CN110933535A

CN110933535A - Automatic screening method based on optical power abnormity of PON optical module

Info

Publication number: CN110933535A
Application number: CN201911207305.9A
Authority: CN
Inventors: 王旭东; 杨伟强; 唐兴刚
Original assignee: Sichuan Tianyi Comheart Telecom Co Ltd
Current assignee: Sichuan Tianyi Comheart Telecom Co Ltd
Priority date: 2019-11-29
Filing date: 2019-11-29
Publication date: 2020-03-27

Abstract

The invention discloses an automatic screening method based on PON optical module optical power abnormity, which comprises the following steps: electrifying a PON optical module to enable the PON optical module to be in a working state, and detecting TX reported power of the PON optical module when the PON optical module is in a normal temperature state, and recording the TX reported power as first TX reported power; placing the PON optical module processed in the step S1 in an aging chamber for temperature rise processing, and detecting TX report power of the PON optical module in the temperature rise processing process, and recording the TX report power as second TX report power; and when the difference between the first TX reported power and the second TX reported power is within the range of +/-1.5 dB, judging that the optical power of the PON optical module is normal, and when the difference between the first TX reported power and the second TX reported power is not within the range of +/-1.5 dB, judging that the optical power of the PON optical module is abnormal. The invention can automatically judge the fault state of the optical module at high temperature, give the judgment result and record the abnormal state.

Description

Automatic screening method based on optical power abnormity of PON optical module

Technical Field

The invention belongs to the technical field of communication equipment parameter testing, and particularly relates to an automatic screening method based on PON optical module optical power abnormity.

Background

In the domestic market and the international market, the optical fiber communication direction with high bandwidth, high speed and multiple service convergence is already applied. Among The numerous solutions, The emergence of Fiber To The Home (FTTH) is considered To be The ultimate solution for broadband access, and FTTH has been widely used in The domestic market. In many schemes of FTTH, Gigabit Passive Optical Network (GPON) is widely used. An Optical Network Unit (ONU) in GPON is also a common article in daily life of people as an internet medium. The vigorous market demand requires a corresponding productivity to meet the demand. However, the ONU is not easy to produce, and before the ONU is put into use, calibration and testing are required to be performed on a Bi-Directional Optical Sub-Assembly (BOSA) interface component, and Optical parameters directly affect the performance, thereby affecting the communication performance and user experience of the product.

In the related art, for calibration test of an optical network unit, the optical network unit to be tested is usually connected in a Telnet control mode, and different test software is selected for different optical network units to perform calibration and test according to the PON type and an APD lookup table provided by a corresponding manufacturer. However, for whether the optical power of the PON optical module is abnormal or not, in the related art at the present stage, there is no good method, so that the optical power of the PON optical module is already abnormal, and a user cannot know that the PON optical module with the abnormal optical power continues to be used, thereby causing a larger fault of the PON optical module.

Therefore, an automatic screening method based on the optical power abnormality of the PON optical module is needed.

Disclosure of Invention

The invention aims to provide an automatic screening method based on PON optical module optical power abnormity, which is used for solving the problems in the prior art, such as: for whether the optical power of the PON optical module is abnormal or not, in the related art at the present stage, there is no good method, which causes the optical power of the PON optical module to be abnormal, and a user cannot know that the PON optical module with the abnormal optical power continues to be used, thereby causing a larger fault of the PON optical module.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

an automatic screening method based on optical power abnormity of a PON optical module comprises the following steps:

s1: electrifying a PON optical module to enable the PON optical module to be in a working state, and detecting TX reported power of the PON optical module when the PON optical module is in a normal temperature state, and recording the TX reported power as first TX reported power;

s2: placing the PON optical module processed in the step S1 in an aging chamber for temperature rise processing, and detecting TX report power of the PON optical module in the temperature rise processing process, and recording the TX report power as second TX report power;

s3: and when the difference between the first TX reported power and the second TX reported power is within the range of +/-1.5 dB, judging that the optical power of the PON optical module is normal, and when the difference between the first TX reported power and the second TX reported power is not within the range of +/-1.5 dB, judging that the optical power of the PON optical module is abnormal.

