GB/T 15118-1994 Technical requirements for 4×139264 kbit/s optical fiber digital line system
Some standard content:
National Standard of the People's Republic of China
GB/T 15118—1994
Technical requirement for digital linesystems on optical fibre cables at 4X139264kbit/s1994-07-12issued
State Administration of Technical Supervision
1995-03-01implemented
National Standard of the People's Republic of China
4×139264kbit/sTechnical requirement for digital linesystems on optical fibre cables at 4X139264kbit/s1994-07-12issued
State Administration of Technical Supervision
1995-03-01implemented
National Standard of the People's Republic of China
4×139264kbit/sTechnical requirement for digital line systemsonopticalfibrecablesat4x139264kbit/sGB/T15118—1994
This standard is formulated with reference to the relevant contents of G.955\Digital line system for transmission of 1554kbit/s and 2048kbit/s series signals on optical cable and G.957\Optical interface for equipment and systems related to synchronous digital series\ of the International Telegraph and Telephone Consultative Committee (CCITT), and in combination with the specific conditions of my country.
1 Subject content and scope of application
This standard specifies the performance requirements and related functions of 4x139264kbit/s optical cable digital line system in my country's public telecommunication network. This standard is applicable to digital line system for transmission of 4x139264kbit/s signals on optical cable. It is the basis for designing 4x139264kbit/s optical cable digital line system. 4x139264kbit/s optical cable digital line system in private telecommunication network can also refer to this standard. 2 Reference standards
GB7611 Pulse code modulation communication system network digital interface parameters GB/T13996 Technical requirements for optical cable digital line system 34×139264kbit/s optical cable digital line system characteristics 3.1 System composition
Figure 1 shows the composition of the 4×139264kbit/s optical cable digital line system. Approved by the State Bureau of Technical Supervision on July 12, 1994 and implemented on March 1, 1995
1 139264tit/s core
GB/T15118—1994
1~21hit
1~1:9261hir/
Figure 14× Schematic diagram of 139264kbit/s optical cable digital line system OLTM—optical line terminal multiplexer T', T—OLTM connected to 139264kbit/s digital equipment; S—optical fiber point immediately behind the optical connector (C) of the optical transmitter (TX) or optical repeater (OREG); R—optical fiber point immediately in front of the optical connector (C) of the optical receiver (RX) or optical repeater (OREG) Note: If an optical fiber distribution frame is used, the optical connectors attached to the distribution frame should be regarded as part of the optical fiber line and are located between points S and R. Figure 1 (a) shows that there is no optical repeater in the system. There may also be one or more optical repeaters in the system, as shown in Figure 1 (b). In the figure, the optical line terminal multiplexer (OLTM) is from reference point T' to reference point S, or from reference point R to reference point T. OLTM consists of a digital line multiplexer and a fiber line terminal.
3.2 Bit rate and tolerance
Bit rate: 4×139264kbit/s.
Tolerance: ±15ppm.
3.3 System performance indicators
3.3.1 Electrical interface indicators
Electrical interface indicators are measured at input port T' and output port T in Figure 1. 3.3.1.1 General requirements
a Bit rate
The bit rate is 139264kbit/s±15ppm. b Code type
The code type is CMI code.
c Overvoltage protection requirements
139264kbit/s input and output ports should be able to withstand the impact of 10 standard lightning pulses (5 negative pulses and 5 positive pulses) without being damaged. The rise time of the lightning pulse is 1.2μs, the width is 50μs, and the amplitude is Upc-20V. When the input and output ports are connected to the coaxial cable, the connection circuit of the differential mode test pulse generator is shown in Figure 2. 2bzxZ.net
3.3.1.2 Output port requirements
GB/T15118—1994
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Figure 21.2/50μs differential mode voltage pulse generator output port indicators should comply with the provisions of Table 2 and Figures 2 and 3 in GB/T13996. 3.3.1.3 Input port requirements
a Attenuation range
The digital signal added to the input port shall comply with the provisions of 3.3.1.2 of this standard and vary with the characteristics of the connecting cable. The attenuation characteristics of the connecting cable follow the approximate variation law of Vf, and the attenuation range is 0-12dB at a frequency of 70MHz. b Allowable input jitter tolerance
The allowable input jitter tolerance shall meet the provisions of item a of 3.3.3.2 of this standard. c Reflection attenuation
The reflection attenuation of the input port shall meet the relevant provisions of GB7611. 3.3.2 Optical interface indicators
3.3.2.1 Average transmitted optical power
The average transmitted optical power is measured at point S in Figure 1, and its value shall be determined according to the length of the relay segment. When an LD light source is used, the average transmitted optical power is generally -9dBm, -6dBm, -3dBm and 0dBm. 3.3.2.2 Extinction ratio
P represents the average transmitted optical power of logic "1", and P represents the average transmitted optical power of logic "0". The extinction ratio EX is: EX=101g(Ps/P)≥10dB
3.3.2.3 Receiver sensitivity
Receiver sensitivity The optical power is measured at point R in Figure 1, and its value should meet the requirements of Table 1. Table 1 Optical receiver sensitivity index
Rate, kbit/s
4×139264
Center wavelength, nm
3.3.2.4 Received optical power dynamic range
Photodetector type
PIN-FET
Receiver sensitivity, dBm
(BER=1X10-11)
The received optical power dynamic range measured at point R in Figure 1 (the difference between the measured maximum received optical power and the measured receiver sensitivity) shall meet the requirements of Table 2.
