Tagged: inmarsat

L-Band Setup with Mini LNA4ALL and Mini Patch Antenna

Over on his YouTube channel Adam 9A4QV has uploaded a new video showing reception of L-band signals with a bias tee powered LNA4ALL and a small patch antenna. The video seems to show a new miniature bias tee powered LNA4ALL device that Adam might be working on. The LNA4ALL is a low noise amplifier that works well with our bias tee capable RTL-SDR dongles.

The patch antenna is made out of a single piece of PCB board which was made by etching out the patch pattern with masking tape. While the patch antenna is not optimal, and tested indoors, Adam is still able to receive some AERO signals.

Later in the video he compares the PCB patch against a GPS patch antenna which gets no reception. He also compares the results when two LNA4ALL’s are used in series. Using two LNA’s improves reception slightly.

https://www.youtube.com/watch?v=NwOERQxx2qE

RTL-SDR Tutorial: Receiving and Decoding Data from the Outernet

Outernet is a relatively new satellite service which aims to be a “library in the sky”. Essentially their service is going to be constantly transmitting files and data like news and weather updates from geostationary satellites that cover almost the entire world. Geostationary means that the satellites are in a fixed position in the sky, and do not move over time. By simply pointing a small patch antenna at the sky (with LNA and RTL-SDR receiver), it is possible to download and decode this data from almost anywhere in the world. Their aim is to provide up to date information to users in locations with little to no internet (rural, third world and sea), or in countries with censored internet. It may also be of interest to disaster preppers who want an “off-grid” source of news and weather updates. It can kind of be thought as a kind of one-way download-only internet service.

Currently the L-band service is being tested, and while they are not yet sending actual Outernet files, they are already sending several daily test files like small videos, images and text documents as well as GRIB files for mariners. At a maximum you can expect to receive up to about 20 MB of data a day from their satellite. Previously they had C-band services but these required large satellite dishes. The C-band service is due to be discontinued at some point in the future.

In this guide we’ll show you how to set up an Outernet L-band receiver with an RTL-SDR dongle. If you enjoy this guide then you might also enjoy our Inmarsat STD-C EGC Decoding Tutorial which has similar hardware requirements.

Outernet Setup: Patch Antenna -> LNA -> RTL-SDR with Bias Tee -> Raspberry Pi

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L-Band Setup with Mini LNA4ALL and Mini Patch Antenna

Over on his YouTube channel Adam 9A4QV has uploaded a new video showing reception of L-band signals with a bias tee powered LNA4ALL and a small patch antenna. The video seems to show a new miniature bias tee powered LNA4ALL device that Adam might be working on. The LNA4ALL is a low noise amplifier that works well with our bias tee capable RTL-SDR dongles.

The patch antenna is made out of a single piece of PCB board which was made by etching out the patch pattern with masking tape. While the patch antenna is not optimal, and tested indoors, Adam is still able to receive some AERO signals.

Later in the video he compares the PCB patch against a GPS patch antenna which gets no reception. He also compares the results when two LNA4ALL’s are used in series. Using two LNA’s improves reception slightly.

https://www.youtube.com/watch?v=NwOERQxx2qE

RTL-SDR Tutorial: Receiving and Decoding Data from the Outernet

Outernet is a relatively new satellite service which aims to be a “library in the sky”. Essentially their service is going to be constantly transmitting files and data like news and weather updates from geostationary satellites that cover almost the entire world. Geostationary means that the satellites are in a fixed position in the sky, and do not move over time. By simply pointing a small patch antenna at the sky (with LNA and RTL-SDR receiver), it is possible to download and decode this data from almost anywhere in the world. Their aim is to provide up to date information to users in locations with little to no internet (rural, third world and sea), or in countries with censored internet. It may also be of interest to disaster preppers who want an “off-grid” source of news and weather updates. It can kind of be thought as a kind of one-way download-only internet service.

Currently the L-band service is being tested, and while they are not yet sending actual Outernet files, they are already sending several daily test files like small videos, images and text documents as well as GRIB files for mariners. At a maximum you can expect to receive up to about 20 MB of data a day from their satellite. Previously they had C-band services but these required large satellite dishes. The C-band service is due to be discontinued at some point in the future.

In this guide we’ll show you how to set up an Outernet L-band receiver with an RTL-SDR dongle. If you enjoy this guide then you might also enjoy our Inmarsat STD-C EGC Decoding Tutorial which has similar hardware requirements.

Outernet Setup: Patch Antenna -> LNA -> RTL-SDR with Bias Tee -> Raspberry Pi

Downloaded Files

Book Download

Video Download

Image Download

Continue reading

New Outernet Products For Sale: E4000 RTL-SDR, L-Band Patch Antenna, L-Band LNA

Outernet is a new satellite service that aims to be a free “library in the sky”. They continuously broadcast services such as news, weather, videos and other files from satellites. Their aim is to provide up to date information to users in locations with little to no internet (rural, third world and sea), or in countries with censored internet. It may also be of interest to disaster preppers. Currently they have an active Ku (12 – 18 GHz, though due to be discontinued shortly) and C-band (4 – 8 GHz) satellite service, and now recently have their L-band (1.5 GHz) service active. The L-band signal is currently broadcasting at 1539.8725 MHz over the Americas, 1545.525 MHz over Europe/Africa/India and 1545.9525 MHz over Asia/Pacific.

