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Problem in the decoding of INMARSAT-C bulletin board.

David L. Wilson
 

If I had an email address, I would have emailed this.
The decoding software MultiPSK when decoding INMARSAT bulletins boards has something that appears to be very wrong.  These are not

listings transmissions of stations in various regions (as MultiPSK decoding indicates) but is instead a transmission of LES on the same

satellite.  The software falsely assigns a region and an erroneous LES number when it states one.  Other software and monitoring of the

frequenceis indicates this.

For example (MultiPSK decode in quotes, mine after after):

Network Version: 2ØØ / Number of LES: 6
"1: Region: POR / LES: Ø / Status: 3ØØ bps return link / Spare satellite / Out of service / Clear / Terrestrial links open / Alerting

supported / Services: ALERT (Maritime Distress Alerting / SafetyNET Traffic / STD-C (Inmarsat-C Traffic) / Enhanced data reporting /

Closed Network / FleetNET Traffic / LES TDM channel number: 11818"

This is LES 001 on channel 11818 (1539.545).          11808*0.0025+1510=1539.545

"2: Region: AOR-E / LES: Ø / Status: 3ØØ bps return link / Spare satellite / Out of service / Clear / Terrestrial links open / Alerting

supported / Services: ALERT (Maritime Distress Alerting / SafetyNET Traffic / STD-C (Inmarsat-C Traffic) / Store & Forward / Enhanced

data reporting / Closed Network / FleetNET Traffic / LES TDM channel number: 11822"

This is LES 002 (STRATOS CSAT-Status Global-Burum, Netherlands per monitoring)  on channel 11822 (1539.555).

"
3: Region: IOR / LES: Ø / Status: 3ØØ bps return link / Spare satellite / Out of service / Clear / Terrestrial links open / Alerting

supported / Services: ALERT (Maritime Distress Alerting / SafetyNET Traffic / STD-C (Inmarsat-C Traffic) / Store & Forward / Enhanced

data reporting / Closed Network / FleetNET Traffic / LES TDM channel number: 11874"

This is LES 003 (KDDI, YAM-Yamaguchi, Japan per monitoring) on channel 11874 (1539.685).


"4: Region: AOR-W / LES: 32 / Status: 3ØØ bps return link / Spare satellite / Out of service / Clear / Terrestrial links open / Alerting

supported / Services: ALERT (Maritime Distress Alerting / SafetyNET Traffic / STD-C (Inmarsat-C Traffic) / Store & Forward / Enhanced

data reporting / Closed Network / FleetNET Traffic / LES TDM channel number: 11826"

This is LES 004 (EIK LES-Eik, Norway per monitoring) and probperly decodes as such; it is not LES 32.
Channel 11826 is 1539.565.

"
5: Region: AOR-W / NCS: 48 / Status: 3ØØ bps return link / Spare satellite / Out of service / Clear / Terrestrial links open / Alerting

supported / Services: ALERT (Maritime Distress Alerting / SafetyNET Traffic / STD-C (Inmarsat-C Traffic) / Store & Forward / Enhanced

data reporting / Closed Network / FleetNET Traffic / LES TDM channel number: 11834'

This is LES 012 (not an NCS but instead NL Burum LES-Burum, Netherlands per monitoring) on channel 11834 (1539.585).

"
6: Region: POR / LES: 4Ø / Status: 3ØØ bps return link / Spare satellite / Out of service / Clear / Terrestrial links open / Alerting

supported / Services: ALERT (Maritime Distress Alerting / SafetyNET Traffic / STD-C (Inmarsat-C Traffic) / Store & Forward / Enhanced

data reporting / Closed Network / FleetNET Traffic / LES TDM channel number: 1181Ø"

This is LES 021 (ASG 21 LES-Ausguel, France per monitoring) on channel 11810 (1539.525).

Note that I think the status indicated are also in errors: these are Operational/In service, not Spare/Out of service. 

The NCS (LES 044) for this satellite is on 1537.700 and that is in the transmission.
Note the LES are often remote uplinked from other locations than there location identified. 
Also, LES numbers are more properly displayed as octal (in Inm-C and Inm-Aero) so that the first digit indicated a region number.

Monitoring shows similar erroneous decoding.  For those who do not know, the transmitted format for these fills out a form and then lookup tables are used.  Something appears to be in error in the decoding parsing of bits.

Patrick Lindecker
 

Hello David,

 

I checked this and yes you are right there is a bug (on lists, there is a problem of bits reading direction). Thanks for the information.

I will fix this.

 

>Note that I think the status indicated are also in errors: these are Operational/In service, not Spare/Out of service. 
It concerns also  the data (Status…) of these lists.

