GB/T 11298.4-1997 Measurement methods for satellite television earth receiving stations - Indoor unit measurements
Some standard content:
GB/T 11298.4-1997
This standard is the measurement method for indoor units of satellite TV earth receiving stations. Based on the electrical performance indicators required by 4.3 of GB/T11442-1995 "General Technical Conditions for Satellite TV Earth Receiving Stations", the GB11298.4-89 standard has been revised. The revision strives to be concise and directly quotes the same parts as other standards without duplication, and all regulations are implemented in accordance with the original standard. All parts that are inconsistent with the technical parameters of GB/T11442-1995 have been modified or deleted. At the same time, due to the development of science and technology, some satellite TV special measuring instruments have been highly integrated, so some parts of the figure have also been appropriately modified. According to the measurement method of this standard, when using the "self-test method" to implement the measurement, more than three representative frequency points should be selected for measurement. After this standard is officially approved and implemented, it will replace GB11298.4-89. Appendix A and Appendix B of this standard are both appendices to the standard. This standard is proposed by the Ministry of Electronics Industry of the People's Republic of China. This standard is under the jurisdiction of the Standardization Research Institute of the Ministry of Electronics Industry. This standard was drafted by the 54th Institute of the Ministry of Electronics Industry and the Broadcasting Science Research Institute of the Ministry of Radio, Film and Television. The main drafters of this standard are Wang Laicun and Li Lingzhi. This standard was first issued in March 1989 and revised for the first time in August 1997. 33
1 Scope
National Standard of the People's Republic of China
Methods of measurement for satellitetelevision earth receive-only stationDoor-in unit measurementWww.bzxZ.net
Methods of measurement for satellitetelevision earth receive-only stationDoor-in unit measurement
This standard specifies the measurement conditions and methods for indoor units of satellitetelevision earth receive-only stations. This standard is applicable to indoor unit measurement of analog satellitetelevision earth receive-only stations. 2 Referenced standards
GB/T 11298.4-1997
Replaces GB 11298.4--89
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised. Parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T11442-1995 General technical conditions for satellite TV earth receiving stations GB/T11298.1-1997 Measurement methods for satellite TV earth receiving stations System measurement GB/T11298.3-1997
7 Measurement methods for satellite TV earth receiving stations Outdoor unit measurement 3 Measurement conditions
3.1 Atmospheric environmental conditions
Temperature: 15℃～35℃;
Humidity: 45%~75%,
Atmospheric pressure: 86kPa106kPa.
3.2 Power supply requirements
AC power supply is 220V±10%, 50Hz±2Hz. 4 Measurement method
4.1 Working frequency band
4.1.1 General considerations
The working frequency band of the indoor unit refers to the frequency range that meets the specified electrical performance indicators within its working frequency band. 4.1.2 Measurement method
The configuration of measuring instruments and equipment is shown in Figure 1
Signal source
Satellite TV
Signal source
Approved by the State Administration of Technical Supervision on August 26, 199734
Coupler
Measured room
Indoor unit
Instrument configuration for measuring working frequency band
Oscilloscope
Implementation on May 1, 1998
GB/T 11298. 4-1997
a) At the low end of the working frequency band, adjust the measuring instrument to display a normal waveform on the oscilloscope; b) Gradually reduce the frequency of the satellite TV signal source and the indoor unit. When noise appears on the displayed waveform and it deteriorates sharply, the frequency indicated by the satellite TV signal source is the low-end frequency of the working frequency band; c) Use the same method to measure the high-end frequency of the working frequency band. 4.1.3 Result Expression
The operating frequency band of the indoor unit is XXXMHz～XXXXMHz. 4.2 IF Filter 3dB Bandwidth (B)
4.2.1 General Consideration
When the input level of the device under test is constant, the response of the IF filter output level to the frequency change is measured, and the 3dB bandwidth is the point where the output level drops by 3dB, see Appendix A (Supplement) of GB/T11442-1995. 4.2.2 Measurement Method
Use the sweep frequency method, and the measurement configuration is shown in Figure 2. DC Blocker
Sweep Oscillator
Oscilloscope
Indoor Unit Under Test
Detector
Figure 2 Measuring 3dB Bandwidth of IF Filter Instrument and Equipment Configuration a) Connect the instruments and equipment according to Figure 2;
b) Set the sweep oscillator to a point within the working frequency band (970MHz～1470MHz), adjust the working frequency of the indoor unit, and display the response waveform of the IF filter on the oscilloscope; c) Measure the 3dB bandwidth on the waveform diagram.
