RTL-SDR Tutorial: Decoding Inmarsat STD-C EGC Messages
Inmarsat is a communications service provider with several geostationary satellites in orbit. They provide services such as satellite phone communications, broadband internet, and short text and data messaging services. Geostationary means that the satellites are in a fixed position in the sky and do not move. From almost any point on earth at least one Inmarsat satellite should be receivable.
Inmarsat transmits in the L-band at around 1.5 GHz. With an RTL-SDR dongle, a cheap $10 modified GPS antenna or 1-2 LNA's and a patch, dish or helix antenna you can listen to these Inmarsat signals, and in particular decode one channel known as STD-C NCS. This channel is mainly used by vessels at sea and contains Enhanced Group Call (EGC) messages which contain information such as search and rescue (SAR) and coast guard messages as well as news, weather and incident reports. More information about L band reception is available at UHF-Satcoms page. See the end of this post for a tutorial on modifying a GPS antenna for Inmarsat reception.
Some examples of the EGC messages you can receive on the STD-C NCS channel are shown below:
|Military Operations: Live Firing Warning||
STRATOS CSAT 4-AUG-2015 03:21:25 436322 SECURITE FM: RCC NEW ZEALAND 040300 UTC AUG 15 COASTAL NAVIGATION WARNING 151/15 AREA COLVILLE, PLENTY CUVIER ISLAND (REPUNGA ISLAND), BAY OF PLENTY 1. LIVE FIRING 060300 UTC TO 060500 UTC AUG 15 IN DANGER AREA NZM204. ANNUAL NEW ZEALAND NOTICES TO MARINERS NUMBER 5 REFERS. 2. CANCEL THIS MESSAGE 060600 UTC AUG 15 NNNN
|Armed Robbery / Pirate Warning||
NAVAREA XI WARNING NAVAREA XI 0571/15 SINGAPORE STRAIT. ARMED ROBBERY INFORMATION. 301845Z JUL. 01-04.5N 103-41.8E. FIVE ROBBERS ARMED WITH LONG KNIVES IN A SMALL UNLIT HIGH SPEED BOAT APPROACHED A BULK CARRIER UNDERWAY. ONE OF THE ROBBERS ATTEMPTED TO BOARD THE SHIP USING A HOOK ATTACHED TO A ROPE. ALERT CREW NOTICED THE ROBBER AND RAISED THE ALARM AND CREW RUSHED TO THE LOCATION. HEARING THE ALARM AND SEEING THE CREW ALERTNESS, THE ROBBERS ABORTED THE ATTEMPTED ATTACK AND MOVED AWAY. INCIDENT REPORTED TO VTIS SINGAPORE. ON ARRIVAL AT SINGAPORE WATERS, THE COAST GUARD BOARDED THE SHIP FOR INVESTIGATION. VESSELS REQUESTED TO BE CAUTION ADVISED.
|Armed Robbery / Pirate Warning||
NAVAREA XI WARNING NAVAREA XI 0553/15 SINGAPORE STRAIT. ROBBERY INFORMATION. 261810Z JUL. 01-03.6N 103-36.7E. DUTY ENGINEER ONBOARD AN UNDERWAY PRODUCT TANKER DISCOVERED THREE ROBBERS IN THE ENGINE ROOM NEAR THE INCINERATOR SPACE. THE ROBBER THEIR BOAT. A SEARCH WAS CARRIED OUT. NO ROBBERS FOUND ON BOARD AND NOTHING REPORTED STOLEN. VTIS SINGAPORE INFORMED. COAST GUARD BOARDED THE TANKER FOR INVESTIGATION UPON ARRIVAL AT SINGAPORE PILOT EASTERN BOARDING AREA.VESSELS REQUESTED TO BE CAUTION ADVISED. CANCEL 0552/15.
|Submarine Cable Repair Warning||
NAVAREA XI WARNING NAVAREA XI 0569/15 NORTH PACIFIC. SUBMARINE CABLE REPAIRING WORKS BY C/V ILE DE SEIN. 05 TO 20 AUG. IN VICINITY OF LINE BETWEEN A. 21-37.3N 156-11.5W AND 25-03.6N 148-43.2E. CANCEL THIS MSG 21 AUG.
