Abstract: A method of signal communication is disclosed comprising providing source data having a predetermined signal power; mapping the source data onto a first modulation scheme to obtain a first set of complex symbols; mapping the source data onto at least one further modulation scheme to obtain at least one further set of complex symbols; combining the first set of complex symbols and the at least one further set of complex signals to form a modulated signal to be forwarded along a communications channel. Beneficially, the predetermined signal power of the source data is split between the first modulation scheme and the at least one further modulation scheme.

Abstract: A demodulation method and apparatus is disclosed that is for use on a modulated communication signal. The method includes receiving the modulated signal including a first set of complex symbols and at least one further set of complex symbols; applying a Forward Error Correction (FEC) decoding technique; applying a first phase estimation technique to the first set of symbols; applying a second phase estimation technique to the further set of symbols to determine phase information for the modulation signal using a first phase estimation means; and repeating in part using at least one further phase estimation means to identify the presence of phase rotation. Beneficially the method enables the use of large block sizes in the FEC technique.

Abstract: A demodulation method and apparatus is disclosed that is for use on a modulated communication signal which comprises source data being mapped onto a first modulation scheme to obtain a first set of complex symbols and at least one further modulation scheme to obtain at least one further set of complex symbols. The method comprises receiving the modulated signal comprising the first set of complex symbols and at least one further set of complex symbols; a. applying a Forward Error Correction (FEC) decoding technique; b. applying a first phase estimation technique to the first set of symbols; c. applying a second phase estimation technique to the second set of symbols to determine phase information for the modulation signal using a first phase estimation means; and d. repeating steps c and d using at least one further phase estimation means to identify the presence of phase rotation. Beneficially the method enables the use of large block sizes in the FEC technique.

Abstract: A method of signal communication is disclosed comprising providing source data having a predetermined signal power; mapping the source data onto a first modulation scheme to obtain a first set of complex symbols; mapping the source data onto at least one further modulation scheme to obtain at least one further set of complex symbols; combining the first set of complex symbols and the at least one further set of complex signals to form a modulated signal to be forwarded along a communications channel. Beneficially, the predetermined signal power of the source data is split between the first modulation scheme and the at least one further modulation scheme.

Abstract: A voltage controlled band-pass filter is in a phase locked loop. The output from a phase detector is applied through a loop filter as the control voltage. The phase detector output is proportional to the difference in phase between first and second signals input to the phase detector. The first signal is fed directly from a local oscillator to the phase detector. The second signal is fed from the local oscillator to the phase detector through the voltage controlled band-pass filter.

Abstract: A radio receiver having a selectable first downconverter stage for each mode to convert radio frequencies to intermediate frequencies, a second downconverter stage to convert the intermediate frequencies to baseband frequencies, said second downconverter stage being common to both modes, and channel selection at baseband frequencies by means of re-configurable filtering. A radio receiver having a selectable first downconverter stage for each mode to convert radio frequencies to intermediate frequencies, a second downconverter stage to convert the intermediate to baseband frequencies, said second downconverter stage being common to all modes, and channel selection at baseband frequencies by means of re-configurable filtering.

Abstract: A heterodyne radio receiver, having a broadband IF, in which the outputs from the second down-conversion mixer of the receiver are high pass filtered to select unwanted signals and low pass filtered to select wanted signals, the unwanted signals being up-converted to IF in an up-conversion mixer, phase shifted and added in anti-phase to an input or inputs of the second down-conversion mixer.

Abstract: A part of the output signal from the voltage control oscillator is down-converted by the down-converting means. The down-converted signal is compared with a modulation signal by the phase detector. The signal has amplitude and polarity based on the comparison effected between the down-converted signal and the modulation signal is provided to the voltage control oscillator. The voltage control oscillator outputs a signal has frequency based on the applied signal.

Abstract: The output of a fixed frequency local oscillator is multiplied in frequency by a frequency multiplier and used in the mixer of the first down-conversion stage of a heterodyne receiver. Receiver channel selection and tuning takes place at IF by means of a PLL, the phase detector for the receiver PLL being used also as the phase detected for the transmitter tracking loop PLL. The multiplied local oscillator output is also used in the mixer of the transmitter tracking loop.

Abstract: A tunable voltage controlled bandpass filter for a direct conversion receiver. A phase locked loop uses the phase change imparted by the bandpass filter to local oscillator breakthrough from the mixer for a measure of frequency difference between input RF and local oscillator output. An error voltage derived from the measured phase change is applied as a tuning control to the bandpass filter. A sample and hold arrangement allows disconnection of the tuning circuit for power saving. The filter is suitable for implementation as an integral part of an ASIC receiver.

Abstract: A calibrator for stabilization of a passband active filter firstly sets a low level of filter supply current to assure filter stability while the filter is tuned to the required passband. The supply current is then gradually increased until the filter becomes unstable. The supply current level is held constant when filter instability is detected and the current is then reduced by a pre-determined amount to maintain stability of the filter. Re-tuning of the filter may then proceed without risk of instability. May be used as part of a phase locked loop for operating channel selection in a radio.

Abstract: An antenna for a mobile telephone for applying to an ordinary gain antenna for GSM and a high gain antenna for ICO. The antenna comprises a strip of flexible insulating material having provided thereon a plurality of lines of conductive material, the strip is formed into a roll with one end at the outside of the roll and the other end inside the roll, the other end is drawable from the roll to extend the strip into an elongated conical shape.