DPLL switches from holdover to free run state within 1minute when GPS signal is lost.

[rmedoji]

DPLL switches from holdover to free run state within 1minute when GPS signal is lost, as per (722960_Intel Ethernet E810-CQDA2T User Guide_Rev1.1) document I could see the holdover time ~4hours when GPS signal is lost.

(Source - From Intel Intel Ethernet E810-CQDA2T User Guide - The ability to maintain time after the reference source is lost is known as holdover. This is estimated to extend holdover time to ~4 hours for ±1.5 µs)


So, the question here is why holdover time is too less??

[Amina_Sadiya]

Hello rmedoji, 

Greetings for the day! 

Thank you for contacting Intel. To proceed further with your inquiry, I kindly request you share the below details:

1. Clear front and back pictures of the adapter ensuring the labels are visible. 

2. Please confirm whether the adapter was purchased separately or is inbuilt.

3. System on which the adapter is installed.

4. Elaborate the issue that you are facing.

Also, Could you please confirm if your query is related to the use of Intel products and solutions in regard to military, intelligence, nuclear/biochemical, defense, or space (MINDS) items?

Regards,  

Amina  

Intel Customer Support Technician  

[rmedoji]

Please find my answers inline below:

1. Clear front and back pictures of the adapter ensuring the labels are visible:
   → Attached are the requested images showing both front and back views with visible labels.
2. Please confirm whether the adapter was purchased separately or is inbuilt:
   → The adapter is an add-on card and not built into the server.
3. System on which the adapter is installed:
   → Dell PowerEdge R750.
4. Elaborate the issue that you are facing:
   → We are using GNSS-based synchronization as per the Intel® Ethernet Network Adapter E810-XXVDA4T User Guide (Rev 1.7). DPLL0/1 successfully lock to the GNSS-1PPS input reference. However, when the GPS SMA cable is disconnected from the NIC, the DPLL transitions from "locked" to "holdover" and then unexpectedly switches to "free run" within approximately one minute. According to the Intel guide, the expected holdover duration should be around 4 hours for ±1.5 µs accuracy.

Question:
Why does the DPLL switch to free run state within 1 minute of GPS signal loss, instead of maintaining the expected holdover duration?

[rmedoji]

Hi Amina,
is there any email contact for customer support?? So that I can share all the information needed?

Thanks.

[MACM]

Hi rmedoji,

Greetings of the day.

Hope you are doing great.

We have sent you a response via email as requested.

Best Regards,

Mohammed Ali CM

Intel Customer Support