GY/T 194-2003Specifications and methods of measurement on optical node used in CATV systems (English PDF)

Foreword

This standard is based on the needs of China 's cable television network construction and operation, and refers to the performance parameters of optical workstations at home and abroad.

The technical requirements and measurement methods of the uplink optical transmitter are specified. The technical requirements and measurement methods of its downstream optical receiver are mainly referenced GB/T 11318.1-1996 "Cable distribution system equipment and components for television and sound signals-Part 1. General specifications" and GY/T 143-2000 "Technical Conditions and Measurement Methods for Amplifier Optical Transmitters and Receivers in Cable TV Systems". In the development of this standard, a comprehensive analysis A large number of test data and the specific requirements for the application of cable television systems. At the same time, both the advanced requirements and the production costs are taken into account in the index requirements.

The need for this and use.

Appendix A to this standard is an informative appendix.

This standard is under the jurisdiction of the National Radio and Television Standardization Technical Committee.

This standard was drafted. Radio and Television Metrology and Testing Center of the State Administration of Radio, Film and Television, Wuxi Lutong Electronic Technology Co., Ltd., Sichuan Jiuzhou Electronic Technology Co., Ltd.

1 Scope

This standard specifies the technical requirements and measurement methods for optical workstations in cable television systems. For tasks that ensure the same measurement uncertainty any equivalent measurement method can also be used. In case of dispute, this standard shall prevail.

This standard applies to the development, production, use, operation and maintenance of optical workstations for cable television systems.

2 Normative references

The clauses in the following documents have become the clauses of this standard after being referenced. For dated references, all subsequent Neither amendments (excluding errata) or revised versions are applicable to this standard, however, parties who have reached an agreement under this standard are encouraged to study is the latest version of these files available? For undated references, the latest version applies to this standard.

GB 5465.2-1985 Graphical symbols for electrical equipment GB/T 11318.1-1996 Cable and distribution system equipment and components for television and sound signals-Part 1. General specifications GY/T 143-2000 Cable TV system AM optical transmitter and receiver technical conditions and measurement methods

3 Terms and definitions

The following terms and definitions apply to this standard.

Return optical transmitter an optical transmitter that transmits an uplink transmission signal.

Forward optical receiver Optical receiver for receiving downlink transmission signals.

Return optical receiver Optical receiver for receiving uplink transmission signals.

Optical node

A transmission device with functions such as a downlink optical receiver and an uplink optical transmitter.

Noise power ratio (NPR) the total power (or power spectrum) of the digital modulation signal output by the uplink optical receiver within the specified temperature, specified link loss and return bandwidth the ratio of the density) to the total noise power (or power spectral density) within the return bandwidth is expressed in decibels.

Noise power ratio dynamic range when the noise power ratio is not less than a specified value within the specified temperature, specified link loss, and return bandwidth, it is added to the upstream optical transmitter the decibel difference between the maximum and minimum total power of the digitally modulated signal.

4 Technical requirements

6 Output optical power stability dB ± 1.5-

7 Link flatness dB ± 1.5

Refers to uplink optical transmitter and uplink Optical receiver and other links index.

8 RF input reflection loss dB >=16-

9 RF input impedance ohm 75-

10 Optical connector form-FC/APC or SC/APC-

Noise power ratio (NPR) Dynamic Range dB >=15 (NPR>=30dB) >=10 (NPR>=30dB) Refers to uplink optical transmitter and uplink Optical receiver and other links index.

4.2.3 Technical Requirements of Uplink Optical Receiver See Appendix A of this standard.

4.3 Environmental condition requirements

4.3.1 Environmental requirements for downlink optical receivers should comply with the relevant provisions of 5.3.2.2 of GY/T 143-2000.

4.3.2 Environmental requirements for uplink optical transmitters should comply with the relevant provisions of 4.3 in GB/T 11318.1-1996.

4.4 Security requirements should comply with the relevant provisions of 4.5 in GB/T 11318.1-1996.

4.5 EMC requirements should comply with the relevant provisions of 4.6 of GB/T 11318.1-1996.

5 Measurement method

5.1 Measuring equipment

5.1.1 Spectrum Analyzer Operating wavelength range. 1280nm ~ 1570nm;

Wavelength resolution. 30dB;

Stability. better than ± 0.1dB;

Light reflection loss at each end. > 50dB.

5.1.4 Network Analyzer Impedance. 75ohm;

Operating frequency range. 1MHz ~ 1000MHz;

Measurement accuracy of flatness. 50dB.

5.1.9 Notch filter

Impedance. 75ohm;

Technical parameter chart. See Figure 1.

