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Transcript of Petter Amundsen Managing Director, VeriSat AS Amundsen Managing Director, VeriSat AS APSCC 2015,...
VSAT Interference
Petter Amundsen
Managing Director, VeriSat AS
APSCC 2015, Seoul , 24th September 2015
Contents
• Causes of VSAT interference
• Why is VSAT interference challenging to combat?
• How can the interfering VSAT be determined?
Causes of VSAT Interference
• Misaligned antenna (frequent)
– Incorrect installation
• Inaccurate pointing
• Inaccurate polarization alignment (linear only)
– Disturbance of antenna pointing after installation
• Strong winds
• Physical damage
• Faulty equipment (less frequent)
– Faulty antenna cable shielding may cause retransmission of local radio signals, such as GSM and FM
– Other electronic or mechanical faults of the VSATcausing unwanted transmission to the satellite
Misaligned VSATs cause Interference
Crosspolar
Interference (XPI)
Adjacent Satellite
Interference (ASI)
Misaligned antenna
VSAT Interference – Spectrum View
VSAT TDMA carriers
ASI/XPI caused by
misaligned VSATs
Adjacent satellite
or Cross polar transponder
Nominal interference
from aligned VSATs (<-10 dB SNR)
VSAT network in
Operational satellite
Disturbed services
VSAT Return Links shared by many Terminals
• The VSATs share one or several return link carriers in TDMA mode
• Each terminal in the VSAT network has a unique ID - the terminal ID
• The terminal ID is the key for network control of each VSAT
• When the terminal ID of an interfering VSAT is known, transmission can be stopped from the network control
• How to determine the interfering terminal ID?
Bursts from different terminals
Combatting VSAT interference
Traditionally manual time-consuming trouble-shooting is necessary:
� Move batches of terminals to operate at new frequencies
� By observing the change in interference, the interfering terminals can be narrowed and eventually identified individually
New solution – SatGuard find the terminal in real-time:
� Detection of interfering VSAT terminal ID
� Interference level below -10 dB SNR
� Currently in operation at Eutelsat and SES
SatGuard technology can be applied to enable geolocation of VSATs terminals
SatGuard determines terminal ID of VSATs causing interference
1. Demodulate the operational links, find the terminal ID for each burst
2. Detect bursts on interfered link
Correlate (by time)
Result: List of interfering VSAT IDs
(i.e. MAC addresses)
SatGuard - Automatic VSAT Interference Monitoring
Terminal Report
Major VSAT Systems Supported
• DVB-RCS (many vendors)
• iDirect iNFINITI
• iDirect Evolution
• ViaSat LinkStar
• ViaSat LinkWay
• HNS IPoS-compatible networks (various models)
• Gilat SkyEdge 1, SkyEdge 2
• DVB-RCS2
• Other proprietary VSAT systems at request
SatScan GSM Classification (retransmitted by VSATs)
Operates with SNR as low as 2 dB
Internet site giving GSM cell location
Conclusions
• VSAT interference can cause severe interference that is difficult to combat
• Introduction of automatic tools (SatGuard) resolves VSAT interference quickly and may also be used proactively
• VSAT interference can be minimized and resolved quickly by:
– Good planning
– Quality cabling and connectors
– Proper installation procedures
– Verification of XPI and ASI for each terminal ID at installation time
– Monitoring of XPI and ASI for each terminal ID under operations.
– Terminals causing interference can then be easily stopped