Abstract: There is provided a method of testing an RF transceiver circuit and an RF transceiver circuit arranged to be operable in a test mode comprising a transmitter circuit portion and a receiver circuit portion, the receiver circuit portion including a mixer. The method involves the transmitter circuit portion generating a modulated signal and the receiver circuit portion receiving a continuous radio frequency wave. The mixer mixes the modulated signal with a signal derived from the continuous radio frequency wave to produce an output. A remainder of the receiver circuit portion processes the output of the mixer.

Abstract: A radio apparatus correlates signal data with stored synchronization data to determine correlation data. The signal data represents a received radio-frequency signal that encodes a data frame, which has a synchronization preamble with a plurality of instances of a predetermined synchronization sequence. The stored synchronization data represents the predetermined synchronization sequence. The radio apparatus identifies a set of peaks in the correlation data, and uses a timing criterion to identify a plurality of subsets of the set of peaks, such that time values of the peaks of each identified subset satisfy the timing criterion. The radio apparatus calculates a correlation score Cj for each of the identified subsets from correlation values of the subset's peaks, and uses the correlation scores Cj to select a subset from the plurality of subsets. Timing or frequency synchronization information for the radio apparatus is determined from the peaks of the selected subset.

Abstract: A radio apparatus correlates signal data with stored synchronization data to determine correlation data. The signal data represents a received radio-frequency signal that encodes a data frame, which has a synchronization preamble with a plurality of instances of a predetermined synchronization sequence. The stored synchronization data represents the predetermined synchronization sequence. The radio apparatus identifies a set of peaks in the correlation data, and uses a timing criterion to identify a plurality of subsets of the set of peaks, such that time values of the peaks of each identified subset satisfy the timing criterion. The radio apparatus calculates a correlation score Cj for each of the identified subsets from correlation values of the subset's peaks, and uses the correlation scores Cj to select a subset from the plurality of subsets. Timing or frequency synchronization information for the radio apparatus is determined from the peaks of the selected subset.

Abstract: A demodulator for a digital radio receiver comprises a frequency discriminator and a Viterbi decoder. The frequency discriminator receives a series digital signal samples representative of an FSK-modulated signal and performs frequency discrimination on the digital signal samples to generate a series of frequency samples. Each frequency sample represents an instantaneous frequency of the signal in a respective frequency-sample period. There are an integer oversampling factor, N>1, of frequency-sample periods in each symbol period. The Viterbi decoder receives the series of frequency samples, determines branch metrics for each symbol period by determining distances between a vector of N successive frequency samples and each of a plurality of reference waveform vectors, each comprising N elements. It use the branch metrics in a Viterbi process to output demodulated symbol values corresponding to a maximum-likelihood decoding of the FSK-modulated signal.

Abstract: A radio receiver device is arranged to receive a radio signal including a data packet having an address portion and a payload portion, said radio receiver comprising: a first demodulation circuit portion arranged to demodulate the data packet and produce a first estimate of the address portion and a first estimate of the payload portion; a second demodulation circuit portion arranged to demodulate the data packet and produce a second estimate of the payload portion; a first comparison circuit portion arranged to compare said first and second estimates of the payload portion and produce a flag only if they are identical; and a second comparison circuit portion arranged, upon receipt of said flag, to compare said first estimate of the address portion to an expected address portion and to discard the data packet if they are not identical.

Abstract: A radio receiver device is arranged to receive a radio signal modulated with a data packet including an address portion. The radio receiver comprises: a synchronisation circuit portion arranged to produce synchronization information corresponding to the data packet; a demodulation circuit portion comprising a correlator, wherein said demodulation circuit portion is arranged to receive the radio signal and to produce an estimate of the address portion comprising a plurality of demodulated bits using said correlator and the synchronisation information; an address checking circuit portion arranged to receive the plurality of demodulated bits, to check said plurality of demodulated bits for a predetermined bit pattern, and to produce a match flag if it determines that the plurality of demodulated bits corresponds to the predetermined bit pattern.

