Abstract: Systems and methods are provided for identifying and locating a plurality of reflector markers implanted within a target tissue region within a patient's body. A probe is provided that is activated to transmit electromagnetic signals into the patient's body, receive reflected signals from the patient's body, and in synchronization with transmitting the electromagnetic signals, deliver light pulses into the patient's body. The markers reflector tags modulate reflected signals from the respective markers based on orthogonal code sequences opening and closing respective switches of the markers to modulate the reflective properties of the markers. The probe processes the return signals to separate the reflected signals based at least in part on the code sequences to identify and locate each of the plurality of reflector tags substantially simultaneously.

Abstract: Systems and methods are provided for identifying and locating a plurality of reflector markers implanted within a target tissue region within a patient's body. A probe is provided that is activated to transmit electromagnetic signals into the patient's body, receive reflected signals from the patient's body, and in synchronization with transmitting the electromagnetic signals, deliver light pulses into the patient's body. The markers reflector tags modulate reflected signals from the respective markers based on orthogonal code sequences opening and closing respective switches of the markers to modulate the reflective properties of the markers. The probe processes the return signals to separate the reflected signals based at least in part on the code sequences to identify and locate each of the plurality of reflector tags substantially simultaneously.

Abstract: Systems and methods are provided for identifying or locating a tag within a patient's body that include a probe that transmits synchronized electromagnetic signals, e.g., RF energy, and optical signals, e.g., infrared light pulses into the patient's body, whereupon the tag converts the optical signals into electrical energy to open and close a switch in the tag to modulate signals, e.g., backscatter signals, transmitted by the tag in response to the electromagnetic signals. For example, the tag may include photodiodes coupled to the switch that transforms the optical signals to alternately short the antenna to modulate the backscatter signals. Alternatively, the tag may include a smart circuit that harvests electrical energy from the optical signals to power the smart circuit and/or modulate the backscatter signals, e.g., to include data related to the tag and/or alternate the tag between an information mode and a distance mode.

Abstract: Systems and methods are provided for identifying or locating a tag within a patient's body that include a probe that transmits synchronized electromagnetic signals, e.g., RF energy, and optical signals, e.g., infrared light pulses into the patient's body, whereupon the tag converts the optical signals into electrical energy to open and close a switch in the tag to modulate signals, e.g., backscatter signals, transmitted by the tag in response to the electromagnetic signals. For example, the tag may include photodiodes coupled to the switch that transforms the optical signals to alternately short the antenna to modulate the backscatter signals. Alternatively, the tag may include a smart circuit that harvests electrical energy from the optical signals to power the smart circuit and/or modulate the backscatter signals, e.g., to include data related to the tag and/or alternate the tag between an information mode and a distance mode.

Abstract: Systems and methods are provided for identifying or locating a tag within a patient's body that include a probe that transmits synchronized electromagnetic signals, e.g., RF energy, and optical signals, e.g., infrared light pulses into the patient's body, whereupon the tag converts the optical signals into electrical energy to open and close a switch in the tag to modulate signals, e.g., backscatter signals, transmitted by the tag in response to the electromagnetic signals. For example, the tag may include photodiodes coupled to the switch that transforms the optical signals to alternately short the antenna to modulate the backscatter signals. Alternatively, the tag may include a smart circuit that harvests electrical energy from the optical signals to power the smart circuit and/or modulate the backscatter signals, e.g., to include data related to the tag and/or alternate the tag between an information mode and a distance mode.

Abstract: Systems and methods are provided for identifying and locating a plurality of reflector markers implanted within a target tissue region within a patient's body. A probe is provided that is activated to transmit electromagnetic signals into the patient's body, receive reflected signals from the patient's body, and in synchronization with transmitting the electromagnetic signals, deliver light pulses into the patient's body. The markers reflector tags modulate reflected signals from the respective markers based on orthogonal code sequences opening and closing respective switches of the markers to modulate the reflective properties of the markers. The probe processes the return signals to separate the reflected signals based at least in part on the code sequences to identify and locate each of the plurality of reflector tags substantially simultaneously.

Abstract: Systems and methods are provided for identifying or locating a tag within a patient's body that include a probe that transmits synchronized electromagnetic signals, e.g., RF energy, and optical signals, e.g., infrared light pulses into the patient's body, whereupon the tag converts the optical signals into electrical energy to open and close a switch in the tag to modulate signals, e.g., backscatter signals, transmitted by the tag in response to the electromagnetic signals. For example, the tag may include photodiodes coupled to the switch that transforms the optical signals to alternately short the antenna to modulate the backscatter signals. Alternatively, the tag may include a smart circuit that harvests electrical energy from the optical signals to power the smart circuit and/or modulate the backscatter signals, e.g., to include data related to the tag and/or alternate the tag between an information mode and a distance mode.

Abstract: In a recording/playback system, increased information is achieved by 4 level biased magnetic recording where the maximum amplitude 4 level recording signal drives the medium's magnetization into a nonlinear region of its transfer function. The bias does not eliminate distortion at the maximum signal input level, however the system's signal to noise ratio is improved due to an increase in the amplitude of the playback signal resulting from the increased recording level. The nonlinear mapping capability of a neural network provides equalization of playback signals distorted due to the record/playback nonlinearity. The 4 level recorded signals provide a factor of 2 in information storage compared to binary recording, and quadrature amplitude modulation (QAM) combined with the 4 level recording technique provides an additional factor of 2, for a factor of 4 in the information content stored.

Abstract: A chaotic carrier pulse position modulation communication system and method is disclosed. The system includes a transmitter and receiver having matched chaotic pulse regenerators. The chaotic pulse regenerator in the receiver produces a synchronized replica of a chaotic pulse train generated by the regenerator in the transmitter. The pulse train from the transmitter can therefore act as a carrier signal. Data is encoded by the transmitter through selectively altering the interpulse timing between pulses in the chaotic pulse train. The altered pulse train is transmitted as a pulse signal. The receiver can detect whether a particular interpulse interval in the pulse signal has been altered by reference to the synchronized replica it generates, and can therefore detect the data transmitted by the receiver. Preferably, the receiver predicts the earliest moment in time it can expect a next pulse after observation of at least two consecutive pulses.

Abstract: A covert communication apparatus exploits chaotic dynamics in the multi-dimensional phase space with a continuous number of states and wide internal spectral bandwidth. The information modulates a chaotically generated signal, and the modulated chaotic signal is shaped for compatibility with the specific constraints demanded by the communication channel. In an analog embodiment, the chaotic signal spectrum is band limited to be compatible with the bandwidth requirements of the transmission link, and in a digital embodiment the word length and baud rate of the transmitted digital data are selected for similar transmission link compatibility. After transmission over the communication link, the received signal is applied to a receiver chaotic signal generator substantially identical to the transmitter chaotic signal generator and the chaotic signal is recovered. This chaotic signal is used to demodulate the received signal for recovery of the information.