This standard is applicable to the comparison method for measuring the near-end crosstalk attenuation and far-end crosstalk protection of manufactured length communication cables. The test step rate is 0.8kHz~1MHz. If the instrument performance allows, it is also applicable to higher frequency ranges. GB 5441.6-1985 Communication Cable Test Method Crosstalk Attenuation Test Comparison Method GB5441.6-1985 Standard Download Decompression Password: www.bzxz.net

Scope of application
National Standard of the People's Republic of China
Test methods for communication cableCrosstalk attcnuation test
Camparison method
UDC 621.315.2
: 621.39 : 621
.317.3.08
GB 5441.6—85
This standard applies the comparison method to measure the incoming frequency attenuation and incoming beat protection degree of communication cables of appropriate length. The test frequency is 0.8kH7~1MHz, the performance of the indicator is allowed, and the test equipment can be divided into symmetrical and asymmetrical test equipment. Figure 18 (a) is the wiring diagram of the symmetrical tester, and (b) is the wiring diagram of the asymmetrical tester. 3
z - 12
1 piece
Figure 1 Near-end attenuation of the south of the axis (simple grid) National Bureau of Standards 1985-09-29 issued
1986-06-01 implementation
2, - 75 $2
Series 2
GB5441.6-85
ST (2.75)
Figure 2 Near-end crosstalk attenuation EEx between pairs of four-wire groups (or between pairs)
21 =750
Main string 9
2#=752
Substring 2,
GB5441.685
ST (z75)
Figure 3 Near-end string head attenuation of coaxial pair string four-wire pair (referred to as coaxial pair four) 752
Upper string z
Substring 750
GB 5441.685
Figure 4 Near-end crosstalk attenuation of four-pair (or line pair) coaxial pair
(referred to as T)
2 @ 752
1:7502
GB5441.6—85
759
5 Selected end crosstalk protection of coaxial pair
Main string 2e
Wei string B
GB5441.6--B5
ST(Z../75)
ST (Z., 75)
± 2> = 750
6 Far-end crosstalk protection between pairs of four-wire group (or between pairs) Z± = 75 2
Z±=750
Main string 750
Stringed string art.
Stringed string Z
GB5441.6-—85
175/150
Main string 759
ST (Z.,/75)
Figure 7 Far-end crosstalk protection degree of four-wire pair = 750
Figure: G
A oscillator:
GB5441.6—85
Figure 8 Far-end crosstalk protection degree of four-wire pair (or pair) out of wide-axis pair (simplified four-wire string)
Characteristic impedance of string line,
Characteristic impedance of stringed line;
A pair of symmetrical to asymmetrical converter (150≤2/752): S
Coaxial sound tester;
Crosstalk tester, variable attenuator in S; A
R String tester S with variable attenuator before the specified height: Z/ =Zc1, Z2 = Zc2-
D.-Frequency-selective level meter;
2./759 Symmetrical to asymmetrical impedance converter (Z is the characteristic impedance of the wired pair). The test instrument shall meet the following requirements:
2.1 According to the different production requirements of symmetrical or solid-axis cables, appropriate series test instruments or general instruments may be used. 7563
GE 5441 6—85
2.2 The test error of the attenuator shall comply with the provisions of Table 1. Table 1
Money reduction model
90-1203
121~161dB
0.8～150kHz
150~300kz
300k2 --1MHz
2.3 The symmetric transformer of the input of the crosstalk tester and the symmetric asymmetric impedance transformer ST of the test circuit should be able to meet the test error requirements specified in Table 1. 2.4 The minimum readable value of the oscillator output level and the indicator measurement level should be able to meet the test requirements, that is, at the maximum measured sound loss value, there should be a clear reading. If necessary, it is allowed to add a power amplifier or preamplifier to improve the test sensitivity. 2.5 The comparison switch of the instrument, lead plug, socket, matching resistor box and other components should maintain good contact. 2.6 All leads used to connect instruments and cables should use wires with sufficient shielding performance. Leads connecting coaxial pairs must use coaxial lines: symmetrical leads must be used to connect symmetrical pairs of four-wire groups. 2.7 The two ends of the line pair to be crosstalked should be connected to load resistors equal to the line characteristic impedance modulus. The difference should not exceed ±5% of the line characteristic impedance modulus. When the test frequency is higher than 30nkH2, a shielded load resistor must be used for matching. 2.8 When the measured line pair is not connected, the sound attenuation caused by the entire test system, including connecting leads, load resistors, impedance transformers, switches, etc., should be 2dB greater than the maximum crosstalk attenuation of the measured line pair. 3 Sample preparation
The sample is a finished cable of a specified length.
