National University of Singapore

Cellonics Incorporated Pte, Ltd.

Agency for Science, Technology and Research

Nat'l. Univ. of Singapore

Jurianto Joe

Kin Mun Lye

Kay Soon Low

Ashok Kumar Marath

Chwee Mei Wong

Jonathan Tun Nan Liu

Siong Siew Yong

Michael Yan Chia

An antenna comprises first and second radiating elements for connecting to a first and second potential levels respectively. The first and second potential levels are substantially different for generating an electrostatic field from the first and the second radiating elements. The antenna further comprises first and second field shaping structures for controlling field propagation in a first and second direction respectively. The first and second field shaping structures are interdisplaced for defining a field pathway while the first and second radiating elements are disposed adjacent to the first and second field shaping structures and along the field pathway for directing the electrostatic field in a propagation direction through a liquid medium. More specifically, the propagation direction is defined by the field pathway and substantially perpendicular to at least one of the first and second directions.

Antenna for underwater communications

Pulse width modulation of a digital signal using a nonlinear type of pulse generator is described. The nonlinear pulse generator is characterized by its transfer characteristic which has alternating stable and unstable operating regions. The pulse width modulated signal is generated by varying the operating point between among the unstable and stable operating regions.

Method and apparatus for generating pulse width modulated waveforms

A circuit to generate antipodal PSK signal and a correlator circuit for recovering information from PSK (phase shift keying) UWB transmissions includes providing a circuit component characterized by a transfer function having alternating stable and unstable regions. By setting the operating point in a stable region or an unstable region, a non-oscillatory or an oscillatory output signal can be produced.

PSK transmitter and correlator receiver for UWB communications system

A clock multiplication technique includes driving two oscillatory circuits by an input signal. One of the circuits has an inverted input. The oscillatory circuits are characterized by a transfer function having an unstable region bounded by two stable region. Oscillations produced during operation of each of the circuits in the unstable regions are combined to produce a signal whose frequency is a multiple of the input frequency.

Method and apparatus for a digital clock multiplication circuit

A multiple receiver approach is disclosed for a pulse decoding communication system, which can enhance system robustness and increase information carrying capacity. Two or more receivers are used to produce groups of pulses from a received signal. In one embodiment, system robustness is enhanced by redundancy. In another embodiment, information capacity is increased by producing independent groups of pulses from one cycle of an analog waveform.

Method and apparatus for a pulse decoding communication system using multiple receivers

A gated oscillator is provided for digital circuits. The gated oscillator is achieved by the unconventional use of controlling the operating point of a Van der Pol oscillator. Oscillations are achieved by Van der Pol self-oscillation behavior. The result is a highly simplified gated oscillator circuit for many digital circuit applications

Method and apparatus for a gated oscillator in digital circuits

Methods and apparatus for detecting ultra wide-band signals using circuitry having nonlinear dynamics characteristics are disclosed. The receiver circuit can be implemented using a simple tunnel diode or using an op-amp to provide dynamic characteristics. The detector can be used in a variety of modulation schemes, including but not limited to an ON-OFF keying scheme, an M-ary pulse position modulation scheme, and a pulse width modulation scheme. The approach requires only a single frame to detect the signal.

Method and apparatus for signal detection in ultra wide-band communications

According to the invention, oscillating signals are generated from analog signals by providing an analog signal having a variable slope or amplitude to a circuit with a variable operating point and having a transfer function characterized by an unstable operating region bounded by a first and a second stable operating region. The unstable operating region contains a first and a second reference point. The circuit is capable of producing an oscillating signal having a variable duty cycle, the duty cycle increasing as the variable operating point is positioned closer to the first reference point, the duty cycle decreasing as the variable operating point is positioned closer to the second reference point. The variable operating point is positioned substantially within the unstable region to produce the oscillating signal. The positioning of the operating point relative to the first and the second reference points is a function of the variable slope or amplitude of the analog signal. The oscillating signal is capable of being used to directly or indirectly generate a delta modulation or sigma delta modulation signal corresponding to the analog signal.

Method and apparatus for delta modulator and sigma delta modulator

A method and apparatus for generating pulses that includes a circuit having a dynamical transfer function is disclosed. The circuitry exhibits oscillatory behavior when its operating point is forced to an unstable region of the transfer function by means of manipulating the transfer function. In an embodiment, a voltage source signal is used to manipulate the transfer function of the circuit. By manipulating the transfer function, the operating points can be dynamically set in the stable or the unstable region.

Method and apparatus for generating pulses using dynamic transfer function characteristics

A decoder for generating output pulses or oscillations in response to input analog waveforms includes a circuit having a variable operating point and having a transfer function characterized by an unstable operating region bounded by a first stable operating region and a second stable operating region. In one embodiment, the circuit is characterized by having a resistive input impedance. The analog waveform forces the operating point of the circuit into its unstable and stable regions to produce oscillatory and non-oscillatory behavior at the circuit's output.

Circuitry with resistive input impedance for generating pulses from analog waveforms

A method and apparatus that allows an analog waveform to carry multilevel of information is disclosed. This allows information capacity enhancement in pulse decoding communication system by concatenating several information regions in one cycle of analog waveform.

Method and apparatus for generating pulses from analog waveforms

A method and apparatus are provided for generating output pulses or oscillations in response to input analog waveforms which involves exciting, with a known but arbitrary analog waveform, a circuit with a variable operating point and having a transfer function characterized by an unstable operating region bounded by a first stable operating region and a second stable operating region. The analog waveform is characterized by having a first information region and a second information region. In response to sensing the first and second information regions, the operating point of the circuit is forced into its unstable and stable regions. This produces a sequence of oscillatory and non-oscillatory behavior at the circuit's output.

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Singapore, Singapore

Jurianto Joe