|Search and Rescue - Missing Vessel||
ON PASSAGE FROM LAE (06-44S 147- 00E) TO FINSCHHAFEN (06-36S 147-51E), MOROBE PROVINCE. VESSEL DEPARTED LAE AT 310500Z JUL 15 FOR FINSCHAFFEN WITH ETA OF 310800Z JUL 15 BUT FAILED TO ARRIVE. ALL VESSELS REQUESTED TO KEEP A SHARP LOOKOUT AND BE PREPARED TO RENDER ASSISTANCE. REPORTS TO THIS STATION OR MRCC PORT MORESBY VIAEMAIL: ******@****.***.**, TELEPHONE +*** *** ****; RCC AUSTRALIA VIA TELEPHONE +*********** INMARSAT THROUGH LES BURUM (POR ***,IOR***), SPECIAL ACCESS CODE (SAC) **, HF DSC ******* NL BURUM LES 204 4-AUG-2015 03:23:14 773980 AMSA_ER 23150928 PAN PAN FM JRCC AUSTRALIA 030858Z AUG 15 INCIDENT 2015/5086 AUS4602 CORAL AND SOLOMON SEAS 23FT WHITE BANANA BOAT WITH BROWN STRIPES, AND A 40HP OUTBOARD AND 5 ADULT MALES IS OVERDUE ON PASSAGE FROM LAE (06-44S 147- 00E) TO FINSCHHAFEN (06-36S 147-51E), MOROBE PROVINCE. VESSEL DEPARTED LAE AT 310500Z JUL 15 FOR FINSCHAFFEN WITH ETA OF 310800Z JUL 15 BUT FAILED TO ARRIVE. ALL VESSELS REQUESTED TO KEEP A SHARP LOOKOUT AND BE PREPARED TO RENDER ASSISTANCE. REPORTS TO THIS STATION OR MRCC PORT MORESBY VIA EMAIL: *******@****.***.**, TELEPHONE +*** *** ****; RCC AUSTRALIA VIA TELEPHONE +************ INMARSAT THROUGH LES BURUM (POR ***,IOR ***), SPECIAL ACCESS CODE (SAC) **, HF DSC *********, EMAIL: ******@****.***.** OR BY FAX +************. NNNN
|Scientific Research Vessel Drilling - Request for wide clearance||
NL BURUM LES 204 4-AUG-2015 02:29:41 709950 AMSA_ER 23153978 SECURITE FM JRCC AUSTRALIA 040224Z AUG 15 AUSCOAST WARNING 202/15 SPECIAL PURPOSE VESSEL JOIDES RESOLUTION CONDUCTING DRILLING OPERATIONS IN POSITION 28 39.80` S 113 34.60` E 2.5NM CLEARANCE REQUESTED. NNNN
PAN PAN TROPICAL CYCLONE WARNING / ISSUED FOR THE NORTH OF EQUATOR OF METAREA XI(POR). WARNING 050900. WARNING VALID 060900. TYPHOON WARNING. TYPHOON 1513 SOUDELOR (1513) 930 HPA AT 19.9N 133.2E WEST OF PARECE VERA MOVING WEST 12 KNOTS. POSITION GOOD. MAX WINDS 95 KNOTS NEAR CENTER. RADIUS OF OVER 50 KNOT WINDS 80 MILES. RADIUS OF OVER 30 KNOT WINDS 240 MILES NORTH SEMICIRCLE AND 210 MILES ELSEWHERE. FORECAST POSITION FOR 052100UTC AT 20.1N 130.6E WITH 50 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 935 HPA, MAX WINDS 90 KNOTS NEAR CENTER. FORECAST POSITION FOR 060900UTC AT 20.8N 128.1E WITH 75 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 935 HPA, MAX WINDS 90 KNOTS NEAR CENTER. JAPAN METEOROLOGICAL AGENCY.=
Equipment and Software
In terms of hardware the recommended products are:
- An RTL-SDR V3 dongle. This dongle includes a bias tee which is required for powering the LNA's or active antennas, and is improved so that L-Band reception is much more stable. Cost: $20.95 USD.
