Bae Systems Information and Electronic Systems Integration Inc.

Gec-Marconi Electronic Systems Corp.

James W Lang

John H Chongoushian

Michael J Berry

An auto-ICAS compliant system and method of avoiding collisions between aircraft linked by a Link 16 network comprises establishing an ICAS datalink between aircraft less than 10 nautical miles apart. Datalink messages generated and processed by ICAS datalink modules are transmitted and received by Link 16 receivers rather than dedicated ICAS transceivers. The datalink messages are embedded within the propagation delay portions of Link 16 timeslots and exchanged among up to 10 nearby aircraft at a data rate of up to 20 Hz each. Because each Link 16 timeslot can contain a Link 16 message and two 768-bit ICAS datalink messages, conventional Link 16 communication is not impeded. Datalink messages can be software encrypted. Link 16 messages can be encoded using an enhanced throughput Link 16 protocol that includes fewer preamble pulses and/or eliminates STN information. Embedded datalink messages can be transmitted at 1 Watt by a MIDS-JTRS CMN4.

Link 16 datalink for integrated collision avoidance system

A wireless receiver and method of wireless communication determines levels of noise, including interference, in communication channels without need of calibration. A digital test signal is digitally added to digitized noise, and a signal-to-noise-and-interference (SNIR) value is determined from a resulting bit error rate and/or message error rate. The level of noise is then determined from the SNIR. The amplitude of the digital test signal is adjusted to cause the SNIR to be sensitive to the noise level, which can require an SNIR between 1 dB and 10 dB. The system can include a digital test signal generator, or the digital test signal can be stored in a memory. The system can further include a channelizer, demodulator, data correlator, decryptor, and message assembler. Noise and interference level determinations can be used to select an optimal communication channel, and to adjust a transmission power and/or rate to suitable values.

Apparatus and method for digitally characterizing communication channel noise and interference

A method for implementing interference mitigation in wireless network such as a Link 16 network does not require interference recognition and does not degrade signal detection even in the absence of interference. An unmitigated correlation score is obtained by correlating received, unmitigated preamble symbols with expected symbols. At least one of the input signals is also correlated after mitigation to obtain a mitigated signal. A mitigated correlation sore is obtained from the mitigated signals, and a mixed correlation score is obtained by combining mitigated and unmitigated signals. A signal is detected if any of the correlation scores exceeds a corresponding threshold. Embodiments use the unmitigated correlation for subsequent message time of arrival determination if the unmitigated correlation score is above its detection threshold. In embodiments, mitigation is applied to only one of the message frequencies. Implementation of the disclosed method does not require excessive additional electronic resources.

Enchanced Link 16 detection with interference mitigation

A system which receives a pseudonoise sequence signal, quantizes the signal during a fixed increment of time, and passes the quantized signal to a single 'split' correlator channel. The system utilizes sub-correlation products from that single 'split' channel to calculate correlation outputs of other desired correlation channels. Specifically, the 'split' correlator channel includes a pair of shift register strings, with the corresponding stages of each string being of equal length, and with a phase rotator being provided between consecutive stages of the shift register strings. In-phase and quadrature components of the received signal are each provided as inputs to a respective one of the shift register strings, and each shift register string stage is correlated with the pseudonoise sequence. These correlation results are utilized to calculate overall correlation scores for each of two substantially equal subdivisions of a range of frequencies centered around a nominal carrier frequency for the received signal to detect acquisition of the received signal and to select the frequency range subdivision with the greatest correlation.

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Wayne, NJ, United States of America

James W Lang