Geoffrey Van Landeghem

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5 years, 7 months ago.

RSSI calculation in UbloxCellularBase (GSM/EDGE)

Hi,

I've noticed the simular topic (https://os.mbed.com/questions/81693/RSSI-calculation-in-UbloxCellularBase) and pulled in the latest changes. However I'm not sure if the formula is correct for GSM/GSM_COMPACT/EDGE:

UbloxCellularBase.cpp:1053

rssiRet = -(113 - (rssi << 2));

If I run this formula [ =-(113 - (BITLSHIFT(<rssi>;2))) ] for all 0-31 values in LibreOffice Calc I get following results:

0	-113
1	-109
2	-105
3	-101
4	-97
5	-93
6	-89
7	-85
8	-81
9	-77
10	-73
11	-69
12	-65
13	-61
14	-57
15	-53
16	-49
17	-45
18	-41
19	-37
20	-33
21	-29
22	-25
23	-21
24	-17
25	-13
26	-9
27	-5
28	-1
29	3
30	7
31	11

Not really within -113 and -51... I get better results using the formula [ =-113+(<rssi>*2) ]

0	-113
1	-111
2	-109
3	-107
4	-105
5	-103
6	-101
7	-99
8	-97
9	-95
10	-93
11	-91
12	-89
13	-87
14	-85
15	-83
16	-81
17	-79
18	-77
19	-75
20	-73
21	-71
22	-69
23	-67
24	-65
25	-63
26	-61
27	-59
28	-57
29	-55
30	-53
31	-51

Could it be I'm missing something here?

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Development team for u-blox positioning and wireless products
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