- An RTL-SDR Blog Patch antenna. This antenna is designed for receiving L-band signals and does a very good job at it. Cost: $39.99 USD.
Below we discuss the hardware in more depth and show some alternatives:
- Receivers: An R820T2 or E4000 RTL-SDR dongle (you might try one of our improved V3 RTL-SDR's with software activatable bias-tee built in so that powering the LNA's or GPS antenna is as easy as plugging them in.)
- Note that generic R820T2 dongles may not receive well above 1.5 GHz if the ambient temperature is too hot - fair warning that RX can be hit or miss at these frequencies. We tested some generic dongles at an ambient temperature of 16 degrees and it worked well, but when run in direct sunlight the RX eventually failed after 30 - 60 minutes. The E4000 should work better at L band frequencies but these tuners are rare and expensive now. NOTE that our RTL-SDR V3 does NOT have this problem thanks to its passive cooling and improved thermal design.
- If you have an Airspy SDR then this is even better (it has good RX at L band frequencies and has a bias tee). The HackRF and SDRPlay should also work.
- Antennas: An active L-band patch antenna, a Helix antenna OR a modified GPS active antenna. We tested two antennas, one was an air gap L-band patch antenna supplied by Outernet which was used together with one or two 15 dB LNA's. The second antenna was a modified active GPS antenna. Both worked well, with the Outernet air gap patch antenna being better. 2019 Update: We have also tested our new active L-band patch antenna that we manufacture and sell and this works very well too.
- GPS (low SNR): You can use a $3 - 10 shipped, 28 - 30 dB gain modified GPS active antenna. We show you how to modify such an antenna at the end of this post. Note that RX with this antenna is just on the edge of being able to decode the signal properly, but at this price it may be worth a shot. Also note that you will need a bias tee, or bias tee compatible dongle to power a GPS antenna.
- Patch (medium SNR): 2019 Update: We now sell an active patch antenna for US$39.95 shipped on our store that is perfect for L-band satellites. See the release post for more information. Also see another post for information from Adam 9A4QV on dimensions for building a home made patch antenna.
- Dish/Helix (highest SNR): If you want the highest SNR, then a dish or helix is the antenna to use. You can build at home a RHCP helix antenna with about 25 turns for about 15dBi of passive gain. With this only one LNA should be needed. UHF-Satcoms L-Band page shows some good information on building such an antenna. If you have a TV dish then this can also be used with a smaller LHCP (LHCP as the dish reflects the polarization) helix antenna as the feed. (Thank you Adam for the comment on these antennas.)
- LNA's: If you're not using an active antenna like our patch, then you'll need an LNA such as this LNA for Inmarsat and Iridium by NooElec. Note that to use this LNA you will need a dongle with a bias tee, such as our RTL-SDR V3, or an external bias tee.
As a second choice Adam's LNA4ALL should also work decently, but in our experience the L-Band SNR is not as good as with a dedicated Inmarsat LNA.
- Software: The demo (or paid) version of the Inmarsat decoder from inmarsatdecoder.com or the Tekmanoid Java based STD-C EGC decoder or Scytale-C. As of 2019 all three have similar performance.
- Audio Piping: You will also need to have installed SDR# or similar and Audio piping software like Virtual Audio Cable, VB Cable, or have enabled stereo mix.
2019/2020 Update: This post was written before we had our own L-band patch antenna, and back then we use the Outernet L band patch antenna which is no longer for sale. Here is what the prototype they sent us looks like. It has a VSWR of about 1.1 at 1.5 GHz and 1.45 at 1.56 GHz. As of 2019/2020 you can instead just use our patch antenna to almost guarantee reception.
- The first step is to find out where in the sky your local Inmarsat satellites are. We think that the easiest way to do this is to use a free Android app called "Satellite AR". Simply open this app and search the satellite database for "Inmarsat". Choose Inmarsat 3-F or 4-F and use the augmented reality camera view to spot the position of these satellites. Note that the satellite position is fixed so the satellite will not move over time - there is no need to do any antenna tracking.