Figure 1 Technical parameters of the notch

5.2 Measurement of output light wavelength

5.2.1 Measurement block diagram See Figure 2.

Figure 2 Block diagram of output optical wavelength measurement of uplink optical transmitter

5.2.2 Measurement procedure

a) Connect the measurement equipment as shown in Figure 2;

b) Set the wavelength and scan width of the spectrum analyzer;

c) At 25 ° C ± 5 ° C, adjust the measured wavelength to the middle of the screen from left to right and up to the reference position. Read directly with cursor Take the output optical wavelength value of the upstream optical transmitter.

5.3 Measurement of output optical power and output optical power stability

5.3.1 Measurement block diagram See Figure 3.

Uplink optical transmitter optical power meter Optical Spectrum Transmitter

Figure 3 Measurement block diagram of uplink optical transmitter output optical power and output optical power stability

5.3.2 Measurement procedure

a) Connect the measurement equipment as shown in Figure 3;

b) adjust the receiving light wavelength of the optical power meter to the working wavelength of the upstream optical transmitter;

c) Read the output optical power of the upstream optical transmitter directly from the optical power meter at 25 °C ± 5 °C, and record it as A (dBm);

d) Place the upstream optical transmitter in a high and low temperature constant temperature test box, and keep it at -25 °C and + 55 °C for 2h, then from the optical power meter Read the output optical power of the uplink optical transmitter at -25 ° C and + 55 ° C, and record them as B (dBm) and C (dBm), respectively.

e) Take the larger absolute value of BA and CA, which is the output optical power stability at -25 ° C and + 55 ° C.

5.4 Link flatness measurement

5.4.1 Measurement block diagram See Figure 4.

Network Analyzer Uplink Optical Receiver Variable Optical Attenuator Uplink Optical Transmitter

Figure 4 Block diagram of link flatness measurement

5.4.2 Measurement procedure

a) Set the corresponding parameters of the network analyzer, connect the input and output of the network analyzer, and calibrate the network analyzer;

b) Connect the measurement equipment as shown in Figure 4;

c) Measure the flatness of the link on the network analyzer.

5.5 Measurement of RF input reflection loss

5.5.1 Measurement block diagram See Figure 5.

Uplink Optical Transmitter Network Analyzer

Figure 5 Measurement block diagram of RF input reflection loss of uplink optical transmitter

5.5.2 Measurement procedure

a) Set the corresponding parameters of the network analyzer and calibrate the network analyzer;

b) Connect the measurement equipment as shown in Figure 5;

c) Select the maximum reflection value in the operating frequency range on the network analyzer, and its absolute value is the RF input reflection loss of the upstream optical transmitter Consuming.

5.6 Measurement of Noise Power Ratio (NPR) Dynamic Range

5.6.1 Measurement block diagram See Figure 6.

Spectrum analysis

Analyzer

Upward light

Receiver

Variable light

Attenuator

10km

optical fiber

Upward light

Sender

Notch

5MHz ~ 65MHz

Bandpass filter

Wideband white noise Sound generator

Figure 6 Block diagram of noise-to-power ratio dynamic range measurement

5.6.2 Measurement procedure

a) Connect the measurement equipment as shown in Figure 6;

b) adjust the variable optical attenuator so that the uplink optical link loss is 5dB;

c) Adjust the output power of the broadband white noise generator according to the RF excitation power requirements of the upstream optical transmitter, the RF excitation power of the sender starts from 25dB below the nominal excitation power and gradually increases in 2dB steps until it is higher than the nominal excitation power.

Power 15dB;

d) use a spectrum analyzer to measure the NPR at the output of the upstream optical receiver point by point;

e) Using NPR as the ordinate and excitation power as the abscissa, draw the relationship between NPR and input excitation power

f) Find out the dynamic range value from the curve within the specified NPR range.

Appendix A

(Informative appendix) Technical requirements for uplink optical receiver the technical requirements of the upstream optical receiver are shown in Table A.1.

Table A.1 Technical requirements for uplink optical receivers

Technical Index of Project Unit

1 Input optical power range dBm -15.0 ~ 1.0

2 Light reflection loss dB >=45

3 Nominal light wavelength nm 1310, 1550 or double window

4 Output frequency range MHz 5 ~ 65

5 RF output signal level dBµV Product specification

6 Link flatness a dB ± 1.5

7 Optical automatic gain control range dB Product specification

8 RF output reflection loss dB >=16

9 RF output level stability dB ± 3.0 (-25 °C ~ 55 °C)

10 Output impedance ohm 75

11 Optical connector form-SC/APC or FC/APC

12 Noise power ratio dynamic range a dB

>=15 (NPR>=30dB)

Optical transmitter uses DFB laser >=10 (NPR>=30dB) Optical transmitter using FP laser a The link flatness and the dynamic range of the noise power ratio are the link indicators composed of the uplink optical transmitter and uplink optical receiver.

references

[1] GY/T 180-2001 Technical specification of physical channel for uplink transmission of HFC network [2] IEC 60728-4 Cable and distribution system equipment and components for television and sound signals. Part 4. Upstream broadband coaxial cable device