Telefonaktiebolaget Lm Ericsson (publ)

Siemens Elema Ab

Roozbeh Atarius

Thomas Ohlsson

Leif Soernmo

Georg Frank

Berthold Gustafsson Kjell

A method and apparatus for synchronizing to a time structure associated with base station transmissions in a radiocommunication system are described. A broadcast control channel can contain synchronization symbols within one or more of a plurality of timeslots. The symbols can be provided as periodic, e.g., exponential, signals which introduce a frequency deviation into the broadcast control channel. This frequency deviation can be recognized by the receiver to synchronize to the time structure of the base station transmissions. Moreover, the variation in the frequency deviation caused by phase rotation associated with local oscillator inaccuracy can also be compensated to achieve frequency synchronization.

Synchronization techniques and systems for spread spectrum radiocommunication

In a communication system including at least one transmitter and at least one receiver, a frequency synchronization signal transmitted from the transmitter to the receiver is detected. An in-phase component of a signal received by the receiver is delayed, and the delayed in-phase component is multiplied by a quadrature component of the received signal. The steps of delaying and multiplying are repeated for a predetermined number of samples of the received signal to produce an estimated cross-correlation value. A determination is made whether the estimated cross-correlation value is at least as great as a predetermined threshold, indicating that the transmitted signal is a frequency synchronization signal.

Method and apparatus for detecting a frequency synchronization signal

In a communication system including at least one transmitter and at least one receiver, a frequency offset between a carrier frequency of the transmitter and a local frequency reference of the receiver is estimated. A phase difference is computed between successively collected samples of a frequency synchronization signal transmitted by the transmitter and detected by the receiver. The phase difference is added to accumulated phase differences. Phase differences of successively collected samples are computed and added to accumulated phase differences until M accumulated phase differences have been added. The sum of the M phase differences is dumped, resulting in zero accumulated phase differences. Phase differences of successively collected samples are computed, the phase differences are added to accumulated phase differences, and the sum of M phase differences is dumped until N sums of M phase differences have been dumped. The N sums of the M phase differences are added to produce the estimated frequency offset.

Method and apparatus for estimating a frequency offset

In a method for enhancing the signal-to-noise ratio of ECG signals, A/D-converted signals from a number of cardiac cycles are time-synchronized to form a signal ensemble, and the correlation between the signals in the ensemble is determined in time intervals, comprising at least two samples, during at least a part of the cardiac cycles. A device for enhancing the signal-to-noise ratio of ECG signals, includes circuitry for recording, A/D-converting and other processing of the ECG signals. A synchronization unit is arranged to time-synchronize the signals from a plurality of cardiac cycles to form a signal ensemble, and a calculator unit controlled by a window unit determines the correlation between the signals in the ensemble in time intervals, comprising at least two samples, during at least a part of the cardiac cycles.

Method and apparatus for enhancing the signal-to-noise ratio of ECG

In a method and apparatus for processing ECG signals for the purpose of detecting low-amplitude signal structures hidden in noise in the ECG signal, the ECG signals, number of cardiac cycles are analog-to-digital converted, and QRS complexes in the converted signals are detected. The signals from at least two cardiac cycles are cross-correlated, and the correlation between these signals in time intervals which comprise at least the time intervals of the two samples is determined. An output quantity representing the degree of correlation is thus obtained, the magnitude of this quantity designating the amplitude of the signal structure in question. This magnitude can then be analyzed to determine if, and where in the signal, the signal structure arises.

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Lund, Sweden

Roozbeh Atarius