- Point the L-band antenna towards the satellite and get it in an unobtructed view of the sky.
- Connect the LNA's near the antenna. We suggest using a few meters of coax to get the RTL-SDR a few meters away from the antenna as it's own unintentional emissions tend to cause interference at L band frequencies. We recommend using low loss RG6 or similar, but if you have two LNA's lower quality cable may be acceptable. Another option to prevent the interference is to shield the RTL-SDR with a metal box.
- Choose and set your default audio piping method in Windows sound recording properties (e.g. Stereo Mix, Virtual Audio Cable or VB Cable).
- Set the audio piping method to have a sample rate of 48 kHz by setting it in the Playback and Recording properties tabs.
- Open SDR# and set the output audio dropdown box to the audio piping method that you have chosen to use.
- Start SDR# and tune to 1.541450 GHz. You should see a thin signal that is about 2.5 kHz in bandwidth, this is the STD-C NCS channel. Since the signal is right hand circularly polarized (RHCP) you might try rotating the antenna you are using for best reception.
- If the signal is not at the correct frequency due to oscillator drift and PPM offset, then carefully center the signal on your tuning bar using the PPM correction in SDR#. Note that at these L band frequencies a 1 PPM adjustment can be quite large for a narrowband signal like this (1 PPM = 1.5 kHz @ 1.5 GHz). If you cannot exactly center the signal using PPM correction alone, then just manually center the signal with the mouse or tuning bar.
- Now set the mode to USB and tune exactly 2 kHz below the center frequency. E.g. in SDR# if the center frequency was exactly 1.541.450.000 kHz then tune to 1.541.448.000 kHz.
- Set the bandwidth to about 4 kHz (4000).
- Open the Inmarsat decoder demo program called tdma-demo.exe. Watch the QUAL values in the lower left. If it is near zero, turn up the volume in SDR# until you start see a number above zero. Keep adjusting the volume until the QUAL value peaks. (Alternatively open the tekamnoid decoder and adjust the volume so that the volume bar is green).
- After a few seconds you should begin to see information in the command window. Check in the Inmarsat decoder folder for automatically saved .txt files of the actual received messages, like the ones in the examples shown above.
Below is an example of what an Inmarsat STD-C NCS channel sounds like when tuned in USB mode, 2 kHz below the center frequency. Also a screenshot showing what running SDR# and Inmarsatdecoder should look like.
Note that if you don't have a TCXO dongle then the frequency may drift significantly for the first half hour or so. Even with a TCXO a 1 PPM temperature drift at 1.5 GHz is 1.5 kHz which can be large enough to cause enough trouble with decoding a 2.5 kHz narrowband signal like this. We recommend waiting long enough for the temperature drift to settle before tuning, probably a couple of minutes with a TCXO dongle and possibly over 30 minutes for a non-TCXO oscillator dongle. After the inmarsatdecoder program gets a lock it will continue to track the signal for drifts of about 500 Hz.
The paid version of the Inmarsat decoder can also decode private messages that are sent through the channel. This includes stuff like personal messaging and emails with attachments like office documents. The full version costs 100 euros. Note that decoding these private messages may not be legal in all countries, so please respect your local laws.
How to Modify a GPS Antenna for Inmarsat Reception
A cheap $10 USD active GPS antenna can be modified for Inmarsat reception (though we need to note that it is not a particular good antenna, but it should be enough for STD-C NCS). Note that GPS antennas are active (as in require DC power), so you will need an external bias tee module, or an SDR with a bias tee option, such as our dongles. Active GPS antennas contain a ceramic patch antenna, LNA and bandpass filter which is tuned for 1575 MHz. The bandpass filter prevents reception from signals more than 1-2 MHz away from 1575 MHz. All that is needed to modify a GPS antenna for wide band reception is for the bandpass filter to be removed. Below we show how this is done on a cheap GPS antenna that we bought.
