C2510Fx / CC2511Fx
For other data rates the user must generate
similar tables to find the CS absolute
threshold.
thus useful to detect signals in environments
with a time varying noise floor. The register
field AGCCTRL1.CARRIER_SENSE_REL_THR
is used to enable/disable relative CS, and to
select threshold of 6 dB, 10 dB or 14 dB RSSI
change
MAX_DVGA_GAIN[1:0]
00
01
10
11
000
001
010
011
100
101
110
111
-99
-93
-87
-85
-82
-80
-78
-76
-73
-70
-81.5
-78.5
-76
14.10.7
Clear Channel Assessment (CCA)
-97
-90.5
-87
The Clear Channel Assessment CCA) is used
to indicate if the current channel is free or
busy. The current CCA state is viewable on
-93.5
-91.5
-90.5
-88
-86
-74
-84
-72.5
-70
P1_5,
P1_6,
or
P1_7
by
setting
IOCFGx.GDOx_CFG=1001.
-82.5
-78.5
-76
MCSM1.CCA_MODE selects the mode to use
when determining CCA.
-84.5
-82.5
-67
-64
When the STXor SFSTXONcommand strobe is
given while CC2510Fx/CC2511Fx is in the RX
state, the TX or FSTXON state is only entered
if the clear channel requirements are fulfilled.
The chip will otherwise remain in RX (if the
channel becomes available, the radio will not
enter TX or FSTXON state before a new
strobe command is being issued). This feature
is called TX-if-CCA.
Table 69: Typical RSSI Value in dBm at CS
Threshold with Default MAGN_TARGETat 2.4
kBaud
MAX_DVGA_GAIN[1:0]
00
01
10
11
000
001
010
011
100
101
110
111
-96
-90
-84
-78.5
-77.5
-75
Four CCA requirements can be programmed:
-94.5
-92.5
-91
-89
-83
• Always (CCA disabled, always goes to
-87
-81
TX)
-85
-78.5
-76
-73
• If RSSI is below threshold
-87.5
-85
-82
-70
• Unless currently receiving a packet
-79.5
-76.5
-72
-73.5
-70.5
-66
-67.5
-65
• Both the above (RSSI below threshold
-83
and not currently receiving a packet)
-78
-60
Table 70: Typical RSSI Value in dBm at CS
Threshold with Default MAGN_TARGETat 250
kBaud
14.10.8
Link Quality Indicator (LQI)
The Link Quality Indicator is a metric of the
current quality of the received signal. If
PKTCTRL1.APPEND_STATUS is enabled, the
value is automatically added to the last byte
appended after the payload. The value can
also be read from the LQIstatus register. The
LQI gives an estimate of how easily a received
signal can be demodulated by accumulating
the magnitude of the error between ideal
constellations and the received signal over the
64 symbols immediately following the sync
If the threshold is set high, i.e. only strong
signals are wanted, the threshold should be
adjusted upwards by first reducing the
MAX_LNA_GAIN
value
and
then
the
MAX_DVGA_GAIN value. This will reduce
power consumption in the receiver front end,
since the highest gain settings are avoided.
word. LQI is best used as
a
relative
14.10.6
CS Relative Threshold
measurement of the link quality (a high value
indicates a better link than what a low value
does), since the value is dependent on the
modulation format.
The relative threshold detects sudden changes
in the measured signal level. This setting is not
dependent on the absolute signal level and is
SWRS055D
Page 201 of 243
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