Analog Devices ADRV9001 User Manual page 178

Reference Manual
RECEIVER GAIN CONTROL
Each threshold has an associated counter such that an overrange condition is not flagged until the threshold is exceeded this amount of times
in a gain update period.
Table 80. Counters for HB Overrange and Underrange Conditions
HB Threshold
hbHighThresh
hbUnderRangeHighThresh
hbUnderRangeMidThresh
hbUnderRangeLowThresh
In the AGC mode, the HB peak detector has programmable gain attack and gain recovery step sizes.
HB Attack and Recovery Step Sizes
Gain Change
Gain Attack
Gain Recovery (hbUnderRangeHighThresh)
Gain Recovery (hbUnderRangeMidThresh)
Gain Recovery (hbUnderRangeLowThresh)
The HB peak detector is held in reset for a configurable amount of time following a gain change to ensure the receiver path is settled at the new
gain setting.
Power Detector
The power measurement block measures the RMS power of the incoming signal at the output of the HB filtering block. The number of samples
used in the power measurement calculation is configurable using the powerMeasurementDuration API parameter.
Power Meas Duration (receiver Sample Clocks) = 8 × 2
where:
receiver Sample Clocks is the number of clocks at the power measurement location.
It is important that this duration does not exceed the gain update counter. The gain update counter resets the power measurement block, and
therefore, a valid power measurement must be available before this event. In the case of multiple power measurements in a gain update period,
the AGC uses the last fully completed power measurement, and any partial measurements are discarded.
Note that, currently, only inner thresholds of power detector are used. The inner thresholds defined in API are related to an ADC dBFS value
using the following equations.
underRangeHighPowerThresh = -(underRangeHighPowerThresh _dBFS + 6)
overRangeLowPowerThresh = -(overRangeLowPowerThresh_dBFS + 6)
The power measurement block has a dynamic range of 60 dB. Signals lower than −60 dBFS cannot be measured accurately. The API function
adi_adrv9001_Rx_DecimatedPower_Get() is used to read the the power measurement.
Detector Overload and QEC
If the device is operating in the AGC mode when an overload is detected, the Rx QEC calibration is frozen. The AGC can adjust the Rx Gain
Index to bring the received signal to a level under the overload threshold so that the input signal no longer triggers the overload detector. Then,
Rx QEC calibration resumes.
If the device is operating in the MGC mode when an overload is detected, the Rx QEC calibration is frozen as well. However, as the device is
operating in the MGC mode, if the input signal remains at a high level above the overload threshold, then Rx QEC remains frozen and does not
recover until the input signal is below the overload threshold.
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Counter
hbUpperThreshPeakExceededCount
hbUnderRangeThreshExceededCount
hbUnderRangeMidThreshExceededCount
hbUnderRangeLowThreshExceededCount
Step Size
hbGainStepAttack
hbGainStepHighRecovery
hbGainStepMidRecovery
hbGainStepLowRecovery
powerMeasurementDuration
ADRV9001
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