Abstract: A communications device configured to generate a first diversity signal comprising: a first single coded signal spanning a first frequency sub-band, and a second single coded signal contemporaneous with the first single coded signal spanning a second frequency sub-band offset from the first frequency sub-band such that the total bandwidth of the first diversity signal is greater than the bandwidths of either of the first and second frequency sub-bands alone; and a signal transmitter configured to transmit the first diversity signal to a first counterpart communications device; the first and second single coded signals each having properties such that, after undergoing a procedure comprising being: transmitted, received, shifted into a receiver frequency sub-band spanning a narrower bandwidth than the total bandwidth of the first diversity signal, and cross-correlated with a replica signal based on the transmitted signal, a single significant peak corresponding to the most direct transmission path is produced.

Abstract: A method of communicating a data chirp signal from a transmitter to a receiver, the data chirp signal comprising a sequence of symbols, each symbol encoding a first symbol value and a second symbol value such that the data chirp signal comprises a first symbol value sequence and a second symbol value sequence, the first and second symbol values being encoded via different properties of the symbol, the first symbol value sequence being selected from values in a primary predetermined sequence and a secondary predetermined sequence, the method comprising: selecting consecutive values of the first symbol value sequence from values in consecutive sequence positions of the primary predetermined sequence and the secondary predetermined sequence; encoding first data in the chirp signal via the selected first symbol value sequence; encoding second data in the chirp signal via the second symbol value sequence; and transmitting the data chirp signal to the receiver.

Abstract: A method of communicating a data chirp signal from a transmitter to a receiver, the data chirp signal including a sequence of symbols, each symbol encoding a first symbol value and a second symbol value such that the data chirp signal includes a first symbol value sequence and a second symbol value sequence, the first and second symbol values being encoded via different properties of the symbol, the first symbol value sequence being selected from values in a primary predetermined sequence and a secondary predetermined sequence, the method including: selecting consecutive values of the first symbol value sequence from values in consecutive sequence positions of the primary predetermined sequence and the secondary predetermined sequence; encoding first data in the chirp signal via the selected first symbol value sequence; encoding second data in the chirp signal via the second symbol value sequence; and transmitting the data chirp signal to the receiver.

Abstract: A method for receiving chirp signals at a receiver device according to a protocol in which each chirp signal has a gradient known to the receiver device, the method comprising: receiving a chirp signal having a first gradient g; generating a reference chirp signal having a second gradient g?, wherein the second gradient g? differs from the first gradient g by a fixed value v; multiplying the reference chirp signal and the received chirp signal so as to form a mixed chirp signal; and detecting the received chirp signal by correlating the mixed chirp signal with a fixed gradient correlating chirp signal.

Abstract: Apparatus for generating and encoding data onto chirp signals, said apparatus including a chirp generator configured to generate a chirp; a cyclic frequency offset modulator configured to set the cyclic frequency offset of the chirp to a cyclic frequency offset selected from a plurality of predetermined cyclic frequency offsets; and a phase modulator configured to modulate the chirp onto a signal to form a chirp signal symbol at a phase offset selected from a plurality of predetermined phase offsets.

Abstract: Apparatus for generating and encoding data onto chirp signals, said apparatus including a chirp generator configured to generate a chirp; a cyclic frequency offset modulator configured to set the cyclic frequency offset of the chirp to a cyclic frequency offset selected from a plurality of predetermined cyclic frequency offsets; and a phase modulator configured to modulate the chirp onto a signal to form a chirp signal symbol at a phase offset selected from a plurality of predetermined phase offsets.

Abstract: An aspect of the invention is directed to a method for maintaining the synchronization of a receiver with a chirp signal sent over a link from a transmitter. The chirp signal comprises at least a first chirp having a gradient greater than one. The transmitter may encode data on to the signal by varying the properties of the chirps it transmits. The receiver correlates the received first chirp with an expected reference chirp to produce a set of correlation results. Should the gradient of the received chirp match the gradient of the expected reference chirp, then a distinct large “prompt” peak will be present having a greater magnitude than any other correlation peaks present in the correlation results. Transmitted data symbols may be inferred from properties of this prompt peak, for example its position in samples in the correlation results.

