Abstract: An adaptive pre-equalizer is disclosed to compensate amplitude ripples in a low cost transmitter pass-band filter. A filtered-x LMS algorithm is proposed to calculate the equalizer coefficients. To this purpose, the modulated RF signal is demodulated at the transmitter and subtracted from a filtered version of the original base band signal. The impulse response of the low-cost transmit filter is approximated by a delay. The disclosure may be applied to direct conversion or heterodyne transmitters using OFDM.

Abstract: A processing device and method for an error adjustment system for equalizing transmission characteristics of N signal processing circuitries according to N signal branches (N>1) are disclosed. An original complex IQ signal of a signal branch of N signal branches and a processed real signal of the signal branch are received. A processed complex IQ signal of the signal branch is calculated from the processed real signal and the original complex IQ signal of the signal branch. Then, a difference between the processed complex IQ signal and the original complex IQ signal is calculated. Finally, control values of a correction function of the signal branch are calculated on the basis of the calculated difference. The calculated control values are supplied to the correction function of the signal branch. The receiving, calculating and supplying operations are performed for all N signal branches.

Abstract: A receiving method and a direct conversion receiver are provided. The receiver comprises a mixer (308) for mixing a received signal into a base band signal com-prising I and Q branches, and an A/D converter (316) for converting the base band signal into digital form, and a phase adjuster (318) for performing a frequency selective IQ phase error estimation and for correcting the digitised signal with frequency selective correction factors based on the error estimation.

Abstract: An error adjustment method of equalizing transmission characteristics of a signal processing circuitry is disclosed. In a first step, an original complex IQ signal is generated, on which error adjustment is performed. Then, the adjusted complex IQ signal is processed in the signal processing circuitry, thereby obtaining a processed real signal. The envelope of the real signal is detected and this real signal envelope and the original complex IQ signal are synchronized. The envelope of the original complex IQ signal is derived and the synchronized real signal envelope is compared with the synchronized original IQ signal envelope at two consecutive time instances. Finally, a processed complex IQ signal is obtained from the real signal envelope on the basis of the comparison result, which processed complex IQ signal is used in performing error adjustment.