Inmarsat .. something different

S

spacedish

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My Satellite Setup
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90cm Greg
90cm offset
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Its quite a while since I last posted and perhaps like me , C band dish owners may be looking for something different to use their C Band kit on.
If , also like me , you have an interest in aviation , you may like to try joining a small group of enthusiasts who are looking at receiving flight tracking data from the Inmarsat fleet.
I help to develop and run Planeplotter ,a non commercial a/c tracking network which is run on
an amateur basis.Most of our 4000 members are either radio amateurs or have an interest in radio/computing or sat comms .Planeplotter network tracks a/c in flight using various techniques , some unique to the software.
In the spirit of co-operation should an aviation incident occur , we volunteer our data to the invetsigating bodies , such as the UK AAIB and other organisations.

Following the MH370 tragedy Inmarsat offered to develop a new oceanic tracking system which would involve long haul oceanic flights "logging in" at least every 15 minutes.That system is still in its infancy but with more and more a/c using satcomm systems it is now possible to monitor the location of oceanic traffic by taking the Inmarsat C band aero feed and running it through recently developed software.
We are looking to set up a small global network of satellite ground staions to pick up the data feeds.
Inmarsat use dishes of 8m plus at their earth stations.
recent tests have shown that using a PLL lnb its possible to see the data using a dish of just 1.8 m

All that is required is a dish , PLL C band lnb , receiver loop through, SDR # software and an rtl tv dongle [cost of latter about £10] and a PC
Most group members probably have all of this!

At present there are just a handful of us doing the tests , worldwide. Ideally we would like a twenty or so sites in the AOR/IOR and POR sectors to set up a global network.

So if your C band dish is sat there doing nothing , why not join us in the groundbreaking work.
The decoding sw is still in the development stages but already producing results.
Ultimately the position reports will be fed into the Planeplotter network to give real time Oceanic coverage.

Its a fascinating aspect of our hobby .

If you fancy giving it a try , let me know.
 
Vipersan

Vipersan

Emmett Browns Ghost
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Sounds like a very interesting project indeed...
Though I suspect most UK Cbanders are limited as to dish size...and certainly the Titanium C1 PLL makes it more likely that amateurs could get a sniff..
Could you perhaps post a list of minimum system requirements ...
Min Dish size ...etc

Plus the all important Sat data ..
ie which Inmar sats ..
Arc locations to check..
Transponder details etc..
Thus we could at least check relative signal strengths ..and viability..

I'm also assuming that to take part in this project ...the Cband dish would have to be 'dedicated '
ie..pointed at a location and left there ?
Sadly this wouldn't appeal to a single BUD owner ...as we do like to DX ..
If it could be done with a smaller dedicated dish ...then maybe .....

Would this also require a dedicated PC running 24/7 to process the received data ...much like a weather station ?
rgds
VS
 
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S

spacedish

Regular Member
Messages
43
My Satellite Setup
1.8PF
90cm Greg
90cm offset
Ka mil lnb
numerous receivers
S band
My Location
north west uk
Hi Vipersan

Many thanks for your reply.
Presently tests have been carried out in N Zealand and Germany with 3 m dishes plus my own set up in UK with 1.8 m dish the dual Titanium PLL lnb.

For Europe we use inmarsat 15 west.This handles three or four earth stations
from the UK across to Italy.Each earth station has its own ident.

My 1.8m dish is giving good level signals .These are burst data mode which is why
expert help has been needed to decode them and AFAIK its the first time anyone has managed this.

Basically I put the dish on 15W , feed the signal into and out of a standard
receiver using loop though to an rtl dongle....that is linked via USB to PC running SDRSharp...you can then fine tune and see the signals.
From there the data is fed to JAERO software, which has just been updated to process the data into readable format.

For a full overview see
JAERO

Once tests have finished , then yes , dedicated systems would be ideal , but not
a must as there would be some redundancy built into the network.
As I mentoned , ultimately the decoded data will be fed into planeplotter so that the location data can be plotted.

PlanePlotter from COAA

the signal from the a/c is rather complex....it goes up to satellite via L Band , then down to the earth station via C band.
Although we can easily see the data from the ground up to the a/c , that data does not contain location info...so its the CBand info that is important.

So in summary , using a titanium PLL Lnb 1.8m is suffiicient.