4.2.3 Result Representation
Use waveform or text description.
4.3 Input Level Range
4.3.1 General Consideration
The input level range refers to the input level corresponding to the normal operation of the indoor unit under test, which gradually increases from the minimum signal input level until the gain is compressed by 1dB. 4.3.2 Measurement method
The configuration of measuring instruments and equipment is shown in Figure 3.
Monitor
Signal source
Image signal
Generator
a)S, set \1"
Satellite TV
Transmitter
Coupler
Attenuator
Input level measurement equipment configuration
Indoor unit
Spectrum analyzer
b) Disconnect the automatic gain control (AGC), adjust the signal source to the center frequency within the working frequency band, and make the instruments and equipment work normally; 35
GB/T 11298.4—1997
c) Change the input level of the indoor unit from small to large, and use a spectrum analyzer to measure the levels when S2 and S are set to "1" and \2 respectively. The input level corresponding to the gain compression of 1dB is the maximum input level value; d) Set S and S to "2", send the image signal at the transmitting end, and observe the image quality from the color monitor; e) Adjust the attenuator to gradually reduce the intermediate frequency level of the input signal. When dynamic threshold noise is observed on the image screen, the corresponding input level is the minimum input level value. 4.3.3 Result Representation
Indoor unit input level range: XXdBm~XXdBm. 4 .4 Secondary local oscillator frequency stability
4.4.1 General considerations
Secondary local oscillator frequency stability refers to the value of the frequency within the specified temperature range that deviates from its nominal value, which can be expressed by absolute frequency deviation △f or relative deviation △f/f., where f. is the nominal value of the secondary local oscillator frequency. 4.4.2 Measurement method
The configuration of the measuring instruments and equipment is shown in Figure 4. Indoor unit under test
Synthesizer
Attenuator
Variable attenuator
Frequency counter
Figure 4 The configuration of instruments and equipment for measuring the frequency stability of the secondary local oscillator of the indoor unit shall be measured in accordance with 4.6 of GB/T11298.3-1997. 4. 5 Secondary local oscillator leakage
4.5.1 General considerations
When the local oscillator of the indoor unit is working, some energy leaks out from the input end of the indoor unit, which is called secondary local oscillator leakage. 4.5.2 Measurement method
The configuration of the measuring instruments and equipment is shown in Figure 5. Spectrum analyzer
Radial current transmitter
Measured indoor unit
Figure 5 Configuration of instruments and equipment for measuring secondary local oscillator leakage of indoor unit a) After the instruments and equipment are working normally, set the frequency of the spectrum analyzer to the local oscillator frequency of the indoor unit, and the local oscillator leakage can be directly measured on the spectrum analyzer Level, when measuring, you should pay attention to calibrate the spectrum analyzer first; b) Select several frequency points in the working frequency band to measure the maximum value of the second local oscillator leakage. 4.5.3 Result representation
Use text description or chart to represent.
4.6 Image interference suppression ratio
4.6.1 General considerations
The image interference suppression ratio describes the ability of the indoor unit to suppress image frequency interference, expressed as the ratio of the signal level to the image frequency level. 36
4.6.2 Measurement method
The configuration of the measuring instrument and equipment is shown in Figure 6. Signal source
GB/T11298.4-1997
Indoor unit
Spectrum analyzer
Figure 6 Image interference suppression ratio measurement instrument and equipment configurationa) Tune the local oscillator frequency of the indoor unit under test, and use the spectrum analyzer to measure the corresponding intermediate frequency level A at the intermediate frequency output end;b) The signal source output signal frequency changes to the image frequency and maintains the same level as the input signal amplitude. Measure the corresponding intermediate frequency level A
c) Calculate the image interference suppression ratio as shown in formula (1): L_AA
Where: L--image interference suppression ratio, dB; A-intermediate frequency level, dB;
A'——intermediate frequency level at the corresponding image frequency, dB. 4.6.3 Result representation
Represented by text description.
