U.S. Philips Corporation

Cornelis C Schuur

Kar B Chan

Hermanus J Vos

Frederik A Dumont

Roelof J De Haas

In a time division multiple access wireless communication system, a wireless radio station performs a timing error compensation method. The wireless radio station receives messages including a synchronisation pattern. The wireless radio station adopts a power down mode between reception of messages, and accumulates a timing error representing an accumulated difference between expected times of arrival of the synchronisation patterns and actual times of arrival of the synchronisation patterns, during a predetermined time interval between reception of successive messages and before an expected reception of a next message. Thereafter, the wireless radio station at least substantially undoes the accumulated timing error, before the expected reception of the next message such that the timing error is compensated before the expected reception of the next message.

Digital wireless communications system and a wireless radio station with

Data terminal comprising a demodulator for a FSK phase-coherent modulated signal having at least two frequencies, comprising a PLL circuit (10) in which a phase detector is combined with a real-time integrator (15) and in which a sequencer (5) is included, so that the modulated signal is integrated around the zero crossings before a clock signal and digital data are extracted from this signal after a phase lock. As long as the PLL circuit (10) is in the unlocked state, the frequency with which the integrator (15) is driven by the sequencer (5) is equal to half the bit rate of the modulated signal while, for that matter, this frequency is equal to the bit rate.

Data terminal comprising a demodulator for a FSK phase-coherent

A digital radio communication system (1) is known, for example based on the DECT standard, in which radio communication of digital speech or data between primary (BS1) and secondary (MS1) stations takes place via duplex FDMA/TDMA connection. Channel allocation therein is dynamic. If necessary because of the receiving conditions, the secondary station (MS1) can initiate a so-called handover by searching for a free channel offering better receiving conditions. In accordance with the invention, this handover is seamless. Digital speech bursts are exchanged via different time slots (ts) during a number of frames (fr), these being digital speech data and copy digital speech data. After verification that the copy data is valid, i.e. that communication has been established via a free channel, handover takes place. The original data and the copy data are stored in a cyclic buffer (SB5) so that the phase shift (d) between the original data and the copy data is eliminated. Subsequently, the channel via which the original data was transported is released. In one embodiment a speech pointer (SPP) for reading speech freely progresses along the cyclic buffer (SB5) and a radio pointer (RFP), progressing along the buffer (SB5) and controlling the writing of speech bursts, is adapted during handover to the phase shift (d) between time slots involved in the handover.

Digital radio communication system and primary and secondary station for

An interface for a connection network between individual stations and a physical medium used for the message traffic between these stations, where signals supplied via the physical medium are converted into a bit stream by means of a demodulator, such a bit stream being converted into signals to be transmitted via the physical medium by means of a modulator, a protocol control unit is connected thereto and communicates, via a communication memory bus, with a communication memory a first part of which is reserved for the communication software which is stored as the primary program. A second part of the communication memory is reserved for the process control software which is stored at least partly as the secondary program for the process to be executed in the station connected to the interface, the protocol control unit consisting of a modem control unit for writing and reading the bit stream received and to be transmitted, respectively, into and from the communication memory, a communication control unit for coordinating the operations of the modem control unit and for ensuring the execution of the primary and the secondary program, and a communication memory bus control unit for assigning time slots for access to the communication memory in response to relevant requests from the modem control unit and the communication control unit, the modem control unit interrupting the execution of the secondary program in the communication control unit each time when a communication instruction is to be executed for the relevant station, after which the communication control unit executes the primary program but continues the execution of the secondary program during waiting periods in the execution of the primary program, for which purpose there is provided a further memory for memorizing the location where and the circumstances under in the primary and the secondary program have been interrupted.

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Eindhoven, Netherlands

Cornelis C Schuur