CC2431 Texas Advanced Optoelectronic Solutions, CC2431 Datasheet - Page 9

• Manufacturer Part Number: CC2431
• Description: System-on-Chip for 2.4 GHz ZigBee/ IEEE 802.15.4 with Location Engine
• Manufacturer: Texas Advanced Optoelectronic Solutions

2.1.2.1.4 Search Boundary Coordinates
It is possible to reduce error and estimation
time by setting search boundaries for the
estimated location X and Y coordinates. The
maximum area that can be considered is with
X and Y in the interval [0.0, 63.75] meters.
Assume that the Location Engine search is to
be limited to include only the rectangular area
bounded by the coordinates [x
[x
Four search boundary parameters are entered
in the following order:
2.1.2.1.5 RSSI Values
The RSSI values are the RSSI measurements
corresponding
coordinates. The RSSI values are within the
interval [-40 dBm, -95 dBm] with precision 0.5
dBm. The negative sign is removed in the
value written. As an example, in the case
where the value RSSI = -50.35 dB, this would
be written into the location engine as 50.5.
2.1.2.2 Loading Parameters
All measured parameters described in the
previous sections are loaded into the RF
register
MEASPARM
max
, y
max
x
min
].
MEASPARM
, x
, a 1 must be written to the register
delta
to
, y
95
90
85
80
75
70
65
60
55
50
45
min
2
the
, y
.
delta
Before
set
Path Loss vs. log-distance for source 0x85, Z=2.1082. A=42.4103, n=2.9773
4
CC2431 Data Sheet (Rev. 2.01) SWRS034B
Figure 2: Path loss vs. log distance
of
min
writing
, y
reference
min
] and
6
to
10*log10(distance)
8
where:
x
y
Note that even when it is chosen to search in
the whole possible search space, these
coordinates
coordinates for the whole space, i.e. the
following values: 0.0, 63.75, 0.0, 63.75.
If some input parameters are omitted the
Location Engine will not estimate correctly.
Note that a value of 0.0 must be written as
RSSI value for unused reference coordinates,
if less than 16 reference nodes are used. The
engine will not function correctly if only some
of the parameters are loaded.
bit
measured parameters are being written. Once
the parameter load process commences
delta
delta
LOCENG.PARLD
= x
= y
10
max
max
- x
- y
min
min
must
12
to indicate that a set of
be
14
entered
CC2431
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as
the