4.7 Noise coefficient
4.7.1 General considerations
The noise coefficient refers to the ratio of the input signal-to-noise ratio to the output signal-to-noise ratio of the measured indoor unit at standard temperature (T. = 290K). 4.7.2 Measurement method
The configuration of the measuring instrument and equipment is shown in Figure 7. Solid-state noise source
Measured indoor unit
Noise coefficient tester
Central output port
Figure 7 Noise coefficient test configuration
a) Do not connect the measured device first, calibrate the measuring instrument, and record the error value; b) Connect the test instrument according to Figure 7;
c) Set the instrument to "automatic" or "manual" and measure the noise coefficient value of each point in the working frequency band (at least five frequency points). 4.7.3 Result representation
Represented in text.
4.8 Static Threshold Value
Measured in accordance with Chapter 7 of this series of standards GB/T11298.1-1997. 4.9 Gain Stability
Measured in accordance with Chapter 5 of this series of standards GB/T11298.1-1997. 4.10 Video Frequency Response
4.10.1 General Consideration
Video frequency response is the ratio change of the output level of the indoor unit relative to the amplitude of the flag signal within the video baseband, in decibels or percentages.
4.10.2 Measurement Method
The configuration of the measuring instrument and equipment is shown in Figure 8. 37
Image test
Signal source
Signal source
Power meter
Analyzer
Oscilloscope
Satellite TV
Signal source
Attenuator
GB/T 11298.4—1997
Degree reducer
DC block
Indoor unit
Monitor
Sacral filter
Measurement system
Figure 8 Video characteristic measurement instruments and equipment configuration Outdoor
Outdoor unit
or load
Switches S1 and S. are respectively set to "1\ position, S, is set to \1 or \2", so that the transmitting end test signal source outputs a multi-burst signal as shown in Figure 9, which is input into the indoor unit under test through the transmitting end equipment, and then measured with a waveform monitor or oscilloscope, and the measured data is substituted into formula (2) to calculate: A(f)=20 lg
Where: A(f)-
The output signal amplitude of the equipment under test relative to the flag signal, dB; U—multi-burst signal amplitude, mV;
U,--flag signal amplitude, mV.
Or measure directly with an inset analyzer.
(2)
4.10.3 Result presentation
Present in a graph or table.
4.11 Continuous random noise signal-to-noise ratio
GB/T11298.4—1997
12162024
Figure 9 Multi-wave group signal
Measured in accordance with Chapter 6 of this series of standards GB/T11298.1-1997. 4.12 Single-frequency interference signal-to-noise ratio
4.12.1 General considerations
The single-frequency interference signal-to-noise ratio is expressed as the ratio of the nominal value of the brightness signal amplitude to the peak-to-peak value of the single-frequency noise amplitude within 10kHz~6MHz.
4.12.2 Measurement method
Connect the instrument and equipment according to Figure 8, set the switches S1.S to the \1\ position, and S: to *2", and the transmitting end test signal source outputs the flat field signal K, as shown in Figure 10. Input the signal into the indoor unit under test through the transmitting end equipment, and measure the nominal value of the brightness signal and the peak-to-peak value of the single-frequency clutter amplitude after removing the flat field signal on the oscilloscope or frequency selection meter. Substitute the obtained values into formula (3) for calculation, and the result can be obtained. The measurement must be carried out under the specified carrier-to-noise ratio C/N conditions.
-300mVl
4.12.3 Result expression
S/N= 20 lg Tong Lai Lai wave amplitude peak-to-peak brightness signal amplitude nominal value
single frequency interference signal-to-noise ratio is XXdB.
