Hi all,
Time is running! My remote tree grabber is now on the air since 1 year.
It has started with a single channel MF receiver (loop antenna).
Meanwhile it has grown to a RDF grabber with two loops on MF and and VLF
grabber with one loop and precise PPS+MNEA timing. So there are two
stereo vorbis streams running. I estimate the availability has been
about 95% during that year. The system is exclusively solar powered and
uses 3x 18 Ah lead gel batteries.
Several 1000 WSPR decodes have been made from that system on MF. A few
EbNaut decodes were made on VLF, as well as spectrograms.
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_remote_Grabber.html
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
Whos know what will be in one year but i am optimistic to run it for
another year and maybe i can add some more stuff there...
73, Stefan
Am 16.12.2015 01:03, schrieb DK7FC:
Hi all,
Finally my new remote forest grabber, version 2.0, is now active in
JN49ik36! There, in a radius of 1000m, there is no electricity. The
new version uses the new Raspberry Pi 2 which performs much better.
The overall power consumption of the system is below 3W. The stereo RF
stream is stable and the CPU load is just about 22%. There are 3 lead
acid gel accus, 18 Ah each.
In the last weeks i finished the last important steps.
-Installed the (first) 50W solar module in an angle of 60 deg (winter
optimised)
-Installed the accu charger circuit which has a variable voltage
limiting depending on the accu temperature (PTC sensores installed)
-Put the stereo MF DC converter into the box
-Painted the WLAN yagi in military green, camouflage-antenne :-)
-Installed scripts to track the battery voltage, WLAN link level and
CPU temperature
- Updated the grabbers website,
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_remote_Grabber.html
So far, there is only one antenna on the tree. A loop for 630m,
beaming NW/SE. Seems to work well from what i saw so far. However
there is still QRM coming from the far field. Some QRM traces are
visible on the DL3ZID grabber in > 500 km distance. Maybe there is
some noise from the DC/DC converter, not sure. Will check that later.
You can't imagine the feeling beeing up on the tree there. Its just
peace and freedom! Worth all the "effort".
Some images at
https://www.dropbox.com/sh/iogg0azyaezrg0y/AADJGvxaq4OEJuNYZ2YyfP_Ca?dl=0
(beeing not happy with seafile as an alternative for dropbox. Will try
owncloud soon)
Next steps are:
-Building a second loop, orthogonal, for MF.
-Building an active antenna for LF/MF. A power saving model, running
at 5V/1mA!
-Starting with first steps for 2200m!
-Installing a web-cam.
-Further crazy ideas...
73, Stefan
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