Qm35825 DL-TDoA time sync

Wireless Connectivity Ultra-Wideband
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Hi guys

For qm35825 DL-TDoA’s python example in the SDK, it’s not clear how the Anchors synchronise their time. Is that done wirelessly?

I am referring to the qm35-sdk/Documentation/Guides/QM35_UWB_Qorvo_Tools_Guide.pdf section 2.4.5 run_fira_dt example.

Thanks guys.

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Hi jzw01,

Yes, in Qorvo’s implementation of DL-TDoA, the time synchronization between the Anchors is done wirelessly via the DTMs (Downlink TDoA Messages), something we refer to as in-band synchronization. In this implementation, you configure one of the Anchors as a Reference Initiator and the Responders in a cluster will sync with this Ref. Initiator local time to establish a Cluster common time.

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Hi @LC_Qorvo

Thanks for the reply. Since we can’t get the dev kit yet, do you have any information regarding how long it usually takes to do a time sync? Eg in the magnitude of ms, tens of ms, hundreds of ms?

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Hi jzw01

If you are referring to the time it takes for all the Anchors in a Cluster to achieve the sync with the Ref. Anchor, then this depends on your slot duration (for example, 2ms). The Time ref. Anchor Initiator sends a Poll DTM and the Responder Anchors respond to this message with a Resp DTM in subsequent slots as per the order defined and all the Anchors sync to the Cluster common time.

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