SPRACF4C June   2018  – January 2023 AWR1243 , AWR1443 , AWR1642 , AWR1843 , AWR1843AOP , AWR2243 , AWR2944 , AWR6843 , AWR6843AOP , IWR1843 , IWR6443 , IWR6843 , IWR6843AOP

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Purpose of Calibrations
    2. 1.2 Purpose of Monitoring Mechanisms
  3. 2Hardware Infrastructure to Support Calibration and Monitoring
  4. 3List of Calibrations
    1. 3.1  APLL Calibration
    2. 3.2  Synthesizer VCO Calibration
    3. 3.3  LO Distribution Calibration
    4. 3.4  ADC DC Offset Calibration
    5. 3.5  HPF Cutoff Calibration
    6. 3.6  LPF Cutoff Calibration
    7. 3.7  Peak Detector Calibration
    8. 3.8  TX Power Calibration
    9. 3.9  RX Gain Calibration
    10. 3.10 IQ Mismatch Calibration
    11. 3.11 TX Phase Shifter Calibration
  5. 4Impact of Calibration on Gain and Phase
  6. 5Impact of Interference on the Calibrations and Emissions Caused Due to Calibrations
  7. 6Scheduling of Runtime Calibration and Monitoring
    1. 6.1 Selection of CALIB_MON_TIME_UNIT
    2. 6.2 Selection of CALIBRATION_PERIODICITY
    3. 6.3 Application-Controlled One Time Calibration
  8. 7Software Controllability of Calibration
    1. 7.1  Calibration and Monitoring Frequency Limits
    2. 7.2  Calibration and Monitoring TX Frequency and Power Limit
    3. 7.3  Calibration Status Reports
      1. 7.3.1 RF Initialization Calibration Completion
      2. 7.3.2 Runtime Calibration Status Report
      3. 7.3.3 Calibration/Monitoring Timing Failure Status Report
    4. 7.4  Programming CAL_MON_TIME_UNIT
    5. 7.5  Calibration Periodicity
    6. 7.6  RF Initialization Calibration
    7. 7.7  Runtime Calibration
    8. 7.8  Overriding the TX Power Calibration LUT
    9. 7.9  Overriding the RX Gain Calibration LUT
    10. 7.10 Retrieving and Restoring Calibration Data
  9. 8References
  10.   A Calibration and Monitoring Durations
    1.     A.1 Duration of Boot Time Calibrations
  11.   Revision History

5 Impact of Interference on the Calibrations and Emissions Caused Due to Calibrations

When an internal measurement is being performed for the calibrations, a presence of strong interference from outside the device could possibly impact the measurements and degrade the calibrations. Most calibrations are robust to such interferences: Tx power calibration, DC offset calibration, APLL calibration, VCO calibration, LO distribution calibration, HPF/LPF calibrations, and power detector calibrations would not be impacted by high power level (< -10 dBm) inband interferers. All the run time calibrations are also robust and are tolerant to such large interference.

Certain calibrations, including Rx gain boot time calibration, Rx IQ mismatch boot time calibration, and phase shifter calibration can potentially be impacted if there is an inband interference during the period of measurement. These are executed only during the Rfinit (boot time). Avoid any interference caused corruption by performing these only at the customer factory in an interference-free environment, and use the device calibration data save and restore APIs to inject that information back to the device in the interference-prone in-field operation. The following steps illustrate this approach:

  1. Perform all the Rfinit calibrations on the sensor in a clean factory environment where interference is not expected.
  2. Save the Rfinit calibrations results in a non-volatile memory of the sensor using the “AWR_CAL_DATA_SAVE_SB” and “AWR_PHASE_SHIFTER_CAL_DATA_SAVE_SB” API.
  3. When the sensor is installed, during the operation of the sensor, the Rx IQ mismatch, Rx gain calibrations, and phase shifter calibration are disabled in Rfinit using the “AWR_RF_INIT_CALIBRATION_CONF_SB” API. This is called before the Rfinit API is issued.
  4. Call the “AWR_CAL_DATA_RESTORE_SB “ and “AWR_PHASE_SHIFTER_CAL_DATA_RESTORE_SB” APIs linking to the previously stored calibration files.
  5. When the restore is complete, the Rfinit API can be called to perform the other enabled calibrations.

The TX power amplifier is enabled for certain boot calibrations (Tx power boot calibration, Tx phase shifter boot calibration, and Rx IQMM boot calibration). This leads to some signals being emitted on air during this process. If this causes a concern for any of the regulatory standards being targeted for the sensor, then the save - restore scheme explained above could be extended to avoid these emissions during bootup. For this, Tx power boot calibration should also be disabled as part of Step 3 in the above sequence. In the AWR294x, the TX phase shifter calibration does not cause emissions, because a fixed look up table is used. Also, the RX IQ MM calibration is not applicable for the AWR294x.

The TX output power run time calibration in CLPC mode also enables the TX power amplifier. The TX power backoff setting used for this calibration chirp is the same as the one in the profile configuration, thus the total power emitted during this run time calibration is the same as the regular chirps of the same profile. However, the calibration chirp sweep bandwidth is between 75 - 100Mhz, thus the spectral density could be different from the functional chirps. If this is a concern for emissions, the TX power run time calibrations can be set to OLPC mode, where there is no transmission involved.