Initial tag sleep period

We are using DW1001 for some ranging testing. We have one tag on a mobile platform which is ranging to two anchors. We have turned off location and are just doing ranging tests. The system works very well apart from when the tag moves out of range and then back into range. When coming back into range the ranging does not occur till much later than expected. Due to our setup (partly outdoors), we lose ranging when we move further away than approx 25m. However, when we are returning back into range this sometimes does not occur till about 10m or closer to the anchors. Max speed is approx 4m/s.

The DW1001 overview document has this statement in it (section 4.5)
“Initially a tag sleeps and periodically wakes up to listen for anchor’s Beacon and Almanacs
messages. It listens for a period before returning to sleep for before waking and trying again.
The sleep period will initially be 10 s and will extend to 60 s.”
Does this “initial” sleep happen on power up or does this occur every time a tag loses the network and then attempts to re-establish? Could this be causing the issue we are seeing? If this is the case is the 10s sleep time able to be changed. Thanks.

Hi Charlie,

You are right. This 10s~60s sleep time is causing your issue here.

This sleep doesn’t happen on power up. It happens when it doesn’t hear UWB signal for a period. The listening (receiving) is very power consuming so the Tag is put to sleep after a while to save power.

Unfortunately this is not changable by user at the moment.

In the upcoming release (R2), a new function that allows the BLE to turn on the UWB will be provided. This may help improve the respond performance in your case.


Hi Weibo,
Thanks for the quick response. In our case we are not concerned about power consumption so we would rather not sleep. I guess the only current solution would be that we do not lose the UWB signal.