Hm. I think that's a packet close to the edge of reception
sensitivity. Different noise floors (a few dB variation) at different
nodes can therefore cause SNR changes that will see significant
shifts in chip correlation.
Phil
On Jan 27, 2008, at 7:37 PM, Omprakash Gnawali wrote:
Here is a small fraction of data form an experiment I did using Tmotes
a few days ago - each node logged the lqi and rssi of each packet it
received from different transmitters. Based on this data, if you read
a value of 212 as rssi field, there is no guarantee that you will have
a particular lqi value. The lqi could be as low as 56 (with a small
probability) or as high as 107 (also with a small probability), more
like that the lqi's will be in the 90's to about 105.
# pkts, rssi, lqi
498 212 100
514 212 101
495 212 102
445 212 103
399 212 104
308 212 105
131 212 106
30 212 107
11 212 56
8 212 57
8 212 60
10 212 61
16 212 62
25 212 63
33 212 64
27 212 65
32 212 66
40 212 67
54 212 68
51 212 69
57 212 70
66 212 71
72 212 72
84 212 73
101 212 74
115 212 75
115 212 76
153 212 77
141 212 78
181 212 79
179 212 80
207 212 81
212 212 82
234 212 83
244 212 84
276 212 85
286 212 86
320 212 87
347 212 88
365 212 89
399 212 90
440 212 91
457 212 92
461 212 93
562 212 94
577 212 95
552 212 96
522 212 97
558 212 98
487 212 99
- om_p
On Jan 27, 2008 4:20 PM, Daria Wotzka (Geb. Zmarzly)
<[EMAIL PROTECTED]> wrote:
The bug was following: "(...)the LQI byte was overwritten by the RSSI
byte.(...)" but it means that RSSI and LQI have to have exactly same
values; my LQIs are in range of 70-130 and RSSIs in range of 220-240.
Could it be still due to the same bug? (Packet payload was 80 bytes)
Daria
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