4.13 Power supply interference signal-to-noise ratio
4.13.1-General consideration
Flat field signal
· (3))
The power supply interference signal-to-noise ratio is the ratio of the nominal value of the brightness signal amplitude to the peak-to-peak amplitude of the noise (fundamental wave and its harmonics) from the AC power supply below 1kHz.
4.13.2 Measurement method
GB/T 11298.4-—1997
Connect the instrument and equipment according to Figure 8, set switches S and S2 to "1\ position respectively, and switch S, to "3", and the transmitting end test signal source outputs a flat field signal K, as shown in Figure 10. It is input into the indoor unit under test through the transmitting end equipment. At the output of the 1kHz low-pass filter (see Figures A1 and A2 in the Appendix), use an oscilloscope to measure the nominal value of the brightness signal and the peak-to-peak value of the noise amplitude after removing the flat-field signal, and then substitute them into formula (4) to calculate the result.
Nominal value of the brightness signal amplitude
S/N = 20 lgTH2peak-to-peak amplitude of the pulse 4.13.3 Result expression
The power supply interference signal-to-noise ratio is XXdB.
4.14 Pulse interference signal-to-noise ratio
4.14.1 General consideration
The pulse interference signal-to-noise ratio is the ratio of the nominal value of the brightness signal to the peak-to-peak value of the pulse noise amplitude. Pulse interference has high-frequency interference and low-frequency interference, and its spectrum is very wide, so the largest one is taken. 4.14.2 Measurement method
Connect the instruments and equipment according to Figure 8, set switches S1 and S2 to "1", and S3 to "2". Measure the nominal value of the brightness signal and the peak-to-peak value of the pulse noise amplitude on the delay oscilloscope, and substitute them into formula (5) to calculate the pulse interference signal-to-noise ratio. Nominal value of brightness signal
S/N=20 lg Peak-to-peak value of pulse noise
4.14.3 Result expression
The pulse interference signal-to-noise ratio is XXdB.
4.15 Color interfering modulation
4.15.1 General considerations
In the video baseband channel, the ratio of the interference caused by the beat difference of the audio subcarrier signal and the color subcarrier signal to the nominal value of the brightness signal amplitude is expressed in decibels D.
4.15.2 Measurement method
Connect the instruments and equipment according to Figure 11. The test signal output by the color subcarrier generator (e.g., the frequency is 4.43MHz) and the test signal output by the audio subcarrier generator (e.g., the frequency is 6.6MHz) are input into the indoor unit under test through the transmitting device. Its video output terminal is connected to a spectrum analyzer or a frequency-selective level meter. The beat voltage and brightness signal voltage are measured and the measured values are substituted into formula (6) for calculation. D. = 20 Ig Audio subcarrier signal and warning color subcarrier signal beat voltage value Nominal value of brightness signal amplitude
Color subcarrier
Generator
Audio subcarrier
4.15.3 Result representation
Color crosstalk modulation is -XXdB.
4.16 Energy spread elimination ratio
4.16.1 General considerations
Coupler
Spectrum analyzer or
Frequency-selective level meter
Color interfering modulation measurement instrument equipment configuration diagram (6)
The energy spread elimination ratio is the ratio of the nominal brightness output signal nominal value S to the peak-to-peak value of the residual spread signal, denoted by R. 4.16.2 Measurement method and steps
Connect the instruments and equipment according to Figure 8, set S1 and S2 to "1"; S: set to "2". 40
GB/T 11298.4-1997
a) Connect the high-sensitivity oscilloscope to the video output terminal of the indoor unit; b) Measure the nominal value S of the brightness signal;
c) Remove the signal source, adjust the oscilloscope, and measure the peak-to-peak value (r) of the triangle wave; d) Substitute the measured value into formula (7) for calculation. R = 20 lg
Where: R - energy diffusion elimination ratio, dB; S - nominal brightness output signal nominal value, mV; residual diffusion signal peak-to-peak value, mV.
4.16.3 Result expression method
Expressed by text description.
