Measure bandwith between a Tag and a Anchor

I am using the DWM1001C-DEV Kit over the UART Shell. Is there a way how i can measure the actual bandwith when i am measure the distance ?

The signal bandwidth? Since you’re using hardware with FCC modular approval then assuming you are using the PANS firmware or at least the exact same radio settings as it uses you can look it up the bandwidth in the FCC test reports.

Alternatively you use a spectrum analyser and measure it directly.

However I suspect that isn’t what you actually mean. I suspect you mean data rate rather than signal bandwidth. That will depend on how often you measure the range.

Yes i mean the data rate between an tag and a anchor for example. How i can measure it ? There isnt a function in the API or ?

There isn’t a constant data link between the two, range is calculated by exchanging a couple of packets between the two. It’s not like wifi where there is constant data being passed to maintain the link. The chip only supports two data rate 850k or 6.8M but that only applies to the data within the packet. Each packet also includes a preamble and a header which are sent in a different way to the data part of the packet. This means calculating exact packet size in terms of data gets a little messy, normally you talk about the duration of the packet rather than the size of it.

The size of the data part of the packet depends on the exact radio protocol used but it should be in the documentation for the API you are using. The total data rate is simply the amount of data needed to measure the range (the sum of the exchanged packets) multiplied by the range measurement rate.

In other words there is no need to measure the data rate. It’s fixed and defined by the radio protocol used.

1 Like

Is there a way to send a bit-stream from tag to anchor ? So i know exactly how long it goes ? So for example i send 10 Bytes from a anchor and receive all bytes after a time on the tag.

Yes. If you are writing your own firmware then this is very simple, if you are using an off the shelf system then it’s a lot harder.

Fortunately there is an even easier way. A while ago before qorvo took over decawave they published a spreadsheet that calculated the time and power taken to transmit a packet for any set of options.
The original link is now dead so you can’t get it from any official sources any more but I’ve put a copy here: Microsoft OneDrive - Access files anywhere. Create docs with free Office Online.

By putting the appropriate radio mode settings in there and setting the data size to 10 you can find out how long the packet would take to transmit.

Total time until reception time will be a little longer since the receiving chip will need a small amount of processing time. But this will be tiny in comparison to the over the air packet length and the time taken to read and write the data from your processor to and from the radio chip.

Keep in mind these parts aren’t designed for bulk data transfer, they are designed for very accurate time stamping of packets. The data part is intended purely so that you know what it is you’re time stamping rather than for any significant level of communication…