When measuring the transmission disturbance of the off-board signal line，that will find two large noise signals at two specific frequencies (one is 659K and the other is 1.977K), After preliminary analysis,that was cause by Switch power chip on board, How to use oscilloscope to measure such noise signal
There are several main factors that oscilloscopes can test for noise signals
The amplitude of the measured signal, Is it small signal.the osciloscope probe cab be test uA signal.
The frequency of the measured signal.
If use wrong connect method regardingprobe,that will cuase noise,also effect test result,