The method for rectifying radiation emission positioning of a passive optical network multi-user unit according to claim 2, characterized in that: after removing the peripheral signal line, if the frequency of EUT Fail is still high, the magnetic field probe detects the circuit board The intensity of the noise interference of the main parts of the above components is compared to find the high point, and the electric field probe or probe probes the component pin connector of the main part to find the high point.
The method for rectifying radiation emission positioning of a passive optical network multi-user unit according to claim 2 or 3, characterized in that: when diagnosing the source and propagation path of interference, check whether the screws of the EUT metal casing are tightened or not, and connect the socket Check whether the grounding is good.
The method for rectifying radiation emission positioning of a passive optical network multi-user unit according to claim 2 or 3, characterized in that: when the peripheral signal line is removed, the power line is reserved, and the unremovable signal line is determined by core .
The method for positioning and rectifying radiation emission of a passive optical network multi-user unit according to claim 2, characterized in that: the specific method for determining the source and propagation path of the power line radiation interference of the EUT itself is as follows:

After unplugging all excess cables, if the radiation is qualified, eliminate the common mode current problem of the cable, and then connect all the cables to the equipment to determine whether the radiation is qualified, complete the judgment if it is qualified, and continue to eliminate the common mode current solution if it fails;

If the radiation is still unqualified after unplugging all the excess cables, add a magnetic ring to the power line. After adding the magnetic ring, the radiation is suppressed, then use a processing filter to eliminate the common mode current. After the elimination, it will be completed. If the radiation behind the loop is not suppressed or is unqualified, check the shielding effect of the chassis.
The method for rectifying radiation emission positioning of a passive optical network multi-user unit according to claim 6, characterized in that: the method of eliminating the common mode current of the cable is to cover the cable with a ferrite magnetic ring, if it cannot be filtered, Use or improve shielded cables, and use circuit filtering if filtering is possible;

If after putting on the ferrite magnetic ring, there is improvement but it is not qualified, then add the magnetic ring and use the circuit to filter until it is qualified.