Hi Stefan
Very interesting! I have been thinking of
some uses to put some old 2.4GHz routers to. I now have some ideas!! I need to
get my new Rasp Pi2 up and running too (courtesy my XYL!)
Cheers
Jim G7NKS
Hi all,
Today it is the first day that my remote receiver is running while hanging 15m
AGL into a tree in my garden outside the city. It is streaming audio from a
MF/630m receiver via WLAN over 2.4 km distance to my home location!! :-)
Since 16:30 UTC, the link is running :-)
It is a large step in this project but not the last. So far, no antenna is
connected to the RX, i still have to lay the cable up into the tree :-) I am
checking the stability/availability of the GHz link and the watchdog scripts,
hopefully keeping the link to the remote end.
There is a website (not up to date) giving more explanations: http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_remote_Grabber_info.html
If all runs well i will be back tomorrow to connect the antenna to stream first MF signals from the garden :-)
It is not only a RF remote link project.
Additionally it became a project for solar
energy systems, i am monitoring the solar battery system voltage to
do some energy management. I'm now getting good impressions and a better
understanding what energy input can be expected from a cloudy day (10%, 50%,
100% cloudy) relative to a sunny day, or the difference between February and
April! A circuit protects batteries from deep-discharges by swicthing the power
supply of the Raspberry Pi OFF but before that, it gives a HIGH level on a GPIO
pin of the Raspi. A script is running on the Raspi which correctly shuts it
down if the input becomes HIGH for > 3 s. This happens at <= 11.2V. But
the best is that at 12.8V, the hysteresis of the circuit switches the supply
voltage ON again, which automatically starts the Raspi again! So, in a longer period
of cloudy days, the energy of the batteries may be insufficient. But this
should neither cause unwanted crashes of the system nor deep-discharge the
batteries, it just affects the availability
of the system, which can be improved then. This circuit consumes
< 50 uA.
The 12V supply voltage is measured by a LTC2400. Each 30 seconds a measurement
is done. 2 averages of a measurement is saved into a text file (each minute)
which is automatically syncronized by btsync software over the WLAN link. So
finally the text file is available on a local PC here which runs LabView
software which generates a voltage-over-daytime plot, automatically generates a
png image which is saved to the webserver which is running this website: http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_remote_Grabber.html
This is fascinating stuff for me. And i can now optimise my solar system
parameters. Do i need to install more solar peak-power or do i need more
batteries, or both? These questions can be answered fairly easily now by
studying the plots.
The overall power consumption of the system is 3W. It is now running on 2x 7 Ah
12V lead acid batteries. One of them is 7 years old ;-) I'm hoping for a stable
link and seeing the voltage rising again tomorrow morning :-)
Another funny feature is: I can remotely switch a bistable relay (energy
saving) which switches the input of the USB soundcard. One input is the RX, the
other one is a microphone which is installed into a feed-through of the
waterproof box. So i can decide to listen to MF or to the birds singing in the
morning, or to wild pigs at night, destroying the lawn! SpecLab and it's
triggered event function could be used to detect and record sudden nightly
audio events :-) It is even possible to send a SMS if this happens so i can
listen to the web-radio steam on my smartphone out of the bed :-) Crazy world!
Two up to date images
https://dl.dropboxusercontent.com/u/19882028/MF/20150411_181847.jpg
https://dl.dropboxusercontent.com/u/19882028/MF/20150411_184112.jpg
To be continued...
73, Stefan
Am 14.10.2014 15:28, schrieb DK7FC:
Hi LF,
I continued with my garden remote VLF/LF/MF RX site.
It is amazing what the Raspberry PI can do! :-) I'm not an expert at all (!)
but i managed, of course with help from the web, to start and run an Icecast2
server on the RPi. It is now laying on a table here, consuming about 2W while
streaming into the web.
In a first step i played music (web radio), an mp3 stream. Now i managed to
change the output format to ogg and run a 300 MB wav file from the RPi. You can
listen and display the stuff in SpecLab, see https://dl.dropboxusercontent.com/u/19882028/VLF/SL%20audio.png
You can open this box in SL and type the url of the stream, which is http://129.206.29.99:8000/mpd
Now it is just a file but later it should become the input of a soundcard or
another ADC. Hope this works.
Does this work on your side as well?
73, Stefan
PS: On http://129.206.29.99:8000/
there is a site showing some description and usage of the stream. All very new
to me and 24 hours ago i knew nothing about that...
