Which signal is inmarsat C std-c?

Joined
Jan 26, 2018
Messages
2
#1
I recently built an inmarsat receiver with an active gps antenna, but I can't get any signal on 1541.5 Mhz. There are many other signals on different frequencies looks very similar to inmarsat signal, but my decoder can't decode any of them. So I am wondering what went wrong, maybe the SNR is not high enough to decode the signal or because I didn't tune to the right frequency? I went through the whole inmarsat spectrum and here is the video. https://streamable.com/fipdb I live in Australia and can receive Inmarsat 3-F1, Inmarsat 3-F3, Inmarsat 4-F1, Inmarsat 4-F2, Inmarsat 5-F1 and Inmarsat 5-F3.
 
Joined
Jun 7, 2006
Messages
42
Location
Dorset, South UK
#2
Inmarsat-C LES

Morning,

Download the SDR# software from airspy.com and point at my Inmarsat spyserver at sdr://pjm.uhf-satcom.com:55555

1541.450 is the NCS, you want to tune about 1541.4485 so about 1.5KHz LF in USB mode.

LES's can be found on my feed at 1539.695 and below, once you get used to looking for a BPSK signal in the FFT they are super easy to spot. I would recommend using a FFT span of 125KHz. See the attached image.

If you get stuck, join #hearsat IRC on starchat and numerous people can help if you ask.

I hope that's useful!

Paul.
 

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Joined
Jan 26, 2018
Messages
2
#3
Morning,

Download the SDR# software from airspy.com and point at my Inmarsat spyserver at sdr://pjm.uhf-satcom.com:55555

1541.450 is the NCS, you want to tune about 1541.4485 so about 1.5KHz LF in USB mode.

LES's can be found on my feed at 1539.695 and below, once you get used to looking for a BPSK signal in the FFT they are super easy to spot. I would recommend using a FFT span of 125KHz. See the attached image.

If you get stuck, join #hearsat IRC on starchat and numerous people can help if you ask.

I hope that's useful!

Paul.
I bought a dish and tried all visible satellites but found nothing. Maybe STD-C service is not available is Australia and ocean pacific region? Anyway, I got very strong aero-I signals, that is interesting enough to decode :)
 

dlwtrunked

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Premium Subscriber
Joined
Dec 19, 2002
Messages
490
#4
I recently built an inmarsat receiver with an active gps antenna, but I can't get any signal on 1541.5 Mhz. There are many other signals on different frequencies looks very similar to inmarsat signal, but my decoder can't decode any of them. So I am wondering what went wrong, maybe the SNR is not high enough to decode the signal or because I didn't tune to the right frequency? I went through the whole inmarsat spectrum and here is the video. https://streamable.com/fipdb I live in Australia and can receive Inmarsat 3-F1, Inmarsat 3-F3, Inmarsat 4-F1, Inmarsat 4-F2, Inmarsat 5-F1 and Inmarsat 5-F3.
You have to tune *very very* slowly and there is usually a little delay before the decoders sync with a received signal. You might want to let something like the program Argo looking at the waterfall display of the audio aid you in tuning at the same time. I use VBcable send the audio to the decoder and Argo at the same time to do that. I do not use Spyserver to do that so not sure how/if you do that with it.
 
Last edited:
Joined
Jun 7, 2006
Messages
42
Location
Dorset, South UK
#5
Hi Github, try these from POR

201 1539.655 Telenor Satellite Services Inc
202 1539.625 Stratos Global New Zealand Auckland
203 1539.515 KDDI Yamaguchi Japan
204 1539.595 EIK Telenor Norway
210 1539.605 Sentosa Singapore
211 1539.665 Beijing MCN China
212 1539.505 Stratos Burum Netherlands
217 1539.635 Nudol Morsviasputnik Russia
221 1539.615 France Telecom MSC

there is a lot more at https://usa-satcom.com/inmarsat-std-c/

regards,

Paul
uhf-satcom.com
 
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