GB/T 15523-1995 General technical requirements for radio frequency modulators for video recorders
Some standard content:
UDC 621.376.32 :621.397.61
National Standard of the People's Republic of China
GB/T15523—1995
General specification for radio frequency modulators of video tape recorders1995-04-06Promulgated
State Bureau of Technical Supervision
Implementation on 1995-11-01
National Standard of the People's Republic of China
General specification for radio frequency modulators of video tape recorders1Subject content and scope of application
GB/T15523—1995
This standard specifies the technical requirements, test methods, inspection rules and marking, packaging, transportation and storage of radio frequency modulators of non-broadcast video recorders (referred to as RF modulators).
This standard applies to various non-broadcasting video recorders and RF modulators for camcorders that conform to my country's television broadcasting standards. RF modulators may include antenna amplifiers and distributors. 2 Reference standardswwW.bzxz.Net
Packaging storage and transportation pictorial signs
GB2421
GB2828
GB2829
GB3174
GB4892
General rules for basic environmental testing procedures for electrical and electronic products Batch inspection counting sampling procedures and sampling tables (applicable to inspection of continuous batches) Periodic inspection counting sampling procedures and sampling tables (applicable to inspection of production process stability) Color television broadcasting
Hard rectangular transport packaging size series
GB6543
GB8171
GB8496
GB8898
GB9383
Equipment reliability testFailure rate and mean time between failures under the assumption of constant failure rateVerification test planCorrugated paper box
Method for testing the mechanical impact fragility of products using cushioning packaging materialsBasic parameters and measurement methods of electronic tuners for television broadcast receiversSafety requirements for household and similar general-purpose electronic and related equipment powered by mains power supplyMeasurement methods for conducted immunity characteristics of broadcast receivers and related equipmentGB9384
Environmental conditions for broadcast radios, broadcast television receivers, tape recorders, audio power amplifiers (amplifiers) Test requirements and test methods
GB13837
Permitted values and measurement methods for interference characteristics of sound and television broadcast receivers and related equipmentGB/T13838 Permitted values and measurement methods for radiated immunity characteristics of sound and television broadcast receivers and related equipmentGB/T13839 Permitted values and measurement methods for internal immunity of sound and television broadcast receivers and related equipmentSJ234
SJ2303
SJ2950
SJ2951
SJ2954
SJ3263
Plastic strapping tape
TX type Concentric plug socket
Acceptance rules for tuners for radio and television receivers Non-matching RF coaxial connectors
Antenna input for color TV broadcast receivers Limit values for conducted immunity of sound and TV broadcast receivers and related equipment Approved by the State Administration of Technical Supervision on April 6, 1995 and implemented on November 1, 1995
3 Terms
GB/T15523—1995
3.1 Antenna amplification unit Antenna amplify unit An amplification unit that amplifies the received TV signal and distributes it to the electronic tuner of the video recorder and mixes the modulated output signal of the video recorder.
3.2 Hybrid modulator Mixed modulator An RF modulator in which the antenna amplification unit and the RF modulator are installed in the same structure. 3.3 Antenna input antenna input point The input port of the RF modulator that receives the TV signal. 3.4 Antenna output antenna output point The RF modulator sends the TV signal to the output port of the electronic tuner of the video recorder. 3.5 RF output terminal radio frequency output point The port where the RF modulator is connected to the TV and outputs the RF signal. 3.6 White peak value out When the white peak level of the input TV signal exceeds the rated value, the RF modulator performs nonlinear cutting processing on the white peak level of the input signal before modulation.
3.7 Ratio of about picture range to synchronization The ratio of the image amplitude to the synchronization level of the video signal modulated by the RF modulator. 4 Technical requirements
4.1 General requirements
4.1.1 TV standard and channel setting
The TV standard should comply with the provisions of GB3174; a.
b. The channel setting should comply with the frequency division of TV channels in my country. Note: It can also be set according to the CCIR TV channel division as needed. 4.1.2 Structural requirements
a. When the RF modulator is connected to a TV, video recorder, antenna equipment, etc., the insertion force, extraction force, mechanical durability, contact resistance and insertion loss of the antenna input/RF output connector shall comply with the relevant provisions of SJ2954. When the RF modulator is connected to the local electronic tuner, the socket separation force of the antenna output shall comply with the relevant provisions of GB8496. b.
