Funny anecdote. Back in 1999 or so, I noticed by happenstance that when I had the cover of my PC off during a HDD defrag (yeah, that was a Windows thing back then), that I could easily pick up the noise from the bus at exactly 100Mhz on a radio I had in the room. At first I suspected I was bugged, because the HDD made noise in the same rhythmic pattern as that data being transferred across the bus, which was creating the EM noise. Can you imagine tuning your radio and coming across the ambient sounds in your room? Kinda terrifying.
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.
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Funny anecdote. Back in 1999 or so, I noticed by happenstance that when I had the cover of my PC off during a HDD defrag (yeah, that was a Windows thing back then), that I could easily pick up the noise from the bus at exactly 100Mhz on a radio I had in the room. At first I suspected I was bugged, because the HDD made noise in the same rhythmic pattern as that data being transferred across the bus, which was creating the EM noise. Can you imagine tuning your radio and coming across the ambient sounds in your room? Kinda terrifying.
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.