摘要:
Methods of providing duplex free-space optical, communication comprising receiving a time-shift keying (TSK) encoded signal and selectively re-modulating—and optionally retro-reflecting —received TSK pulses so as to transmit an on-off keying (OOK) signal wherein modulation is achieved by operating a micro-opto-electronic mechanical system (MOEMS) device having a oscillation period, the difference in timing between logic 1 and logic 0 pulses of the TSK encoded signal being such that each pulse arrives at a time within a single MOEMS device oscillation period chosen to ensure high or low transmissivity through the MOEMS device independent of incident TSK encoded signal pulse value (0 or 1).
摘要:
Methods of providing duplex free-space optical, communication comprising receiving a time-shift keying (TSK) encoded signal and selectively re-modulating—and optionally retro-reflecting—received TSK pulses so as to transmit an on-off keying (OOK) signal. Related apparatus and signals are also provided.
摘要:
Apparatus and methods for detecting angle of incidence of an optical beam. The apparatus employs two optical detectors, the first of which has placed in front of it a coating or layer which exhibits an angle-dependent optical transmission characteristic distinct from that of the light path in front of the second detector. The difference in a characteristic of the light received at the respective detectors therefore provides an indication of the angle of incidence of the light beam. The angle detector may be used particularly, though not exclusively, in conjunction with free space optical communications systems.
摘要:
A method of synchronising an optical transmitter and modulator comprising transmitting a calibration sequence of pulses from the transmitter to the modulator; varying a control timing drawn from the set comprising the transmit interval timings and the modulator transmission interval timings; monitoring the resulting pulses transmitted by the modulator and selecting a preferred control timing; controlling the optical transmitter and/or modulator responsive to the selected control timing. Corresponding apparatus, systems, signals and programs for computers to implement or control the arrangement are also provided.
摘要:
Apparatus (100) is provided which is arranged to accept an input data stream. In some embodiments, the apparatus (100) comprises a sampler arranged to sample the input data stream to provide k samples thereof, wherein each of the samples is n bits long and a string selector arranged to select m binary strings n bits long from at least a chosen subset of all random binary strings of a predetermined length. The apparatus (100) may further comprise a logical operator arranged to perform a logical function for each of the k samples with each of the selected binary strings to provide a vector, a memory arranged to store a matrix of the vectors generated from k samples, and an address generator arranged to generate RAM address segments from the matrix. In embodiments, the apparatus (100) may comprise a processor for, for example, pattern matching; feature detection, image recognition.
摘要:
An optical correlation apparatus is described which forms first and second parallel optical signals in response to a serial input data stream. The first parallel optical signal is arranged to have bright pulses represent binary 1 and the second parallel optical signal is arranged to have bright pulses represent binary 0. A channel select means, such as an optical switch or amplitude modulator, deselects or blocks channels in the first parallel optical signal which correspond to binary 1 in a reference data string and also deselects or blocks channels in the second parallel optical signal which correspond to binary 0 in the reference data string. The remaining optical signals are combined at one or more detectors. Where the input data matches the reference data string each bright pulse in the first and second parallel optical signals is deselected and the detector registers zero intensity. However when there is any mismatch at least one channel will pass a bright pulse to the detector. An instance of zero intensity can therefore be used as an indication of pattern match.
摘要:
An optical correlation apparatus is taught which provides a parallel optical signal having a phase modulation representing input data to which a parallel phase modulation based on reference data is applied. In the event of correlation the resulting wavefront is planar and can be interferometrically coupled to give a high intensity signal. The invention involves use of parallel amplitude modulation means for selectively blocking the optical signal in one or more of the channels of the parallel optical signal which allows different sized reference data strings to be searched more easily and also aids in calibration.
摘要:
This invention relates to a ranging apparatus capable of ranging simultaneously to a three dimensional scene. An illumination means (22) illuminates a scene with a two dimensional array of spots (12). A detector (6) is located near to the illumination means (22) and arranged to look toward the scene. A processor (7) responds to the output from the detector (6) and, from the location of a spot in the image of the scene, determines the range to that spot. A variety of techniques are used to resolve ambiguity in determining which projected spot is being considered.
摘要:
A pattern matching apparatus for matching input data to a reference data string, wherein: it is implemented in electronic hardware and can be implemented using commercially available FPGAs using all digital processing; it is capable of very fast correlation; input data is received by a 1:N demultiplexer which reduces the clock speed and produces an N channel parallel data signal which is passed to an N wide, M stage shift register; the shift register has an output at each intermediate stage to produce an N by M parallel data signal, each representing a different bit of the input data; the input data is compared with reference data by combining each channel with an appropriate reference data channel using an XOR combination; the results of the bit level XOR comparisons are then combined using OR combinations, conveniently at byte level and then at string level; and the result is a simple match/no match signal.
摘要:
An optical correlation apparatus is described which forms first and second parallel optical signals in response to a serial input data stream. The first parallel optical signal is arranged to have bright pulses represent binary 1 and the second parallel optical signal is arranged to have bright pulses represent binary 0. A channel select means, such as an optical switch or amplitude modulators deselects or blocks channels in the first parallel optical signal which correspond to binary 1 in a reference data string and also deselects or blocks channels in the second parallel optical signal which correspond to binary 0 in the reference data string. The remaining optical signals are combined at one or more detectors. Where the input data matches the reference data string each bright pulse in the first and second parallel optical signals is deselected and the detector registers zero intensity. However when there is any mismatch at least one channel will pass a bright pulse to the detector. An instance of zero intensity can therefore be used as an indication of pattern match.