Koninklijke Philips Corporation N.V.

Nxp B.v.

St-ericsson Sa

U.S. Philips Corporation

Robert Fifield

Brian John Minnis

David Hillary Evans

Richard J Caldwell

Richard John Caldwell

A radio receiver () comprises an analogue to digital converter () for generating a data word representative of a received radio signal and a gain control stage () comprising a first register () for storing the data word. The gain control stage () is adapted to control the numerical value of the data word by controlling the position of the data word in the first register ().

Radio receiver gain control

An arrangement () and a method for digitally filtering a time-discrete digital signal, wherein the signal is transformed to the frequency domain using discrete Fourier transformation (), the signal is filtered in the frequency domain (), wherein a filter response can be adapted in real time as required to respond to changes in the interference environment, and the filtered signal is transformed back to the time domain using inverse discrete Fourier transformation () to create an output signal, and wherein bin frequencies of said signal in the frequency domain are translated by a real amount and the sampling rate of the output signal is changed by a real factor.

Fractional frequency and sampling-rate change in the frequency domain

A receiver comprises an adaptive filter having an input for a digitized input signal, means for storing a pre-designed filter characteristic, means for analyzing a digital. representation of the input signal to determine a desired position of the filter characteristic to match the system requirements, and means for adapting the stored pre-designed filter characteristic in the frequency domain and/or the time domain to match the system requirements and for transforming the adapted filter characteristic to the time domain to update coefficients for the adaptive filter and for loading updated coefficients into adaptive filter. The updating of the coefficients may be done periodically. The adaptation may be one or more of adjusting bandwidth, frequency shift and, in the case of a bandpass characteristic, superimposing characteristics.

Receiver having an adaptive filter and method of optimizing the filter

A device processes signals from a plurality of signal channels that are received in parallel. A channel processing circuit (), applies a series of filtering operations selectively to the signal from a first one of the signal channels. A filter management circuit () detects a reception condition from reception of a signal in a second one of the signal channels. The filter management circuit () controls application of at least a part of said filtering operations to the signal from the first one the signal channels by the channel processing circuit (), dependent on the detected reception condition. Selected filter operations may be enabled or disabled. Thus, power consumption may be reduced. In an embodiment, the detected reception condition is determined as a by-product of functional reception of another channel. Thus power consumption for the detection of the reception condition is also reduced. From reception of specific types of channels, for example, it may be detected whether the device is indoors or outdoors and filtering of other channels may be adapted accordingly.

Multi-channel receiver device

A receiver comprises an adaptive filter having an input for a digitized input signal, means for storing a pre-designed filter characteristic, means for analyzing a digital representation of the input signal to determine a desired position of the filter characteristic to match the system requirements, and means for adapting the stored pre-designed filter characteristic in the frequency domain and/or the time domain to match the system requirements and for transforming the adapted filter characteristic to the time domain to update coefficients for the adaptive filter and for loading updated coefficients into adaptive filter. The updating of the coefficients may be done periodically. The adaptation may be one or more of adjusting bandwidth, frequency shift and, in the case of a bandpass characteristic, superimposing characteristics.

Receiver having an adaptive filter and method of optimising the filter

A receiver uses a sigma delta ADC () and an adaptable digital filter (). Detector circuitry detects information about unwanted parts of the signal from an oversampled digital signal, before the filtering, and feeds forward the detected information to the filter, to adapt the filter. By feeding forward the detection information, rather than feeding back an output of the filter, the adaptation can respond much more quickly to rapid changes in the unwanted interference. This enables reduced filtering to save power when interference is low, without risking a sudden increase in interference causing an avalanche of errors before the filter can be adapted correctly. The filter receives the oversampled digital signal combines decimation and channel filtering in one stage.

Adapting filter to detected interference level

In a radio communication system comprising a plurality of stations () operating in a peer-to-peer mode, each station stores information relating to the transmission parameters of other stations. Such information may include the frequency offset and received signal strength of signals from the other stations. One station acts as central controller and allocates time slots for transmission from a first station () to a second station (). Before the first station () receives a signal from the second station () it makes initial adjustments to its receiver circuitry depending on the stored information about previous signals received from that station (). This simplifies the task of adjusting the receiver circuitry during the preamble of the signal transmitted by the second station ().

Radio communication system

A method of operating a radio communication system uses orthogonal signals for transmission of packets of data between two or more stations. In the transmitter data is encoded onto a plurality of orthogonal carriers by a differential phase modulation technique, for example DQPSK. The carriers are combined into a single signal by an inverse discrete Fourier transform and clipped at a predetermined amplitude before being transmitted to reduce the crest factor of the transmitted signal. The phase of one or more of the carriers is randomized before each data packet, hence a different crest factor will result for retransmissions of the same packet. This ensures that if a packet is difficult to transmit, because of reduced signal to noise ratio caused by clipping, it will retransmit successfully.

Radio local area network

A method of operating a wireless network comprising a plurality of wireless terminals and optionally a base station uses a transmission frame ( ) including an association section ( ) for use by wireless terminals wishing to join the network. A variable number of association sections ( ) is scheduled in response to operating characteristics such as the load on the network or the presence of a high security application on the network.

Wireless network

A method of operating a wireless network comprising a plurality of public wireless terminals and private wireless terminals, and optionally a base station uses a transmission frame including a control section which may schedule encrypted communication between private wireless terminals and unencrypted communication between public wireless terminals and between public and private wireless terminals. Wireless terminals may join the network as private or public terminals.

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Redhill, United Kingdom

Robert Fifield