Rate, kbit/s
4X139264
3.3.2.5 Optical channel cost
The maximum optical channel cost is 1dB.
3.3.3 Transmission performance indicators
GB/T15118—1994
Table 2 Received optical power dynamic range
Center wavelength, nm
Photodetector type
PIN-FET
Dynamic range, dB
(BER=1X10-11)
The following performance indicators are all specified for the 4×139264kbit/s optical cable digital line system assuming a reference digital segment length of 280km or 420km.
3.3.3.1 Error Performance
Based on the error performance indicators and allocation principles of the 27500km 64kbit/s full-length hypothetical reference connection, and considering the redundancy, the error performance indicators of the 64kbit/s port of the 4×139264kbit/s optical cable hypothetical reference digital segment with a length less than or equal to 280km and 420km shall meet the requirements of Table 3.
The continuous test time of the error performance indicators is one month. For the 4×139264kbit/s optical cable digital line system with a length not exceeding 280km or 420km, the system average bit error rate BER≤1×10-10. (Continuous test time is not less than 24h) Table 3 Error performance index of digital segment at 64kbit/s port Error performance index
Digital segment length, km
≤420
<280
3.3.3.2 Jitter performance
aLower limit of maximum allowable input jitter
Severe error second
≤0.000067%
≤0.000045%
Error second
≤0.0054%
≤0.0036%
The input jitter tolerance is measured at T' of the four 139264kbit/s input ports in Figure 1. When the attenuation characteristics of the input port connecting cable follow the approximate variation law of Vf and have a maximum insertion attenuation of 12dB at a frequency of 70MHz, the input jitter tolerance of each 139264kbit/s input port shall meet the requirements of Figure 3. The test signal is a 223-1 level pseudo-random signal sequence modulated by a sinusoidal jitter having the amplitude/frequency relationship specified in Figure 3. 4
Heat industry standard
b Jitter transfer characteristics
GB/T15118—1994
The standard is based on the standard, 1
20di1014
The rate of the excitation is respectively generated,
Figure 3 The lower limit of the maximum allowable input jitter
4×139264kbit/s optical cable assumes that the maximum gain of the reference digital segment jitter transfer function is not greater than 0.9dB. The jitter test frequency should be as low as possible. If limited by the test instrument, the lowest frequency of the jitter test can be measured to 10Hz. c Output jitter when there is no input jitter
The output jitter is measured at the four 139264kbit/s output ports T in Figure 1. For each 139264kbit/s output port, the output jitter when there is no input jitter should comply with the relevant provisions of GB/T13996. 3.3.3.3 System Reliability
a System Reliability Index
If a 5000km 4×139264kbit/s optical cable digital line system is allowed to have four full resistance failures per year in both directions, then a 420km 4×139264kbit/s optical cable digital line system (digital section) is allowed to have a full resistance failure once every three years in both directions, that is, the MTBF is not less than 3 years, and a 280km 4×139264kbit/s optical cable digital line system (digital section) is allowed to have a full resistance failure once every five years in both directions, that is, the MTBF is not less than 5 years.
b Light Source Life
LD light source life should be greater than 20×10°h.
c Photodetector Life
PIN-FET component life should be greater than 50X10°h. APD life should be greater than 20X10h.
