Living on the East Coast means my radio-controlled atomic wall clock is completely deaf to the atomic (WWVB) signal from Colorado.
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Living on the East Coast means my radio-controlled atomic wall clock is completely deaf to the atomic (WWVB) signal from Colorado. In the attached video, I am using my smartphone to force the clock to sync to exact Internet time via a clever hardware hack. 1/4
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Standard smartphones cannot broadcast a 60 kHz radio wave. But if you play a 20 kHz square wave at max volume, the physical distortion in the analog amplifier generates a 60 kHz harmonic. The speaker's voice coil acts as a localized magnetic transmitter. 2/4
The clock's internal ferrite rod antenna is deaf to the loud 20 kHz audio but perfectly resonates with the faint 60 kHz magnetic pulse. Because it relies on near-field magnetic induction, the phone must be very close the clock to overcome the rapid cubic signal drop-off. 3/4
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The clock's internal ferrite rod antenna is deaf to the loud 20 kHz audio but perfectly resonates with the faint 60 kHz magnetic pulse. Because it relies on near-field magnetic induction, the phone must be very close the clock to overcome the rapid cubic signal drop-off. 3/4
I wrote a deep dive into the physics of this hack, the challenges of low-frequency radio propagation, and how our methods of measuring time have evolved from maritime sand-glasses to digital synchronization. Read the full post here: https://josephhall.org/blog/texture-of-time-wwvb/
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Living on the East Coast means my radio-controlled atomic wall clock is completely deaf to the atomic (WWVB) signal from Colorado. In the attached video, I am using my smartphone to force the clock to sync to exact Internet time via a clever hardware hack. 1/4
Standard smartphones cannot broadcast a 60 kHz radio wave. But if you play a 20 kHz square wave at max volume, the physical distortion in the analog amplifier generates a 60 kHz harmonic. The speaker's voice coil acts as a localized magnetic transmitter. 2/4
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I wrote a deep dive into the physics of this hack, the challenges of low-frequency radio propagation, and how our methods of measuring time have evolved from maritime sand-glasses to digital synchronization. Read the full post here: https://josephhall.org/blog/texture-of-time-wwvb/
@joebeone Cool hack!
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R relay@relay.infosec.exchange shared this topic