The strength of the terminal connected to the RF modulator and the printed circuit board shall meet the requirement that when the bending moment is less than or equal to the standard value (specified in the product standard), the connected printed circuit board or the through-hole capacitor body is not allowed to be damaged. d. The antenna input/RF output of the RF modulator shall use a TC connector and comply with the provisions of SJ2951. The antenna output of the RF modulator shall use a TX socket and comply with the relevant provisions of SJ2303. 4.1.3 Adaptability to power supply
a. The working voltage of the RF modulator is one of DC 5, 9, and 12V, and the preferred voltage is 5V or 12V. It should be able to work normally under the following power supply conditions:
Power supply deviation: ±5%;
Power supply ripple: not more than 30mV (peak-to-peak); b. Power consumption: modulator not more than 0.6W;
antenna hybrid amplifier unit not more than 1W.
4.2 Appearance requirements
The appearance of the RF modulator should be neat, and there should be no obvious defects such as dents, scratches, cracks, deformation, burrs, mildew, rust, etc. on the surface. The surface coating should not bubble, crack, or fall off. The text, graphic symbols and signs describing the function should be clear, correct and firm. 4.3 Performance requirements
4.3.1 Video characteristics
The video characteristics of the RF modulator are shown in Table 1.
Basic parameters
Video input impedance
Video signal input level
Video modulation degree ((Md)
White peak cutting
Not greater than
Image signal and synchronization signal amplitude ratio
Video amplitude-frequency characteristics
Not inferior to
Influence of APL change on modulation degree
Differential gain,
Differential phase,
Video signal-to-noise ratio,
Color/brightness delay difference
Not greater than
Not inferior to
Not less than
Not inferior to
Included test signal line synchronization period
Audio characteristics
The audio characteristics of the RF modulator are shown in Table 2.
Basic parameters
Audio Input impedance,
not less than
Audio signal input level
Pre-emphasis time constant
Audio amplitude-frequency characteristics
Audio modulation
Audio signal-to-noise ratio,
Audio distortion,
RF output characteristics
not inferior to
not less than
not greater than
v(peak-to-peak value ）
Technical requirements
80±10
(7±0.3)/（3000.3）
Technical requirements
-5～—6.5
Error range to be determined
80±18
Measurement method number
Measurement method number
Unbalance
Positive polarity
0.5~6MHz takes
1MHz point as 0dB
Take APL50% as the benchmark
0.1~10kH,
1kHz point as 0dB
Take ±50kHz frequency deviation
as 100% modulation
The output characteristics of the RF modulator are shown in Table 3.
Basic parameters
Image carrier frequency (f)
Image and sound carrier distance (f.-f,)
RF output level
Image and sound carrier level difference
Output channel level difference
Out-band spurious signal suppression ratio
In-band spurious signal suppression ratio
Color subcarrier suppression ratio
Antenna amplification unit characteristics
GB/T15523—1995
Not inferior to
Not inferior to
Not inferior to
The antenna amplification unit characteristics of the RF modulator are shown in Table 4. Table 4
Basic parameters
Power gain within transmission bandwidth
Noise figure
Antenna output
RF output
Voltage standing wave ratio
Antenna input
Antenna output
RF output
Attenuation level
Carrier intermodulation ratio (IM)
Leakage at antenna input
Isolation of mixer
Basic parameters
Not inferior to
Not inferior to
Not greater than
Not greater than||tt ||Not greater than
Not inferior to
Not greater than
Not inferior to
Technical requirements
Comply with Article 4.1.1
(f.-fp)±8
Technical requirements
See Table 5
Test method number
Measurement method number
Basic parameters
RF input level
Intermodulation level
Note: f(IM)=f2—f or f(IM)=2f2-f14.3.5 Temperature characteristics
The temperature characteristics of the RF modulator are shown in Table 6.
