Abstract: A dual-mode communication device adapted for communication over a public network, wherein the dual-mode communication device is adapted to be operated in a normal mode and in an obfuscated mode. The dual-mode communication device includes a processor and a network interface device. The processor develops a frame from a payload received by the dual-communication device and, if the dual-mode communication device is operating in the obfuscated mode, an obfuscated frame from the frame. The frame and the obfuscated frame comprise a preamble that conforms with protocols associated with the public network and the processor. A network interface transmits one of the frame or the obfuscated frame using the public network. The payload may be extracted from the frame by any receiving device operating in the normal mode in the public network and the payload may be extracted from the obfuscated frame only by another communication device also operating in the obfuscated mode in the public network.

Abstract: A frequency hopping Global Positioning System (GPS) system comprises an on-orbit reprogrammable digital waveform generator configured to generate a GPS signal comprising a resilient frequency-hopping spread spectrum GPS signal that hops at a hop rate between two or more GPS channels. The GPS signal further comprises a legacy direct-sequence spread spectrum signal for at least two of the two or more GPS channels. Further, a receiver is configured to receive the GPS signal, wherein the receiver is further configured to decode the GPS signal.

Abstract: A system for generating a frequency hopping Global Positioning System (GPS) system includes: an on-orbit reprogrammable digital waveform generator (ORDWG) configured to generate a GPS signal comprising a resilient frequency-hopping spread spectrum GPS signal that hops at a hop rate between two or more GPS channels, the GPS signal further comprising a legacy direct-sequence spread spectrum signal for at least two of the two or more GPS channels; and a receiver configured to receive the GPS signal, the radio further configured to decode the GPS signal.

Abstract: An amplitude and phase modulation circuit for modulating an M-ary digital signal having pulses onto a carrier wave for transmission by direct digital synthesis. The modulation circuit includes a digital source that generates a digital signal including pulses representing logical 1s and no pulses representing logical zeros, where a group of M pulses represents a constellation point to be transmitted. The modulation circuit further includes a phase control circuit that provides phase control and an amplitude control circuit that provides pulse width control for the constellation point to be transmitted. A saturated amplifier amplifies the phase and amplitude controlled digital signal and a filter integrates and averages the digital signal to remove noise from the signal so as to convert the digital signal to an analog signal, where the digital source operates to reduce the amplifier power consumption requirements.