4 Test steps
4.1 Connect the test system according to the wiring method selected in the wiring diagrams of Figures 1 to 8, and check the following items: 4.1.1 Check the correctness of the test system connection and whether the various connectors are in good contact. 4.1.2 Check the correctness of the indicator frequency selection, and check the sensitivity of the test system according to the requirements of Article 2.4. Under the condition of the maximum measured mid-tone attenuation value, when the attenuator changes by 0.5dB (or 1dB), the frequency meter reading should change significantly. 4.1.3 When the measured line is connected, the attenuator reading is at the maximum measured single-tone attenuation value, and the difference in the frequency meter reading when the comparison switch is in the "instrument" and "line" positions, should meet the requirements of Article 2.8. 4.1.4 Change the attenuation value of the attenuator by 10dB, and the indicator should have a corresponding change in value. 4.2 When the inspection results of Articles 4.1.3.4.1.4 do not meet the specified requirements, the original internal separation or grounding test should be carried out. After removing the interference, the formal test work can be carried out. 4.3 Connect the cable to be tested, put the comparison switch on the "line", adjust the input attenuator and sensitivity of the frequency selector to make the pointer of the selector to the appropriate position. Then put the comparison switch on the "instrument" position, adjust the variable attenuator to make the pointer of the selector reach the original position, and record the attenuator reading.
5 Calculation of test results
5.1 The near-end crosstalk attenuation between coaxial pairs and symmetrical line pairs is calculated according to the following formula: GB 5441:6
5.1.1 When using wiring diagram 1 (a), 1 (b) and Figure 2 (b): B, = br
5.1.2 When using wiring diagram 2 (a):
B, =b, + 101g
5.2 The far-end crosstalk protection T2 degree between coaxial pairs and symmetrical line pairs is calculated according to the following formula: 5.2.1 When using wiring diagram 5 (a), 5 (b) and Figure 6 (b): B, = hr
5.2.2 When using wiring diagram 6 (a):
B,=b + 10lg
5.3. The near-end crosstalk attenuation of a coaxial pair in series with a quad pair is calculated using the following formula: When using wiring diagram 3 (a):
E, = br - 10lg
5.3.2 When using wiring diagram 3 (b):
Bp =br
5.4. The far-end sound protection value of a coaxial pair in series with a quad pair is calculated using the following formula: 5.4.1 When using wiring diagram 7 (a):
B, -br + 10lg
5.4.2 When using wiring diagram 7 (b):
B, = br
5.5. The near-end crosstalk attenuation of a quad pair in series with a coaxial pair is calculated using the following formula: 5.5.1 When using wiring diagram 1 (a):
Bo=br + 10lg
5.5.2 When using wiring diagram 4 (b):
B, = br
5.6 The far-end crosstalk protection of a four-wire pair of coaxial pairs is calculated according to the following formula 5.6.1 When using wiring diagram 8 (a):
B,= br - 10lg
5.6.2 When using wiring diagram 8 (h):
actual near-end crosstalk attenuation value, dB,
where: B.—bzxz.net
actual far-end crosstalk protection, dB; B
attenuation tester reading.
(3)
6 Notes
GB5411.6-85
6.1 The test system may not be grounded under normal circumstances. If grounding is required, it should be grounded through the indicator. 6.2 When measuring four in series or four in series, when a symmetrical-to-asymmetrical transformer is connected at the measuring end, the shorter the lead length connecting the transformer and the measured line pair, the better, generally not exceeding 0.5m. 6.3 The ends of all the four-wire groups to be tested should be short-circuited with a shielding tape layer. 6.4 When wiring, the external conductor of the shaft should be fully inserted into the lead plug. 6.5 During testing, the oscillator and power amplifier should be as far away from the test system as possible. Additional remarks:
This standard is proposed by the Ministry of Machinery Industry of the People's Republic of China. This standard is under the jurisdiction of the Shanghai Cable Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Shanghai Cable Research Institute of the Ministry of Machinery Industry and others. The person in charge of drafting this standard must be a student.
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.