Analog Devices ADRV9001 User Manual page 220

Reference Manual
DIGITAL PREDISTORTION (DPD)
Table 94. DPD/CLGC Post Initial Calibration Parameters (Continued)
Parameter
dpdSamplingRate_Hz
clgcLoopOpen
clgcGainTarget_HundredthdB
clgcFilterAlpha
clgcLastGain_HundredthdB
clgcFilteredGain_HundredthdB
captureDelay_us
The following sections describe each parameter.
numberOfSamples
It specifies the number of samples used per DPD/CLGC data capture, with a limit of 4096. The DPD/CLGC performance can be improved if
more samples are used. Currently, the linearization channel (LCH) is not supported for TETRA 1. So, set the numberOfSamples to 4096. When
LCH is supported, change the numberOfSamples to a different value.
For LTE, set the number of samples to 4096 without frequency hopping.
additionalPowerScale
magnitude of each of the power terms about the same to avoid ill condition of the correlation matrix. The scaling factor α can be defined as
α ≈ 2 × std d n , where "std" stands for standard deviation. Measure α and then pass the information through this parameter.
This parameter scales the higher power terms when calculating the auto-correlation matrix using transmit data d(n). It keeps the nominal
rxTxNormalizationLowerThreshold/rxTxNormalizationUpperThreshold
These are required parameters to normalize the magnitude and phase of the receive and transmit data. These thresholds are used to pick a
linear region to normalize the data. The chosen region must be below the compression point but above the noise. In the AM-AM and AM-PM
plot shown in Figure 188, a possible choice of the linear region is highlighted in red. In general, set the rxTxNormalizationUpperThreshold
to 0.5 of the peak signal amplitude, and set the rxTxNormalizationLowerThreshold to 0.3 of the peak signal amplitude. Once set, fix the
threshold values and these should not vary from capture to capture. Therefore, by knowing the peak transmit signal in dBFS, set the
rxTxNormalizationUpperThreshold to "peak Tx dBFS – 6 dB", and set the rxTxNormalizationLowerThreshold to "peak Tx dBFS – 10.5 dB". The
peak transmit signal is usually set at P1 dB by adjusting the transmitter attenuation setting.
Enter these thresholds in dBFS through TES. If using API, use the linear numbers, which can be calculated as 10
detectionPowerThreshold
It detects an invalid data capture for the DPD/CLGC operation if a specified number of samples (countsLessThanPowerThreshold) are below
the defined power threshold.
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Type Description
uint32_t Sampling rate in Hz for the DPD
actuator and capture.
uint8_t Open or close the gain loop.
int32_t Set as the gain target.
uint32_t Gain filter coefficient.
int32_t Unfiltered gain measured when loop
is open.
int32_t Filtered gain measured when loop is
open.
uint32_t Amount of time that DPD capture is
delayed (beyond normal) relative to
the start of the frame.
Min Max Default
0
0 1 0.75
0 0
(threshold_dBFS/10)
ADRV9001
Note
Read only. No effect on
DPD configuration.
If true, the loop is open
and the TX attenuators
are not updated. Used
to measure a target
gain.
When it is 0, the filter is
disabled.
Only valid for user to
retrieve.
Only valid for user to
retrieve.
This parameter applies
to both DPD and CLGC.
.
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