Hi Terry,
Am 08.08.2017 09:08, schrieb Terry G0EZY:
I see from ntpq - p that you left the on-line ntp servers
operational, in addition to your gps
Yes. Sometimes i want the GPS module to set the time because i have no
internet access (portable) and sometimes vice versa.
(I understood Paul's email to disable external ntp by removing
these lines as part of the ntp.conf modification)
I don't think it is problematic to leave a few servers in the file. The
GPS server entry has a 'prefer' added, so i think this server will be
preferred when many are available. It is not critical...
In your photo of the complete assembly, it is interesting
to see your modifications. I can see clearly the gps interface
connected to the RaPi gpio pins extended through the Octo board.
Yes, the simplest and compactest and energy savingst way to go i bet.
It looks as though you have made your own interface plug
for the input of the Octo and using only Ch1, Ch2 with Ch3 as PPS?.
Correct. I wanted to get rid of the ribbon cable and use RG174 instead,
as well as BNC connectors, for RF, not for AF!
The ribbon cable can't be a good choice when thinking about EMC and/or
cross talk...
What are the two vertical boards on the left? the smaller one
looks like (but not exactly) the DC/DC inverter.
Sounds like your inverter order has not been delivered yet :-) These
two boards are the DC/DC converter, vertically mounted.
Also a direct power connection to the RaPi, as you are not using
the microUSB power connector.
Yes, i just soldered two cables on the bottom of the board. No
mechanical instabilities. It is one unit.
BTW my 64 GB stick arrived, now i can record 2 channels for 4 days or 3
channels for a week or so :-)
Have you added the modifications to give the RaPi a "soft" on/off
switch (to protect the SDCard) and a reset button?
In the upper vertical plate on the photo you can see a red key button.
This is for shutting down the Raspi (running a dedicated shutdown
script started by crontab). Then there is a red LED which quickly
starts to blink when the boot process is completed. Also it starts to
shine permanently when the shutdown process is in progress, until it
stops when it is completed. 10 seconds later i can disconnect the
power. A restart is done by shutting down, removing the supply and
connecting the supply again.
Another LED is the clear one (blue). It is for giving feedbacks from
the record process: When switching the green key in the upper plate,
the record script start to leave its while loop, configures the GPS
module for a 2 ms pulse width, starts gpsd, waits until GPS-system-time
is less than 2 seconds, starts all the vt processes including vtwait
inbetween. During that time the blue LED shines permanently, so i know
that the preparation is in progress. After that, when the recording has
been started successfully, it blinks, 10 ms each 3 seconds. So then i
know that everything is fine and the recording is running.
Yesterday i made a first recording in the forest. It was good to have
that kind of feedback there. All went well.
Finally, I see you have a USB plug connected - is this for the
wifi? I think you are using a RaPi2 without an onboard wifi..
Correct. This is not used in the field of course. Usually i connect to
the Raspi only by PUTTY, command line only...
and I remember from your earlier posts that you are using 2.4 GHz
WiFi to link from your remote forest listening post back to your main
site in the University.
Correct. This project is running nearly 2 years now and meanwhile the
system availability is > 95%
This must be a LoS path?
I don't know what that means.
Even so, quite impressive to work with the interference from the
mass of other Wifi in the city...
I'm unsing high gain yagis on both sides. The one in the forst is 1.1m
long! The other one is on the top of the building in 33m above the
ground. This already helps a lot to cause interferences (to my link and
to others).
It gives me the thought to run a RaPi system at my local radio
club which is in a relatively radio-quiet site outside the City of
Doncaster. But this is about 12km away and not LoS. It would be a good
LF/VLF education for the members as their main interest is microwave
and nanowaves (light transmissions).....
Yes, do it! It makes a lot of fun (even without beeing fully solar
powered, the next thing!) and we need more monitors :-)
73, Stefan
73 Terry
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