Update: It turns out that not all GPS antennas have a bandpass filter installed. Many very cheap GPS antennas simply don't have one installed as a cost cutting measure. These ones without filters should be good to go for Inmarsat already. Many GPS antennas will also look different on the inside with different shaped filters used.
First carefully remove the plastic case. On some antennas this can just be pulled apart with a flat head screwdriver, but on others you may need to cut apart the plastic with pliers. Inside will be the antenna. On the top will be a ceramic patch antenna, and on the bottom will be a metal reflector which will be covering the circuitry.
Using a soldering iron carefully remove the bottom reflector by desoldering the joints in the four corners. This is all that holds the reflector down. Removing the reflector will reveal the circuit.
You should be able to notice the bandpass filter on the circuit. It should be the largest component on the board and it may be labelled with the number 1575. On our antenna it was labelled with 1575P.
Carefully remove the bandpass filter. If you have the tools you can do it carefully with hot air. If you don't have the tools you can just rip it from the board by levering and twisting it off. Just note that this will probably pull up some of the PCB pads too.
Now with the filter removed, bridge together the IN and OUT filter pads by soldering on a wire or 100 pF capacitor. These are usually the pads in the center of the filter. If the pads got completely removed when you ripped off the filter, then you can still bridge the gap by soldering to the connected components.
NOTE: Not all GPS antennas are the same! Some may have smaller looking filters (it seems that some don't even have filters and require no modification, though those seem to be rare) and some may require a capacitive bridge instead of a wire bridge. See Adams video for an explanation. If the filter is connected directly between the two amplification transistors (no capacitor block already in place) then you should use a ~100pF capacitor instead of a wire bridge.
Now solder back on the reflector and put the whole thing back into the plastic case and your done! You may also want to experiment with reducing the length of the lossy RG-174 coax used on most cheap active GPS antennas, or with instead using lower loss coax like RG6.
The GPS antenna is not as good as the dedicated L-band patch antenna with LNA(s), but it was still good enough to decode the signal. See below for a waterfall comparison between the two antennas. Mouse over to see the GPS antenna waterfall. The STD-C NCS channel is the first thin line to the left of the red tuning bar.
In this setup we used two LNA's on the Outernet patch antenna, and 3M of extension RG174 (RG174 is very bad at L-band frequencies which is why we needed to use two LNA's, if you use RG6 cabling or similar then only one LNA should be needed). Without the extension cable only one LNA was needed for similar SNR levels. The GPS antenna used the 3M of RG174 coax that it came with. You can also improve the reception with a GPS antenna by placing it on a large metallic surface, like a cookie tin. Using the metallic surface may be the difference between getting decodes and not.
What else is at L Band?
There are many signals at L band frequencies coming from Inmarsat and other satellites like Iridium. You may be interested in Iridium pager decoding which occurs at 1.626 GHz. Some YouTube talks and links about decoding Iridium can be found here and here, plus notes by a user on our forum here.
| If you enjoyed this tutorial you may like our book available on Amazon. Available in eBook and paperback formats.
The Hobbyist's Guide to the RTL-SDR: Really Cheap Software Defined radio.
No .. But I did use the scytalecUI and scytalecC and really liked it … Gave the commercial versions a real run for their money. I find SDRSharp just not reliable and it crashes after a while.
Cool! If you don’t mind me asking, out of the ones you’ve tried, which SDR/software you found to be the most reliable? Would help me as well as a developer to know this. Much appreciated!
Funny that .. I haven’t found anything that’s stable besides using a Raspberry pi and a win computer. I wish I could find a STD-C decoder in linux.
It might take some time, but some weeks ago I have made the changes and compiled the scytalec decoder for RPi. The decoder takes IQ as input and spits out Inmarsat frames as needed by the Scytalec QuickUI. I could package that if anyone interested to test. On the 3b it barely scratches the surface in terms of processor so the idea is that a handful of channels (based on the sdr BW) can be decoded at the same time. The idea is to use the ftp sdr to tap into the BW, and then process individually the 4k channels with a small app that only does this.Then feed the IQ into the decoder which already outputs the inmarsat frames as mentioned above.The problem is the time, not the actual coding. If anyone interested into writing the code, I would be happy to help with all the parts need be put together.