Preferably, in step S1 and step S2, the specific method for detecting the TX reported power of the PON optical module is as follows:

in the ONU, a BOSA acquires an optical signal through a backlight detector inside the BOSA, converts the optical signal into a current signal through a photodiode PD inside the BOSA, inputs the current signal into a preamplifier to amplify the current signal into a voltage signal, a main amplifier of a driving chip receives the voltage signal and then performs secondary amplification, and then the driving chip outputs a demodulated electrical data signal to the main chip; after receiving the demodulated electrical data signal, the main chip transmits an electrical analog signal at an MPD pin of the main chip to the driving chip through a differential line in a form of a modulated signal, the driving chip processes the received modulated signal and then drives a semiconductor laser LD in the BOSA to transmit a debugging optical signal with a corresponding rate to the OLT, and finally the OLT directly displays TX reporting power.

Preferably, the photodiode PD may be replaced with an avalanche diode APD.

Preferably, the preamplifier, when amplifying the current signal, uses a large gain amplification factor for the small-amplitude current signal and a small gain amplification factor for the large-amplitude current signal.

Preferably, the current signal is an analog signal, and the current signal is further subjected to analog-to-digital conversion before being input to a preamplifier for amplification.

The beneficial technical effects of the invention are as follows: if the optical power of the optical module is in an abnormal state, the fault state of the optical module at high temperature can be automatically judged through the scheme, the judgment result is given, the abnormal state is recorded, the optical module with abnormal optical power in the communication link can be abandoned in time, the optical module with abnormal optical power can not be used continuously, and further the condition of larger fault of the PON optical module is caused.

Drawings

FIG. 1 is a flow chart showing steps of embodiment 1 of the present invention.

Fig. 2 is a schematic diagram of an ONU module according to embodiment 1 of the present invention.

Fig. 3 is a schematic circuit diagram of an ONU according to embodiment 1 of the present invention.

Fig. 4 is a logic block diagram of analog-to-digital conversion according to embodiment 1 of the present invention.

FIG. 5 is a flow chart illustrating the steps of embodiment 2 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to fig. 1 to 5 of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1:

as shown in fig. 1, an automatic screening method based on PON optical module optical power abnormality includes the following steps:

In the above scheme, the monitoring value of the backlight current Im at normal temperature and high temperature is kept unchanged, and the light output power Po at normal temperature and high temperature and the normal temperature and the high temperature of Po are recorded, wherein the difference is TE and unit dB. TE ═ Po normal temperature-Po high temperature, with a normal TE range of ± 1.5 dB. With the rise of the temperature, the change trend of the backlight value is small, and the change trend of the light output power is large. The optical module can constantly track a backlight set value in the using process, the backlight current compensation can be increased to ensure the stability of TX power in the temperature rising process under the normal condition, but the backlight current compensation of a fault optical module is small, and the stability of TX light output power cannot be supported, so that the TX power is reduced.

The test data of the fault prototype are shown as follows:

namely, the skew efficiency of the optical module at about 50 ℃ is obviously reduced along with the temperature rise, so that the fiber output optical power (TX optical power) is reduced, and meanwhile, TE does not meet the requirement of a range of +/-1.5 dB.

as shown in fig. 2 and 3, in the ONU, the BOSA collects an optical signal through a backlight detector inside the BOSA, converts the optical signal into a current signal through a photodiode PD inside the BOSA, inputs the current signal into a preamplifier to amplify the current signal into a voltage signal, a main amplifier of the driving chip receives the voltage signal and then performs secondary amplification, and then the driving chip outputs a demodulated electrical data signal to the main chip; after receiving the demodulated electrical data signal, the main chip transmits an electrical analog signal at an MPD pin of the main chip to the driving chip through a differential line in a form of a modulated signal, the driving chip processes the received modulated signal and then drives a semiconductor laser LD in the BOSA to transmit a debugging optical signal with a corresponding rate to the OLT, and finally the OLT directly displays TX reporting power. Preferably, the photodiode PD may be replaced with an avalanche diode APD. Preferably, the preamplifier, when amplifying the current signal, uses a large gain amplification factor for the small-amplitude current signal and a small gain amplification factor for the large-amplitude current signal. Preferably, the current signal is an analog signal, and the current signal is further subjected to analog-to-digital conversion before being input to a preamplifier for amplification.

In the above scheme, the ONU circuit is mainly composed of a driver chip (left side) and a BOSA (right side, including an LD chip and a PD chip).

