Speechless! There will be a noise bump in the spectrum when there is no signal input at low frequency. Can you experts see what's going on?

秋天的琴湖

Speechless! There will be a noise bump in the spectrum when there is no signal input at low frequency. Can you experts see what's going on? [Copy link]

This thing will definitely raise my noise floor and worsen my noise factor. I don’t know what’s going on? Please help! !

chunyang

It may come from the oscillation circuit within the system, such as the conduction of a clock.

秋天的琴湖

chunyang published on 2020-8-25 15:46 It may come from the oscillation circuit in the system, such as the conduction of the clock.

The crystal oscillator of my microcontroller is 25MHz, so it can never reach more than 80MHz.

chunyang

Qinhu in Autumn published on 2020-9-1 14:22 The crystal oscillator of my microcontroller is 25MHz, and it can never reach more than 80MHz.

Then change the system clock frequency significantly and test again, and compare the results. If it is external interference, you should be able to observe the same background noise spectrum without powering on your system.

btty038

This is not the device's own interference, but the device acting as an antenna to receive

秋天的琴湖

This is caused by radiation interference on the power cord of my amplifier. It can be fixed by rewiring the wires and adding a filtering magnetic ring.

秋天的琴湖

Qinhu in Autumn published on 2020-11-15 11:01 This is caused by the radiation interference of the power cord of my amplifier. It can be fixed by rewiring and adding a filtering magnetic ring.

I need to learn more about electromagnetic compatibility. This has been bothering me for a long time.