Hi VLF,
I've now configured and installed a 10 EUR cheap NEO-6M GPS module on
the tree. It consumes about 45 mA at 3.3V, i.e. abt 0.15W. This can be
accepted and i can switch it off remotely if not needed. The module
feeds 1 pps + NMEA into the right soundcard channel of my stereo
soundcard (one of two) which is running on the Raspi Pi 2B. Some
images:
https://www.dropbox.com/sh/sge3dbp4yp7du5s/AACRxEHRQQiODt0fb2y8E8-Ya?dl=0
The sound data is streamed to the PC(s) in the shack where the 1 pps to
NMEA is read by SpecLab to compensate the soundcard drift and eventual
phase glitches.
The Alpha trace at
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
has no glitches any more, except the original one at 21UTC.
However there seems to be some phase jitter. Unfortunately the config
data of the module was not saved but i assume that in unintentionally
short cut the backup battery while carrying the module to the tree in a
plastic bag containing other electronic parts. Now the NMEA data
collidates with 1 pps (again). I will soon re-configure the module and
hope the jitter is gone then.
Does someone ever played with SpecLab and NMEA and know the jitter
effect and its reasons?
But, now i'm running a 47 uHz, 'DFCW-60000' instance and another one
generating txt files for an eventual decode of DJ8WX' VLF EbNaut
transmission tomorrow morning. The VLF RX loop is pointing into his
direction!
Ah, yes, and, there is some QRM in the wideband spectrum during sunny
afternoons. This is my solar charger which was still re-designed to
regulate (clipping) the voltage depending on the temperature. The VLF
loop is just in 3m distance to that regulator and cables. I will
further improve...
Now let's hope for Uwe :-)
73, Stefan
Am 10.04.2016 22:30, schrieb [email protected]:
the carrier
is on the air.
the message:
start
2016-04-11 07:00:00
coding 8K19A
CRC 16
period 30
length 3
duration 03:28:00:00
Have fun
Uwe/dj8wx
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