To receive their L-Band service you will need an RTL-SDR capable of receiving 1.5 GHz, like a R820T/2 RTL-SDR (preferably at least passively cooled like our RTL-SDR Blog models as some R820T/2 units tend to fail at 1.5 GHz without cooling) or an E4000 dongle. You will also need an appropriate L-Band antenna and L-Band amplifier.

To help with these hardware requirements, Outernet have just released for sale an E4000 RTL-SDR with bias tee enabled ($39), an L-band satellite patch antenna ($24) and an L-Band LNA ($19). There is also a E4000 + LNA bundle ($49) available. The E4000 comes in a metal case, and has the bias tee always on. The LNA requires bias tee power and is also compatible with our RTL-SDR Blog units that have the bias tee. The patch antenna is tuned for 1525 – 1559 MHz and is the production version of the prototype antenna we used in our Inmarsat STD-C tutorial. Combined with an LNA we found that the patch antenna gives good performance and can also be used to receive other services such as Inmarsat STD-C and AERO. Currently shipping is only available within the USA, but they write that they will have international shipping available shortly.

EDIT: For international buyers the Outernet store is now started selling these products at http://store.outernet.is.

The L-Band Outernet signal decoders aren’t finalized yet, but we expect them to be released in a matter of days to weeks. They will have decoders available for the $9 CHIP computer and Raspberry Pi 3 platforms. They way it works is that you plug your RTL-SDR with L-band LNA and patch antenna connected into the CHIP or Raspberry Pi 3 which is running their customized image. The CHIP/Pi3 then broadcasts a WiFi access point which you can then connect to with any device, and access the files as they are downloaded. Once these decoders are released we’ll do a full tutorial on receiving the Outernet L-Band service with an RTL-SDR.

The Outernet L-Band Patch Antenna
The Outernet L-Band Patch Antenna
The Outnernet L-Band LNA
The Outernet L-Band LNA
The Outernet E4000 RTL-SDR in metal case with bias tee.
The Outernet E4000 RTL-SDR in metal case with bias tee.

Testing L-Band Inmarsat Reception with Three LNA4ALL’s + Two Filters

Over the last few weeks Adam 9A4QV has been testing L-Band Inmarsat reception with his LNA4ALL low noise amplifiers. In a previous post he tested reception with two LNA4ALL and found that he got an improved SNR ratio over using just one LNA4ALL. In his latest video he tests Inmarsat reception with three LNA4ALL’s and two L-band filters. His results show that the SNR is improved over using two LNA4ALL’s, and can almost match the results obtained by a commercial L-band front end which he also demonstrated in a previous video.

https://www.youtube.com/watch?v=gkVy3L_cBtU

Reverse Engineering a Commercial Inmarsat Front-End to use with the RTL-SDR

Over on his YouTube channel Adam 9A4QV has uploaded a video showing a commercial Inmarsat front end which he reverse engineered to use with his RTL-SDR. The front end is a duplexor, which allows both receive and transmit to occur on the same channel, but to use with the RTL-SDR Adam only uses the receive part. Inside the front end is a large cavity filter, ceramic filter, and about 60 dB of total L-band gain from MMIC amplifiers.

In the second video Adam hooks up the Inmarsat front end to his RTL-SDR and home made patch antenna. The results show that the signals are very strong when using the commercial front end. In a previous post we showed Adam’s results with two LNA4ALL amplifiers. The commercial front end seems to give much stronger signals, but the results with one or two LNA4ALL are adequate enough for decoding.

https://www.youtube.com/watch?v=cVnpKAjwAck
https://www.youtube.com/watch?v=qWZ5RJcpMvY

More L-Band Videos from 9A4QV: Testing 2x LNA4ALL + Filter + Patch, Receiving the Outernet Signal, L-band Filter

Adam 9A4QV has once again uploaded three new videos to YouTube, all related to L-band satellite reception. The first video shows how much L-band reception can be improved by using two LNA4ALL low noise amplifiers together with a filter placed in between them. Using two LNA’s instead of one improves the reception by about 2-6 dB. He also shows that L-band Inmarsat satellite signals at 1.5 GHz can even be received by his 1090 MHz folded monopole ADS-B antenna placed indoors.

The second video shows a reception report of the new Outernet signal. The Outernet signal is a new satellite data service being provided that broadcasts up to date news as well as various files and information such as educational videos and books for people in third world countries without internet. They have said that they are working on free decoding software for their service which should be released soon. The Outernet signal is a bit weaker than typical AERO signals, but can still be received quite easily with an RTL-SDR, patch antenna and 2 x LNA4ALL. The Outernet downconverter mentioned in a previous post should of course also work well.

