Anything which depends on high amplification of an analog signal has potential interference problems.  You need a physical phenomenon which produces discrete events, or good shielding.  It&#x27;s not hard to shield against RF and magnetic interference, but it takes some metal and size, which can be a problem for a USB connector sized device.  You also have to filter the power going into the shielded area.<p>It&#x27;s useful to take the output of the noise generator and run it into a spectrum analyzer while using electric motors and walkie-talkies close to the device.  If the noise spectrum change shape when you do that, it&#x27;s not random.