Basic parameters
Video modulation stability
Image carrier frequency stability
Image and sound carrier range stability
RF output level stability
Image signal and synchronization signal amplitude ratio
Stability
Image and sound carrier level difference
Audio modulation stability
Differential gain stability
4.4 Safety requirements
Not inferior to
GB/T15523—199 5
Continued Table 5
Technical requirements
80±16
f,±500
(f.—f)±15
(7±0.4)/(3d0.4)
80±25
752Unbalanced
Antenna outputRF output
Measurement method Article number and measurement conditions
Method: Article 5.3.1.3
Conditions: -103℃ and 60±2℃
Method: 5.3 .3.1
Conditions: 10±3℃ and 60±2℃
Method 5.3.3.2
Conditions: -10±3℃ and 60±2℃
Method: 5.3.3.3
Conditions: -10±3℃ and 60±2℃
Method: 5.3.1.5
Conditions: -10±3℃ and 602℃
Method: 5.3.3.4
Conditions: -10±3℃ and 60±2℃
Method Method: 5.3.2.5
Condition: -10±3℃ and 60±2℃
Method: 5.3.1.8
Condition: -10±3℃ and 60±2℃
The safety requirements for simulated lightning strike and antenna withstand voltage of RF modulator shall comply with the provisions of 10.1 and 10.3 of GB8898 respectively, and after the test, the transmission bandwidth and power gain of the antenna amplifier of the RF modulator shall not change abnormally, the noise coefficient change shall be less than or equal to 2dB, and the modulator output shall comply with the product standard. 4.5 Electromagnetic compatibility requirements
4.5.1 Interference characteristics
The limit value of interference characteristics shall comply with the provisions of GB13837. 4.5.2 Anti-interference characteristics
4.5.2.1 Conducted anti-interference characteristics
The limit value of conducted anti-interference shall comply with the provisions of SJ3263. 4.5.2.2 Radiated immunity characteristics
The radiated immunity limit value shall comply with the provisions of GB/T13838. 4.5.2.3 Internal immunity characteristics
GB/T15523—1995
The internal immunity characteristics shall comply with the provisions of GB/T13839. 4.6 Environmental requirements
4.6.1 Working environment
The working environment shall meet the use requirements of the video recorder and shall be specified by the product standard. 4.6.2 Requirements after the test
4.6.2.1 Appearance, structure and function requirements
After the test, the samples shall be inspected according to the provisions of Article 5.2, and there shall be no unqualified contents in items 2 to 5 in Table 16. 4.6.2.2 Electrical performance requirements
After the test, the items listed in Table 7 shall be tested, and the parameters shall comply with the provisions of this standard. Table 7
Note: The modulator does not detect items 16 and 17. 4.6.3 High temperature load
Video modulation
Amplitude ratio of image signal and synchronization signal
Video amplitude-frequency characteristics
DG, DP
Video signal-to-noise ratio
Color/brightness delay difference
Audio amplitude-frequency characteristics
Audio modulation
Audio signal-to-noise ratio
Audio distortion
Image carrier frequency
Image, sound carrier distance
RF output level
Image and sound clipping level difference
Output channel level difference
Power gain within transmission bandwidth
Noise coefficient
The sample shall work continuously for 16 hours at a temperature of 60±2℃ and shall comply with the requirements of Table 6 at this temperature. After returning to normal temperature, it shall comply with the provisions of Article 4.6.2.1.
4.6.4 High temperature storage
The sample shall be stored at 70±2℃ for 168h and shall meet the requirements of 4.6.2 after 1h recovery. 4.6.5 Steady heat
GB/T15523—1995
The sample shall be stored at 40±2℃ and relative humidity (93)% for 168h and shall meet the requirements of 4.6.2 after 1h recovery. 4.6.6 Low temperature load
The sample shall be able to work continuously for 1h after being stored at -10±3℃ for 2h and shall meet the requirements of Table 6 at this temperature. After returning to normal temperature, it shall meet the requirements of 4.6.2.1.