4.17 Line time waveform distortion (K,)
4.17.1 General consideration
When a square wave signal with the same period as the line period and the amplitude of the nominal value of the brightness amplitude passes through the device under test, the top of the waveform appears tilted, which is called line time waveform distortion.
4.17.2 Measurement method
Method 1: Connect the instrument and equipment according to Figure 8, set the switches St and S. to the "1" position respectively, and the image test signal source at the transmitting end outputs the bar pulse B3, as shown in Figure 12 (b), which is added to the input end of the indoor unit through the satellite TV signal source, and measured at its output end with an oscilloscope. During measurement, the changes in the 1μs period before and after the pulse should be ignored. The deviation amplitudes b1 and bz and the center amplitude L are measured, as shown in Figure 12(a), and then substituted into formula (3) for calculation:
Where: Kb - line time waveform distortion, %; 61
X100 or Kb=
b1, b2 - are the values of the top deviation from the center point, respectively, as shown in Figure 12(a). When measuring, take the larger value of b1 and bz; L
is the midpoint amplitude of the pulse.
1/(1-4K)
1/(1+4K)
(a) Output pulse B: waveform distortion
(b) B,, B. Pulse distortion scale plate (Kb, Kp scale plate) Figure 12 Line time tilt and Kb, Kp scale plate (8)
Method 2: According to method 1, on the waveform monitor, adjust the bar pulse B, to K. On the scale plate, see Figure 12(b), so that the midpoint coincides with point B, and measure the line time tilt K, value at the maximum offset of the bar pulse. When measuring, the changes in the leading and trailing edges of the top of the bar pulse within each 1us period should be ignored.
4.17.3 Result representation
Represented with text description.
4.18 Field time waveform distortion (Kso)
4.18.1 Generally consider
When a square wave signal with a period of the same order as the field period and an amplitude of the nominal value of the brightness signal is sent to the device under test, the tilt generated at the top of the output waveform 41
is called field time waveform distortion. 4.18.2 Measurement method
GB/T 11298.4-1997
Method 1: Connect the instruments and equipment according to Figure 8. The image test signal source at the transmitting end outputs a field square wave signal F, which is added to the input end of the indoor unit under test through the satellite TV signal source. The waveform shown in Figure 13 (a) is measured at the output end with an oscilloscope. The changes in the leading and trailing edges of the field square wave during the 250us period should be ignored. Substitute the measured value into formula (9): b,
Koo=×100 or Kso=—
Where: K50～
Field time waveform distortion, %;
b2×100·
bi,b2——
The value that deviates from the median L in Figure 13(a), take the larger one, mV; L—the midpoint amplitude of a field square wave, mV.
250μs
250μs
(a) Field square wave output distortion waveform
250μst
250psl
(b) Ks scale plate
Figure 13 Field time tilt
Method 2: According to method 1, adjust the field square wave on the waveform monitor so that the midpoint coincides with point B on the scale plate of K5o(%) in Figure 13(b), that is, the maximum offset (positive or negative) value of the top of the corresponding field square wave is measured. When measuring, the changes of the leading and trailing edges of the field square wave within the period of 250μs are ignored. Calculate according to formula (10):
4.18.3 Result representation
It can be represented by graphics or text.
4.192T wave amplitude distortion (Kpb)
4.19.1 Generally consider
×100 or —Kso=
2T sine square wave amplitude distortion Kb is the ratio of the 2T sine square wave amplitude to the bar pulse amplitude after transmission. 4.19.2 Measurement method
（10）
Connect the instrument and equipment according to Figure 8. The image test signal source at the transmitting end outputs the sine square wave Bi and the bar pulse signal B3 (as shown in Figure 14 (a)). The signal is added to the input end of the indoor unit under test through the transmitting end equipment. The deviation value Kpb (%) between the sine square wave B and the bar pulse bee point is measured at its output end using the Kp (%) scale plate of the waveform monitor, as shown in Figure 14 (b). Its value is calculated by formula (11): Kpb
Where: Kpb
2T wave amplitude distortion, %;
X 100 or Kp =
bar pulse amplitude at the output end of the indoor unit, mV, amplitude of the sine square wave at the output end of the indoor unit, mV. Note: This indicator can also be measured using an interpolation analyzer. 42
× 100
-300mvl
4. 7μs 12. 5μs15μs
GB/T 11298. 4—1997
(a) 2T sine square wave B, and bar pulse signal B: (b) Output distortion waveform of the device under test
Figure 14 Test signal and short-time waveform distortion diagram 4.19.3 Result representation
It can be represented graphically or described in words. 4.202T wave phase distortion (Kp)
4.20.1—General consideration
When a 2T sine square wave is added to the device under test, a waveform as shown in Figure 15(b) is obtained at its output end. The value of the waveform deviating from the original waveform is the 2T wave phase distortion Kp.
