Hi,
I am a student at University of L’Aquila and I am new to Loco Positioning System.
I have read on Decawave documentiation about different low power mode I can use in order to set DW1000 anchors in TWR (i.e. “Low-Power Listening”, “Sniff Mode”, “Low Duty Cycle Sniff Mode”).
As far as I can work out, if I want to save power, I can choose one of these modes configuring my anchors and using the following configuration mode: PRF (16MHz), data rate (6.8 Mbps), Preamble length (128 symbols), releated to the Short Range TWR use-case.
I wonder know according to what I can select one low power mode or the other in order to minimize the power consumption and if it is possible to do that for TWR.
Thanks
Low power mode in TWR
Re: Low power mode in TWR
I am not sure to understand the question. You are interested into lowering the power consumption of the anchors in a TWR system.
The biggest power consumption for a TWR anchor is that the anchor is continuously in receive mode, and receive mode for a UWR radio can easily consume more than transmitting. I am not aware of big differences of receive mode consumption when changing the PRF, but the datarate and preamble length will most likely not have a great effect. What Decawave is proposing with the low duty cycle sniff is to disable the radio most of the time, this will work best with a long preamble actually since for ranging you want receive as much as possible of the preamble.
As a side note, the lowest power anchor we have is TDoA2 and the reason is that TDoA2 is using timeslots: the radio is switched ON only when needed. I think that at the end of the day this is the goal: the radio in any modes will consume power when turned-ON, it should be OFF most of the time to optimize the power consumption.
The biggest power consumption for a TWR anchor is that the anchor is continuously in receive mode, and receive mode for a UWR radio can easily consume more than transmitting. I am not aware of big differences of receive mode consumption when changing the PRF, but the datarate and preamble length will most likely not have a great effect. What Decawave is proposing with the low duty cycle sniff is to disable the radio most of the time, this will work best with a long preamble actually since for ranging you want receive as much as possible of the preamble.
As a side note, the lowest power anchor we have is TDoA2 and the reason is that TDoA2 is using timeslots: the radio is switched ON only when needed. I think that at the end of the day this is the goal: the radio in any modes will consume power when turned-ON, it should be OFF most of the time to optimize the power consumption.
Re: Low power mode in TWR
Thank you for your answer, it was very useful.
One more question please.
In 802.15.4 standard there is a section about the LQI (Link Quality Indicator).
I wonder know if does Decawave implement this parameter and eventually where can I find that implementation.
Thanks.
One more question please.
In 802.15.4 standard there is a section about the LQI (Link Quality Indicator).
I wonder know if does Decawave implement this parameter and eventually where can I find that implementation.
Thanks.
Re: Low power mode in TWR
I have not been looking at that in details. Decawave has a lot of documentation and application notes discussing the estimation of the receiving quality. One that is of most interest for us is a formula that would allow to estimate if the packet we received has been flying in direct line of sight or not. Unfortunately I have never managed to get reliable line of sight/non line of sight estimation using Decawave's formula. If you find anything in your research that works and can indicate the timing quality of a received packet do not hesitate to share the info back here .