Getting Inmarsat through my wall- awesome!

[MrBungle]

I'm in Utah, and it's cold out so I'm not sitting on the back patio using my SDR and antenna. I tried it inside. While it's not ideal (that constellation is super weak), it works way better than I thought it would. I'm going to order some better coax. I also have a new mount coming tomorrow.

 

[MrBungle]

Would my antenna benefit from a solid copper wire? I currently have strand copper wire.

 

[thebaldgeek]

Fantastic effort to not give up and make the best of your setup.
Whats the app that you are using to get the cross hairs?

I've had to talk many people into moving their helix out of pointing out a window to pointing through the wall or roof.
The windows in the USA often have a UV filter coating, ie, thin metal and it really blocks RF. Its frustrating for people as they can 'see' the antenna, but yeah, moving the helix out of the window and pointing it through the roof/wall and it will go much better.
If you have any wriggle room, try different spots on the wall, often the wall / roof construction changes in unexpected RF ways.

@MrBungle There wont be much difference. Better still is 4mm coper tube.
Have your read these L-Band pages? How to build an L-Band ground station.
Its got some good hints.

 

[spongella]

Nice setup and decoding of Inmarsat marine messages. I dabbled with Inmarsat antennas connected to an RTL-SDR.com SDR several years ago, very exciting. However I could not find software to decode. After much shopping around confusion I decided to call it quits. But you seem to be very successful and the Inmarsat messages have quite a bit of interesting information for the marine radio hobbyist. Thank you for sharing.

 

[dlwtrunked]

As it is drywall (supported by wood), that works as you found. I get better signals but then again I am using a 4 ft dish antenna (in my bedroom) and a better pre-amp. If you have not seen the list below put together by Sergi (an myself helping), it is the *best* that you will find of INMARSAT frequencies. Log In
I expect we will check soon to see if it needs updated.

 

[MrBungle]

Fantastic effort to not give up and make the best of your setup.
Whats the app that you are using to get the cross hairs?

Have your read these L-Band pages? How to build an L-Band ground station.
Its got some good hints.

Yeah so thanks to you for your website and information! I've been on your pages several times reading through. I've gotten some great information there. I've read all over the window is a no-go so I went right through the wall. I have a better mount arriving today so I'm going to work on that.

The app is Satellite Finder in iOS.

I noticed an hour later, once it got darker out, the signal vastly improved, like a ton better. I also noticed that while the frequency was locked all night long, it wasn't set to auto- meaning it sat on the one single frequency and decoded all night. The frequency never changed and was decoding this morning. 1.537.700.000 all night long.

 

[MrBungle]

As it is drywall (supported by wood), that works as you found. I get better signals but then again I am using a 4 ft dish antenna (in my bedroom) and a better pre-amp. If you have not seen the list below put together by Sergi (an myself helping), it is the *best* that you will find of INMARSAT frequencies. Log In
I expect we will check soon to see if it needs updated.

Thank you, I just signed up.

 

[thebaldgeek]

However I could not find software to decode.

Depends on what service you want to receive and what you want to do with the data.
For STDC Marine you have quite a few options, they are listed and explained on this page: STD-C aka InmarsatC aka NCSC aka EGC aka Marine Messages.
For ACARS, your have two, SatDump and Jero. Jaero is the most popular. Details are here: Ins and outs of Jaero.

seen the list below put together by Sergi (an myself helping)

I cant log into that link. Can you please confirm that your list on my site that you gave me last year is still up to date.
A _lot_ of people use the L-Band page to reference those frequencies and modes: How to build an L-Band ground station.
The frequencies are at the bottom of that page.

Thanks.

 

[thebaldgeek]

Inmarsat messages have quite a bit of interesting information for the marine radio hobbyist.

You can read all the messages from 4 of the Inmarsats (not just the one you are 'under') on my site here:

Node-RED Dashboard 2.0

Node-RED Dashboard 2.0

tbg.airframes.io

Also you can search the past months messages on that page.

If you have any suggestions for the layout or filtering of marine messages, please let me know. I've been asking folks for help to better make use of the messages, how to filter and display them, but so far no one has offered any insight.

 

[MrBungle]

So another question- today the signal went to nothing, but as the sun goes down and later in the day, the signal is coming back into view on my waterfall. I don't remember this happening last summer when it was warm-maybe it did and I don't remember.

New mount came, way more stable.

 

[dlwtrunked]

Depends on what service you want to receive and what you want to do with the data.
For STDC Marine you have quite a few options, they are listed and explained on this page: STD-C aka InmarsatC aka NCSC aka EGC aka Marine Messages.
For ACARS, your have two, SatDump and Jero. Jaero is the most popular. Details are here: Ins and outs of Jaero.


