[Tinyos-help] Help on LQi

Philip Levis pal at cs.stanford.edu
Tue Feb 26 11:04:34 PST 2008

On Feb 24, 2008, at 8:21 PM, Edmund wrote:

> Hi,
> Does the LQI in trawler accurate? I run the trawler program and I  
> realize the link quality doesn’t seems to be so accurate. Does  
> anyone knows why? If link quality is correlated with the distance,  
> I’m puzzled. How come a node(nearer to the base) has the same  
> quality value with another node(further away from the base) .
> Can anyone pls help and explain to me? I need it urgently.  Thanks  
> a lot

Read the CC2420 data sheet, or just read through the mail archives.  
This is discussed a lot. In short, LQI is a soft chip correlation on  
the chips of the first few symbols of a CC2420 packet. It is,  
technically, not LQI (an 802.15.4 term), but rather an SNR indicator.  
If any of the terms above don't make sense, the web has lots of  
information on them.


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