Few *times* ago I started to check on GOES 16 transmissions to see if I can get any data from it and make OpenSatelliteProject work with it. Me and @usa_satcom noticed that the HRIT signal was transmitting using differential encoding that was not predicted on NOAA’s HRIT Specification (You can check it here http://www.goes-r.gov/users/hrit-links.html ). So I decided to send an email to NOAA asking what was the current HRIT specs for GOES-16. Of course I expected no answer from them (they would probably be really busy with GOES-16 Testing), but surprisingly they answered sending the specs and saying that any feedbacks would be helpful and appreciated. So the HRIT indeed uses Differential Encoding (NRZ-M to be more specific). Knowing that I could start changing OpenSatelliteProject to be compatible with HRIT.
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.
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.
So I’m still mad about the FM Spectrum (88-108MHz) noise I get when using a LNA or something else. So I’m still looking for a nice and easy way to filter out these signals.
Last time I posted about a TV/FM Diplexer, that works great, but doesn’t attenuate enough the signals. So the solution would be cascading several of them, but I found that is very hard to find one Diplexer or FM Trap filter those days.
So I started looking out how to make my own filters. So I reopened Adam’s Website (LNA4ALL) that have a small filter he did for FM Trap and tried (again) to make my own.