4.6.7 Low temperature storage
The sample shall be stored at -25±3℃ for 96h and shall meet the requirements of 4.6.2 after 1h recovery. 4.6.8 Temperature Cycle
The sample shall be able to withstand the temperature change test specified in Figure 1, for a total of 10 cycles. After the test, the sample shall comply with the provisions of Article 4.6.2.1. U
First statement
4.6.9 Frequency Sweep Vibration
Temperature Cycle Diagram
The sample shall be able to withstand the vibration test specified in Table 8. After the test, the sample shall comply with the provisions of Article 4.6.2.1. Table 8
Frequency range
7~30～7
30~55~30
4.6.10 Impact
Displacement amplitude
Number of sweep cycles on each axis
The sample shall vibrate in sequence on
three mutually perpendicular axes
according to the working position
The sample shall be able to withstand a collision test with a pulse peak acceleration of 100m/s2, a pulse duration of 16ms, a pulse repetition frequency of 40~80 times/min, a collision number of 1000±10 times, and a pulse waveform similar to a half-sine wave. After the test, the sample shall comply with the provisions of 4.6.2.1. 4.6.11 Free fall
Packaged samples with a mass not exceeding 100kg shall have the same packaging as the transportation packaging in the circulation process (the packaging shall be a parallelepiped shape), and the sample shall be subjected to a drop test in accordance with the provisions of Table 9. After the test, the sample should meet the requirements of 4.6.2. 7
Sample weight
≥10~20
≥20～30
≥30~40
≥40~50
4.6.12 Knock
Drop height
Face drop
GB/T15523—1995
Corner and edge drop
Drop surface
The figure shows the normal working position of the sample, which falls downward in the order of
3-2-5-4-6
(2 means the front and top surface will not fall)
Drop height||tt ||Drop edge
Drop edge is
Drop angle
Three edges
Drop angle
Drop angle is
Any
Number of drops
on the front
of the sample below
Once each
When the RF modulator is struck, the connected TV will be deemed unqualified if its synchronization is destroyed, the picture quality is reduced, or the color bar is abnormal. However, a small amount of white or black lines on the screen of the connected TV is allowed. When the connected TV is struck, no white or black lines are allowed on the screen. 4.7 Reliability requirements
Quantitative reliability requirements The lower limit value Q1 of the mean time between failures (MTBF) should be greater than or equal to 50,000 h. 5 Test methods
5.1 Test conditions
General test conditions
Temperature: 5~30℃;
Relative humidity: 45%~85%;
Atmospheric pressure: 86~106kPa.
Preset of modulation output channel: high channel for dual channels; middle channel for multi channels.
b. Arbitration test conditions
Temperature: 25±3℃;
Relative humidity: 60%±70%;
Atmospheric pressure: 86~106kPa.
Preset of modulation output channel: high channel for dual channels; middle channel for multi channels.
5.2 Structure and appearance inspection
Inspect by visual inspection and feel method. Under normal illumination, the visual distance is about 30cm. 5.3 Performance test method
5.3.1 Video characteristics
5.3.1.1 Video input impedance
The test block diagram is shown in Figure 2.
GB/T15523—1995
The RF modulator under test is placed in the modulation state, and the video input terminal is fed with the 100/0/75/0 color bar signal specified in Appendix A (Supplement) of GB3174, as shown in Figure 3. The unused terminal is terminated with a rated load resistor, and the signal amplitude at the video input terminal is measured with an oscilloscope. Then switch K is switched to the variable resistor terminal, and the resistance value of R1 is changed so that the signal amplitude measured by the oscilloscope is the same as the amplitude before switch K is switched. The resistance value of R1 is the video input impedance of the RF modulator, expressed in ohms. Note: When the signal amplitude cannot be measured accurately, the brightness step wave signal amplitude shall prevail. 5.3.1.2 Video signal input level The test block diagram is shown in Figure 4. The RF modulator under test is placed in the modulation state, and the color bar signal shown in Figure 3 is sent to the video input terminal. The RF output is connected to the modulation index tester, and the unused terminals are terminated with the rated load resistor. When the modulation index meets the technical requirements, the signal amplitude at the video input terminal of the RF modulator is measured with an oscilloscope, expressed in V (peak-to-peak value).
5.3.1.3 Video modulation
Standardized number of instruments
GB/T15523—1995
Figure 4 Video signal input level test block diagram The test block diagram is shown in Figure 5.
Assume that the RF modulator under test is in the modulation state, and the video input terminal is sent to a step wave signal with an average picture level (APL) of 50%, as shown in Figure 6(a). The RF output is sent to the modulation tester, and the unused terminal is terminated with a rated load resistor. The modulation of the amplitude modulated wave output by the RF modulator is measured with the modulation tester and expressed in percentage. Figure 5 Video modulation test block diagram (average 2% Figure 6 Step wave signal 5.3.1.4 White peak cutting The test block diagram is shown in Figure 5. The RF modulator under test is placed in the modulation state, and a step wave signal with an amplitude of 1.5V (peak-to-peak value) is sent to the video input terminal, as shown in Figure 6 (a) 10 GB/T15523-1995, and the RF output is sent to the modulation tester, and the unused terminal is terminated with a rated load resistor. The modulation of the amplitude modulated wave output by the RF modulator is measured with the modulation tester and expressed in percentage. 5.3.1. 5 The image signal and synchronization signal amplitude ratio test block diagram is shown in Figure 7.