Abstract: A digital radio receiver (7) is arranged to receive and process data frames, each data frame comprising (i) a plurality of identical synchronization sequences; (ii) identification data different from the synchronization sequences; and (iii) convolution-encoded message data. An initial-synchronization section of the receiver (7) uses the plurality of synchronization sequences in a received data frame to perform a frequency-synchronization or symbol-timing-synchronization operation. A frame-synchronization section determines frame-synchronization information by correlating at least a part of the received identification data against reference identification data stored in a memory. A convolution-decoding section uses the frame-synchronization information to decode the message data.

Abstract: A radio receiver device is arranged to receive a radio signal including a data packet having an address portion and a payload portion, said radio receiver comprising: a first demodulation circuit portion arranged to demodulate the data packet and produce a first estimate of the address portion and a first estimate of the payload portion; a second demodulation circuit portion arranged to demodulate the data packet and produce a second estimate of the payload portion; a first comparison circuit portion arranged to compare said first and second estimates of the payload portion and produce a flag only if they are identical; and a second comparison circuit portion arranged, upon receipt of said flag, to compare said first estimate of the address portion to an expected address portion and to discard the data packet if they are not identical.

Abstract: A radio receiver device is arranged to receive a radio signal modulated with a data packet including an address portion. The radio receiver comprises: a synchronisation circuit portion arranged to produce synchronization information corresponding to the data packet; a demodulation circuit portion comprising a correlator, wherein said demodulation circuit portion is arranged to receive the radio signal and to produce an estimate of the address portion comprising a plurality of demodulated bits using said correlator and the synchronisation information; an address checking circuit portion arranged to receive the plurality of demodulated bits, to check said plurality of demodulated bits for a predetermined bit pattern, and to produce a match flag if it determines that the plurality of demodulated bits corresponds to the predetermined bit pattern.

Abstract: A digital radio receiver (7) is arranged to receive and process data frames, each data frame comprising (i) a plurality of identical synchronization sequences; (ii) identification data different from the synchronization sequences; and (iii) convolution-encoded message data. An initial-synchronization section of the receiver (7) uses the plurality of synchronization sequences in a received data frame to perform a frequency-synchronization or symbol-timing-synchronization operation. A frame-synchronization section determines frame-synchronization information by correlating at least a part of the received identification data against reference identification data stored in a memory. A convolution-decoding section uses the frame-synchronization information to decode the message data.

Abstract: A radio transmitter (4) comprises an encoder (5) that receives one or more variable message bits, and encodes each message bit that has a first value as a predetermined first binary chip sequence and encodes each message bit that has the opposite value as a predetermined second binary chip sequence. The radio transmitter (4) transmits data packets, each comprising (i) a predetermined synchronization portion, comprising one or more instances of the first binary chip sequence, and (ii) a variable data portion, comprising one or more encoded message bits output by the encoder. A radio receiver (9) receives such data packets. It uses the synchronization portion of a received data packet to perform a frequency and/or timing synchronization operation, and then decodes message bits from the data portion of the data packet.

Abstract: A method of digital radio communication between a first device (2) and a second device (8), where each device comprises a radio transmitter (4, 10) and a radio receiver (6, 12), the method comprising: a) said first and second devices (2, 8) establishing a connection using a predetermined protocol having at least one predefined message format; and b) said first and second devices (2, 8) agreeing that in the event of said connection being broken a re-connection may be established using a coding scheme in which at least some bits specified in said predefined message format are represented by a plurality of bits transmitted.

Abstract: A digital radio receiver is adapted to receive radio signals modulated using continuous phase modulation. The receiver includes components for receiving analogue radio signals having various carrier frequencies and a plurality of correlators corresponding to different bit sequences. Each of the plurality of correlators share a common estimator for estimating a frequency offset between the radio signals carrier frequencies and nominal carrier frequencies. The receiver further includes components allowing the estimator to determine which of the correlators produce the most optimal output signal.

