Possible use of electronic warfare against the SPS may include consideration of any one, or combination, of the following approaches: o Jamming the receivers in the SPS transmitting array. If the jamming signals are sufficient to saturate the receiving capability to identify pilot beam coding or process the phase control information, phase control will fail, resulting in power beam defocusing. o Injecting false signals into the ground safety control system. If successfully accomplished, this could create the impression of unacceptable changes in power density in the vicinity of the rectenna, resulting in transmission of commands to the satellite to cease operation. o Attenuating the uplink pilot beam to prevent detection of control signals by receivers in the satellites. If successfully accomplished this would result in automatic defocusing of the power beam. The pilot beam provides a double sideband suppressed carrier signal which is symmetrical about the downlink power beam frequency (2.45 GHz). The frequency separation between the sidebands and the downlink frequency is greater than 10 MHz. Both sideband frequencies should be jammed if ECM techniques are directed against the satellite receivers. The SPS receiving system is not highly directional since the phase control system was designed to permit multiple SPS access from one pilot beam transmitter. Accordingly, the constraints on jammer location are not very severe. The jamming signal at the receiver location must be significantly greater than pilot beam signal if receiver saturation is to be achieved. Estimates of the jamming-to-signal ratio requirements are not provided at this time. However, if the requirements are sufficiently high, jamming from surface sites will be precluded even with powerful jammers and high-gain jamming antennas. If the location of the ground control safety sensor can be determined, it may be possible to illuminate the sensors with microwave energy to generate safety signals associated with unacceptable SPS power density levels. This approach ap- 2 pears impractical if power densities in excess of 0.1 mW/cm are required to activate safety control sensors. The use of a reasonably powered microwave radiator at reasonable ranges simply cannot provide the required power densities. Chaff use may be considered for attenuation of the pilot beam signal to below the threshold required for maintaining pointing control over the SPS power beam. A signal passing through a cloud of uniformly distributed chaff elements is attenuated by a factor exp where n is the number of effective chaff
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