Nokia Mobile Phones Limited

Haltian Oy

Juha Pikkarainen

Raimo K Kivari

Marko Parttimaa

Jyrki Okkonen

Veijo L Kontas

Teemu Vaattovaara

Ville Ylläsjärvi

Jussi Kivilinna

Aleksandre Pekki

Pertti Kujala

Active radio-frequency identification, RFID, tag, and a product surveillance method using active RFID tags. The method includes: transmitting (), by an active RFID tag, continuously a signal comprising an own identifier according to a predetermined schedule; receiving (), by the active RFID tag, continuously a plurality of signals comprising a plurality of foreign identifiers transmitted by a plurality of other active RFID tags according to the predetermined schedule; measuring (), by the active RFID tag, a received signal strength indication, RSSI, of each received signal; storing (), by the active RFID tag, each foreign identifier of a signal whose RSSI exceeds a predetermined strength threshold; detecting (), by the active RFID tag, that a signal with a stored foreign identifier is no more received according to the predetermined schedule and marking (), by the active RFID tag, said stored foreign identifier.

Active RFID tag and product surveillance method

A method and modulator for modulating a digital signal to an analog intermediate-frequency signal. A baseband digital signal (I, Q) is taken to a digital-to-analog converter (71, 710) in which it is sampled at a certain sampling frequency (f.sub.in) and converted to an analog signal. The conversion produces a baseband signal (f.sub.sig) and signals (N*f.sub.in, f.sub.Ni) at multiples of the sampling frequency (f.sub.in). The sampling frequency is increased, advantageously according to a sigma-delta D/A conversion, and one of the signals (N*f.sub.in,f.sub.Ni) at multiples of the sampling frequency (f.sub.in), produced by the conversion, is selected as the output signal (f.sub.IF), advantageously a multiple (N*f.sub.in, f.sub.Ni) of the sampling frequency that is directly at the intermediate frequency or transmission frequency.

Method and modulator for modulating digital signal to higher frequency

Apparatus operable with different cellular telephone systems and signalling protocols is described. Signalling messages, both data messages and supervisory related signals between a cellular telephone microcontroller (4) and a base station are transferred via a baseband signalling circuit (10). The baseband signalling circuit is operable to employ different signalling protocols, the protocol being selected by control bits provided from the microcontroller to the signalling circuit. In a preferred embodiment, the signalling protocol selection is made between an AMPS/TACS signalling protocol and a NAMPS/NTACS subaudible signalling protocol.

Cellular telephone signalling circuit operable with different cellular

A switched capacitor decimator circuit (20) is shown to be useful in a cellular telephone that operates in accordance with a subaudible signalling protocol. The switched capacitor decimator circuit has an input node for inputting a received signal that includes a subaudible signalling component and an interfering voice component. The switched capacitor decimator circuit further has an output node for outputting a signal having an amplified subaudible signalling component and voice component. The circuit includes an operational amplifier (22) having an input and an output and a characteristic DC offset voltage. A first capacitance (Cint) is switchably coupled, at a rate equal to a first frequency, between the input and the output of the operational amplifier. A second capacitance (Cin) is coupled between the input node and the input of the operational amplifier. A gain (G) of the circuit is given by Ncin/Cint, where n is a ratio of the first frequency to a second, lower frequency. The circuit further includes circuitry (C3, C4) for DC offset compensating the switched capacitor decimator circuit such that the DC offset voltage of the operational amplifier appears at the output node amplified only with a gain of unity.

Switched capacitor decimator

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Oulu, Finland

Juha Pikkarainen