Jamming

Jamming is the deliberate transmission of interfering radio-frequency signals to disrupt or deny satellite communications. Jamming may be classified as uplink or downlink jamming, with uplink jamming generally more effective due to the satellite receiver’s limited power and antenna gain. Intentional jamming is prohibited under international telecommunications regulations but remains a significant concern in conflict and contested-spectrum environments.

Because a GEO satellite is visible from approximately 43% of the Earth’s surface, GEO satellite systems are particularly vulnerable to uplink jamming: a jammer need not be located near the intended user terminals and may operate from any location within the satellite’s field of view.

LEO satellites have a much smaller instantaneous footprint on the Earth’s surface, reducing their exposure to jamming. In addition, a jammer targeting a LEO system must track the satellite as it moves across the sky, and jamming of a single LEO satellite typically affects only the relatively small number of users within that satellite’s footprint at a given time.

Military satellite systems may employ anti-jamming techniques such as spread-spectrum modulation and frequency hopping to mitigate the effects of jamming. Similar techniques are increasingly being adopted by commercial satellite systems, although these measures generally incur a reduction in achievable data rate. Furthermore, many satellites used by military forces are commercial or dual-use systems and may not incorporate dedicated anti-jamming protection.