Receiving Outernet with a Grid Antenna and LeanDVB
Recently Luigi Freitas wrote in to us and wanted to share his fairly unique Outernet setup which is based on a Grid dish antenna, low cost SPF-5189 LNA, C.H.I.P mini single board computer generic RTL-SDR, and the open source LeanDVB decoder software.
Last month we made a post about LeanDVB, a lightweight DVB-S decoder, which with a few configuration changes can be used to also demodulate the Outernet signal. Luigi places his 2.4 GHz WiFi grid antenna (which still works for the 1.5 GHz Outernet signal) on a tripod and points it towards the Outernet satellite in his area. He connects the antenna up to a SPF-5189 based LNA, which is a 50 – 4000 MHz LNA that is very cheaply found on eBay for about $7 USD. Then a cheap generic no-TCXO $8 RTL-SDR is used together with the LeanDVB software.
In his post Luigi shows how to set up the LeanDVB software for decoding the Outernet signal by piping the output of rtl_sdr into it, and getting all the settings correct. To get the final files he then shows how to pipe the decoded packets in the Skylark decoder, and then the files can be accessed from the regular Outernet web GUI.
Looking for a dish antenna i found this one
http://www.karimunjawaadventure.com/item-detail/1500mhz-225dbi-long-range-grid-parabolic-wireless-antenna-for-dab-system.html
would it be something for inmarsat?
I have orderd one,would it be possible to adapt the grid antenna with a ringfeed for inmarsat
Ring feed has linear polarization so you will lose (theoretically) some 3dB against the circular polariziation that has been in use mostly on the Inmarsat birds. Other than that it can be done. Working really nice.
For people who are microphobic (i.e. have trouble building small antennas for microwave) I wonder if you could build a yagi designed for 500-ish MHz, since the Outernet signal at 1.5-ish GHz would be on the third harmonic.
It’s definitely easier to tune and prune when you’re dealing in large fractions of an inch/centimeter than when dealing with mm precision.
My experience is that 40 meter dipoles tend to tune up really well on 15 meters (still requires a tuner when transmitting with more than a few watts). This should be the same principle.
Uhm i would look to the radiation pattern more than to the SWR; it’s a Yagi not a dipole, lobes would go crazy, check this http://dk7zb.darc.de/Duoband/4-El-hor-70cm.gif