Wow.. I would be .. I am not really a programmer but I can try help as I have a 24/7 feed off a 1M dish
Thank you..will try again
Thank you. I will try I have a nooelec LNA. What must the QUAL be to start decoding
If you are refering to the Tekmanoid decoder, then the SIGNAL really needs to be 80% minimum and the QUALITY needs to be 100%.
Out if interest. What’s the smaller dish I could use that’s not off center.
Difficult to say, it depends on where you are in relation to the satellite. Some people in Europe for example, simply place the patch antenna on their window sill. I’m some 40,000 Km away from the nearest Sat so i need the 1M dish.
Thanks Phil. Ordered a 1.2m C band dish… Hope that dies the trick.. also opens many other areas. I also have a bladerf so gonna try that
By any chance any of you have tested the SDRSharp plugin or the decoder at https://bitbucket.org/scytalec/scytalec/downloads/ ?
Thanks guys.. to I have had no luck. Fustrated beyond and means. I build a (Adam)patch and modified a GPS antenna ..bought a version 3 rtl_sdr dongle. Have a nooelec filter but no go…is the QUAL value suppose you get to 100 or just over 0… Tried everything.. maybe I can’t get inmarsat in South Africa but I see a lot of peaks
You will need to run an LNA for best results. I’m running the patch antenna on a 1m dish and i get no decodable L band signals without one. They make all the difference.
When modifying the GPS antenna could you simply bridge the bandpass filter with a couple of wires/capacitors, or do you really need to unsolder and or destroy the filter chip?
Perhaps do you know what its about this gps-pcb (cirocomm 580).
Especially the Y1 marked component (is it a crystal?, but for what, i cant see an ic?).
Can I use it like that or is there any Function to Filter with this oscillator(Timer or what ever)?
The PCB: https://pasteboard.co/H9J35Ep.png
i want built a inmarsat dish antenna – now i look for the best solution – shold i use a Helix or a Outernet patch?
99.999% of all this “OuterNet” stuff is pure B.S. These guys send folks off on snipe hunts. Load this, run this, gotta have this hardware, nope that hardware has been deprecated, need THIS new hardware from our store, now you need all this new software and don’t forget to load these images and let’s not forget all the changed satellites, nope not using that one anymore, gotta use this one, and BTW it requires all THIS new hardware and software. Let’s not forget about all the damn virii in all these software installs. SNIPE hunting for wiper fluid, from luxury-class douchebags.
Which frequency is used in europe for inmarsat stds-eg
how to modiify this&
I might be wrong, but i guess you gotta remove this big element with “1575P” written on it, and bridge some pads. Just look at the guide, seems to be the same one.
I have an excellent signal on L band, and am trying to decode the Sat C messages. I am using both TDMA-DEMO and the Java app Tekmanoid. To say it’s frustrating is an understatement. The TDMA-DEMO app decodes the first frames of many messages, but the Tekmanoid just shows the frames but no EGC messages. I am interested how the author of this article was able to decode the EGC messages. Incidentally I can decode Inmarsat Aero easily.
Or you sure you are connected to the good satellite ? From France I’m connect to AOR-E. Verify the direction of your antenna. You can see the ACCARS inmarsat in 1545mhz and not 1541mhz EGC. the difference between 2 sat is some degrees…
If the frame number on the right keeps incrementing you are doing fine. (and you are on the NCS channel)
You just have to wait for the EGC messages to appear
/Alex – tekmanoid
Am succesfully runnuing piAware on an RTL-SDR stick, and am active in the FlightAware forums, so know a little bit about this area.
Never done anything with satellite or SDR# like this though.
I (believe) succesfully removed and bridged the filter from the GPS antenna.
However, when I tried to follow the tutorial re SDR#, even though I followed each step and matched the settings shown in the screen grab, my frequency graph looked nothing like that shown above.
Interestingly, JAERO got to the stage where it had a green light on both Volume and Signal, but never got any data – the java tool above also showed activity in the “volume” area, but never got any data.
