Spread-Spectrum Electromagnetic Penetrator Data Link

On current Air Force penetrator weapons, hard-target smart fuzes in the tail receive information from sensors in the nose. Future weapons are expected to incorporate additional sensors, which will greatly increase the data available, to more than 250 kilobits per second, which must be transmitted through the earth to a surface receiver or to an aircraft receiver. This proposal describes a CDMA spread spectrum wireless penetrator data link with multiple channels to transmit the high-rate data through the earth between underground targets and surface or airborne receivers. Phase I effort will analyze and model electromagnetic radiation patterns and signal propagation through the earth. US Positioning will accommodate high-bandwidth data by using a CDMA spread-spectrum system with high process-gain, along with orthogonal codes to separate data onto many parallel channels and process the data simultaneously. We will analyze, simulate, and test the performance of the through-the-earth data link under high g loads and will characterize important system parameters, including latency, reliability, security, operating frequency, modulation scheme, and transmit output power. We intend to emphasize the use of 433MHz UHF band for this through-the-earth penetrator data link.