The RF modulator under test is placed in the modulation state, and the video input terminal is fed with the step wave signal shown in Figure 6(a). The RF output is sent to the standard demodulator for demodulation, and the unused terminals are terminated with the rated load resistor. The ratio of the demodulated video image signal level to the synchronization level is measured with an oscilloscope. 5.3.1.6 The video amplitude-frequency characteristic
test block diagram is shown in Figure 7.
The RF modulator under test is placed in the modulation state, and the video input terminal is fed with the sweep frequency signal shown in Figure 8. Fixed frequency markers are 0.5, 1, 2, 3, 3.5, 3. 95, 4.43, 4.93, 5.5, 6, 7MHz. The RF output is sent to a standard demodulator for demodulation, and the unused terminals are terminated with a rated load resistor. Use an oscilloscope to measure the amplitude of each frequency point of the demodulated video sweep signal. Take the output level at 1MHz as 0dB, and measure the level difference with each frequency point from 0.5MHz to 6MHz, expressed in dB. mt
Video sweep signal
5.3.1.7The test block diagram of the effect of APL change on modulation is shown in Figure 5.
The RF modulator under test is placed in the modulation state, and a step wave signal with an average image level of 12.5% to 87.5% is sent to the video input terminal, as shown in Figure 6. The RF output is sent to the modulation tester, and the unused terminals are terminated with a rated load resistor. The rated load resistance is terminated with the terminal. The modulation change of the amplitude modulated wave output by the RF modulator is measured with a modulation tester, expressed as a percentage, with APL=50% as the benchmark. 5.3.1.8 The differential gain
test block diagram is shown in Figure 9. The RF modulator under test is placed in the modulation state, and the video input terminal is fed with a step wave signal superimposed with a color subcarrier as shown in Figure 10. The RF output is sent to a standard demodulator for demodulation, and the rated load resistance is not terminated with the terminal. The gain change of the color load wave of the demodulated video signal is measured with a DG/DP tester, expressed as a percentage. The differential gain of the color video signal after demodulation output can also be measured with a vector oscilloscope. In case of dispute, the DG/DP tester shall prevail.1 Video input impedance
Test block diagram is shown in Figure 2.
GB/T15523—1995
The RF modulator under test is placed in the modulation state, and the 100/0/75/0 color bar signal specified in Appendix A (Supplement) of GB3174 is sent to the video input terminal, as shown in Figure 3. The rated load resistance is not terminated at the terminal, and the signal amplitude at the video input terminal is measured with an oscilloscope. Then switch K to the variable resistor terminal, change the resistance value of R1 so that the signal amplitude measured by the oscilloscope is the same as the amplitude before switch K is switched, and the resistance value of R1 is the video input impedance of the RF modulator, expressed in ohms. Note: When the signal amplitude cannot be measured accurately, the brightness step wave signal amplitude shall prevail. 5.3.1.2 Video signal input level The test block diagram is shown in Figure 4. The RF modulator under test is placed in the modulation state, and the color bar signal shown in Figure 3 is sent to the video input terminal. The RF output is connected to the modulation index tester, and the unused terminals are terminated with the rated load resistor. When the modulation index meets the technical requirements, the signal amplitude at the video input terminal of the RF modulator is measured with an oscilloscope, expressed in V (peak-to-peak value).
5.3.1.3 Video modulation
Standardized number of instruments
GB/T15523—1995
Figure 4 Video signal input level test block diagram The test block diagram is shown in Figure 5.
Assume that the RF modulator under test is in the modulation state, and the video input terminal is sent to a step wave signal with an average picture level (APL) of 50%, as shown in Figure 6(a). The RF output is sent to the modulation tester, and the unused terminal is terminated with a rated load resistor. The modulation of the amplitude modulated wave output by the RF modulator is measured with the modulation tester and expressed in percentage. Figure 5 Video modulation test block diagram (average 2% Figure 6 Step wave signal 5.3.1.4 White peak cutting The test block diagram is shown in Figure 5. The RF modulator under test is placed in the modulation state, and a step wave signal with an amplitude of 1.5V (peak-to-peak value) is sent to the video input terminal, as shown in Figure 6 (a) 10 GB/T15523-1995, and the RF output is sent to the modulation tester, and the unused terminal is terminated with a rated load resistor. The modulation of the amplitude modulated wave output by the RF modulator is measured with the modulation tester and expressed in percentage. 5.3.1. 5 The image signal and synchronization signal amplitude ratio test block diagram is shown in Figure 7.
