Post Go back to editing

Experiencing inconsistency with MYKONOS_waitInitCal timing out With the TX_QEC init cal flag enabled

Category: Choose a category
Software Version: SI = 1, Major = 5, Minor = 2, Build = 3566

We're running into an issue where 9.7% of the time MYKONOS_waitInitCals returns the error: MYKONOS_ERR_WAIT_INITCALS_ARMERROR. The data we measured was over a span of 1300+ configurations of the chip across a few unique mykonos profiles. This specific error is split evenly across profiles that target RX and TX only configurations. To be clear, the profilesValid mask is set to 0x7, which means the TX,RX, and ORX profiles are valid, however when we run a "TX only" configuration we only run initial calibrations for the TX side (including the QEC calibration). Same goes for RX only configuration.

Essentially, 5% of the time our configuration sequence times out for initial calibrations when we used TX calibration flags, and 5% of the time it happens with RX.

The kicker to all of this is, 90% of the time we don't experience these timeouts on the same set of unique configurations. As I mentioned, we logged this data over 1300+ configuration sequences, but there's a small set of unique configurations that are getting repeated. So the question is, why does the MYKONOS_waitInitCals timeout so inconsistently? Why does this number drop to zero when QEC calibration flags are commented out?

I tried looking at similar posts to this forum about this very issue but it doesn't seem to be very clear. One thing mentioned is making sure the ports are impedance matched, but these configurations are all happening in the same environment so why would it fail 10% of the time?

Parents
  • When you are using TX only configuration , are you enabling the ORX path as well alongwith the TX path? The QEC calibration takes the ORX path into account while running.  Can you pls check if the ORX path is enabled.

    Why does this number drop to zero when QEC calibration flags are commented out?

    Do you mean that both  the TX and the RX only configuration runs successfully when you disable QEC cals?

    Have you tried increasing the wait init cal time, to see if the cals converges?

  • Can you pls check if the ORX path is enabled

    profilesValid = 7, the 3rd bit of this byte represents the `ORX_PROFILE_VALID` so it is enabled

    Do you mean that both  the TX and the RX only configuration runs successfully when you disable QEC cals?

    That's correct, they complete the initial calibration sequence. But remember, even with QEC cals enabled, those calibrations complete 90% of the time as well.

    Have you tried increasing the wait init cal time, to see if the cals converges?

    Yes I have. Initially the timeout was 60 seconds, but I increased it to 90 seconds and there was no statistically significant difference. In fact I think when running those tests slightly more ended up failing (so that difference is just noise)

Reply
  • Can you pls check if the ORX path is enabled

    profilesValid = 7, the 3rd bit of this byte represents the `ORX_PROFILE_VALID` so it is enabled

    Do you mean that both  the TX and the RX only configuration runs successfully when you disable QEC cals?

    That's correct, they complete the initial calibration sequence. But remember, even with QEC cals enabled, those calibrations complete 90% of the time as well.

    Have you tried increasing the wait init cal time, to see if the cals converges?

    Yes I have. Initially the timeout was 60 seconds, but I increased it to 90 seconds and there was no statistically significant difference. In fact I think when running those tests slightly more ended up failing (so that difference is just noise)

Children
  • TXQEC calibrations can fail either because of bad matching or if the ORX is disabled.  Make sure that the matching is proper for the 10 %of the lots for which it is failing. Check the current drawn at each differential output. At full output power, each differential output side draws approximately
    100 mA of dc bias current. 

    Can you check the ORX enabled state using the API 

    MYKONOS_getObsRxPathSource