Hi MF,
Now, first time i'm streaming MF radio signals from the garden to the
home location!
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_remote_Grabber.html
Somehow the signal is a bit low, to close to the soundcard noise.
Somewhere i'm loosing 15 dB signal level. But that will be solved soon.
Still not running perfectly but it another step to the remote RX system
:-)
73, Stefan
Am 11.04.2015 20:27, schrieb DK7FC:
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...
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