I cant log into that link. Can you please confirm that your list on my site that you gave me last year is still up to date.
A _lot_ of people use the L-Band page to reference those frequencies and modes: How to build an L-Band ground station.
The frequencies are at the bottom of that page.

Thanks.

To get to the link, join the group (no cost), then log in, and then go to the link.

 

[dlwtrunked]

Depends on what service you want to receive and what you want to do with the data.
For STDC Marine you have quite a few options, they are listed and explained on this page: STD-C aka InmarsatC aka NCSC aka EGC aka Marine Messages.
For ACARS, your have two, SatDump and Jero. Jaero is the most popular. Details are here: Ins and outs of Jaero.


I cant log into that link. Can you please confirm that your list on my site that you gave me last year is still up to date.
A _lot_ of people use the L-Band page to reference those frequencies and modes: How to build an L-Band ground station.
The frequencies are at the bottom of that page.

Thanks.

In case it was you, here is the current file. I think one typo was corrected since the original list. I have been too busy with other projects to check current status. (Other project have focused around the HF trading stations and radars.)

 

[thebaldgeek]

today the signal went to nothing, but as the sun goes down and later in the day, the signal is coming back

Keep in mind that the Inmarsat's are in a geosynchronous orbit. They wobble in a big fat sloping '8' in the sky.
If you happen to setup your helix when the sat is at the top or bottom of the orbit, then yes, you will lose it at some point in the day as the helix beam width is narrow enough for the sat to drift out of the sweet spot.
The RTLSDR patch antenna is much boarder and wont have the issue, but it also wont work anywhere near as well. (Or work much at all inside a house!).

The solution? Peak up in the middle of the orbit. Then the beamwidth will still get the tops and bottoms of the orbit. Yes, I have set an alarm to get out of bed at 2am to do this, but I am a lot more hard core since so many folks rely on the site data.
Tips and links are here: Inmarsat - Finding ‘your’ sat.
And here: How to build a C-Band ground station.

 

[MrBungle]

Keep in mind that the Inmarsat's are in a geosynchronous orbit. They wobble in a big fat sloping '8' in the sky.
If you happen to setup your helix when the sat is at the top or bottom of the orbit, then yes, you will lose it at some point in the day as the helix beam width is narrow enough for the sat to drift out of the sweet spot.

Ahh yes I forgot about that-thanks!

 

[merlin]

Would my antenna benefit from a solid copper wire? I currently have strand copper wire.

Not worth the work to rewind the helix, likely undetectable change in performance.
There may be a little absorbtion passing through the wall,ceiling structure.
I started indoors, then mounted my antenna to a Peltor pan and tilt (CCTV cam mount) Moved it to the roof.
Using WXTrack, it will follow the satillites horizon to horizon.
That greately improve my capture angles and signal significantly.
My walls are stucco with tin underneath, like a Faraday cage. the roof /ceiling has no metal, I even get GPS here at the bench.

 

[Ubbe]

I'm going to order some better coax.

For the helix? RF travels on the surface so it doesn't matter what coax you are using. Perhaps a thicker one will improve bandwidth a little. You have a SAW filter and preamp and that will make any coax work to the SDR as you will give plenty of signal compensating for any coax losses. RG6 are well shielded, at least 2 layers and sometimes 4 layers, and are made to be used with frequencies up to 2GHz.

/Ubbe

 

[merlin]

For the helix? RF travels on the surface so it doesn't matter what coax you are using. Perhaps a thicker one will improve bandwidth a little. You have a SAW filter and preamp and that will make any coax work to the SDR as you will give plenty of signal compensating for any coax losses. RG6 are well shielded, at least 2 layers and sometimes 4 layers, and are made to be used with frequencies up to 2GHz.

/Ubbe

Those QFH antennas are quite critical of coax impedance and length for the right phasing. at the 50 ohm feed point, any lenghth of 50/75 ohm coax can be used to the receiver.
The saw filter is more about the bandpass for the satellites.

 

[kd5dga]

Lots of interesting reading here. I have two antennas up and running. My location is Central Texas. RTL-SDR v2 patch pointed at 3F5 and a NooElec Inmarsat mesh antenna pointed at 4F3> The updated reading material is a must and thanks for providing it. Right now I am just running Satdump to get used to SATCOMS and the program does work quite well.

 

[MUTNAV]

I'm in Utah, and it's cold out so I'm not sitting on the back patio using my SDR and antenna. I tried it inside. While it's not ideal (that constellation is super weak), it works way better than I thought it would. I'm going to order some better coax. I also have a new mount coming tomorrow.

View attachment 175621


View attachment 175622

View attachment 175623

View attachment 175624

View attachment 175625

I love the mount, how many times can you literally say "armchair copy", for anything.

Thanks
Joel