3.3.3.4 System availability
When the 5000km 4×139264kbit/s optical cable digital line system is allowed to have four full-block faults per year and the average fault repair time is 6h, the availability index of the 5000km full-block bidirectional line is about 99.73%. The corresponding availability index of the 280km 4×139264kbit/s optical cable digital line system is about 99.985%; the corresponding availability index of the 420km 4×139264kbit/s optical cable digital line system is about 99.977%.
3.3.4 Line code type
In addition to the 5B6B and 8B1H code types, the line code type of the 4×139264kbit/s optical cable digital line system can also use other code types approved by the competent department, such as NRZ scrambling code, etc. 4 Basic requirements for optical fiber cables
4×139264kbit/s optical cable digital line system The optical fiber used should be single-mode optical fiber with zero dispersion wavelength of 1310nm and dispersion-shifted single-mode optical fiber with zero dispersion wavelength of 1550nm. 5
GB/T15118—1994
4.1 Basic requirements for single-mode optical fiber with zero dispersion wavelength of 1310nm Mode field diameter: The nominal value is a value between 9~9.5μm, and the deviation is not more than ±5%. Cladding diameter: The nominal value is 125μm, and the deviation is not more than ±2μm. Working wavelength: 1310nm (1285~1330nm) and 1550nm (1480~1580nm). Cut-off wavelength: The cut-off wavelength of single-mode optical fiber is a value between 1100~1280nm. The maximum cut-off wavelength of single-mode optical cable is 1260nm or 1270nm. Dispersion coefficient: When the working wavelength is in the range of 1288-1339nm, the dispersion coefficient is not more than 3.5ps/nm·km; when the working wavelength is in the range of 1271-1360nm, the dispersion coefficient is not more than 5.3ps/nm·km; when the working wavelength is in the range of 1550nm, the dispersion coefficient is not more than 20ps/nm·km. Attenuation coefficient: In the wavelength range of 1310nm, the attenuation coefficient is less than 0.5dB/km; in the wavelength range of 1550nm, the attenuation coefficient is less than 0.3dB/km. 4.2 Basic requirements for dispersion-shifted single-mode optical fiber Mode field diameter: At 1550nm, the nominal value is a value between 7.0 and 8.3μm, and the deviation is not more than ±10%. Cladding diameter: The nominal value is 125μm, and the deviation is not more than ±2uμm. Working wavelength: 1550nm (1480-1580nm). Dispersion coefficient: When the working wavelength is in the range of 1525~1575nm, the dispersion coefficient is not greater than 3.5ps/nm·km. Attenuation coefficient: In the 1550nm wavelength region, the attenuation coefficient is less than 0.27dB/km. In the 1310nm wavelength region, the attenuation coefficient is less than 0.5dB/km. 5 System redundancy
The redundancy of each relay segment in the system is divided into two parts: the cable redundancy M. and the equipment redundancy M., as shown in Figure 4. Figure 4 Optical channel of a relay segment
Note: If an optical fiber distribution frame is used, the additional optical connector on the distribution frame is located between point S and point R. 5.1 Cable redundancy M.
Cable redundancy M. Includes the redundancy required for the following three factors. a Redundancy required when the optical cable configuration changes and an additional optical fiber connector is required or the length of the optical cable is increased. b Redundancy required when the performance of the optical cable changes due to environmental conditions. The redundancy required when the performance of the connector between point S and point R deteriorates. The redundancy of single-mode optical fiber is 0.1-0.15 dB/km, and the M. of a relay section is at least 3 dB and at most 5 dB. 5.2 Equipment redundancy M
Equipment redundancy M. includes the redundancy required for the decrease in transmitted optical power and the degradation of receiver sensitivity due to changes in time and environmental conditions, as well as the degradation of the performance of the optical connector attached to the equipment. M. should not be less than 3 dB.
6 System relay section attenuation and dispersion specifications
GB/T15118—1994
As shown in Figure 4, the performance parameters between point S and point R of the relay section optical channel include total attenuation (the sum of the total attenuation of the optical cable and the cable redundancy M.) and maximum dispersion. As the minimum requirement under the maximum relay segment length, under the condition of BERv, not worse than 1×10-11, the total attenuation and maximum dispersion allowed between the relay segment S and R of the 4×139264kbit/s system shall comply with the provisions of Table 4. Table 4 Tolerance bit rate between the relay segment optical channel S and R on single-mode optical fiber, kbit/s
4×139264
Note: 1) The value of this indicator is for further study.