I apreciate a blog post like this may not be the ideal place for a full discussion – are there any appropriate forums for such a discussion / support / to get involved with?
Thanks – looking forward to getting this working! 🙂
I share Bill’s frustration. Can’t get the Tekmanoid program to work, seems there is no option to select the sound card for piping in the audio. The other software, when attempting to download has some severe warnings, sort of like a software armageddon if downloaded. Oh well, maybe it’s me, will keep trying. Great post though.
You can usually set the audio source, in Windows, from the Mixer application. It usually has the recording device options , so if you do have Virtual Cable installed it should show as a source .
I added a soundcard select option… 🙂
Thank god for these posts! I thought I was going nuts! I have been trying to find info on this program, and the virus. is it possible to buy the full version(Happy to pay even double) How , Where, Who?????? I’m Handicapped and in a wheel chair and this is a important hobby for me. Any info on sucsessfully down loading std c decoder would be greatly appreciated!!!!! Thank You! Bill.
Great great article. A few things that might help when building that RHP helical. First off, a spray can of Febreze has the exact diameter needed for making the coil. Next, if you get some plastic straws (I used at least 2) and make holes in the straws (I used a heated wire to melt the holes) at the correct spacing, you can thread the straws through the coil to stabilize the windings. Then you can epoxy the coil at the holes in the straw for a strong fit. For the counterpoise (ground plane) I got a 1 x 1 foot piece of galvanized sheet metal at Home Depot and cut it to size.
My plan is to use the RHP antenna and a 1 meter satellite dish aimed at 15.4W (Inmarsat F2). Coincidentally, Telstar 12 is a FTA Ku band satellite at 15W, so the plan is to first find that and I should be near F2. Just a note, Invacomm makes a LNB for both linear and circular polarization, the QPH-031 which has outputs for both linear and circular polarization, but as per the specs the output frequency is only up to 1.45 GHz. However it is worth a try to see if it will work. Again a great article, thanks!
With the demo decoder, what can one see? Only the header info, or possibly the full message, like the many shown in the 1st post and then in the tutorial post. I think I need the paid version of the decoder to see all of the message. If so, probably the demo is good enough for me.
With the demo (and alternative mentioned) you can see full public safety broadcast messages, like the ones shown in the article. You just cannot see the private messages.
Thanks about what I can copy. I live on west coast of Southern California. I’m thinking Inmarsat 4-F3 would be an easy aim, for its azimuth is about 150 degrees and elevation about 45 degrees. Am I correct?
what if you put the GPS antenna in the focus of an satellite dish? This should give a plenty amount of power to the antenna. You have to try the real distance / focus where to place the GPS patch thing.
73 de DE8MSH
– tell me the link to download?
Demo from http://www.inmarsatdecoder.com
Full version for personal use is available for 100€.
For demo https://www.virustotal.com/ru/file/fec9e74d6aa172ef16801c6d883ec789c4c705d97aff3b6b3b12d1cbc815a8db/analysis/1419921960/
Yes see the explanation in the article under the software heading. We believe the virus detection is a false positive. You can talk to other users of the software and the author on #hearsat on starchat IRC who will verify that it is clean. But if you don’t want to risk it then use the alternative, but the alternative is not as good.
Too many false positives on so many vendors. Perhaps their utility is developed.
I can’t get Windows 7 to let me run the .exe file. It say “this file may have a virus in it” (or something similar) and removes it. I think Inmarsat doesn’t want us to have it anymore. Is there a workaround other than the other decoder mentioned?
just add the file to the exception list. (should be relativly easy task depending on your antivirus)
Have you actually been successful in doing what you suggest for this particular file: tdma-demo.exe?
When I used tdma-demo.exe I had to un-quarantine the file and then add it as an allowed item in Microsoft Security Essentials (the default Windows AV). The steps depend on what antivirus you use.
Well, I got the decoder running by making 2 exceptions, one in the the Firewall and one in Security Essentials. And I do have have Stereo Mix in PC, so it’s on to the next step. I tell you, it’s sure scarry seeing the .exe being deleted over and over without the exclusions. Makes you want to quit the whole project!