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Globalization of commerce and interlinking of economics of all the countries in the world have changed the configurations of local/national/regional Communication links. They have now become truly global network centric. Satellite communication links offer flexible data transmission for ground, sea and airborne units. For military, these satellites have enhanced their capabilities with better co-ordination of command and control. Military satellites use more expensive, complex and jam resistant technologies to reduce their vulnerability to jamming. As of now large number of countries including India do not have adequate number of Mil-Satellites. Even advanced countries used the existing Commercial Satellites by leasing the transponders in times of need like in Desert storm, Iraq war, Afgan war etc. Commercial satellites use FDM-FDMA, FDM-TDMA modulations, which are vulnerable to jamming unlike the Mil - Satellites which use spread spectrum, EHF frequencies, multiple beam transmitting and receiving antennas with nulling capabilities against jamming, processing transponders etc. There are number of instances where in the rogue states and terrorists have disrupted communication. This has become a key concern for military and civilian governments.

Another area where satellites are increasingly being usded are in Personal communication field also known as Mobile Satellite Services. The location of increasing number of Base Stations in the vicinity of domestic dwellings as a part of cellular phone infrastructure, has created scare about the RF safety among health conscious public (through it is not conclusively proved). Mobile Satellite services are now being considered as a Green alternative to cellular phones.

The subject for presentation is to assess the vulnerability of these links, considering the satellite parameters like location, distance, frequency, type of modulation, power transmitted/received, antenna size, polarization, figure of merit, C/N Ratio, link margin, bit rate error etc. The present day Anti jamming techniques and the protection of target satellite from anti-satellites will be briefly discussed.

The study carried out deals with the vulnerabilities that exist in Communication Satellites and how some of these are mitigated in the Military Satellites. Two existing satellites, INTELSAT and THURAYA (providing mobile satellite services) are modelled and their sustainabilities against Jammers have been demonstrated.