Transmitting longwave radio signals from wired headphones
summary
Replicates regional longwave time broadcasts using a laptop or phone and wired headphones by driving the headphone driver at 20 kHz (or other audio fundamental) so the third harmonic radiates near 40–60 kHz; encodes time as amplitude-duration pulses similar to Morse at about one bit per second; demonstrated working with a C program on GitHub (GPL) that outputs sine waves tied to the host clock (best with GNSS-synced time) and can set WWVB/DCF77-style radio clocks when placed inches from the driver.
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chapters (12)
- 0:00Introduction
- 0:21Longwave time signals matter
- 2:11Longwave time transmission history
- 3:56Longwave vs GNSS signals
- 4:39Headphones transmit longwave
- 6:04Software implementation
- 7:32Other applications and tools
- 7:52Live longwave demo
- 8:57Alternative time distribution
- 10:01Q&A
- 11:53Consumer devices transmit longwave
- 13:18Licensing and legal
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