RTL SDR lets you mess about like this. I was able to figure out what was causing my wifi to be awful - an old wired Linksys was putting out hash and the cables

RTL SDR lets you mess about like this. I was able to figure out what was causing my wifi to be awful - an old wired Linksys was putting out hash and the cables attached were really long antennas, increasing the noise floor. I also discovered that one of my ham radios leaked RF when my computer's keyboard started randomly hitting buttons, including windows key plus other buttons. The stock RTL device only goes to 30mhz or so, and up to about 2ghz, so any older/low power computers will spray hash all over that bandwidth. Spread spectrum on the fsb or whatever actually reduces the noise floor as the noise is distributed across a wider bandwidth, necessarily reducing the perceived power.