Regards


John
 
S

spacedish

Regular Member
Messages
43
My Satellite Setup
1.8PF
90cm Greg
90cm offset
Ka mil lnb
numerous receivers
S band
My Location
north west uk
Sorry forgot to mention
Signals are in the 1535-1545mhz IF range.

I am away from QTH at present but back in a few days when I can post specific freqs for 15west
 
Vipersan

Vipersan

Emmett Browns Ghost
Staff member
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My Satellite Setup
IP9000HD +
TD110 Dish and TD88 Dish in Tandem
66°East to 60°West.
AZbox PrmHD + OpnbxS9HD + Skybox + DrHD F15
2x VboxII AZ-EL
2 m+ Alcoa PF + BSC421 C-Band lnbf...
+SS2/TwHnS2-3200 pci/TBS6925 pci
1.5 Fortec Star -Gbox - HtoH Ku/Ka/C
My Location
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Thanks for the reply SD ...
certainly has my interest though perhaps not until winter is over ..
Cold weather does not do my MS any favours ...lol
btw ..whereabouts in the NW are you ..?
I am a Mancunian ..

What I can assure you is that the more info you post on the project ...the more interest it will generate ..
cheers
VS
 
S

spacedish

Regular Member
Messages
43
My Satellite Setup
1.8PF
90cm Greg
90cm offset
Ka mil lnb
numerous receivers
S band
My Location
north west uk
Thanks VS.

I'm presently S Spain but home QTH is wirral

More info to follow once back home.
 
PaulR

PaulR

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QTH? Wirral? Do I know you?
 
S

s-band

Contributor
Messages
855
My Satellite Setup
1.5m IRTE PF, Octagon OSLO external Ref., TBS6983,
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Interesting. Having just done this Retro-fitting C-band to an old IRTE 1.5m PF I had a look. I think I found the signals but they appear to be centred on about 3618MHz RHCP. The strongest ones are about 20dB s/n in 10kHz which should be enough to decode. They pop up all over the range though which will complicate things. Attached is a plot from an analyser max. held for about 5 minutes. It looks like there were 12 different frequencies over that time. Looking at single signals, the bandwidth seems bout right for the data rate. See the png attachment.
It is quite difficult to peak on those signals so I looked for a beacon. I think I found one on 3950.665MHz LHCP. It is in the range listed on Satbeams but could be from Express on 14W, perhaps. Does anyone know the beacon frequencies for Inmarsat-3F2?
15w_rhcp_27-2-15.png 15W_RHCP_0940-27-2-15.jpg
 
S

spacedish

Regular Member
Messages
43
My Satellite Setup
1.8PF
90cm Greg
90cm offset
Ka mil lnb
numerous receivers
S band
My Location
north west uk
Hi S-band

Nice work , looks like you are getting there

Have a look at the JAERO link I posted earlier

Jonti has just updated his C band page which should help you zone in on the signals

I am just back in the UK /home QTH and having found my main PC is knackered have some catching up to do.
However using JAERO and jonti's instructions have managed to start getting the C Band T channel data around
1535 IF
These are short bursts of data containing location info.
 
S

spacedish

Regular Member
Messages
43
My Satellite Setup
1.8PF
90cm Greg
90cm offset
Ka mil lnb
numerous receivers
S band
My Location
north west uk
Sample data from a/c to ground.
Note the position reports

Acknowledgement ADS Contract Request Number = 1

Basic_Report:

Lat = 44.5381 Long = -13.9413 Alt = 37000 feet. Time past the hour = 25m
51s
FOM = 1F

Flight ID BAW248

Next waypoint Lat = 45 Long = -12.9999 Alt = 37000 feet. ETA = 00:07:24

Wind speed = 131.5 knots. True wind direction = 357 deg. Temperature =
-59.5
deg C.


11:27:15 27-02-16 AES:3C7205 GES:43 2 .D-ALPE ! B6 0 Flight AB7000




J90AAB7000/YQXE2YA.ADS.D-ALPE0729D1A79532488B59601D0C0854B7C30C201059B75E120D29F4A78E3908CA01772B60BF555548CA008C49




Basic_Report:

Lat = 58.8078 Long = -18.7741 Alt = 34996 feet. Time past the hour = 27m
04s
FOM = 1D

Flight ID BER7000

Wind speed = 89.5 knots. True wind direction = 311 deg. Temperature =
-61.75
deg C.

Next waypoint Lat = 59 Long = -19.9999 Alt = 36000 feet. ETA = 00:06:15


11:27:22 27-02-16 AES:3965A2 GES:43 2 .F-GZNC ! H1 0 Flight AF439




D64DAF0439#DFB...............................................

