Abstract: Systems and methods for cancelling interference from a received signal in order to properly detect a signal of interest are disclosed. A combined signal of interest plus interference signal may be received. A copy or sample of the interference signal may be determined. The interference signal and the combined signal of interest plus interference signal may be converted to the optical domain. The interference signal may be optically phase shifted by ?180 degrees, which may result in an optically inverted interference signal. The optically inverted interference signal may be variably optically attenuated and/or variably optically time delayed, for example based on a detected output power of an optical subsystem of the interference cancellation system. As a result, interference cancellation of the interference signal from the combined signal of interest plus interference signal may be achieved, resulting in 50 dB or more of cancellation of the interference signal.

Abstract: Systems and method for detecting and removing an arbitrary phase difference between a sum channel signal and a difference channel signal in a monopulse system. A sum channel signal is received from a sum channel signal source and a difference channel signal is received from a difference channel signal source. The difference channel signal is shifted according to various potential arbitrary phase differences ?i and ?i+? (where ?i is from 0 to ? radians, i=0, 1, . . . , n; ?i+? going from ? to 2? radians) between the sum and difference channel signals to thereby generate difference channel signals each having a different phase. The difference channels having a different phase are combined with the sum channel signal to generate a plurality of sum+difference signals and sum?difference signals. Based on the plurality of sum+difference signals and sum?difference signals, maximum in-phase and out-of-phase correlations are determined from the ?i and ?i+? pairs.

Abstract: Methods and systems are disclosed for testing and/or validating that an untrusted device is operating according to an expected state or configuration. The methods and systems may be designed such that the volatile memory of the untrusted device is brought to a known state for validation, for example upon ingress to or egress from a protected mode of operation. The device may execute a first operating system when operating outside of the protected mode. Upon determining to transition to protected mode, an operational image of a second operating system may be loaded into the device. The device may write a pattern to unused memory for validation. The device may receive a first challenge request from a trusted monitor (TM). In order to be successfully validated, the device may answer the challenge correctly within a given response window based on the current state of its volatile memory.

Abstract: Systems and methods for cancelling interference while performing direction/location. A combined signal of interest plus interference signal may be received. A copy or sample of the interference signal may be determined. The interference signal and the combined signal of interest plus interference signal may be converted to the optical domain. The interference signal may be optically phase shifted by ?180 degrees, which may result in an optically inverted interference signal. The optically inverted interference signal may be variably optically attenuated and/or variably optically time delayed. As a result, interference cancellation of the interference signal from the combined signal of interest plus interference signal may be achieved, resulting in 50 dB or more of cancellation of the interference signal. Direction and/or location finding techniques can be applied to received signals during and/or after interference cancellation.

Abstract: Disclosed herein are methods and systems for configuring and using one or more block ciphering techniques in order to encrypt/decrypt serial data streams while maintaining cryptographic synchronization and attempting to minimize the amount of overhead introduced into the stream. The techniques disclosed herein may be used to encrypt and decrypt serial data streams using a block cipher in a manner that can be substantially transparent to the devices involved in the serial communication session. For example, the serial user data may be left unframed by the encryption device while monitoring for opportunistic times to transmit framed cryptographic synchronization information during periods of relative inactivity in an asynchronous serial data stream. A cryptographic device implementing the techniques described herein may be configured to implement one or more of an encryption device or a decryption device.