Communications jamming receiver
AssigneeBAE Systems Information and Electronic Systems Integration Inc.
InventorsNicholas Senio, William H. Jeffrey
Life of this patent
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Abstract
An improved communications jamming receiver is disclosed wherein time division multiplexing techniques are utilized that permit monitoring enemy radio frequency transmissions while in essence concurrently transmitting signals to jam selected enemy transmissions. The time division multiplexing alternately enables the communications receiver and a jamming transmitter at a frequency higher than the Nyquist rate of the threat signal being received to effectively continuously receive enemy transmissions while preventing reception of the jamming signals from the associated jammer transmitter. The multiplexing is carried on in a random fashion that prevents the enemy from determining the rate and transmitting during the period that the improved receiver is disabled.
Claims8
An apparatus for alternating the reception of an enemy signal and the transmission of a jamming signal on the same or a different frequency, the repetition rate of the receiving intervals being sufficiently high to allow utilization of the intelligence carried by the received signal while the direction of the received interval is sufficiently short so that the transmitted jamming signal appears continuous to the enemy, said device comprises:
- first switching means for periodically alternating the intervals in which the receiver is enabled and intelligence is withdrawn from the signal, with the intervals in which the receiver is in a disabled state;
- second switching means for periodically alternating the intervals in which the transmitter is enabled to jam the enemy signal with the intervals in which the transmitter is disabled so that said first means is enabled when said second means is disabled and said first means is disabled when said second means is enabled;
- switch control means for operating said first and second switching means above the Nyquist rate of the intelligence used to modulate the radio received signal;
- and
- sample and hold means having the demodulated receiver output intelligence signal periodically applied thereto as said receiver is enabled by said first switching means, said sample and hold means operating to effectively reconstruct the intelligence signal used to modulate the signal received by the receiver;
- and
- means for controlling said switch control means to continually vary the periods said first and said second switch means are operated to prevent the enemy from knowing or predicting the periods in which the transmitter is disabled.
A method for alternating the reception of a received enemy signal and the transmission of a jamming signal on the same or a different frequency, the repetition rate of the receiving intervals of the received signal being sufficiently high to allow utilization of the intelligence carried by the received signal while the duration of the received interval is sufficiently short so that the transmitted jammed signal appears continuous to the enemy, said method comprising the steps of:
- periodically switching said transmitter between an enabled state wherein it is jamming, and a disabled state wherein said transmitter is not jamming,
- periodically switching said receiver between an enabled state where it is obtaining intelligence samples and a disabled states where it is not obtaining intelligence samples at a frequency greater than the Nyquist rate for the intelligence received by said receiver, said disabled states occurring when said transmitter is enabled, said enabled state being when said transmitter is disabled,
- storing said intelligence samples produced when said receiver is enabled in a sample-and-hold circuit to produce an output which reconstructs the original signal used to modulate the radio frequency carrier received by said receiver, and
- randomly varying the periods that said receiver and said transmitter are switched between their enabled and disabled states.
Dependencies are inferred from the claim text.