Ningbo Qiaopu Electric Co.LTD AC power line test steps

1 Ningbo qiaopu Electric Co.,LTD color camera video signal can be used as " standard video source " : test engineering with the camera video output , the magnitude of the 75 ohm load should be 1Vp-p, sync that line the bottom of the head to the video signal highest white level " peak - " ; note line sync rate is "-0.3V", the burst head (4.43M sine pulse ) amplitude 0.3Vp-p; selected oscilloscope sensitivity magnitude hit calibration status . Selected indicators measure a better camera as a " video source " ;
2 Ningbo qiaopu Electric Co.,LTD try to test the AC power cord take a little longer, to reduce measurement error, such as 1000 meters , in the middle AC power cord connector must use "F -connector " and coaxial two-way ( cable television equipment ) , do not by welding , because the welding destroys the coaxial line and the characteristic impedance of the AC power continuity .
3 Ningbo qiaopu Electric Co.,LTD measure the DC resistance data AC power cord : the power cord as SYV75-5AC 1000 meters , the DC resistance of 35-40 ohm wire , outer shield resistance of 1000 meters is 24-36 ohms ( shield compiled several different , very different resistance ); SYWV75-5AC power lines 1000 meters , the DC resistance wire is 18-22 ohms, the outer shield is 24-36 ohm resistor 1000 m ; accumulation of this information is useful, not only AC power cord to determine the quality of the timber , and is used for wiring works , wear tube quality checks as attendants wearing tube , pull off the line , the resistance becomes larger, the video signal is weak , interference should not occur , there have been such " accidents " the probability is very high, but is often overlooked ;
4 Ningbo qiaopu Electric Co.,LTD AC power cord measuring high frequency attenuation characteristics : measure at the end of the line head head head and burst amplitude to 0.3V to 0db basis to calculate the attenuation amount Butou line with the representatives of the low-frequency attenuation , color synchronization head behalf 4.43M frequency attenuation , - eg : measured 1000 meters of sync head as 0.15V, db attenuation calculated according to the number of multiples 20log as "-6db/1000m", measured 4.43M burst head 1000 m attenuation after the magnitude is 30mv, or 1/ 10 times attenuation -20db/1000m; using this method can accurately grasp the different transmission quality AC power cord , and on the " frequency distortion ( difference between high and low frequency attenuation ) " With intuitive the concept that you can compare accurately measure the power cord SYV and SYWVAC differences and performance quality and structure of the same model , compare the difference between products from different manufacturers and performance is good or bad , you can compare different batches of the same product manufacturers changes to ;
5 The above method can also detect the performance of video transmission systems and equipment : If the transmission characteristics of each channel coaxial video AC power cord , Optical transmission characteristics of the project (which can be measured or bad, do not think are so good ) , the RF transmission microwave transmission characteristics of the transmission characteristics of the twisted pair , the distribution characteristics of video distributor , the switching characteristics of the host matrix , should pay special attention when multiple outputs simultaneously switch the same input signal, if found , the more the greater the attenuation switch ones , not a right , it should be the same, you will master the test after a lot of substandard products ;