7 Power supply mode of relay station
Working wavelength
Range, nm
Light source type
MLM-LD
SLM-LD
Tolerance between S and R (BER≤1X10-11)Total attenuation, dB
Maximum dispersion, ps/nm
The power supply mode of relay station is divided into long-distance power supply and local power supply. Local power supply should be used as much as possible where conditions permit. Long-distance power supply adopts DC constant current power supply. Local power supply adopts DC voltage power supply. In addition to using the local power grid, natural energy power supply or various complementary power supply methods can also be used.
8 Protection conversion function
In situations where the system availability index needs to be improved, the 4×139264kbit/s optical cable digital line system should have an automatic protection conversion function. The established call connection should not be interrupted during the automatic conversion of the main and standby systems. Main and standby ratio: The configuration ratio of n main and 1 standby (n=1~11) can be adopted, and the n value can be selected according to the actual situation. Conversion conditions: The receiving end has instant alarms such as no light, loss of step, BER≥10-3, and the standby system is normal. Conversion mode: There are two types of automatic conversion mode and manual control conversion mode. In the automatic conversion mode, once the conversion conditions are met, the main system automatically switches to the standby system. When the main system returns to normal 512 minutes later, it automatically switches back to the main system. In the manual control conversion mode. The main system automatically switches to the backup system by manual operation, and the backup system automatically switches back to the main system by manual operation. Conversion signal transmission mode: The conversion signal should be transmitted in the same optical fiber as the main signal. The interface point of automatic conversion is the nominal 139264kbit/s digital interface point. 9 Working conditions
9.1 Environmental conditions
a Equipment environmental conditions
Environmental temperature:
Manned maintenance station 5~40℃.
Unmanned maintenance station rack type -5~40℃;
Box type -10~40℃.
Relative humidity:
Manned maintenance station 85% (at 25℃).
Unmanned maintenance station ≤90% (at 35℃).
b Optical cable environmental temperature
Overhead optical cable: -30~50℃.
Direct buried optical cable: 0~26℃.
Optical cable for urban pipelines: -5~40℃.
9.2 Inflatable
GB/T15118—1994
4X139264kbit/s optical cable digital line system box-type repeater adopts inflatable maintenance, and the maintenance air pressure is not greater than 40kPa. When an inflatable box-type repeater is used, the monitoring system should be able to monitor the air pressure. 9.3 Supply voltage
Rated supply voltage (V)
9.4 Protection against interference
Allowable voltage variation range (V)
—40～-57
—21.6~-26.5
-56~-66
4×139264kbit/s optical cable digital line system The 565Mbit/s optical line terminal multiplexer, optical repeater and remote supply equipment used should be able to resist the influence of induced voltage and induced current generated by lightning strikes or electrical interference sources such as fluorescent lamps and power tools. This system should not affect other communication equipment when working. The optical cable line should have anti-vibration, waterproof, anti-corrosion, lightning protection and other protective properties, and should also have anti-rat bite, insect bite and other properties when necessary. The box-type repeater should have good sealing and waterproof and anti-corrosion properties. 10 Business contact
In order to enable communication between stations in the system, there should be business contact telephones between terminal stations in the system, between terminal stations and optical relay stations, and between optical relay stations.
Business contact adopts site selection calling and conference calling, and has the function of forced demolition of terminal stations. Business contact signals should be transmitted in the same optical fiber as the main signal. 11 Monitoring and fault location
The 4X139264kbit/s optical cable digital line system should be equipped with a monitoring system to detect system performance and locate faults without interrupting communication.
The monitoring signal should be transmitted in the same optical fiber as the main signal. The monitoring system should have the following functions:
Performance monitoring function, LD pre-bias current, AGC voltage, rack power supply voltage, rack temperature, error seconds, severe error seconds, and cumulative number of errors.
