The present application provides a signal demodulation apparatus and method in a closed communication system. The signal demodulation apparatus includes: an analog voltage comparator, configured to convert a received modulated signal into a digital signal, and output the digital signal; and a sampling decider, configured to sample the received digital signal, and acquire a value represented by the digital signal according to a feature of a sampled digital signal to complete a signal demodulation. The present application improves signal-to-noise ratio of pressure detection, reduces power consumption and increases refresh rate. The apparatus and method according to the present application have the advantages of simple structure, easy to implement, small circuit area and low power consumption, and thus are suitable for a scenario imposing strict requirements on the power consumption and area, for example, a wearable device and the like.

A transmitter transmits payload data using Orthogonal Frequency Division Multiplexed (OFDM) symbols, the transmitter including a frame builder to receive the payload data and to receive signalling data for use in detecting and recovering the payload data at a receiver, and to form the payload data into data-units for transmission. A modulator modulates plural sub-carriers of one or more OFDM symbols with the signalling data and the payload data in accordance with a modulation scheme to provide for each of plural sub-carriers a modulation symbol, a prefixing circuit prefixes a guard interval to the one or more OFDM symbols, and a transmission circuit transmits the one or more OFDM symbols. The modulator includes an I/Q interleaver to receive a real component of the modulation symbol of each of the one or more sub-carriers and to interleave the real component of the modulation symbols differently to the imaginary component.

A synchronizer can include a symbol estimator, an inner-pattern de-mapper, a timing tracker, and a correlator. The symbol estimator can be configured to estimate one or more symbols of a received signal based on a phase signal. The inner-pattern de-mapper can be configured to de-map the one or more symbols to generate an inner-pattern de-mapped symbol estimation. The timing tracker can be configured to accumulate the inner-pattern de-mapped symbol estimation and to determine a peak position based on the accumulated inner-pattern de-mapped symbol estimation. The correlator can be configured to correlate the accumulated inner-pattern de-mapped symbol estimation based on a reference signal. The correlation of the accumulated inner-pattern de-mapped symbol estimation can be independent of a signal over sampling rate (OSR). The synchronizer can be adapted in a long range Bluetooth low energy (BLE) receiver.

The communication process for high-sensitivity and synchronous demodulation signals between a transmitter (2) and a receiver (3) comprises a first synchronisation phase followed by a modulation and demodulation phase of the data. To achieve this, the transmitter transmits a pseudo-periodic chirp signal to the receiver, where a frequency conversion of the chirp signal is performed in a mixer (33) by an oscillating signal (So) at constant frequency of a local oscillator (34) to supply an intermediate signal, which is filtered and sampled for a logic unit (37). An assembly (38) of m pairs DFT blocks phase-shifted in relation to one another and operating in parallel is provided in the logic unit. A processing unit (39) receives the result of the pairs of the assembly to determine frequency and phase errors between the transmitter and the receiver on the basis of two peaks detected by one of the pairs above a threshold to synchronise the receiver.

A receiver detects a received signal, transmitted by a transmitter to carry payload data as Orthogonal Frequency Division Multiplexed (OFDM) symbols in divided frames, each frame including a preamble including plural bootstrap OFDM symbols. A detector circuit detects, from the bootstrap OFDM symbols, a synchronization timing for converting a useful part of the bootstrap OFDM symbols into the frequency domain. A bootstrap processor detects an estimate of the channel transfer function from a first OFDM symbol, and a demodulator circuit recovers the signaling data from the bootstrap OFDM symbols using the estimate. The bootstrap processor includes an up-sampler configured to receive the bootstrap OFDM symbols, to form an up-sampled frequency domain version of the bootstrap OFDM symbol, and an output processor configured to identify a peak correlation result, to determine frequency offset of the received signal from a relative position of the peak correlation result in the frequency domain.

A frequency-shift keying (FSK) demodulator includes a digital phase-locked loop (DPLL) based frequency estimator to convert a phase signal to a frequency signal, a frequency offset estimator to estimate and track direct current (DC) component of the frequency signal, and an average filter communicatively coupled to the frequency offset estimator to perform an accumulate-and-dump operation to improve a symbol-level signal to noise ratio (SNR) of the frequency signal.

A method to determine the magnitude M.sub.A of a signal component with frequency .sub.A from a set of N digital samples of an input signal acquired at a sampling rate R, said input signal having a discrete spectral representation having n bins with frequencies .sub.1, . . . , .sub.n and corresponding magnitudes M.sub.1, . . . , M.sub.n, the spectral representation being derivable from the input signal using a transform, involving choosing an extraction bin with index k[1, . . . , n] and frequency .sub.k.sub.A from the spectral representation; determining a magnitude M.sub.k of this extraction bin; determining an allocation factor indicating a portion M.sub.ks of a sinusoidal signal with frequency .sub.A and unity magnitude that is allocated to the extraction bin when the transform is applied to the sinusoidal signal to generate a spectral representation out of the sinusoidal signal; and determining the magnitude M.sub.A of the signal component from the magnitude M.sub.k of the bin in combination with the factor.

The present application provides a signal demodulation apparatus and method in a closed communication system. The signal demodulation apparatus includes: an analog voltage comparator, configured to convert a received modulated signal into a digital signal, and output the digital signal; and a sampling decider, configured to sample the received digital signal, and acquire a value represented by the digital signal according to a feature of a sampled digital signal to complete a signal demodulation. The present application improves signal-to-noise ratio of pressure detection, reduces power consumption and increases refresh rate. The apparatus and method according to the present application have the advantages of simple structure, easy to implement, small circuit area and low power consumption, and thus are suitable for a scenario imposing strict requirements on the power consumption and area, for example, a wearable device and the like.

A transmitter transmits payload data using Orthogonal Frequency Division Multiplexed (OFDM) symbols, the transmitter including a frame builder to receive the payload data and to receive signalling data for use in detecting and recovering the payload data at a receiver, and to form the payload data into data-units for transmission. A modulator modulates plural sub-carriers of one or more OFDM symbols with the signalling data and the payload data in accordance with a modulation scheme to provide for each of plural sub-carriers a modulation symbol, a prefixing circuit prefixes a guard interval to the one or more OFDM symbols, and a transmission circuit transmits the one or more OFDM symbols. The modulator includes an I/Q interleaver to receive a real component of the modulation symbol of each of the one or more sub-carriers and to interleave the real component of the modulation symbols differently to the imaginary component.

A weather band receiver, which may be part of an FM receiver, is disclosed. FSK-encoded data units in an alert packet transmission are detected using a quadrature matched filter circuit. At least one FSK-encoded data unit is captured from the alert packet transmission. Soft quantized bits are extracted from the FSK-encoded data units. The soft quantized bits are saved to memory and used to recover an alert message. Soft quantized bits from two or more FSK-encoded data units may be combined before recovering the alert message.