摘要:
A method for ultra wideband (UWB) communication in which UWB pulses encode binary data as either normal or inverted (anti-podal) pulses. In the case of pulses of a carrier signal, each pulse has the carrier signal either inverted or in phase, that is, shifted by 180°, or not. For example, a binary “1” may be encoded as a normal or non-inverted pulse and a binary “0” as an inverted pulse. After each carrier pulse is rectified and filtered, detection is effected using a threshold value of zero, resulting in increased immunity to noise, compared with detection of unidirectional pulses. In one aspect of the invention, data pertaining to multiple communication channels are encoded in time-divided portions of each UWB pulse.
摘要:
A phase locked loop (10) for generating an output frequency signal. The phase locked loop (10) includes a controlled oscillator (14) to generate the output frequency signal in response to a tune signal. A phase detector (18) generates an error signal representing a difference between a reference frequency signal and the output frequency signal. A loop filter (12) having a filter characteristic, filters the error signal and generates the tune signal. The loop filter (12) includes a bandwidth switching circuit (19) to vary the filter characteristics. A charge cancellation circuit (22) is coupled to the loop filter (12). In response to the error signal, the charge cancellation circuit (22) cancels errors associated with the bandwidth switching circuit.
摘要:
A family of logic circuits using nonhysteretic superconducting quantum interference devices (SQUIDs) connected together to perform various functions using a common operating principle. Each circuit has an output line, first and second power supply lines having first and second voltage states, and input lines that can have one of the two voltage states. A pull-up circuit, having at least one SQUID, is connected between the output line and the first power supply line, and the input lines are coupled to the pull-up circuit in such a manner as to pull the output line to the first voltage state only if the input lines conform with a selected combination of voltage states. A pull-down circuit, also having at least one SQUID, is connected between the output line and the second power supply line, to pull the output line to the second voltage state only when input lines do not conform with the selected combination of voltage states. A single configuration of SQUIDs can be connected to perform any of six different basic Boolean logic functions on signals applied to the input lines. Additional SQUIDs allow the performance of more complex logic functions. A slightly different arrangement of SQUIDs operates as a two-port random access memory cell.
摘要:
A switched low pass filter (18) minimizes transients generated during filter switching events and eliminates active circuit random noise. The switched low pass filter (18) includes a filter input terminal (26) for receiving an input base band signal, and an RC circuit (R1, C1, S1, S2) for receiving the input base band signal and for passing only a filtered portion of the input base band signal depending on a wide, mid or narrow band mode of filter operation. The switched low pass filter (18) also includes a transient reduction circuit (34) in switchable communication with the RC circuit (R1, C1, S1, S2) for minimizing transients and switching events caused by transitioning to the mid and narrow band modes of filter operation.
摘要:
A plurality of differential encoders encodes a plurality of parallel data bit streams. XOR gates interleave the outputs of the differential encoders forming a single high speed differentially encoded bit stream with a data rate that is the sum of the data rate of the parallel data bit streams. The high speed data stream provides a single differentially encoded input to a differential phase shift keying modulator that generates symbols for a high speed optical communication system.
摘要:
A phase locked loop (10) for generating a variable output frequency signal. The phase locked loop (10) includes a controlled oscillator (14) to generate the variable output frequency signal in response to a tune signal. A phase detector (18) is activable in response to a gating signal (20) to generate an error signal representing a difference between a reference frequency signal and the variable output frequency signal. A loop filter (12) having a filter characteristic, filters the error signal and generates the tune signal. An offset cancellation circuit (22) is coupled to the loop filter (12). In response to an error signal representing phase offset of the phase locked loop (10), the offset cancellation circuit (22) supplies a compensating signal to reduce the phase offset.
摘要:
The present invention provides a phase locked loop (10) for generating a variable output frequency signal. The phase locked loop (10) includes a controlled oscillator (14) to generate the variable output frequency signal in response to a tune signal. A feedback frequency divider (16) coupled to the controlled oscillator (14) is operable to generate a divided frequency signal from the variable output frequency signal. A phase detector (18) generates an error signal representing a difference between a reference frequency signal and the divided frequency signal. A sample and hold circuit (22) is activable in response to a gating signal (20) derived from the reference frequency, to sample the error signal and generate a sampled signal. A loop filter (12) filters the sampled signal and generates the tune signal.
摘要:
A plurality of differential encoders encodes a plurality of parallel data bit streams. XOR gates interleave the outputs of the differential encoders forming a single high speed differentially encoded bit stream with a data rate that is the sum of the data rate of the parallel data bit streams. The high speed data stream provides a single differentially encoded input to a differential phase shift keying modulator that generates symbols for a high speed optical communication system.