....................................................................

....................................................................
 
S

s-band

Contributor
Messages
855
My Satellite Setup
1.5m IRTE PF, Octagon OSLO external Ref., TBS6983,
Various L, S, C, X & Ka bits. 1.2m S/X/Ku/Ka Prodelin on Az-El
My Location
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Hi spacedish, maybe I'm doing something wrong but all I get are entries like this:
11:27:15 27-02-16 AES:3C7205 GES:43 2 .D-ALPE ! B6 0 Flight AB7000
It is quite marginal on my set-up with Eb/No of 10 or less and the constellation looks rough. It logs plenty of planes but no position information or other reports.

Each signal seems to be part of a group of 4, spaced at about 15kHz with number 3 being longer bursts which JAERO does not decode (1534.020 on attached SDR# plot). Is this the T channel? Any ideas where the position info etc is to be found?
There are also some stronger wider bandwidth signals which I think may have been what I saw on the plots in my earlier post

BTW, I could not get JAERO and SDR# to run on the same PC without JAERO crashing (Win XP). .

jaero.PNG SDR_Sharp_JAERO.jpg
 
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S

s-band

Contributor
Messages
855
My Satellite Setup
1.5m IRTE PF, Octagon OSLO external Ref., TBS6983,
Various L, S, C, X & Ka bits. 1.2m S/X/Ku/Ka Prodelin on Az-El
My Location
SE UK
Answering my own questions: I got it going on one PC by setting the audio in JAERO before SDR# and it now decodes the T channel (1534.02 on plot). So that is where the interesting data comes from. I think that there were problems with the physical audio connection as signals are decoded ok with Eb/No of 7ish. Using the virtual audio link fixed it.
 
S

spacedish

Regular Member
Messages
43
My Satellite Setup
1.8PF
90cm Greg
90cm offset
Ka mil lnb
numerous receivers
S band
My Location
north west uk
Hi S-band

Good to hear you have cracked it.

I am trying to rationalise the settings in SDR# so that we can all work to the same level.

Any chance you could put up a screen shot of the main settings section ?

Thanks.
 
S

s-band

Contributor
Messages
855
My Satellite Setup
1.5m IRTE PF, Octagon OSLO external Ref., TBS6983,
Various L, S, C, X & Ka bits. 1.2m S/X/Ku/Ka Prodelin on Az-El
My Location
SE UK
Hi, Here are screenshots of SDR# and JAERO. I found that one of my R820T sticks would not run for long at that frequency. I used an R820T-2 version in the end. It does get hot so I removed the case. I'm not sure about the frequency cal on the plots as I have not set the R820 offset.
JAERO works extremely well down to low Eb/No now I have sorted the audio feed.

SDR_Sharp_for_JAERO.jpg jaero.jpg
 
S

s-band

Contributor
Messages
855
My Satellite Setup
1.5m IRTE PF, Octagon OSLO external Ref., TBS6983,
Various L, S, C, X & Ka bits. 1.2m S/X/Ku/Ka Prodelin on Az-El
My Location
SE UK
Very interesting. I found this page
There is something strange with the Titanium. It looks like there is a 25MHz comb (or some of its teeth) present at the output. It would seem like the reference harmonics as opposed to synth sidebands. I have seen some comments here about "spikes". I plan to look when I get some time. I am also not convinced that the polarisation is very clean as I get better s/n with linear polarisation on Inmarsat.
 
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S

spacedish

Regular Member
Messages
43
My Satellite Setup
1.8PF
90cm Greg
90cm offset
Ka mil lnb
numerous receivers
S band
My Location
north west uk



Example of live tracking from Inmarsat
Red are real time locations , blue are the next two waypoints.
This is from 15West GES 43
 
Analoguesat

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Im impressed with that


Rather a shame

1) theres no way I can put a 1.8m dish in the garden
2) there are trees in the way anyway
 
Captain Jack

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That is very cool. I am surprised they don't encrypt this kind of data... but then, this is available via numerous sites anyway.
 
S

spacedish

Regular Member
Messages
43
My Satellite Setup
1.8PF
90cm Greg
90cm offset
Ka mil lnb
numerous receivers
S band
My Location
north west uk
Don't confuse this type of data with standard ACARS and ADS-B which we have been receiving for
well over ten years...this is a totally new concept.
 
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