Nokia Mobile Phones Limited

Kari Kananen

Jorma Matero

Juha H Rapeli

Jari Rajaniemi

A method for use by a multi-mode, dual band mobile terminal ( ) for identifying a presence of a GSM1900 carrier that is channelized into first channels having a bandwidth of 200 kHz, and for distinguishing the GSM1900 carrier from at least a TDMA1900 carrier that is channelized into second channels having a bandwidth of 30 kHz. The method includes steps of (a) tuning a receiver ( ) to a frequency of a candidate GSM1900 channel; (b) determining a value of a received signal strength indicator (RSSI) using a 200 kHz receiver passband filter; (c) if the RSSI value is above a predetermined threshold, converting the frequency of the candidate GSM1900 channel into a frequency of a TDMA1900 channel using a predetermined relationship; (d) retuning the receiver to the frequency of the TDMA1900 channel; (e) determining a RSSI value using a 30 kHz receiver passband filter for the TDMA1900 channel, and also for at least two adjacent TDMA1900 channels, assuming that two adjacent TDMA1900 channels are not used together in a same cell; and, if the at least three RSSI values are all found to be approximately equal within some threshold value, (f) making at least an initial assumption of the presence of the GSM1900 carrier. A further step can be executed of verifying that the assumed GSM1900 carrier is not actually a CDMA1900 carrier. The method has an initial step of camping on a channel of a carrier in another frequency band (e.g., a TDMA800 channel), and the steps of tuning and retuning are executed without changing a baseband clock frequency from a frequency associated with the channel that the mobile terminal is camped on.

Mobile terminal employing 30kHz/200kHz carrier identification

This invention teaches methods and apparatus for providing a low cost, low complexity, and low component count transmitter feedback function for use in mobile station transmitter linearization and self-test operations. Disclosed is a method for operating a mobile station of a type that includes a transmit chain having an output coupled to an antenna and a receive chain having an input coupled to the same or a different antenna. The method includes steps of: during a transmission time, (a) sampling an amplified signal prior to the amplified signal being applied to the antenna for transmission from the transmit chain; (b) downconverting a frequency of the sampled amplified signal to a lower frequency signal using a receive chain local oscillator signal normally used for downconverting a received signal to the first IF; and (c) demodulating the lower frequency signal to a baseband signal with a receive chain demodulator by using a second local oscillator signal that is normally used as a transmit chain modulator injection frequency signal. A further step of the method determines from the baseband signal an amount of predistortion of an input signal to the transmit chain in order to obtain a desired amount of linearization of the amplified signal.

Dual band architectures for mobile stations having transmitter

A frequency difference signal of a modulated signal (f.sub.1) and an unmodulated signal (f.sub.2) is produced maintaining the information of the frequency or phase modulation. According to the method, the time-related order of entry of the front edges of the pulses of the modulated and the unmodulated signal is controlled and the edge of the frequency difference signal in question at any moment is formed timewise at the same point as the edge of such modulated signal at which the time-related order of arrival of the modulating signal and the unmodulated signal has changed. Hereby, the frequency or phase shift of the modulated signal can be detected as an equivalent change in the frequency difference signal, and the modulation of the frequency difference signal is detected on the basis of the location of the pulse edge of the frequency difference signal.

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Oulu, Finland

Kari Kananen