Paul (microp11) is the programmer behind the Scytale-C Inmarsat decoder which has become very popular with RTL-SDR owners. With Scytale-C, and RTL-SDR and an appropriate L-band antenna and amplifier it is possible to receive STD-C NCS data from Inmarsat satellites. This is a public broadcast which contains information like search and rescue (SAR) and coast guard messages as well as news, weather, pirate activity and other incident reports. If you're interested, we have a tutorial available here which uses different software.
Paul has recently created a 6-part video series explaining Scytale-C and all it's features. As well as showing how to setup a Scytale-C decoder with the SDR# plugin in order to receive the STD-C text data via the UI, Paul's series goes into more depth showing how to review and inspect the raw data packets, how to monitor multiple Inmarsat channels at once using SDR# Spyservers and how to use the map feature for plotting coordinate and region data.
Recently RTL-SDR.COM reader Bert has been experimenting with our active L-band patch antenna product. He's written in to share that he's found that using it as a feed for a satellite dish works well to improve SNR on those weaker 10500 AERO signals which Bert found that he could not decode from his location due to insufficient SNR. Our active L-band patch antenna receives signals from 1525 - 1637 MHz and can be used for signals from Inmarsat, Iridium and GPS satellites.
To use the patch as a feed Bert used a 40mm drain pipe and mounted the antenna on the end of the pipe. The drain pipe fits perfectly into the LNB holder, and once mounted the distance and polarization rotation can easily be adjusted for best SNR. He also found that adding a secondary sub-reflector about 17x17cm in size helped to boost SNR by about 3-5 dB too.
Bert has tested the active L-band patch as a feed on a 65cm satellite dish and a smaller 40cm dish, both with good results.
Just a heads up that the preorder sale on our new L-Band Patch antenna set will be ending October 21 as we are almost ready to ship the units out. After the preorder sale ends the pricing will rise from $34.95 to $39.95 USD.
Preorder has now ended and shipping will begin shortly. Thank you!
The product is a ready to use active patch antenna set that is designed to receive L-Band satellites such as Inmarsat, Iridium and GPS. It is enclosed in a waterproof plastic case, and can easily be mounted to a window using the provided suction cup and 2M coax extension cable. It can also be mounted to almost anything else using the included flexible tripod legs, or if you prefer, use the standard 1/4" camera screw hole to connect it to any mount that you like.
The antenna is powered via 3.3V - 5V bias tee power, so any bias tee capable SDR such as our RTL-SDR Blog V3 can be used to power it.
Over on his YouTube channel Corrosive from the SignalsEverywhere YouTube channel has uploaded a video where he tests out the new US$29.95 NooElec PCB patch antenna for receiving L-band satellite signals. In the video he shows how it can be combined with one of their SAWBird L-band low noise amplifiers in order to receive L-band satellite signals such as Inmarsat STD-C and AERO.
We note that our own RTL-SDR Blog Active L-band patch antenna will be ready to ship out before the end of this month, and while waiting for it we are currently having a preorder sale for US$34.95 including free shipping over on our store. For US$34.95 our patch antenna is fully contained in a waterproof enclosure, includes an LNA built in, and comes with several mounting options, so we believe that it is really a great deal. The patch design is based on the Outernet ceramic patch that was compared against the NooElec PCB patch shown in Corrosives video, so performance will be very similar.
Nooelec NEW Inmarsat Patch Antenna with Airspy SDR
Over the last several months we've been working on a versatile active L-band patch antenna that can cover Inmarsat to Iridium satellite frequencies. That antenna is now almost ready, and should be able to ship out from our Chinese storage warehouse by week 1 or 2 of October NOTE: Due to an unfortunate Typhoon near the factory in Taiwan, and the Chinese National Week long holidays and Taiwan National day we are expecting them to ship out in week 3 or 4 of October now. Apologies for the delays. No other components like filters or amplifiers are required to be able to use this antenna, as it is an all in one system.
The expected price will be US$39.95, but right now we're releasing it for a discounted PREORDER price of US$34.95 incl. free shipping.
Your preorder will ship out as soon as it's stocked in the warehouse in China. If you prefer to wait we'll also have this product on Amazon (at retail $39.95) about 2-3 weeks after it is stocked in our Chinese warehouse.
The antenna is based on the active (low noise amplified with built in filter) ceramic patch design that was used by Othernet (aka Outernet), back when they had their L-band service active. We've asked them to modify the antenna to cover a wider range of frequencies, and include an enclosure that allows for easier mounting.
The antenna is 3.3 - 5V bias tee powered, so you will need a bias tee capable RTL-SDR like our RTL-SDR Blog V3, or a 5V external bias tee. It draws about 20-30mA of current, so it is compatible with other SDRs like the SDRplay, HackRF and Airspy too.
With this antenna we've paid close attention to the mounting solutions. One major difficulty with these patch antennas is finding a convenient place to mount them. The patch is designed with a built in 1/4" camera screw hole, so any standard camera mount can be used. In the kit we're including a window suction cup, a flexible tripod and 2 meters of RG174 cabling to help with mounting. Your own longer coax cabling can be used, however we'd recommend using lower loss cabling like RG59/58 or RG6 for anything longer than 3 meters.
The patch is also fully enclosed in an IP67 weather proof plastic case, so it can be kept mounted outdoors in the rain.
With the patch receiving AERO, STD-C and GPS should be a breeze. Simply point up at the sky, or towards the Inmarsat antenna, apply bias tee power and receive. Below are some sample screenshots showing reception.
