This standard is applicable to the measurement of the coaxial end impedance and internal impedance non-uniformity of coaxial cables with manufacturing lengths of 2.6/9.5mm, 1.2/4.4mm, and 0.7/2.9mm by pulse echo method. GB 5441.4-1985 Communication cable test method Coaxial end impedance and internal impedance non-uniformity test Pulse method GB5441.4-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test methods for communication cableImpedance and impedance irregularitiestest of cuaxial pair
Pulse method
Scope of application
UDC 621.315.2
:621.39 : 621
GB5441.4-85
This standard applies 1 The pulse wave method is used to measure the axial impedance and internal impedance of the 2.6/9.5mm, 1.2/4.4mm: 0.7/2.9mm manufacturing length of the axial cable.
2 Symbols
The symbols and their definitions are shown in Table 1.
Coaxial series A temperature resistance value
Xie pulse needs to be sent into the track xA, the country chain for internal unevenness Yao with no reflection coefficient technology small pulse from the time A is still sent, the time series for internal unevenness with reflection attenuation and the value shown by the auxiliary B end
Mountain gland gland pulse auxiliary B Hong sent people, the auxiliary for internal unevenness with no reflection coefficient when the pulse from the axis to B Ding sent people, the coaxial pair internal unevenness with reflection attenuation and the value shown by the full door cable production standard A is now determined. 3 Test equipment
Test system wiring schematic diagram as shown in Figure 1.
Shanghai Axis Cable Heat Tester
National Bureau of Standards 1985-09-29 Issued
19860601 Implementation
W Balance Network (Pulse Accessory);
C. Tested Axis Pair:bzxZ.net
Z Terminal Matching Impedance:
1. Test Line (No Lead Wire Allowed). The tester shall meet the following requirements:
GB 5441.485
3.1 Test System Accuracy: The measurement error of the terminal attachment shall not exceed 0.052 for 2.6/9.5mm type, 10.12 for 1.2/4.4mm type: 0.7/2.9mm type shall not exceed F±0.2, and the error of the impedance non-uniformity of the axis pair shall not be greater than -10% of the measured value~+10.01%.
3.2 Connection system: The frequency characteristics of the internal amplifier and input attenuator should not fluctuate more than +3dH in the frequency range of 0.1~0.5zMH2.
3.3 Transmit pulse: The output transmit pulse amplitude should not be less than 20V, the waveform should be a square wave, and the difference of the half-width (1) of the transmit pulse should not exceed ±15% of the value selected according to Article 5.2. 3.4 Differential correction: While meeting the requirements of Article 3.2, for the test instrument using lead wire test or using standard coaxial pair to calibrate the network calibration, the symmetry of the output at both ends should not be less than 52dR. For the instrument without lead wire and using standard coaxial pair to calibrate the network calibration, the symmetry of the output at both ends should not be less than 7dB. 3.5 Equalization network: The impedance frequency characteristics should simulate the impedance frequency characteristics of the measured axis pair. When measuring 2.6/9.5mm coaxial pairs, the real impedance value when the network scale is 2.5MHz: when measuring 1.2/4.4mm and 0.7/2.9mm coaxial pairs, the real impedance value when the network scale is 1MHz.
The scale of the network should be calibrated with a standard coaxial pair before testing, and the scale error after calibration should not be greater than ±0.032. For networks where the Z and R links can be divided into 1, the scale of the standard coaxial pair with a temperature coefficient below 1×10-52/℃ can also be used for calibration.
3.6 Test leads: When using a 10s width pulse test, the length of the two leads should not be less than 10m; when using a 501s width pulse test, the length of the two leads should not be less than 30m; when using a pulse test with a width greater than 50ns, the length of the two leads should not be less than 50m. The length difference of the two limit leads should not exceed 20mm, the impedance is 75=22, the capacitance is not greater than 76/m, and the internal impedance unevenness should not exceed 10%. The impedance of the lead end connected to the single network and the impedance of the line end connected to the measured axis pair should be as close as possible, and the difference should not exceed 0.5.
3.7 Standard coaxial pair: The coaxial pair structure of the selected standard coaxial pair should be similar to that of the test sample. The calibration temperature of the end resistor is -20℃. The calibration value of the 0.7/2.9mm standard shaft pair should be within the range of 74.0～76.02℃, and the calibration value should be within the range of +0.12℃. The calibration value of the 1.2/4.4mm standard shaft pair should be within the range of 74.5～75.5℃, and the error should not be greater than +0.059℃. The calibration value of the 2.6/9.5mm standard shaft pair should be within the range of 74.0～76.02℃, and the error should not be greater than +0.12℃. 8~75.222, the error is not greater than ±0.022. 3.8 Standard resistance: The calibration temperature of the resistor is +20℃, and the calibration signal during flow is 72.0~73.02 for 0.7/2.9mm type inter-conductor pairs, 73.0~74.082 for 1.2/4.4mm type coaxial pairs, and 74.0~75.09 for 2.6/9.5mm type axial pairs. The error of the current value should not be less than ±0.022. 3.9 Time scale display circuit: The error at the test distance should not be greater than 1%. 3.10 PL circuit board: that is, the calibration circuit board for the unevenness of the P slip length. The curve should conform to the characteristics of the amplitude changing with the length when the selected test pulse is transmitted in the sample. 4 Sample preparation
The sample is a finished cable of manufacturing length.
