[time-nuts] VLF time is not dead :-)
phk at phk.freebsd.dk
Mon Oct 18 10:26:09 EDT 2004
I found some time to play with my Software Defined Radio VLF receiver
again and have done a little bit of tracking of VLF carrier frequencies:
The Y-axis is seconds, the X-axis are seconds.
It's a bit hard to see the legend, so:
Red: RBU 66.666 kHz
Green: DR LW broadcasting 243 kHz
(20 miles away, Rb reference not calibrated)
Blue: DCF77 77.5 kHz.
Purple: MSF 60.0k kHz (from the UK, not the US transmitter!)
Cyan: HBG 75.0 kHz
The receiver is homegrown: A loop antenna, an amplifier and an A/D
card in a computer. The program generates a reference sine/cosine
frequency for the carrier mixes with the a/d samples and averages
over a second. Sample-rate is 1MHz, 12 bits. CPU is 560MHz P3.
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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