Abstract: A method of digital radio communication between a first device 2 and a second device 8, where each device comprises a radio transmitter 4, 10 and a radio receiver 6, 12, the method comprising: a) said first and second devices 2, 8 establishing a connection using a predetermined protocol having at least one predefined message format; b) if said connection is subsequently broken, said second device 8 transmitting an advertising message at a first data rate indicating a desire to reconnect; and c) if a reconnection is not established, said second device 8 transmitting a further advertising message at a second data rate indicating a desire to reconnect, wherein said second data rate is lower than the first data rate.

Abstract: A digital radio receiver adapted to receive radio signals modulated using continuous phase frequency shift keying, CPFSK. The receiver comprises means for receiving a radio signal (2), a correlator (8) arranged to estimate a frequency offset between the carrier frequency of the received radio signal and a nominal carrier frequency, means for correcting said frequency offset (4) and outputting a frequency-corrected radio signal (6), and a matched filter bank, MFB, which comprises a plurality of filters (20,22), each of which corresponds to a different bit pattern, for determining a bit sequence (36) from the frequency-corrected radio signal (6).

Abstract: A method of digital radio communication between a first device (2) and a second device (8), where each device comprises a radio transmitter (4, 10) and a radio receiver (6, 12), the method comprising: a) said first and second devices (2, 8) establishing a connection using a predetermined protocol having at least one predefined message format; b) if said connection is subsequently broken, said second device (8) transmitting an advertising message at a first data rate indicating a desire to reconnect; and c) if a reconnection is not established, said second device (8) transmitting a further advertising message at a second data rate indicating a desire to reconnect, wherein said second data rate is lower than the first data rate.

Abstract: A radio transmitter (4) comprises an encoder (5) that receives one or more variable message bits, and encodes each message bit that has a first value as a predetermined first binary chip sequence and encodes each message bit that has the opposite value as a predetermined second binary chip sequence. The radio transmitter (4) transmits data packets, each comprising (i) a predetermined synchronisation portion, comprising one or more instances of the first binary chip sequence, and (ii) a variable data portion, comprising one or more encoded message bits output by the encoder. A radio receiver (9) receives such data packets. It uses the synchronisation portion of a received data packet to perform a frequency and/or timing synchronisation operation, and then decodes message bits from the data portion of the data packet.

Abstract: A digital radio receiver 54 is adapted to receive radio signals which are modulated using continuous phase modulation. The receiver comprises means for receiving an analogue radio signal having a carrier frequency, a plurality of correlators 6, 8 each corresponding to a different bit sequence which share a common estimator 4 for estimating a frequency offset between said carrier frequency and a nominal carrier frequency, and means 12 for determining which of said correlators 6, 8 produces a desired output signal.

Abstract: A method of digital radio communication between a first device (2) and a second device (8), where each device comprises a radio transmitter (4, 10) and a radio receiver (6, 12), the method comprising: a) said first and second devices (2, 8) establishing a connection using a predetermined protocol having at least one predefined message format; and b) said first and second devices (2, 8) agreeing that in the event of said connection being broken a re-connection may be established using a coding scheme in which at least some bits specified in said predefined message format are represented by a plurality of bits transmitted.

Abstract: A method of digital radio communication between a first device (2) and a second device (8), where each device comprises a radio transmitter (4, 10) and a radio receiver (6, 12), the method comprising: a) said first and second devices (2, 8) establishing a connection using a predetermined protocol having at least one predefined message format; b) if said connection is subsequently broken, said second device (8) transmitting an advertising message at a first data rate indicating a desire to reconnect; and c) if a reconnection is not established, said second device (8) transmitting a further advertising message at a second data rate indicating a desire to reconnect, wherein said second data rate is lower than the first data rate.