Tag Archives: Open Satellite Project

GOES GRB First Light!

When the GOES-16 was first announced I got interested in their GRB Downlink (although the first try was at HRIT downlink). Basically GRB is a replacement for the old PDR downlink in GOES 13/14/15 generation, which gives few advantages over the old link:

  • Uses market standard DVB-S2 Generic Stream
  • Have FEC (as defined by DVB-S2)
  • Higher bandwidth
  • Easier to receive due DVB-S2 FEC

For those who don’t know, the GRB is a direct rebroadcast of GOES data, with minimum processing as possible (usually just packaged into NetCDF files with calibration parameters) and is intended for anyone that want’s to get full data from the satellite.

The down-link itself is split into two channels transmitted at same frequency (1684.5 MHz) with different circular polarities. That makes extremely necessary to use Circular Polarized feeds, since a Linear Feed will suffer with cross polarization (sum of each channel at the same signal).

For HRIT downlink usually a 1 meter dish is enough for receiving with a good signal (needs a very good hardware setup though). But for GRB, the minimum dish size listed by NOAA is 3.8m for the best regions.

GRB Recommended Dish Size by NOAA

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GOES 16 Test Week Results

In the week from March 27th to 31 NOAA performed some new downstream tests over HRIT link on GOES-16. The idea was to transfer some CMI (Cloud and Moisture Imaging) products and see if the software developers and current stations could receive it fine. Before starting talking about that, please notice that all data sent so far is stated as test data and should not be used for any real world measurements. As NOAA states (and I forwarded on my last post):

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 I kept my dish pointed to GOES-16 all over the week and did record the Monday testing (that contained CMI images) and recorded all files sent all over the week. Some of them are automatically posted on Twitter / Instagram by my OSP Bot but not all of them. I had discovered some issues with my Virtual Channel Ingestor on GOES Dump, and also most of the new data was not being handled correctly by Goes Dump. Working together with @usa_satcom we managed to almost zero-out the bugs in GOES Dump.

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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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