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Old 29-08-2016, 21:52   #1
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Grib files for Mariners transmitted by Outernet L-Band Satellite

Outernet is testing a L-Band satellite service over Inmarsat satellites. They are looking for Ideas on the best way to send Grib files. I know we already have the Grib file plug in for Opencpn so If this could be combined with the RTL-SDR dongle plugin and people put a simple four inch Satellite dish and diy receiver kit, next to their solar panels they can now receive grib files from space. Please head over to their forum if you have any ideas to add on the best way for them to do it. https://discuss.outernet.is/t/grib-f...satellite/2251
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Old 12-11-2016, 05:30   #2
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Re: Grib files for Mariners transmitted by Outernet L-Band Satellite

Outernet has a new L-Band Inmarsat service of NOAA animated grib weather it is excellent.
Outernet is sending down 20mb a day of News, animated NOAA Grib files and Amateur Radio APRS messages every hour.

It is a very impressiveness service for a small boat owner.
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Old 12-11-2016, 06:27   #3
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Re: Grib files for Mariners transmitted by Outernet L-Band Satellite

Interesting, this could make a fun winter/hibernate project for ~$100. I am digging into it and so far found a good tutorial on rtl-sdr..com:
RTL-SDR Tutorial: Decoding Inmarsat STD-C EGC Messages - rtl-sdr.com


I got to wonder what business model is behind outernet? Having a dedicated channel transmitting 24/7 on three Inmarsat satellites must cost something..

Dirk
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Old 12-11-2016, 14:55   #4
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Re: Grib files for Mariners transmitted by Outernet L-Band Satellite

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Originally Posted by LeaseOnLife View Post
far found a good tutorial on rtl-sdr..com:
RTL-SDR Tutorial: Decoding Inmarsat STD-C EGC Messages - rtl-sdr.com


I got to wonder what business model is behind outernet? Having a dedicated channel transmitting 24/7 on three Inmarsat satellites must cost something..

Dirk

I am not sure on the business model. But they were a very successful kick starter and raised over $600k. This got them started.

They then temporarily used Ku band satellite to test some of their ideas. Now two years later they have the L-Band Working.

They did charge $5.00 to resend tweets addressed to payees over their satellite service worldwide.

If you have a boat then the satellite receiver is a great thing. Mine has been an enormous amount of fun.
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Old 12-11-2016, 15:20   #5
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Re: Grib files for Mariners transmitted by Outernet L-Band Satellite

How do you deal with pitch&roll&yaw (antenna direction towards satellite)?
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Old 12-11-2016, 16:19   #6
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Re: Grib files for Mariners transmitted by Outernet L-Band Satellite

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How do you deal with pitch&roll&yaw (antenna direction towards satellite)?
We have not done any trips yet.

I have mounted the patch antenna dead flat looking upwards and it gets a SNR of approx 6 db.

The receiving hardware needs at least, a SNR of 2 to function correctly.

From the Philippines If I aim the standard $29.00 Outernet patch antenna

https://www.amazon.com/L-Band-Patch-.../dp/B01JTE7NHU

at the 4F1 Inmarsat L-Band satellite above New Guinea I get a SNR of 10 or 11.

Outernet also uses FEC (forward error Correction) . Basically it sends the data twice.

My gut feel is see what happens with the standard patch antenna mounted flat. I had a Worldspace Radio satellite receiver 10 years ago and I mounted it flat and it never had any problems.

I am certain it will be fine at anchor.

Underway I think heeling could be dealt with by just hinging / gimbaling the flat Patch antenna and adding a old 12 volt 10000 RPM hard-drive underneath that would act as a gyro-stabilizer. This is very common with DIY camera enthusiasts.

The other option is follow what Inmarsat do and use a small 6" L-Band Hemispherical Helical antenna.

The Outernet L-Band download rate is about 2kbps or approx 1 MB an hour so a highly directional / high gain antenna is not really required.
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Old 12-11-2016, 17:42   #7
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Re: Grib files for Mariners transmitted by Outernet L-Band Satellite

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Originally Posted by bcn View Post
How do you deal with pitch&roll&yaw (antenna direction towards satellite)?
Forgive me if I am mistaken. But from what I read, a cheap GPS antenna is ideal. See the tutorial at the bottom of RTL-SDR Tutorial: Decoding Inmarsat STD-C EGC Messages - rtl-sdr.com

I'm new to all of this and still trying to wrap my head around it. Howerver, this all looks pretty doable and on the cheap.
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Old 12-11-2016, 19:32   #8
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Re: Grib files for Mariners transmitted by Outernet L-Band Satellite

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Forgive me if I am mistaken. But from what I read, a cheap GPS antenna is ideal. See the tutorial at the bottom of RTL-SDR Tutorial: Decoding Inmarsat STD-C EGC Messages - rtl-sdr.com

I'm new to all of this and still trying to wrap my head around it. Howerver, this all looks pretty doable and on the cheap.

The $29.00 standards patch antenna does a lot for the money.

Approx 11 SNR in Tropics possibly 7 SNR in say New York.

You still have to factor in Attenuation FADE. Which can be caused by interference from adjoining signals, storm fronts, Cloud, Rain, Sun etc.

If you get a old GPS antenna to work it will have a much lower Gain than the $29 Outernet Patch antenna.