5 Test steps
5.1 Connect the pulse tester to the power supply, preheat it, and then adjust the knobs to the correct position according to the instrument manual. 5.2 Except as specified in the technical documents of the tested cable, the half width of the test pulse should be selected according to the maximum frequency of the transmission system of the coaxial pair and the half width of the test pulse should be adjusted to the selected value according to Table 2. Sample specifications
GB 5441:4-B5
Analog transmission system
Digital transmission system
Mbit/s
5.3 "Calibrate" the amplitude of the transmitted pulse according to the instrument manual. 5.4 Use standard interaxial pairs or standard resistors to calibrate the impedance scale value of the half-balance network according to the instrument manual. Test pulse half width
5.5 Connect the coaxial pair to be tested according to Figure 1.
5.6 Adjust the high-frequency compensation capacitor and "Q" adjustment knob on the balancing network according to the instrument instructions to achieve the standard "M" shape or "W".
5.7 Read the end impedance ZA or Z value from the half-balance network, read the coaxial pair internal unevenness PA or P value from the PL curve, or adjust the attenuation of the input attenuator so that the amplitude of the reflected pulse at the uneven point is exactly equal to the reference height during calibration, and read the reflection attenuation value Ar or 4n value.
6 Test results and calculations
There are two methods to obtain the test results. One is the direct reading method that uses the already drawn -L calibration curve plate to directly read on the instrument; the other is the calculation method that reads the attenuation value from the attenuator and then performs calculation correction. 6.1 Direct reading method
Read the Z or Z value from the instrument's balance network; read the maximum unevenness PA or P using the -L calibration curve plate. The drawing of the P-Orange positive line board can be done by point measurement on the cable of different lengths, or it can be drawn according to the calibration values ​​given for different types of shaft pairs in Table 3.
2.6/9.5mm
Avoidance x
6.2 Lett's method
r =sonsf-t
Pulse amplitude
Reverse frequency load reduction A value can be obtained as follows:
1.2/4.4mm
t = 50s 3
Pulse helicity
0,452
0.7/2.9mm
7-100ns+
Pulse amplitude
*1 number. For 1-2.6/9,5mm type, the calculation is based on a1=2.337d13/km: for 1.2/4.4mm type coaxial number, 5.3,k is used; for 0.7/2.9mm type coaxial pair, a=9.068dB/k is used. GB 5441.4--85
A =-A +A, - A (dB)
Where: 2-the attenuator reading when the pulse is "calibrated", dBA-the attenuation value of the input attenuator when the reflected pulse at the uneven point is adjusted to the "calibrated" point, B, A-the transmission attenuation value of the pulse when the coaxial pair under test is not transmitting, d. A. Calculate according to the following formula:
A,-2a:VTix (dB)
1MIIz The attenuation constant of the sample, dB/km, can be measured by: the distance from the sample uneven point to the starting end, km, f--… pulse effective frequency, MHz.
For the coaxial length of less than 0.6km, it can be calculated by the following formula: fp(ut:tx)fr(MHz)
×10 (MHz)
p(ai,tx) =Aix +H
武ih: t
is the half width of the transmitted impulse, ns
1, B is the coefficient of the function (α:, 1x). For different types of coaxial pairs, the A and B values ​​are shown in Table 4. Cut 4
shoe pair size
fx according to the following formula: Party:
2.6/9.5nmm
1.2/4.4mm
The transmission speed of the ball agent in the measured room, km/μs; the time for the reflected pulse band at the uneven point measured by the time scale display device to expand the transmitted pulse, μs. 6.3 (or 4) values ​​(P or,) values ​​are converted as follows: --1,2n
P = 10
6.4 When the impedance difference of the uneven point is required, it can be calculated as follows: \ within .5km, 1, = -0.[1341\ +0,06171, = 1155(1)
0.7/2.9mm
Formula: P—reflection coefficient of the uneven point, AZ—impedance deviation of the uneven point, Q;
2Z-——nominal value of characteristic impedance of the sample, 92. Notes
GB5441.4-85
7.1 Where the network calibration is calibrated with a standard shaft pair, when the ambient temperature changes, the network calibration should be recalibrated with a standard shaft pair.
7.2 When testing with a test lead (as shown in Figure 1), if the end of one lead in the power line is damaged, equal lengths should be cut off at the corresponding ends of the two leads.
7.3 When it is necessary to use a t=10ns pulse for testing, a coaxial cable pulse tester with automatic correction of pulse amplitude and phase should be used for testing.
Additional Notes:
This standard was proposed by the Ministry of Machinery Industry of the People's Republic of China. This standard was drafted by the Shanghai Cable Research Institute of the Ministry of Machinery Industry and others. The drafter of this standard is Jiang Zhengquan.
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