Patent ID: 8441966

Claim:
An active antenna array for a mobile communications system comprising: a plurality of receive paths, for carrying a plurality of analogue receive signals, an individual one of the receive paths being connected between an individual one of a plurality of antenna elements and an individual one of a plurality of analogue to digital converters; a sounding signal generator for generating a digital sounding signal; wherein an analogue sounding signal, based on the digital sounding signal, is injected to at least two of the plurality of receive paths; and wherein, for each receive path of said at least two of the plurality of receive paths, the individual one of the plurality of analogue to digital converters is configured to digitize the analogue receive signal and the analogue sounding signal to form a digitized receive signal; a receive signal subtraction device for subtracting a processed digitized receive signal from the digitized receive signal to generate a processed digitized sounding signal; and a sounding signal subtraction device for subtracting the digital sounding signal from the digitized receive signal to form the processed digitized receive signal.