We have all had good luck building the DIY ORxPi receivers operating over geosynchronous Ku Band satellites. Of course, not without some glitches
Now, with L Band potentials being worked by Outernet, I think it would be a good idea to collect L Band work in one spot.
Questions to addressed would be how modify the ORxPi for L Band, how to make a Lighthouse work in L band, etc. I would also suggest we leave out the Lantern receiver since none of us have one yet.
Ken this is a great idea putting all L-Band ideas in one3 spot.
My L-Band interest would be a L-Band Antenna for a moving vehicle if such a thing is possible.
I would also appreciate if the people with Industry experience could take the Time to use all the Correct abbreviations and terms so I can start to learn L-Band terminology.
What will the footprint look like?
What will the data rate be?
What size antennas will we need?
Can RTL-sdr realtek usb dongle work with a “UP” converter or will we need different hardware?
But, what can we do now with our Raspberry Pi ORxPi devices to receive an L Band signal when Outernet starts to broadcast one? I’m thinking we add some appropriate software defined dongle type receiver with an appropriate L Band antenna and create an LORxPi
Hopefully, we can add the same dongle/antenna to a Lighthouse and do L Band downloads there too.
Rather than beating the ORxPi/Lighthouse to death in Ku Band, we start working it over in L Band. Ken
The goal is to definitely offer an L-band version of ORxPi, but there is a serious bit of work that needs to take place before that can happen. You’ll note that in ORxPi there is one closed source binary blob. This is a piece of code that turns the DVB-S2 stream into files. For L-band, the modulation scheme is highly proprietary (not by our choice; it belongs to ViaSat) and so they need to release a software-based demodulator. Once we have that, then we can use general processing power to demodulate and decode the content that is delivered over L-band.
They have already done a comprehensive engineering study and they peg the project to take 6 months. ORxPi-L will be awesome, as it will only require a 4-inch antenna. But we may be jumping the gun a bit, because the software to make it run won’t be available for a little while.
Syed does this mean the Lantern hardware release will be effected by this same issue?
If you have solved this issue for lantern why cant we use that solution with the Linux Vesion of Outernet Rx which could on a powerful pc have plenty of decoding grunt.
Actually, the new Lantern handles demodulation with an FPGA and DSP. The goal of the software demodulation project is to move all of that processing into a PC. The engineering review showed that an Intel i3 should be able to do the job.
That’s actually old information now. This is prior to us signing the ViaSat relationship. The antenna is still usable, but we’ll need to use ViaSat’s waveform. We could always lease our own bandwidth and install our own modulator, but that adds considerable cost to the equation.
ViaSat’s waveform is proprietary. The benefit of working with them is leveraging their engineering efforts, as it relates to hardware development–especially much lower cost satellite terminals that they have in their roadmap. We also benefit from their experience in developing network hubs. If we were to limit ourselves to just a broadcast service, this is something we could/can do ourselves. But adding in even a tiny return link significantly complicates things. And lastly, there was also the matter of dollars and sense. Satellite bandwidth is the most expensive line item in our budget.
Has any one tried decoding Inmarsat L-Band frequencies as per the tutorial below. These frequencies will be very very close to Outernet’s future frequencies and also GPS frequencies. Hence you can use a old GPS antenna possibly. Any antenna you build could also work with Outernet L-Band offering.
I have a Circular UHF TV antenna with 15 meters of 75ohm coax that I have connected a RTL dongle with the highly sensitive e4000 (Elonics tuner no longer available). This plugs into my Ubuntu Linux I7 Laptop. I run Andy 18 Ham radio 64 Bit Ubuntu virtual disk in Virtualbox as for some reason the RTL dongle crashes in 32 bit Ubuntu.
I can get the Windows Inmarsat decoding software and the Java decoding software to go into sync mode when monitoring Inmarsat L-Band frequencies. But I cannot get it to receive text safety and Navigation warnings from Inmarsat.
I am unable to be certain that I am connecting to the Correct NCS transponder on the Inmarsat 4-F1 Satellite that is above the Philippines. Does any one know the NCS frequencies that can be publicly monitored on the Inmarsat satellites?
L Band. Ken
