Getting DL-TDoA working with iOS devices

Wireless Connectivity Ultra-Wideband
1

hey folks,

hobbyist here. i bought some DWM 3001CDK boards with the hope of using TWR with iOS devices.

due to iOS privacy limitations, i decided to pursue DL-TDoA instead, which is in developer preview on iOS 27.

i had to re-write the firmware for DWM3001CDK(since its only available for QWM35). this wasnt a huge trouble, i was able to get it working with another DWM board.

but, when it came to getting it working with my iphone 16 pro on iOS 27, no luck. ive already enabled nearby interaction for the app.

apple has not published a ton of documentation regarding DL-TDoA ranging( i am calling them today to discuss). but regardless, sharing where im at.

for more details on the iphones progress in DL-TDoA path:

  1. we got the initial config via bluetooth
  2. the iphones UWB radio detected preamble
  3. found the SFD and validated it
  4. started STS (though not sure if it actually processed the pulses and determined an accurate estimation for when the first pulse arrived)
  5. attempted to receive the PHR, but failed with the 0x18 status code.

0x18 means the iphones radio tried decoding the header response, but it failed the SECDED correction check.

i’ve already triple checked that i am using the expected PHY config for apple, but, alas, still erroring.

has anyone here tried working with iOS for TWR or DL-TDoA? do you have any tips/recs for how to resolve the problems above?

2

We use the CDK boards for iOS twr ranging without trouble with the QANI firmware

We have tested the CDK and Murata Type2ab together using the UCI firmware. As the CDK board only has one antenna, it can report distance, but cannot report AoA for the other device, regardless of UCI role.

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