General > General Technical Chat
Spooky Wireless Reception of EEVBlog
srruhl3701:
Hi all,
I recently discovered EEVBlog. I've been binging on the playlist. Today I received a cheap TecSun AM/FM/SW radio. As expected, there is a lot of noise when sitting by my laptop watching Dave.
I looked up a program guide and found the Beeb was broadcasting on 12.95 MHz. The last scale marking on that band is 12.05. I cranked to the stop and got reception. The voice sounded more Aussie than Brit. Then I tuned better and it was Dave. I knew he was expanding everywhere, but SW?
I turned down the radio and realized it was in sync with Dave's Rev C power supply video which I was rewatching. It's getting spooky now. I turned the dial and found Dave again somewhere around 11 MHz too. I turned the radio off then.
It's a basic Dell laptop of 2011 vintage, with WiFi. I have external speakers, but they are not wireless. The audio comes from the Line Out jack. They use USB just for power.
The spooky wireless audio happens at a few feet from the laptop. From the multiple receptions, I figure it must be an image frequency thing, but where is it coming from. I guess I just grab the scope and take a look for RF on the audio out and uSB.
Brumby:
Dave ..... are you experimenting with something we don't know about? ;)
aargee:
It has to be this...
https://www.amazon.com/Spirit-Ghost-Hunting-Equipment-Radio/dp/B00NABGFSM/ref=sr_1_1?dchild=1&keywords=Spirit+Box&qid=1593661640&sr=8-1
:-DD
james_s:
It's probably harmonics of the class D audio amplifier, or the switching regulator that powers the audio IC.
A few years ago I was playing with a chiptunes player on one of my FPGA boards and found that an AM radio could pick up the music from several feet away.
srruhl3701:
Thanks, that has to be it. The amp has to be in the in line volume control. There's not much room in there for anything but Class D.
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