Noise on scope due to laptop.

[Mattjd]

So today in the lab I was at a work station, had a scope, generator, power supply on and in use, they were all plugged into the same surge protector. Additionally, my laptop was plugged into that same surge protector. My laptop (a macbook pro) was using the power supply that didnt have a ground plug (there are two types), there was a lot of noise on the scope, and when I unplugged the laptop it went away. Why?

[Sylvi]

Hi

Laptops like cell phones have practically no shielding, which is why you should not have either one near your body. In both cases, all the emitted noise is microwave energy which is bad for you. There are a range of frequencies that intermodulate each other making a broad spectrum of noise that extends downward to frequencies your scope can easily see and that other equipment can pick up.

You might also want to check if the wireless is turned on in the lap top. We bought a printer that was connected via USB but every time it was sent a print job it was trying to find a wireless connection. We had to go into the printer's menu to turn the wireless off. We have nothing wireless - no cell phones, no cordless phones, no cloud-printers, no wireless LAN. Everything is wired. Pretty much all wireless stuff and every CPU clock is in the microwave range. Desk top computers generally have better shielding. Your DSO has a computer, too, but it is a piece of industrial equipment with a designed longer life than the lap top, so it has proper shielding.