4.20.2 Measurement method
Connect the instruments and equipment according to Figure 8.
a) Make the transmitting end image signal generator output 2T sine square wave B, and add it to the input end of the indoor unit under test through the transmitting end equipment, and connect the waveform monitor to the output end of the indoor unit;
b) Adjust the amplitude and position knobs to make the baseline of the 2T pulse coincide with the horizontal line marked \0" on the scale plate Kp (%), and at the same time make the pulse beep point on the top horizontal line of the scale plate Kp (%) (see Figure 15a)); c) Measure the Kp (%) value at the maximum deviation of the waveform to the undistorted state of the pulse; d) Calculate according to formula (12), formula (13), and formula (14). At the first ringing soil on both sides of the 2T sine square wave At 2T: Kp
Where: Kp——2T wave phase distortion, %; α(2)—is α or α (take the larger value). At the second ring ±4T on both sides of the 2T sine square wave: Kp
Where: α\(2)—is α or αz (take the larger value). At the fourth ring ±8T on both sides of the 2T sine square wave: Kμ
Where: α1(2)—is α or α, (take the larger value). Q1(2)
1（2）
（12）
(13）
4.20.3 Result expression
GB/T 11298.41997
(a) Kp scale plate
(b) Kp value
Figure 152T sine wave distortion waveform, K factor evaluation method The above three parameters can be represented by a graph or a text description, as shown below: 2T sine square wave phase distortion at the first ring ±2T: Kp=X,%; at the second ring ±4T: Kp=X;
at the third ring ±8T: Kp=X,%.
4.2 1 Luminance/chrominance gain inequality (△K) is measured in accordance with Chapter 9 of this series of standards GB/T11298.1-1997. 4.22 Luminance/chrominance delay inequality (△t) is measured in accordance with Chapter 8 of this series of standards GB/T11298.1-1997. 4.23 Differential gain distortion (DG)
is measured in accordance with Chapter 10 of this series of standards GB/T11298.1-1997. 4.24 Differential phase distortion (DP)
is measured in accordance with Chapter 10 of this series of standards GB/T11298.1-1997. Measured in Chapter 11 of the standard GB/T11298.1-1997. 4.25 K coefficient
The K coefficient includes Kb, Kpb, and Kp, which is the superposition of the three. The law has not yet been determined. For the test of Kb, Kpb, and Kp, please refer to 4.17, 4.19, and 4.20 of this standard. The one with the larger absolute value of the three is called the K coefficient of the indoor unit under test. 4.26 Synchronous pulse amplitude distortion
4.26.1 General considerations
In the device under test The input end is connected to a synchronization signal with a specified average image level and a nominal amplitude of 300mV, and the deviation of the synchronization pulse midpoint amplitude at the output end from the nominal value is called synchronization pulse amplitude distortion. 4.26.2 Measurement method
Connect the instrument and equipment according to Figure 8. The output of the image test signal source at the transmitting end is the B signal in Figure 12(b) and is added to the indoor unit under test through the transmitting end equipment. At its output end, an oscilloscope is used to measure the output end synchronization pulse midpoint amplitude S and the bar pulse midpoint amplitude L, as shown in Figure 16. The measured synchronization pulse amplitude distortion D.The calculation is shown in formula (15). D =
X 100·
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