Tag Archives: Antenna

Some LNA tests for HRIT/LRIT

So I was talking with @luigi on OSP RocketChat and he noticed that one of the LNA’s I suggested alogn with the LNA4ALL (the SPF5189) got a comment on ebay saying that it doesn’t work on L Band.

So that was weird to me, since I have 5 of them, and one currently in use with my GOES setup. So I decided to do a small and crude benchmark for L Band comparing no LNA with LNA4ALL and SPF5189.

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GOES 16 Test Week

Yesterday I received an email from NOAA (I’m on their “tester” list) about some tests on GOES-16 that will happen this week. Before I start talking about what will be the tests I want to be clear that GOES-16 is NOT operational yet and any data received from the LRIT/HRIT downlink are test only data. This means the user of that link assumes all risks related to the use of their data and NOAA disclaims and any and all warranties, whether express or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose.

So this week ( from 27th to 31th march ) HRIT will go into a new test phase that will send out DCS, Environmental Messages and charts through. They also will send from 16h to 20h UTC on Monday (27th) some CMI (Cloud and Moisture Imaging) data. That might be interesting for anyone that have a 1.5m+ dish that can run Linear Polarization at 1694MHz and be interested in trying out the super-alpha version of OpenSatelliteProject, that is already compatible to HRIT.

Please keep in mind that while OSP does support HRIT, it doesn’t mean it will support the new products coming out from HRIT link. They’re currently testing sending NetCDF files over HRIT, and so far OSP doesn’t support those. In normal case (no bugs) the output product should be stored in a folder named Unknown with the filename provided by NOAA. Regardless of that I will be trying to record the IQ / decoder output in the CMI period and run the OSP over all week in GOES-16.

While running in GOES-16 the Twitter / Instagram bots will not be outputing any GOES-13 data (sadly I only have one dish so far) but may output the products from GOES-16.

Some usefull links for you if you’re interested in more information:

New 2.2m dish from Embrasat!

It has been some time since I posted something here about my satellite projects. So now I finished assembling my new dish! Previous (on GOES Satellite Hunt) I use a 1.9m TV dish that was cheap (R$200 or about US$70) and got really nice results (about 6dB SNR on LRIT and 10dB SNR on EMWIN). But I was willing to get the new GRB Signal from GOES-16 (previous named as GOES-R) that went up to Geostationary orbit last month. The GRB is the replacement for the GOES 13/14/15 GVAR signal. Basically GVAR is a rebroadcast of the partially processed data from the satellite. It is basically the raw sensor data packed in a format so the users can get and process by their own. The disadvantage of GVAR system over LRIT is that it does not have any error correcting methods. So either you have a very good signal, or you don’t have anything at all. The GRB signal that is on GOES-16 will send same raw data as the GVAR (actually it will send more data than GVAR, but thats another point) but now it will use DVB-S2, a market standard, for transmitting their data. Being DVB-S2 it does have error correcting like LRIT signal ( wikipedia has a good info about DVB-S2). But the bandwidth of GRB is much higher than LRIT and GVAR (LRIT is 600kHz wide, GVAR is 2.5MHz wide and GRB is 9MHz wide) so I would need a bigger dish to get a good signal.

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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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Play with SDR and Intel Edison!

So some people already saw in my facebook that I started playing with SDRs (Software Defined Radio).

I always wanted to do my own radio receiver, and I did some in the past. But it’s very hard to adapt the radio for anything new you want do to, and also when you want to process data in your computer things become harder.

So a few months ago I found a nice tutorial of how to get NOAA Satellite Images using a cheap DVB-T (Digital Video Broadcast – Terrestrial) dongle that can be used as SDR. It costs about R$70 (roughly US$10) and the model I got (with R820T2 tuner) can tune from 24MHz to 1.74GHz!!!

What is inside this spectrum?

Actually a lot:

  • FM Audio Radio Broadcasts
  • VHF / UHF Television (Both Digital and Analog)
  • Weather Satellites (APT, LRPT, HRPT)
  • ADB-S (Air Traffic Telemetry)
  • FM Air Traffic Radio
  • And more

So my goal was to receive NOAA APT Signals (I even made a decoder!) but I don’t have a good enough antenna (yet).

The problem

So I made up a piece of antenna with two copper pipes (I call a piece, because its a dipole from a Double Cross Antenna) (I will make a tutorial later how to do it) to have better reception for the 2m band (~135Mhz) but every time a satellite was in range, I would need to go outdoor and turn on my laptop and start capturing. This was annoying.

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