 

>Note the LES are often remote uplinked from other locations than there location identified. 
I’m not sure to understand…

 

>Also, LES numbers are more properly displayed as octal (in Inm-C and Inm-Aero) so that the first digit indicated a region number.

I’ll add this indication.


73

Patrick

 

De : multipsk@groups.io [mailto:multipsk@groups.io] De la part de David L. Wilson via groups.io
Envoyé : mardi 23 juin 2020 13:19
À : multipsk@groups.io
Objet : [multipsk] Problem in the decoding of INMARSAT-C bulletin board.

 

If I had an email address, I would have emailed this.
The decoding software MultiPSK when decoding INMARSAT bulletins boards has something that appears to be very wrong.  These are not

listings transmissions of stations in various regions (as MultiPSK decoding indicates) but is instead a transmission of LES on the same

satellite.  The software falsely assigns a region and an erroneous LES number when it states one.  Other software and monitoring of the

frequenceis indicates this.

For example (MultiPSK decode in quotes, mine after after):

Network Version: 2ØØ / Number of LES: 6
"1: Region: POR / LES: Ø / Status: 3ØØ bps return link / Spare satellite / Out of service / Clear / Terrestrial links open / Alerting

supported / Services: ALERT (Maritime Distress Alerting / SafetyNET Traffic / STD-C (Inmarsat-C Traffic) / Enhanced data reporting /

Closed Network / FleetNET Traffic / LES TDM channel number: 11818"

This is LES 001 on channel 11818 (1539.545).          11808*0.0025+1510=1539.545

"2: Region: AOR-E / LES: Ø / Status: 3ØØ bps return link / Spare satellite / Out of service / Clear / Terrestrial links open / Alerting

supported / Services: ALERT (Maritime Distress Alerting / SafetyNET Traffic / STD-C (Inmarsat-C Traffic) / Store & Forward / Enhanced

data reporting / Closed Network / FleetNET Traffic / LES TDM channel number: 11822"

This is LES 002 (STRATOS CSAT-Status Global-Burum, Netherlands per monitoring)  on channel 11822 (1539.555).

"
3: Region: IOR / LES: Ø / Status: 3ØØ bps return link / Spare satellite / Out of service / Clear / Terrestrial links open / Alerting

supported / Services: ALERT (Maritime Distress Alerting / SafetyNET Traffic / STD-C (Inmarsat-C Traffic) / Store & Forward / Enhanced

data reporting / Closed Network / FleetNET Traffic / LES TDM channel number: 11874"

This is LES 003 (KDDI, YAM-Yamaguchi, Japan per monitoring) on channel 11874 (1539.685).


"4: Region: AOR-W / LES: 32 / Status: 3ØØ bps return link / Spare satellite / Out of service / Clear / Terrestrial links open / Alerting

supported / Services: ALERT (Maritime Distress Alerting / SafetyNET Traffic / STD-C (Inmarsat-C Traffic) / Store & Forward / Enhanced

data reporting / Closed Network / FleetNET Traffic / LES TDM channel number: 11826"

This is LES 004 (EIK LES-Eik, Norway per monitoring) and probperly decodes as such; it is not LES 32.
Channel 11826 is 1539.565.

"
5: Region: AOR-W / NCS: 48 / Status: 3ØØ bps return link / Spare satellite / Out of service / Clear / Terrestrial links open / Alerting

supported / Services: ALERT (Maritime Distress Alerting / SafetyNET Traffic / STD-C (Inmarsat-C Traffic) / Store & Forward / Enhanced

data reporting / Closed Network / FleetNET Traffic / LES TDM channel number: 11834'

This is LES 012 (not an NCS but instead NL Burum LES-Burum, Netherlands per monitoring) on channel 11834 (1539.585).

"
6: Region: POR / LES: 4Ø / Status: 3ØØ bps return link / Spare satellite / Out of service / Clear / Terrestrial links open / Alerting

supported / Services: ALERT (Maritime Distress Alerting / SafetyNET Traffic / STD-C (Inmarsat-C Traffic) / Store & Forward / Enhanced

data reporting / Closed Network / FleetNET Traffic / LES TDM channel number: 1181Ø"

This is LES 021 (ASG 21 LES-Ausguel, France per monitoring) on channel 11810 (1539.525).

Note that I think the status indicated are also in errors: these are Operational/In service, not Spare/Out of service. 

The NCS (LES 044) for this satellite is on 1537.700 and that is in the transmission.
Note the LES are often remote uplinked from other locations than there location identified. 
Also, LES numbers are more properly displayed as octal (in Inm-C and Inm-Aero) so that the first digit indicated a region number.

Monitoring shows similar erroneous decoding.  For those who do not know, the transmitted format for these fills out a form and then lookup tables are used.  Something appears to be in error in the decoding parsing of bits.