Abstract: A method of communicating a chirp signal from a transmitter suitable for receipt at a proximal receiver and a distal receiver, the chirp signal including a plurality of packets, each packet including at least one symbol, each symbol including one or more identical chirps, the method including: generating the chirp signal by interleaving constituent packets of: (i) a first set of packets encoded with first data, each packet including one or more symbols having a first time period t1, and (ii) a second set of packets encoded with second data, each packet including one or more symbols having a second time period t2, where t1<t2; and transmitting the generated chirp signal.

Abstract: A method for receiving a chirp signal at a receiver, the chirp signal communicated over a link from a transmitter, the chirp signal comprising at least one symbol, each symbol comprising a plurality of identical chirps, each chirp encoding a symbol value, the method comprising: determining a measure indicative of error in the received chirp signal; determining the number of coherent integrations and non-coherent integrations to apply per symbol in dependence on the indicated error; for each symbol, coherently and non-coherently integrating the plurality of chirps in accordance with the determined numbers so as to form an integrated symbol; and for each symbol, decoding the symbol value from the integrated symbol.

Abstract: A communications device configured to generate a first diversity signal comprising: a first single coded signal spanning a first frequency sub-band, and a second single coded signal contemporaneous with the first single coded signal spanning a second frequency sub-band offset from the first frequency sub-band such that the total bandwidth of the first diversity signal is greater than the bandwidths of either of the first and second frequency sub-bands alone; and a signal transmitter configured to transmit the first diversity signal to a first counterpart communications device; said first and second single coded signals each being such that, after undergoing a procedure comprising being: transmitted, received, shifted into a receiver frequency sub-band spanning a narrower bandwidth than the total bandwidth of the first diversity signal, and cross-correlated with a replica signal based on the transmitted signal, a single significant peak corresponding to the most direct transmission path is produced.

Abstract: A transmitter configured to communicate a data chirp signal to a receiver, the chirp signal comprising at least one symbol, each symbol comprising one or more identical chirps, each symbol having a different gradient to another symbol in the chirp signal, each chirp encoding a symbol value, the transmitter comprising: an address encoding module configured to encode an address associated with the communication via the sequence of gradients of the symbols in the chirp signal; a data encoding module configured to encode data in the chirp signal via the symbol value of each chirp; and a transmitting module configured to transmit the data chirp signal to the receiver.

Abstract: A method of synchronizing the frequency and timing of a receiver with a synchronization chirp signal from a transmitter, comprising: receiving the synchronization chirp signal, the synchronization chirp signal comprising a sequence of symbols, the sequence of symbols including at least a first symbol having a first gradient g1 and a second symbol having a second gradient g2, wherein the magnitudes of the first gradient and the second gradient are both greater than one, and the magnitude of the first gradient is different to the magnitude of the second gradient; correlating the sequence of received symbols with expected symbols to form a correlator output; determining timing and frequency offsets between the transmitter and the receiver from the correlator output; and adjusting the timing and frequency of the receiver by the determined timing and frequency offsets.

Abstract: An aspect of the invention is directed to a method for maintaining the synchronisation of a receiver with a chirp signal sent over a link from a transmitter. The chirp signal comprises at least a first chirp having a gradient greater than one. The transmitter may encode data on to the signal by varying the properties of the chirps it transmits. The receiver correlates the received first chirp with an expected reference chirp to produce a set of correlation results. Should the gradient of the received chirp match the gradient of the expected reference chirp, then a distinct large “prompt” peak will be present having a greater magnitude than any other correlation peaks present in the correlation results. Transmitted data symbols may be inferred from properties of this prompt peak, for example its position in samples in the correlation results.

