Great, i'm now recording my own VLF stream from the tree to a HDD here
in the city. The stream is resampled to 24 kS/s and i just need to
record one channel.
My 1 PPS pulse is just 20 ms long and there are additional NMEA data
signals on the channel but it seems to work anyway. I just get
occasianal messages from vttime, like
vttime: unreliable PPS interval 47999.959405 - skipped
vttime: wild PPS pulse interval 32425.608608 - skipped
vttime: invalid phase slope - skipped
Such a message appears once in 10 minutes maybe, quite acceptable.
So far, after > 2 hours the stream did not interrupt.
From my post-processing of the 970 Hz 40.5 km experiment i learned a
lot, so i was able just to write down the full command line to produce a
spectrum plot of my still running 1570.01 Hz carrier in 3.5 km distance,
attached.
It looks like the sample rate is actually corrected.
I'm going to try to analyse Joe's carrier in a few days, when some data
is collected.
73, Stefan
Am 06.05.2018 06:21, schrieb Paul Nicholson:
A new version 0.9b of vlfrx-tools is available at
http://abelian.org/vlfrx-tools/
This version has some significant improvements -
- vttime now has options to use a short or long rectangular
GPS pulse-per-second, with timing methods -m pulse for
short (circa 10uS pulses) and -m edge for long (100mS)
pulses.
carrier_spectrum_peak.png
Description: PNG image
|