The patch is designed to be used with a 1m+ length of coax cable. It may perform poorly if the RTL-SDR is placed right at the antenna due to interference.
If receiving Inmarsat, the patch antenna should ideally be angled to face the satellite.
Rotate the patch until the signal strength is maximized. Rotating the patch optimizes the polarization of the antenna for the satellite and your location. NOTE: Using the wrong orientation could result in 20 dB attenuation, so please do experiment with the rotation.
You can also use the patch on a flat surface for Inmarsat (and rotate for best reception), but signal strength may be a little reduced. Depending on your location and the satellites elevation it should still be sufficient for decoding.
For receiving Iridium and GPS signals you can use the antenna flat, pointing straight up towards the sky. Try to get it seeing a clear view of the sky horizon to horizon to maximize the satellites that it can see.
If you happen to have a very marginal signal, you can clamp on a flat sheet of metal behind the patch antenna for improved performance.
AERO C-Channel: C-Channel transmissions are at 1647-1652 MHz which are outside of the advertised range of this antenna. However, the filter cut off is not that sharp, and you may be able to get results, although we cannot guarantee this. (If you want to test this for us and can demonstrate that you can receive C-Channel already, please contact us at [email protected] for a sample)
Over on his YouTube channel Tech Minds has been testing some antennas for Inmarsat and Iridium L-Band satellite reception. Inmarsat is a satellite service that runs on geostationary satellites, and one can be received from almost anywhere in the world. There are various services, but the ones that are easily decodable are STD-C EGC and AERO. EGC contains text information search and rescue (SAR) and coast guard messages as well as news, weather and incident reports, and AERO is a form of satellite ACARS, and typically contains short messages from aircraft.
In the first video Tech Minds tests what appears to be an as of yet unreleased prototype PCB patch antenna being designed by NooElec. The PCB patch antenna is combined with a SAWBird Inmarsat LNA and an RTL-SDR. With it he's able to receive STD-C and AERO signals.
In the second video Tech Minds tests an L-Band QFH antenna salvaged from a Vaisala weather balloon radiosonde. The QFH is designed for GPS frequencies, but can potentially be used at the slightly higher Inmarsat and Iridium frequencies. Tech Minds combines the QFH antenna with a SAWBird Inmarsat LNA, but unfortunately finds that reception is too weak for any AERO decoding to be possible. However, when used on the higher Iridium frequencies the antenna works well, and he's able to decode packets with Iridium Toolkit.
New Inmarsat Antenna from NooElec
Testing A QFH Antenna For Inmarsat And Iridium
RTL-SDR Blog L-Band Patch Antenna Preview
We note that over the last several months we have been working on our own L-band patch antenna that will cover Inmarsat, GPS and Iridium frequencies all in one. We expect manufacturing to be completed near the end of the month, or early next month.
The antenna is a ceramic patch, and will come in a waterproof enclosure. It will be possible to easily mount the antenna on a window or elsewhere using the standard suction cup and bendy legs tripod included with our dipole kits. Target price is US$39.95 including the suction cup, tripod, 2M coax and shipping, but we may have it initially on sale for a lower price.
This is cheaper than buying an Inmarsat & Iridium LNA, but a bit more than the SDR-Kits patches that they brought out a few weeks ago. Although performance of our patch is much better. Keep an eye out for the initial information post coming in the next few days.
SDR-Kits.net have begun selling low cost GPS antennas that are modified to receive the Inmarsat satellite frequencies between 1535 MHz to 1550 MHz. They also have a version for Iridium satellites that receives 1610 MHz to 1630 MHz. The antennas are powered by a 3-5V bias tee, so they should work fine with SDRplay, Airspy and RTL-SDR Blog V3 units.
AERO messages are a form of satellite ACARS, and typically contain short messages from aircraft. It is also possible to receive AERO audio calls. STD-C aka FleetNET and SafetyNET is a marine service that broadcasts messages that typically contain text information such as search and rescue (SAR) and coast guard messages as well as news, weather and incident reports. Some private messages are also seen. To decode AERO Mike uses JAERO, and for STD-C he uses the Tekmanoid STD-C decoder.
Mike has also created a very handy bank of frequencies for the SDRUno frequency manager which can be downloaded from here.
We note that if you're interested in waiting, at the end of September we will have an L-band patch antenna set available too. Our antenna will work from 1525 up to 1637 MHz. Prototypes have shown have shown good Inmarsat, Iridium and GPS reception. More details coming next month when manufacturing gets closer to finishing up.
On his latest video Corrosive from the SignalsEverywhere YouTube channel discusses Inmarsat LES EGC and AERO ACARS decoding. Inmarsat is a satellite provider that has multiple geosynchronous satellites that can be received from almost anywhere in the world at around 1.5 GHz with an RTL-SDR and appropriate antenna + LNA. Inmarsat EGC and AERO are two channels on Inmarsat satellites that can easily be decoded.
The Enhanced Group Call (EGC) messages typically contain text information such as search and rescue (SAR) and coast guard messages as well as news, weather and incident reports. AERO messages on the other hand are a form of satellite ACARS, and typically contain short messages from aircraft. More interestingly with a bit of work compiling audio decoders, it is also possible to listen in to AERO C-Channel conversations, which is an emergency phone call service available on some aircraft.
In his video Corrosive gives an overview and demonstration of EGC and AERO reception.