Analog Devices ADRV9001 User Manual page 133

Preliminary Technical Data
The HB detector has a number of programmable thresholds. Some of these thresholds are only used in the fast recovery mode of the peak
detect AGC configuration, as summarized in Table 58.
Table 58. HB Overload Thresholds
HB Threshold
hbHighThresh
hbUnderRangeHighThresh
hbUnderRangeMidThresh
hbUnderRangeLowThresh
For more details of how these thresholds are used by the AGC, refer to the relevant sections in this document.
The thresholds are related to an ADC dBFS value using the following equations:
Each threshold has an associated counter such that an over-range condition is not flagged until the threshold has been exceeded this
amount of times in a gain update period.
Table 59. Gain Steps for HB Overrange and Underrange Conditions
HB Threshold
hbHighThresh
hbUnderRangeHighThresh
hbUnderRangeMidThresh
hbUnderRangeLowThresh
In AGC mode, the HB peak detector has programmable gain attack and gain recovery step sizes.
Table 60. 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 that 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 HB Filtering block. The number of
samples that are used in the power measurement calculation is configurable using the powerMeasurementDuration API parameter:
Power Meas Duration (Rx Sample Clocks) = 8 × 2
where Rx Sample Clocks is the number of clocks at the power measurement location.
It is important that this duration 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 occurring in a gain
update period, the AGC will use the last fully completed power measurement, any partial measurements being discarded.
The power measurement block has a dynamic range of 60dB. Signals lower than −60 dBFS may not be measured accurately. The power
measurement could be read through the API function adi_adrv9001_Rx_DecimatedPower_Get().
Usage
Used for gain attack in both peak and peak/power detect AGC modes.
Used for gain recovery in peak detect AGC mode. In peak/power detect AGC mode it is used to prevent
overloads during gain recovery.
Used only when the fast recovery option of the peak detect AGC mode is being utilized.
Used only when the fast recovery option of the peak detect AGC mode is being utilized.
Counter
hbUpperThreshPeakExceededCount
hbUnderRangeHighThreshExceededCount
hbUnderRangeMidThreshExceededCount
hbUnderRangeLowThreshExceededCount
powerMeasurementDuration
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Step Size
hbGainStepAttack
hbGainStepHighRecovery
hbGainStepMidRecovery
hbGainStepLowRecovery
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