FHM Calibration Resolution


Would it be possible to elaborate on what setting bit 23 of the table in UG1295 does in the ARM firmware? Although it does not appear to be documented in the user guide, from reading on the forums and the wiki I understand that it initiates FHM calibrations.

What I am looking to understand better is:

  1. What calibrations are performed during FHM calibrations?
    1. Are they the same calibrations that are run in normal mode, but just in a batch mode per-frequency?
    2. If so, are they dependent on the other bits in the calibration bit mask?
    3. For example, if you want RX_PHASE_CORRECTION (bit 15) to happen during FHM calibration, do you need to set that bit in addition to bit 23 prior to calibrating, or is setting bit 15 unnecessary for FHM mode?
  2. Is there a frequency resolution (number of calibration points) that FHM calibrations are performed at, regardless of the fhmMinHz and fhmMaxHz values from UG1295 Table 47?
    1. For example, if fast frequency hopping is needed from 1-5 GHz, if the FHM bounds were set to the full range, would the frequency resolution of the calibration be the same as if a subset of the range, such as 1-2 GHz were used?
    2. The reason I'm interested in this is I have an application that may require fast hopping over a limited bandwidth, with allowable reconfiguration gaps between bandwidth ranges, and I'm trying to figure out if there is any reason to ever set the FHM bounds smaller than the total frequency range of the RF path



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    •  Analog Employees 
    on Apr 6, 2020 7:30 AM in reply to ahelak

    In FHM mode, is something like TAL_RFPLLMCS_INIT_AND_SYNC used to lock quickly with no further adjustments, so performance may approach Figure 70 initially but no guarantees are made about performance over time? 

    Yes. FHM mode is meant for frequency hopping applications (where dwell time is less). If you are concerned about performance over time please normal mode of operation.

    That is the heart of the question I am trying to answer, as I have requirements in degrees of channel to channel phase variance for my application that I need to ensure I can meet, and it sounds like they may require a full exit. 

    Please use the full exit mode to return back the normal mode operation.

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