The RF modulator under test is placed in the modulation state, and the video input terminal is fed with the step wave signal shown in Figure 6(a). The RF output is sent to the standard demodulator for demodulation, and the unused terminals are terminated with the rated load resistor. The ratio of the demodulated video image signal level to the synchronization level is measured with an oscilloscope. 5.3.1.6 The video amplitude-frequency characteristic
test block diagram is shown in Figure 7.
The RF modulator under test is placed in the modulation state, and the video input terminal is fed with the sweep frequency signal shown in Figure 8. Fixed frequency markers are 0.5, 1, 2, 3, 3.5, 3. 95, 4.43, 4.93, 5.5, 6, 7MHz. The RF output is sent to a standard demodulator for demodulation, and the unused terminals are terminated with a rated load resistor. Use an oscilloscope to measure the amplitude of each frequency point of the demodulated video sweep signal. Take the output level at 1MHz as 0dB, and measure the level difference with each frequency point from 0.5MHz to 6MHz, expressed in dB. mt
Video sweep signal
5.3.1.7The test block diagram of the effect of APL change on modulation is shown in Figure 5.
The RF modulator under test is placed in the modulation state, and a step wave signal with an average image level of 12.5% to 87.5% is sent to the video input terminal, as shown in Figure 6. The RF output is sent to the modulation tester, and the unused terminals are terminated with a rated load resistor. The rated load resistance is terminated with the terminal. The modulation change of the amplitude modulated wave output by the RF modulator is measured with a modulation tester, expressed as a percentage, with APL=50% as the benchmark. 5.3.1.8 The differential gain
test block diagram is shown in Figure 9. The RF modulator under test is placed in the modulation state, and the video input terminal is fed with a step wave signal superimposed with a color subcarrier as shown in Figure 10. The RF output is sent to a standard demodulator for demodulation, and the rated load resistance is not terminated with the terminal. The gain change of the color load wave of the demodulated video signal is measured with a DG/DP tester, expressed as a percentage. The differential gain of the color video signal after demodulation output can also be measured with a vector oscilloscope. In case of dispute, the DG/DP tester shall prevail.1 Video input impedance
Test block diagram is shown in Figure 2.
GB/T15523—1995
The RF modulator under test is placed in the modulation state, and the 100/0/75/0 color bar signal specified in Appendix A (Supplement) of GB3174 is sent to the video input terminal, as shown in Figure 3. The rated load resistance is not terminated at the terminal, and the signal amplitude at the video input terminal is measured with an oscilloscope. Then switch K to the variable resistor terminal, change the resistance value of R1 so that the signal amplitude measured by the oscilloscope is the same as the amplitude before switch K is switched, and the resistance value of R1 is the video input impedance of the RF modulator, expressed in ohms. Note: When the signal amplitude cannot be measured accurately, the brightness step wave signal amplitude shall prevail. 5.3.1.2 Video signal input level The test block diagram is shown in Figure 4. The RF modulator under test is placed in the modulation state, and the color bar signal shown in Figure 3 is sent to the video input terminal. The RF output is connected to the modulation index tester, and the unused terminals are terminated with the rated load resistor. When the modulation index meets the technical requirements, the signal amplitude at the video input terminal of the RF modulator is measured with an oscilloscope, expressed in V (peak-to-peak value).
5.3.1.3 Video modulation
Standardized number of instruments
GB/T15523—1995
Figure 4 Video signal input level test block diagram The test block diagram is shown in Figure 5.
Assume that the RF modulator under test is in the modulation state, and the video input terminal is sent to a step wave signal with an average picture level (APL) of 50%, as shown in Figure 6(a). The RF output is sent to the modulation tester, and the unused terminal is terminated with a rated load resistor. The modulation of the amplitude modulated wave output by the RF modulator is measured with the modulation tester and expressed in percentage. Figure 5 Video modulation test block diagram (average 2% Figure 6 Step wave signal 5.3.1.4 White peak cutting The test block diagram is shown in Figure 5. The RF modulator under test is placed in the modulation state, and a step wave signal with an amplitude of 1.5V (peak-to-peak value) is sent to the video input terminal, as shown in Figure 6 (a) 10 GB/T15523-1995, and the RF output is sent to the modulation tester, and the unused terminal is terminated with a rated load resistor. The modulation of the amplitude modulated wave output by the RF modulator is measured with the modulation tester and expressed in percentage. 5.3.1. 5 The image signal and synchronization signal amplitude ratio test block diagram is shown in Figure 7.
