I am interested in clarifying the following three "different" power measurement in the AD9361 RX chain:
1. Dec power measurement in Fast AGC stage 2 and 3.
2. Power measurement in Fast AGC stage 5.
3. RSSI power measurement.
Based on descriptions in UG-570 and UG-671, I drew the following four conclusions.
Conclusion A: Because each of the three above power measurements has its own configurable measurement length, they are independent measurements, not relying on each other in calculation, and are implemented separately in the circuit.
Conclusion B: Register 0x15C is only used for the Dec Power measurement in Fast AGC stage 2 and 3, including choosing whether using HB1 output or RFIR output. It only effects Fast AGC stage 2 and 3. Note in UG-671, [D6] is specifically named as "Use HB1 Out for Dec Pwr Meas".
Conclusion C: RSSI power measurement ALWAYS uses the RFIR output, even if RFIR is bypassed. Although Reg0x15C is put in the RSSI section in UG-671, it has nothing to do with RSSI power measurement.
Conclusion D: Power measurement in Fast AGC stage 5 ALWAYS uses HB1 output. This measurement point is not configurable.
Please review and correct me if any of the above conclusions are wrong. Thanks!