actually applied on i 3 and q 3 after phase rotation digital filtering and phase de rotation the feedback loop may work in three stages acquisition transition and tracking typical parameters used in our current design are as follows in acquisition the digital agc estimates the gain required to keep the signal level at the desired value every 0 05 ms this agc gain may be applied to both the i and q channels the gain imbalance may be estimated over averaging periods of approx 0 4 ms and correction is applied every time a new estimate is calculated to the q channel only in one embodiment no phase imbalance may be estimated or corrected for at this stage when the agc has locked the transition stage is entered by now the gain imbalance estimate is very close to steady state in transition the agc gain may be estimated every 3 ms and the gain imbalance every 25 ms this keeps the variation in the signal level very small which is required for highly mobile environments at this point the phase imbalance estimation is started with time averaging periods of approximately 6 ms when two such estimates have been made and corrections applied the tracking stage is entered in tracking the phase estimation time averaging interval is increased to around 25 ms in some embodiments the results are as follows in a digital video broadcasting terrestrial dvb t television receiver european telecommunications standards institute etsi sophia antipolis cedex france standard en300 744 v1 5 1 digital video broadcasting these results show that the phase imbalance is reduced to less than 0 5 degree within about 20 ms this time may be put into context with typical acquisition.