The RF modulator under test is placed in the modulation state, and the video input terminal is fed with the step wave signal shown in Figure 6(a). The RF output is sent to the standard demodulator for demodulation, and the unused terminals are terminated with the rated load resistor. The ratio of the demodulated video image signal level to the synchronization level is measured with an oscilloscope. 5.3.1.6 The video amplitude-frequency characteristic
test block diagram is shown in Figure 7.
The RF modulator under test is placed in the modulation state, and the video input terminal is fed with the sweep frequency signal shown in Figure 8. Fixed frequency markers are 0.5, 1, 2, 3, 3.5, 3. 95, 4.43, 4.93, 5.5, 6, 7MHz. The RF output is sent to a standard demodulator for demodulation, and the unused terminals are terminated with a rated load resistor. Use an oscilloscope to measure the amplitude of each frequency point of the demodulated video sweep signal. Take the output level at 1MHz as 0dB, and measure the level difference with each frequency point from 0.5MHz to 6MHz, expressed in dB. mt
Video sweep signal
5.3.1.7The test block diagram of the effect of APL change on modulation is shown in Figure 5.
The RF modulator under test is placed in the modulation state, and a step wave signal with an average image level of 12.5% to 87.5% is sent to the video input terminal, as shown in Figure 6. The RF output is sent to the modulation tester, and the unused terminals are terminated with a rated load resistor. The rated load resistance is terminated with the terminal. The modulation change of the amplitude modulated wave output by the RF modulator is measured with a modulation tester, expressed as a percentage, with APL=50% as the benchmark. 5.3.1.8 The differential gain
test block diagram is shown in Figure 9. The RF modulator under test is placed in the modulation state, and the video input terminal is fed with a step wave signal superimposed with a color subcarrier as shown in Figure 10. The RF output is sent to a standard demodulator for demodulation, and the rated load resistance is not terminated with the terminal. The gain change of the color load wave of the demodulated video signal is measured with a DG/DP tester, expressed as a percentage. The differential gain of the color video signal after demodulation output can also be measured with a vector oscilloscope. In case of dispute, the DG/DP tester shall prevail.5% step wave signal, as shown in Figure 6. The RF output is sent to the modulation index tester, and the unused terminals are terminated with the rated load resistor. The modulation index tester is used to measure the modulation index change of the amplitude modulation wave output by the RF modulator, expressed as a percentage, with APL=50% as the benchmark. 5.3.1.8 The differential gain
test block diagram is shown in Figure 9.
The RF modulator under test is placed in the modulation state, and the video input terminal is sent to the step wave signal superimposed with the color subcarrier as shown in Figure 10. The RF output is sent to the standard demodulator for demodulation, and the unused terminals are terminated with the rated load resistor. The DG/DP tester is used to measure the gain change of the color load wave of the demodulated video signal, expressed as a percentage. The differential gain of the color video signal after demodulation output can also be measured with a vector oscilloscope. When there is a dispute, the DG/DP tester shall prevail.5% step wave signal, as shown in Figure 6. The RF output is sent to the modulation index tester, and the unused terminals are terminated with the rated load resistor. The modulation index tester is used to measure the modulation index change of the amplitude modulation wave output by the RF modulator, expressed as a percentage, with APL=50% as the benchmark. 5.3.1.8 The differential gain
test block diagram is shown in Figure 9.
The RF modulator under test is placed in the modulation state, and the video input terminal is sent to the step wave signal superimposed with the color subcarrier as shown in Figure 10. The RF output is sent to the standard demodulator for demodulation, and the unused terminals are terminated with the rated load resistor. The DG/DP tester is used to measure the gain change of the color load wave of the demodulated video signal, expressed as a percentage. The differential gain of the color video signal after demodulation output can also be measured with a vector oscilloscope. When there is a dispute, the DG/DP tester shall prevail.
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