Also remember that After the antenna is a Saw filter and 34 db Low noise amplifier combined.

My feeling to any one thinking about a Outernet Inmrsat L-Band receiver kit is get the basic Outernet kit and Patch antenna working.

and then by all means experiment with alternative components and let us all know what works and does not work.
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Old 12-11-2016, 21:00   #9
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Re: Grib files for Mariners transmitted by Outernet L-Band Satellite

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Originally Posted by yachtmanforfun View Post
The $29.00 standards patch antenna does a lot for the money.

Approx 11 SNR in Tropics possibly 7 SNR in say New York.

You still have to factor in Attenuation FADE. Which can be caused by interference from adjoining signals, storm fronts, Cloud, Rain, Sun etc.

If you get a old GPS antenna to work it will have a much lower Gain than the $29 Outernet Patch antenna.


Also remember that After the antenna is a Saw filter and 34 db Low noise amplifier combined.

My feeling to any one thinking about a Outernet Inmrsat L-Band receiver kit is get the basic Outernet kit and Patch antenna working.

and then by all means experiment with alternative components and let us all know what works and does not work.
Thanks for the info!
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Old 13-11-2016, 06:30   #10
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Re: Grib files for Mariners transmitted by Outernet L-Band Satellite

Quote:
Originally Posted by yachtmanforfun View Post
Outernet is testing a L-Band satellite service over Inmarsat satellites. They are looking for Ideas on the best way to send Grib files. I know we already have the Grib file plug in for Opencpn so If this could be combined with the RTL-SDR dongle plugin and people put a simple four inch Satellite dish and diy receiver kit, next to their solar panels they can now receive grib files from space. Please head over to their forum if you have any ideas to add on the best way for them to do it. https://discuss.outernet.is/t/grib-f...satellite/2251
Until I have my own kit, can you post a sample grib file you received? I would like to see content of such grib file.

Dirk
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Old 13-11-2016, 06:48   #11
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Re: Grib files for Mariners transmitted by Outernet L-Band Satellite

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Originally Posted by LeaseOnLife View Post
Until I have my own kit, can you post a sample grib file you received? I would like to see content of such grib file.

Dirk

Hi Dirk above in a earlier message I have attached a screen grab showing the NOAA weather Animated Grib data.

The NOAA world wide weather / grib data sent each day by Inmarsat L-Band satellite is apparently 1mb in size.

It provides a 4 day forecast for any where on earth.

I suggest you go the Outernet forum and post a more detailed question.

Outernet | Discussions

Seasalt
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Old 13-11-2016, 07:20   #12
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Re: Grib files for Mariners transmitted by Outernet L-Band Satellite

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Originally Posted by yachtmanforfun View Post
Hi Dirk above in a earlier message I have attached a screen grab showing the NOAA weather Animated Grib data.
This screenshot is from nullschool.net and has nothing to do with a grib file received from Outernet as LeaseOnLife has asked for.

Gerhard
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Old 17-11-2016, 11:16   #13
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Re: Grib files for Mariners transmitted by Outernet L-Band Satellite

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Originally Posted by CarCode View Post
This screenshot is from nullschool.net and has nothing to do with a grib file received from Outernet as LeaseOnLife has asked for.

Gerhard
It's data downloaded from satellite using the nullschool web page to display.
Same data as gribs, different display but still from a satellite.

Fast forward to 6:45

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Old 18-11-2016, 06:16   #14
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Re: Grib files for Mariners transmitted by Outernet L-Band Satellite

Interesting. But what is the GRIB data? What resolution? What data is included; wind, pressure, rain, 500mB, clouds, etc.? I can't find anything on this so far.

I can see that it seems to be GRIB2 format but not much else.

Very tempted to order an antenna kit to play with.
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Old 24-11-2016, 01:01   #15
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Re: Grib files for Mariners transmitted by Outernet L-Band Satellite

Outernet , possible alternative for Iridium or SSB weather ?
a couple of weeks ago i wrote:
"THE CHALLENGING PART is to make an antenna that can and will recieve the signal with the boat in movement, make the whole system in the way that is drawing power as low as possible, while recieving, and last but not liest make it waterproof and EASY INSTALL that way annyone can install it with no problems onboard.
The past days I'm gathering pieces and setup test ambients to make an omnidirectional antenna suitable for recieving outernet.
Since is working on relatively high frecvencyes i had to rent somme pieces of test equipament nedded for testing and building such antenna and still waiting for couple of bit and pieces for the antenna.
I'll keep you posted on how the tests are going and what results I've came with.
the goal is to make an antenna that cost under 150usd (one inmarsat L band antenna that could work is around 700usd) and an autonomus system under 300usd everything included.
Like outernet everythig is open source and who has the time and will to help is welcome, soon will be an online project site dedicated to this topic."
wee tryed the patch antennas onboard but with the movement is not a suitable alternative, the dish is out of discussion and the gps antennas do not work well in this case (for those that do not know the gps system has always at liest 4 satellites in sight overhead and the signal is much stronger than outernet)
UPDATE: We managed to have a decent signal on our antenna with no amplification at all, and now waiting for the high frecvency parts to start with the first circuit boards for testing... the antenna will have no moving parts and it's almost omnidirectional...

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