Alarm monitoring function: interruption of branch input signal, loss of transmission optical power, loss of reception optical power, line code frame loss, multiplexing frame loss, BER≥10-6, BER≥10-3, LD life, power failure and conversion status. Control function: loop control, conversion control, remote control switch, telemetry switch. 12 Fault alarms and corresponding measures
The alarm conditions that should be detected by the 4X139264kbit/s optical cable digital line system and the corresponding measures to be taken are listed in Table 5. 8
Fault conditions
Power failure
Branch input
Signal disappearance
LD transmit light
Power disappearance
LD life
Receive light
Signal disappearance
Line code frame
1×10-8
1×10-6
Multiplexing frame
Detected the opposite end
Alarm indication
Faulty equipment
GB/T15118—1994
Table 5 Fault conditions and corresponding measures
Maintenance alarm
Immediate
Delayed
Send
Alarm indication to the other end
AIS is added to
all branches
If feasible
In the
relevant time slot of the composite signal
"Two" in the table means that in the relevant fault conditions, if the condition is unique, then Note: "To" in the table means that measures should be taken in the relevant fault conditions. No corresponding measures need to be taken. If more than one fault condition occurs at the same time, and at least one of the fault conditions stipulates that measures should be taken, relevant measures should be taken.
1) The equivalent binary content of the alarm indication signal AIS is a series of "1"s
Additional notes:
This standard is proposed by the Ministry of Posts and Telecommunications of the People's Republic of China. This standard is under the jurisdiction of the Telecommunication Transmission Research Institute of the Ministry of Posts and Telecommunications. This standard was drafted by the Wuhan Post and Telecommunications Science Research Institute of the Ministry of Posts and Telecommunications. The main drafter of this standard is Chen Jingxian.LD life, power failure and conversion status. Control functions: loop control, conversion control, remote switch, telemetry switch. 12 Fault alarms and corresponding measures
The alarm conditions that should be detected by the 4X139264kbit/s optical cable digital line system and the corresponding measures to be taken are listed in Table 5. 8
Fault conditions
Power failure
Branch input
Signal disappearance
LD transmit light
Power disappearance
LD life
Receive light
Signal disappearance
Line code frame
1×10-8
1×10-6
Multiplexing frame
Detected the opposite end
Alarm indication
Faulty equipment
GB/T15118—1994
Table 5 Fault conditions and corresponding measures
Maintenance alarm
Immediate
Delayed
Send
Alarm indication to the other end
AIS is added to
all branches
If feasible
In the
relevant time slot of the composite signal
"Two" in the table means that in the relevant fault conditions, if the condition is unique, then Note: "To" in the table means that measures should be taken in the relevant fault conditions. No corresponding measures need to be taken. If more than one fault condition occurs at the same time, and at least one of the fault conditions stipulates that measures should be taken, relevant measures should be taken.
1) The equivalent binary content of the alarm indication signal AIS is a series of "1"s
Additional notes:
This standard is proposed by the Ministry of Posts and Telecommunications of the People's Republic of China. This standard is under the jurisdiction of the Telecommunication Transmission Research Institute of the Ministry of Posts and Telecommunications. This standard was drafted by the Wuhan Post and Telecommunications Science Research Institute of the Ministry of Posts and Telecommunications. The main drafter of this standard is Chen Jingxian.LD life, power failure and conversion status. Control functions: loop control, conversion control, remote switch, telemetry switch. 12 Fault alarms and corresponding measures
The alarm conditions that should be detected by the 4X139264kbit/s optical cable digital line system and the corresponding measures to be taken are listed in Table 5. 8
Fault conditions
Power failure
Branch input
Signal disappearance
LD transmit light
Power disappearance
LD life
Receive light
Signal disappearance
Line code frame
1×10-8
1×10-6
Multiplexing frame
Detected the opposite end
Alarm indication
Faulty equipment
GB/T15118—1994
Table 5 Fault conditions and corresponding measures
Maintenance alarm
Immediate
Delayed
Send
Alarm indication to the other end
AIS is added to
all branches
If feasible
In the
relevant time slot of the composite signal
"Two" in the table means that in the relevant fault conditions, if the condition is unique, then Note: "To" in the table means that measures should be taken in the relevant fault conditions. No corresponding measures need to be taken. If more than one fault condition occurs at the same time, and at least one of the fault conditions stipulates that measures should be taken, relevant measures should be taken.
1) The equivalent binary content of the alarm indication signal AIS is a series of "1"s
Additional notes:
This standard is proposed by the Ministry of Posts and Telecommunications of the People's Republic of China. This standard is under the jurisdiction of the Telecommunication Transmission Research Institute of the Ministry of Posts and Telecommunications. This standard was drafted by the Wuhan Post and Telecommunications Science Research Institute of the Ministry of Posts and Telecommunications. The main drafter of this standard is Chen Jingxian.
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