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AD9361 Average Signal Power Measurement During Fast AGC

Question asked by c3commsystems on Dec 7, 2016
Latest reply on Dec 9, 2016 by sripad

According to UG-570, during AGC, the signal power "measurement is an average of a certain number of samples set by the decimated power measurement duration, which is set in the ad9361_set_rx_gain_control_mode function. The duration is common to both receivers. At the end of each measurement period, the average signal power value updates."


(Q1) In both equation (16) and (17), it is indicated explicitly that duration is a multiple of "Rx Sample Period". Is this the clock rate after RX FIR or before RX FIR, if RX FIR decimates the signal?


(Q2) How should we interpret "at the end of each measurement period" ? Does that mean the measurement is NOT a moving window? Instead, the measurement circuit chops up the signal according to the configured measurement length and updates the average signal power after each section? If so, is there any overlap between consecutive measurement segments?


(Q3) In fast AGC state 5, the average signal power measurements are compared to the Energy Lost Threshold and Stronger Signal Threshold for a period of time configured by Gain Lock Exit Count. If the signal power measurement is not a moving window, how many signal measurements would you suggest to be covered within the "Gain Lock Exit Count" window?