His third video shows some tests on his L-band filter, showing return and insertion loss.

https://www.youtube.com/watch?v=1ceyF04ZeW8
https://www.youtube.com/watch?v=G166-xe5A3Q
https://www.youtube.com/watch?v=Soq8hl17teE

Testing a Prototype of the Outernet L-Band Downconverter

Outernet are a startup company that hope to revolutionize the way people in regions with no, poor or censored internet connectivity receive information. Their service is downlink only, and runs on C and L-band satellite signals, beaming up to date news as well as other information like books, educational videos and files daily. To receive it you will need one of their official or homemade versions of the Lighthouse or Lantern receivers (the latter of which is still to be released), or an RTL-SDR or similar SDR. Recently they began test broadcasts of their new 5 kHz 1539.8725 MHz L-band signal on Inmarsat I4F3 located at 98W (covers the Americas), and they hope to begin broadcasts in more regions soon too.

The typical RTL-SDR is known to often have poor or failing performance above 1.5 GHz (though this can be fixed to some extent), so Outernet have been working on an L-band downconverter. A downconverter works by receiving signals, and shifting them down to a lower frequency. This is advantageous because the RTL-SDR is more sensitive and does not fail at lower frequencies, and if used close to the antenna, the lower frequency allows longer runs of cheap coax cable to be used without significant signal loss.

Earlier this week we received in the mail a prototype of their downconverter. The downconverter uses a 1.750 GHz LO signal, so any signal input into it will be subtracted from this frequency. For example the STD-C frequency of 1.541450 GHz will be reduced to 1750 MHz – 1541.450 MHz = 208.55 MHz. This also means that the spectrum will appear reversed, but this can be corrected by selecting “Swap I & Q” in SDR#. The downconverter also amplifies the signal with an LNA, and has a filter to remove interfering out of band signals.

The Outernet downconverter circuit board.
The prototype Outernet downconverter circuit board.
Specsheet for the downconverter.
Specsheet for the downconverter.

We tested the downconverter using their patch antenna which they had sent to us at an earlier date (the patch antenna is used and shown in this Inmarsat STD-C reception tutorial). Our testing found that overall the downconverter works extremely well, giving us much better signal levels. Previously, we had used the patch + LNA4ALL and were able to get reception good enough to decode STD-C and AERO signals, but with the requirement that the patch be carefully pointed at the satellite for maximum signal. With the downconverter the signals come in much stronger, and accurate pointing of the patch is no longer required to get a signal strong enough to decode STD-C or AERO.

The downconverter can be powered by a bias tee connection, and this works well with our bias tee enabled RTL-SDR dongles. We also tested with the bias tee on the Airspy R2 and Mini and had no problems. It can also be powered with a direct 5V connection to a header, and they note that the header will be replaced by a USB connector in the production version.

The release date and exact price that these will be sold at is not confirmed, but we believe that it will be priced similarly to upconverters at around $50 USD or less. A good low cost downconverter should help RTL-SDR and other SDR users receive not only the Outernet signal better, but also other satellite signals such as STD-C and AERO. Although the input is filtered and the RF frequency is specified at 1525 to 1559 MHz, we had no trouble receiving signals up to GPS frequencies of 1575 MHz, and even up to Iridium signals at 1.626 GHz, though reception was much weaker up that high.

Below are some screenshots of reception. Here we used the Outernet patch antenna sitting in a windowsill with the downconverter directly after the antenna, and then 10 meters of RG6 coax cable to the PC and bias tee enabled RTL-SDR. We found that with the downconverted ~200 MHz signal the loss in the RG6 coax was negligible. Better reception could be obtained by putting the patch outdoors. In some screenshots we used Vasilli’s R820T driver with the decimation feature, which allows you to zoom into narrowband signals much more clearly.

Some AERO Signals Zoomed in with the Decimation feature in SDR#.
Some AERO Signals Zoomed in with the Decimation feature in SDR#. Received with the Outernet downconverter and patch antenna.
Some AERO and other Signals Zoomed in with the Decimation feature in SDR#.
Some AERO and other Signals Zoomed in with the Decimation feature in SDR#. Received with the Outernet downconverter and patch antenna.
Signals zoomed out.
Signals zoomed out. Received with the Outernet downconverter and patch antenna.

Comparing Home Made Inmarsat Antennas

Over on his blog “coolsdrstuff”, the author has uploaded a new post showing his comparisons of various home made Inmarsat antennas. In his post he tests a tin can helix antenna, a 10-turn helix antenna, and a LHCP helix feed on a 81cm DirecTV dish.

His results show that the dish outperforms the helix antennas by a significant amount, but only once he took it outdoors. The 10-turn helix antenna also worked better than the tin can helix, although he found that it required very accurate pointing.

Inmarsat are geostaionary satellites that transmit signals on L-band at around 1.5 GHz. They transmit signals that can be decoded with an RTL-SDR, such as STD-C EGC (weather, messaging and safety messages for boats), as well as AERO (the satellite version of ACARS for aircraft).

Good Inmarsat reception with the dish.
Good Inmarsat reception with the dish.