ONU circuit transmission rationale: the ONU sending working principle is briefly described as follows: the electric signal with a certain code rate is transmitted to the driving chip from the main chip in the form of a modulation signal through the differential line, and the driving chip can drive the semiconductor laser LD to emit a modulation optical signal with a corresponding rate after processing the received data signal.

The ONU circuit receives the basic principle: after receiving the optical data signal, the BOSA is converted into a current signal by an internal Photodiode (PD) (or avalanche diode APD), and then the current signal is input to a preamplifier (transimpedance amplifier) to be amplified into a voltage signal, the preamplifier has an AGC function (automatic gain control), and a large-gain amplification factor is adopted for a small-amplitude current signal after the conversion of the optical signal with smaller input optical power, and a small-gain amplification factor is adopted for a large-amplitude current signal after the conversion of the optical signal with larger input optical power, so that the amplitude fluctuation of the output voltage signal is "equal to" the fluctuation amplitude of the input optical signal power.

The main amplifier of the driving chip receives the signal amplified by the preamplifier to carry out secondary amplification, and then the driving chip outputs a demodulated electrical data signal to the MAC chip. (the amplifier LA: the TIA outputs the analog voltage signal of different amplitude to process into the digital signal of the same amplitude, at the same time, the ONU has the strong light input, the drive chip outputs the electrical signal to maintain at the certain value, in the state of limiting the good fortune).

The TX reporting monitoring is monitored by an MPD pin of an upper graph, an analog signal adopted by the MPD pin is from a backlight detector in BOSA, and a sampled current value is subjected to analog and digital conversion:

as shown in fig. 4, the TX Power performs a time-single point calibration, i.e., its default offset is 0. The calibration quantity is the current optical POWER after debugging OK, the independent variable is ADC _ TX _ POWER under the current output POWER, and the dependent variable is the current optical POWER (regarded as a linear equation). The optical power is in units of 0.1uW, and needs to be converted correspondingly.

It is worth noting that: because the monitoring quantity inside the optical module is acquired through the ADC, the CPU obtains digital information actually, and the information is required to be corresponding to real analog quantity during production, and the process is calibration and is also called calibration. For the parameters in which the analog quantity and the digital quantity are in a linear relationship, a first-order function fitting (for example, emission power reporting) is adopted, and the 8472 protocol can be referred to specifically.

The ADC TX POWER register depends on the current value of the target display photodiode. The first three bits of the ADC _ TX _ POWER register are always zero. This gives an equivalent LSB value of 112.5 μ a/512 ═ 0.22 μ a/bit, as follows for the corresponding register values of the TX sample power to current value mapping:

example 2:

as shown in fig. 5, on the basis of embodiment 1, the actual optical power of the TX in the faulty optical module at a high temperature decreases, and the reported power (monitoring power) of the TX decreases along with the actual power of the TX, so that the condition of the actual TX power can be determined according to the condition of the reported power of the TX, and if the actual power of the TX is abnormal (decreases), the reported power also decreases. The actual TX power can be judged by judging the reported TX power.

The screening procedure was as follows (the following TX powers are reported):

and after the power is electrified for half an hour, reading a TX optical power report value every half an hour, judging whether the TX power is larger than >0.8dBm or not, judging for three times (1.5 hours) in total, and if the judgment results of the three times are that the TX power is larger than 0.8dBm, determining as a normal prototype. If the TX power is less than 0.8dBm at any time in the three judgment results, the sample machine is a fault sample machine, and the state of the optical fiber signal lamp is changed from red lamp flickering to red lamp normally-on.

In the description of the present invention, it is to be understood that the terms "counterclockwise", "clockwise", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are used for convenience of description only, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be considered as limiting.

Claims

1. An automatic screening method based on PON optical module optical power abnormity is characterized by comprising the following steps:

2. The method as claimed in claim 1, wherein in steps S1 and S2, the specific method for detecting TX reported power of the PON optical module is as follows:

3. The method as claimed in claim 2, wherein the photodiode PD is replaced by an avalanche photodiode APD.

4. The method as claimed in claim 2, wherein the pre-amplifier amplifies the current signal by a large gain for a small-amplitude current signal and a small gain for a large-amplitude current signal.

5. The method according to any one of claims 2 to 4, wherein the current signal is an analog signal, and the current signal is further subjected to analog-to-digital conversion before being input to a preamplifier for amplification.