Hi tv84,
thanks for the information. It is a lot of information. I didn't managed to restore the firmware yet. I downloaded another firmware from Rigol and now the model is "DS1104Z" and software version is "04.06.01". This one the wave noise is back to normal so I think I can use this firmware for some time.
Hi Fungus,
I didn't mean to update the old ds1000z scope to a ds1000z-e scope.(e means enchanced?). I was using the UART decoder function, and it lags. I didn't check the firmware updates since I bought it and entered the option code a few year ago. so I hope rigol has made a better firmware. and then I "accidently" updated the wrong firmware.