The scope is DSOZ594A. I measured the noise floor of 4 ports at 100mV/div, 200mV/div and 500mV/div,
and the noise floor of port3 is "significantly" lower then others at 200mV/div, is that a problem?
Vrms of port1~4:
100mV/div: 4.3mV 4.5mV 4.2mV 4.4mV
200mV/div: 10.5mV 10.7mV 8.2mV 10.8mV
500mV/div: 22.2mV 23.0mV 21.5mV 22.7mV