2006-11-30 01:26:02

by Loreno Oliveira

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Subject: [Bluez-users] estimating distance between two devices

Hi list,

I need to someway estamate the distance between two bluetooth devices
already connected. I thought in using RSSI for this, but RSSI, as far as I
know, is not a mandatory feature of bluetooth. Besides, in the tests I have
made the scale of the RSSI measurements I got had not a good sensibility as
I moved. So now I am thinking on someway measuring the rate of
retransmissions for estimating this.

Well, my question is twofold: Does it make any sense the idea of estimating
the distance through the rate of retransmissions?? and, does anybody would
have some hint in this field??

Thanks in advance to any help!

Loreno


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2006-12-03 13:49:37

by Marcel Holtmann

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Subject: Re: [Bluez-users] estimating distance between two devices

Hi Loreno,

> I need to someway estamate the distance between two bluetooth devices
> already connected. I thought in using RSSI for this, but RSSI, as far
> as I know, is not a mandatory feature of bluetooth. Besides, in the
> tests I have made the scale of the RSSI measurements I got had not a
> good sensibility as I moved. So now I am thinking on someway measuring
> the rate of retransmissions for estimating this.
>
> Well, my question is twofold: Does it make any sense the idea of
> estimating the distance through the rate of retransmissions?? and,
> does anybody would have some hint in this field??

you don't get this information without special vendor commands. The
specification only allows you to use the RSSI and Link Quality value and
while Link Quality is meant to be vendor specific, the RSSI is not, but
its usage in various Bluetooth chips is different.

Regards

Marcel



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