Tag Archives: APT

137MHz Bandpass filter for NOAA / Meteor Satellites

Yesterday I saw a new blog post by Adam (9a4qv) in LNA4ALL. The post (here) talks about a band pass filter he did for Weather Satellites and I decided to try as well.

Unfortunately I don’t have a exact match for that components at home, so I tried to do something with the components I have. So the lower value I had for capacitors was 10pF, and the needed values for Adam’s Filter is 1pF, 4.7pF and 15pF. I decided then to use 10 in series to do the 1pF, 2 in series for the 4.7pF (that will be 5pF) and then one in parallel with two in series to give me the 15pF. Its a very close match, and I’m unsure about the effects of serialization of capacitores in the filter (increase inductance maybe?). So here is the results.

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GQRX NOAA 18 Signal

GQRX NOAA 18 Signal

So you all saw my last posts [ Play with SDR and Intel Edison! QFH Antenna and my first reception of NOAA! ] but I actually didn’t explained how to capture and decode APT Signals using your computer (in this case, with Linux). So here it is! For this article I’m using Ubuntu 15.04, but actually any distro will work well (I think most of them have the needed packages)

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QFH Antenna and my first reception of NOAA!

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So in my last post I was playing with my RTL-SDR with an Intel Edison. So I decided to build a QFH Antenna to ble able to receive NOAA APT Signals. These NOAA Weather Satellites broadcast a APT signal with about 5 to 8 Watts at 2m band, and considering how low this power is, it might suprise you that these signals arrive pretty strong at earth surface. But the biggest challenge to receive this signals are not its power. Its all about movement.

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