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AD9364 AGC with the split table and phase tracking with dual receivers

Question asked by gizmoaudio on Apr 17, 2015
Latest reply on May 7, 2015 by gizmoaudio

I have two different questions.


First one: How does the split table mode work in slow AGC?


For the Full Table Mode, this is easy to understand. There is one signal, one table so it's easy to see how this is controlled. I've looked at the documentation and in split mode it is not clear as to how the AGC loop is controlled. You have two tables, an LMT table and an LPF table. That much I understand. You can set a threshold for the first table based on the LMT Peak Overload Detector. This then decrements the index of the LMT table to bring it out of overload? As long as there is an overload condition, this continues to decrement the LMT index? Once the LMT Peak Overload Detector comes out of overload how are the two AGC indexes controlled?  My question is, in split mode how are the indexes of the two tables controlled? There is no explanation of this in UG-673, in "AD9361 Gain Control and Received Signal Strength Signal Indicator (RSSI) User Guide" or in the Register Map doc.


Second question:

In a phased array MIMO of two receivers, will the AGC for the two receivers phase track each other? How much phase shift is there with variations in AGC table index at a single frequency? Should I use one receiver for AGC and slave the other receiver to the same AGC indexes?