Abstract: A method of synchronising the frequency and timing of a receiver with a synchronisation chirp signal from a transmitter, comprising: receiving the synchronisation chirp signal, the synchronisation chirp signal comprising a sequence of symbols, the sequence of symbols including at least a first symbol having a first gradient g1 and a second symbol having a second gradient g2, wherein the magnitudes of the first gradient and the second gradient are both greater than one, and the magnitude of the first gradient is different to the magnitude of the second gradient; correlating the sequence of received symbols with expected symbols to form a correlator output; determining timing and frequency offsets between the transmitter and the receiver from the correlator output; and adjusting the timing and frequency of the receiver by the determined timing and frequency offsets.

Abstract: A method of communicating a data chirp signal from a transmitter to a receiver, the data chirp signal including a sequence of symbols, each symbol encoding a first symbol value and a second symbol value such that the data chirp signal includes a first symbol value sequence and a second symbol value sequence, the first and second symbol values being encoded via different properties of the symbol, the first symbol value sequence being selected from values in a primary predetermined sequence and a secondary predetermined sequence, the method including: selecting consecutive values of the first symbol value sequence from values in consecutive sequence positions of the primary predetermined sequence and the secondary predetermined sequence; encoding first data in the chirp signal via the selected first symbol value sequence; encoding second data in the chirp signal via the second symbol value sequence; and transmitting the data chirp signal to the receiver.

Abstract: A method for receiving a chirp signal at a receiver, the chirp signal communicated over a link from a transmitter, the chirp signal comprising at least one symbol, each symbol comprising a plurality of identical chirps, each chirp encoding a symbol value, the method comprising: determining a measure indicative of error in the received chirp signal; determining the number of coherent integrations and non-coherent integrations to apply per symbol in dependence on the indicated error; for each symbol, coherently and non-coherently integrating the plurality of chirps in accordance with the determined numbers so as to form an integrated symbol; and for each symbol, decoding the symbol value from the integrated symbol.

Abstract: A method of communicating a chirp signal from a transmitter suitable for receipt at a proximal receiver and a distal receiver, the chirp signal including a plurality of packets, each packet including at least one symbol, each symbol including one or more identical chirps, the method including: generating the chirp signal by interleaving constituent packets of: (i) a first set of packets encoded with first data, each packet including one or more symbols having a first time period t1, and (ii) a second set of packets encoded with second data, each packet including one or more symbols having a second time period t2, where t1<t2; and transmitting the generated chirp signal.

Abstract: A method of securely communicating a data chirp signal from a transmitter to a receiver, the chirp signal comprising at least one symbol, each symbol comprising one or more identical chirps, each chirp encoding a symbol value, the method comprising: negotiating between the transmitter and the receiver encryption parameters of the chirp signal, the encryption parameters defining at least one property of each symbol of the chirp signal; at the transmitter, encrypting the chirp signal as negotiated; at the transmitter, encoding data in the chirp signal via the symbol value of each chirp; and transmitting the encrypted and encoded chirp signal from the transmitter to the receiver.

Abstract: A method for receiving chirp signals at a receiver device according to a protocol in which each chirp signal has a gradient known to the receiver device, the method comprising: receiving a chirp signal having a first gradient g; generating a reference chirp signal having a second gradient g?, wherein the second gradient g? differs from the first gradient g by a fixed value v; multiplying the reference chirp signal and the received chirp signal so as to form a mixed chirp signal; and detecting the received chirp signal by correlating the mixed chirp signal with a fixed gradient correlating chirp signal.

Abstract: A transmitter configured to communicate a data chirp signal to a receiver, the chirp signal comprising at least one symbol, each symbol comprising one or more identical chirps, each symbol having a different gradient to another symbol in the chirp signal, each chirp encoding a symbol value, the transmitter comprising: an address encoding module configured to encode an address associated with the communication via the sequence of gradients of the symbols in the chirp signal; a data encoding module configured to encode data in the chirp signal via the symbol value of each chirp; and a transmitting module configured to transmit the data chirp signal to the receiver.