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www.avast.com


David L. Wilson
 

>Note the LES are often remote uplinked from other locations than there location identified. 
I’m not sure to understand…

INMARSAT has decided for "legacy purposes" when sometimes a different LES or uplink location takes over an operation to not change the LES number.  For example, all the Aero uplinks for 97W are normally from Laurentides, Canada and for 54 W  Burum, although the LES numbers were used by other locations in the past.  And if that were to change, they would probably not change the LES.  This was in some web releases by INMARSAT.  I am not sure how true that is for INMARSAT-C (that is, where the LES identifying is actually the site doing the uplink which might actually be relayed from another location).  But INMARSAT does say things in some documents like Southbury (Eik) for LES 001 and 101 leaving one to wonder who is actually uplinking and controlling that one.  Watching activity has not answered that.   But activity does show:

Identified in bdc     ATL-W  ATL-E
STRATOS CSAT    002       102  Burum, Netherlands
KDDI YAM              003       103  Yamaguchi, Japan
EIK LES                 004       104  Eik, Norway
NL BURUM LES     012       112  Burum, Netherlands
ASG 21 LES          021       121  Aussaguel, France

Obviously at least Japan is being uplinked from some Europe or N American location

>Also, LES numbers are more properly displayed as octal (in Inm-C and Inm-Aero) so that the first digit indicated a region number.

I’ll add this indication.

I would give both the HEX and OCT.  The OCT is more useful and show the region but some are used to the HEX and some other software only shows that.



Patrick Lindecker
 

Hello David,

 

Thanks for the explanation. Nothing to simplify the SWL…

 

My new list (inside Multipsk) will be the following (number in decimal, without the region):

9  Beijing/China

17 Aussaguel/France

6  Pune/India

5  Fucino/Italy

29 Fucino/Italy

3  Yamaguchi/Japan

2  Burum/Netherlands

10 Burum/Netherlands

1  Eik/Norway

4  Eik/Norway

15 Nudol/Russia

24 Hai Phong/Viet Nam

36 NCS

 

>I would give both the HEX and OCT.  The OCT is more useful and show the region but some are used to the HEX and some other software only shows that.

HEX has no interest and would confuse everybody. And it’s true that on papers octal is only used. So I will give the number in octal.

 

73

Patrick

 

De : multipsk@groups.io [mailto:multipsk@groups.io] De la part de David L. Wilson via groups.io
Envoyé : jeudi 25 juin 2020 05:23
À : multipsk@groups.io
Objet : Re: [multipsk] Problem in the decoding of INMARSAT-C bulletin board.

 

>Note the LES are often remote uplinked from other locations than there location identified. 
I’m not sure to understand…

INMARSAT has decided for "legacy purposes" when sometimes a different LES or uplink location takes over an operation to not change the LES number.  For example, all the Aero uplinks for 97W are normally from Laurentides, Canada and for 54 W  Burum, although the LES numbers were used by other locations in the past.  And if that were to change, they would probably not change the LES.  This was in some web releases by INMARSAT.  I am not sure how true that is for INMARSAT-C (that is, where the LES identifying is actually the site doing the uplink which might actually be relayed from another location).  But INMARSAT does say things in some documents like Southbury (Eik) for LES 001 and 101 leaving one to wonder who is actually uplinking and controlling that one.  Watching activity has not answered that.   But activity does show:

Identified in bdc     ATL-W  ATL-E
STRATOS CSAT    002       102  Burum, Netherlands
KDDI YAM              003       103  Yamaguchi, Japan
EIK LES                 004       104  Eik, Norway
NL BURUM LES     012       112  Burum, Netherlands
ASG 21 LES          021       121  Aussaguel, France

Obviously at least Japan is being uplinked from some Europe or N American location

>Also, LES numbers are more properly displayed as octal (in Inm-C and Inm-Aero) so that the first digit indicated a region number.

I’ll add this indication.

I would give both the HEX and OCT.  The OCT is more useful and show the region but some are used to the HEX and some other software only shows that.

 




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L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
www.avast.com


tseug
 

Situation as shown by Inmarsat in late 2019 (ie. well after the change to the virtual I3  network over I4 sats):

Patrick Lindecker
 

TKS for the document. I knew it but I did not know its date issue.

 

73

Patrick

 

De : multipsk@groups.io [mailto:multipsk@groups.io] De la part de tseug via groups.io
Envoyé : jeudi 25 juin 2020 08:36
À : multipsk@groups.io
Objet : Re: [multipsk] Problem in the decoding of INMARSAT-C bulletin board.

 

Situation as shown by Inmarsat in late 2019 (ie. well after the change to the virtual I3  network over I4 sats):




Avast logo

L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
www.avast.com