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US 2002/0154364 A1Published application
Signalling system
OwnerAlan Edward Green, Euan Morrisoninventors
Life of this patent
Estimating the term…
Abstract
An optical communications system is provided comprising first and second signalling devices in which a duplex communications link between the signalling devices can be established. The first signalling device includes a retro-reflector and the second signalling device includes at least one light source for directing light towards the retro-reflector. Half-duplex embodiments and full-duplex embodiments are described. A wave division multiplex retro-reflecting communication system is also described.
Claims70
An optical signalling system comprising first and second signalling devices,
- the first signalling device comprising means for receiving an optical signal transmitted from said second signalling device and carrying uplink data transmitted from said second signalling device;
- an optical to electric converter for converting a portion of the received optical signal into a corresponding electric signal;
- means for processing the corresponding electric signal to retrieve said uplink data;
- means for modulating a portion of the received optical signal with downlink modulation data for the second signalling device and for reflecting the portion of the received optical signal back to the second signalling device;
- and
- the second signalling device comprising means for generating an optical signal;
- means for modulating the generated optical signal with said uplink data for the first signalling device;
- means for outputting the optical signal towards said first signalling device;
- means for receiving the reflected optical signal from said fist signalling device carrying said downlink data;
- and means for retrieving the downlink data from said reflected signal;
- characterised in that said modulating and reflecting means also acts as said optical to electric converter.
8 more elements
An optical signalling system comprising first and second signalling devices,
- the first signalling device comprising means for receiving an optical signal transmitted from said second signalling device and carrying uplink data transmitted from said second signalling device;
- an optical to electric converter for converting a portion of the received optical signal into a corresponding electric signal;
- means for processing the corresponding electric signal to retrieve said uplink data;
- means for modulating a portion of the received optical signal with downlink modulation data for the second signalling device and for reflecting the portion of the received optical signal back to the second signalling device;
- and
- the second signalling device comprising means for generating an optical signal;
- means for modulating the generated optical signal with said uplink data for the first signalling device;
- means for outputting the optical signal towards said first signalling device;
- means for receiving the reflected optical signal from said first signalling device carrying said downlink data;
- and means for retrieving the downlink data from said reflected signal;
- characterised in that said second signalling device comprises:
- first and second generating means for generating first and second optical signals;
- means for combining the first and second optical signals output by said first and second generating means;
- wherein said modulation means of said second signalling device is operable to modulate said first optical signal;
- and
- wherein said first signalling device is arranged so that the first optical signal carrying said uplink data is directed onto said optical to electric converter means and so that said second optical signal is directed onto said modulating and reflecting means.
13 more elements
An optical signalling system comprising first and second signalling devices,
- the first signalling device comprising means for receiving an optical signal transmitted from said second signalling device;
- means for modulating the received optical signal with modulation data for the second signalling device and for reflecting the received optical signal back to the second signalling device;
- and
- the second signalling device comprising means for generating an optical signal;
- means for outputting the optical signal towards said first signalling device;
- means for receiving the reflected optical signal from said first signalling device carrying said modulation data;
- and means for retrieving the modulation data from said reflected signal;
- characterised in that said second signalling device comprises:
- first and second generating means for generating first and second optical signals having different wavelengths;
- means for combining the first and second optical signals output by said first and second generating means;
- in that said first signalling device comprises:
- a wavelength sensitive beamsplitter for splitting said first and second optical signals;
- and
- wherein said modulating and reflecting means comprises a first modulation and reflecting means for modulating and reflecting the first optical signal with first modulation data and second modulation and reflecting means for modulating the second optical signal with second modulation data;
- and
- wherein said second signalling device further comprises a wavelength sensitive beamsplitter for separating the reflected first and second optical signals and wherein said retrieving means comprises first and second retrieving means for retrieving the first and second modulation data respectively.
13 more elements
A signalling system comprising first and second signalling devices,
- the first signalling device comprising a receiver for receiving a signal output from the second signalling device and carrying uplink data transmitted from the second signalling device;
- a converter for converting a first portion of the received signal into a corresponding electric signal;
- a processor for processing the corresponding electric signal to retrieve said uplink data;
- and a modulator and reflector for modulating a second portion of the received signal with downlink data for the second signalling device and for reflecting the second portion of the received signal back to the second signalling device;
- and
- the second signalling device comprising a generator for generating a signal;
- a modulator for modulating the intensity of the generated signal between a first non-zero intensity level and a second non-zero intensity level in dependence upon said uplink data for the first signalling device;
- an outputter for outputting the intensity modulated signal towards said first signalling device;
- a first receiver for receiving the reflected signal from said first signalling device carrying said downlink data;
- and a data retriever for retrieving the downlink data from said reflected signal;
- characterised in that said second signalling device further comprises a second receiver for receiving a signal indicative of current signal attenuation characteristics of a signalling channel between said first and second signalling devices through which said output signal and said reflected signal pass;
- and a controller for dynamically varying the difference in intensity between said first and second intensity levels in dependence upon the received signal indicative of the current signal attenuation characteristics of said signalling channel.
