National University of Singapore

Kin Mun Lye

Jurianto Joe

Kay Soon Low

Weng Ho Yung

Siong Siew Yong

Jonathan Tun Nan Liu

Wee Peng Goh

Paul Kar Ming Ho

Teck Chien Pek

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 method and apparatus for detecting ultra wide-band (UWB) signals using multiple detectors having dynamic transfer characteristics. A receiver circuit is implemented using devices such as op-amps to provide the required dynamic characteristics. Detectors used in the UWB communication systems of the present invention utilize direct sequence spread spectrum (DSSS) technology for multiple access reception.

Method and apparatus for ultra wide-band communication system using multiple detectors

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 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 radio conferencing method and apparatus for transmitting packets of data from a plurality of radios over a transmission channel within a series of frames of predetermined duration, each packet of data having a predetermined time length, which method comprises the steps of: sensing the status of the channel; if the channel is idle, then transmitting the packet of data; if the channel is busy with another packet of data being sent, then disposing the packet of data and re-scheduling the transmission of the next packet of data to a time equal to a fraction of the time length of the packet of data plus the duration of the frame; and repeating the above steps.

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Singapore, Singapore

Kin Mun Lye