The exemplary embodiments of the present invention relate to a transmission part (500), to a receiver part (600), to a transceiver comprising the transmission and receiver parts, to a radio base station comprising the transceiver, to a method in the transmission part (500) and to a method in a receiver part (600). According to the embodiments of the present invention, the transmission part (500) is configured to generate calibration sequences; process the sequences to determine a resulting calibration signal prior to transmission to a receiver part for enabling the receiver part to detect group delay of the received resulting calibration signal for calibration of the transceiver and/or of the radio base station in a wideband communications system.