9 more elements
A signalling system comprising first and second signalling devices,
- the first signalling device comprising a receiver for receiving a signal output from the second signalling device and carrying uplink data transmitted from the second signalling device as a small signal modulation of the output signal;
- a converter for converting a first portion of the received signal into a corresponding electric signal;
- a processor for processing the corresponding electric signal to retrieve said uplink data;
- a modulator and reflector for modulating a second portion of the received signal with downlink data for the second signalling device and for reflecting the second portion of the received signal back to the second signalling device;
- and
- the second signalling device comprising a generator for generating a signal;
- a modulator for applying a small signal modulation to said generated signal with said uplink data for the first signalling device;
- an outputter for outputting the modulated signal towards said first signalling device;
- a receiver for receiving the reflected signal from said first signalling device carrying said downlink data;
- and a data retriever for retrieving the downlink data from said reflected signal;
- characterised in that said second signalling device further comprises:
- a second receiver for receiving a signal indicative of current signal attenuation characteristics of a communications channel between said first and second signalling devices through which said output signal and said reflected signal pass;
- and a controller for dynamically varying a modulation depth of the small signal modulation applied to said generated signal in dependence upon the received signal indicative of the current signal attenuation characteristics of said communications channel.
10 more elements
A drive circuit for applying a drive current to a signal generator, the drive circuit comprising:
- a current source for generating a drive current;
- a first solid state switch having first and second main electrodes and a control electrode, the first main electrode being connected, in use, to said current source and the second main electrode being connected, in use, to a reference potential;
- a second solid state switch having first and second main electrodes and a control electrode, the first main electrode being connected, in use, to said current source and the second main electrode being connected, in use, to said signal generator;
- a first connector for receiving a first data signal and a second data signal, the second data signal being the inverse of the first data signal;
- a second connector for applying said first data signal to the control electrode of said first solid state switch to open and close said first solid state switch in dependence upon the first data signal;
- and
- a third connector for applying said second data signal to the control electrode of said second solid state switch to open and close said second solid state switch in dependence upon said second data signal;
- whereby current from said current source passes, in use, either through said first solid state switch to said reference potential or through said second solid state switch to said signal generator in dependence upon said first and second data signals;
- wherein the drive circuit further comprises a capacitor connected between the control electrode of said first solid state switch and the second main electrode of said second solid state switch.
6 more elements
A signalling system comprising first and second signalling devices,
- the first signalling device comprising a receiver for receiving a signal output from the second signalling device;
- a modulator for modulating a portion of the received signal with modulation data for the second signalling device and for reflecting the portion of the received signal back to said second signalling device;
- and
- the second signalling device comprising a generator for generating a signal;
- an outputter for outputting the generated signal towards said first signalling device;
- a receiver for receiving the reflected signal from said first signalling device carrying said modulation data;
- and a data retriever for retrieving the modulation data from said reflected signal;
- characterised in that said second signalling device further comprises a processor for processing the reflected signal received at said second signalling device to derive a measure of the dynamic range of variation of the reflected signal;
- a comparator for comparing the derived measure with a predetermined threshold value to provide a comparison result;
- and a controller for dynamically varying the signal level of said generated signal in dependence upon the comparison result.
7 more elements
A signalling device comprising:
- a generator for generating a signal;
- a modulator for varying the intensity of the generated signal between a first non-zero intensity level and a second non-zero intensity level in dependence upon uplink data to be transmitted to a remote signalling device;
- an outputter for outputting the intensity modulated signal towards said remote signalling device;
- a first receiver for receiving a reflected signal back from said remote signalling device carrying downlink data transmitted from the remote signalling device;
- and
- a data retriever for retrieving the downlink data from said reflected signal;
- characterised in that the signalling device further comprises a second receiver for receiving a signal indicative of current signal attenuation characteristics of a signalling channel between said signalling device and said remote signalling device through which said output signal and said reflected signal pass;
- and a controller for dynamically varying the difference in intensity between said first and second intensity levels in dependence upon the received signal indicative of the current signal attenuation characteristics of said signalling channel.
5 more elements
A signalling device comprising:
- a generator for generating a signal;
- an outputter for outputting the generated signal towards a remote signalling device;
- a receiver for receiving a reflected signal from said first signalling device carrying modulation data;
- and
- a data retriever for retrieving the modulation data from said reflected signal;
- characterised in that said signalling device further comprises a processor for processing the reflected signal to derive a measure of the dynamic range of variation of the reflected signal;
- a comparator for comparing the derived measure with a predetermined threshold value to provide a comparison result;
- and
- a controller for dynamically varying the signal level of said generated signal in dependence upon the comparison result.
6 more elements
Dependencies are inferred from the claim text.