CC2510FX Datasheet, PDF (205/253 Pages) List of Unclassifed Manufacturers – True System-on-Chip with Low Power RF Transceiver and 8051 MCU

CC2510Fx / CC2511Fx
0.0
-10.0
-20.0
-30.0
-40.0
-50.0
-60.0
-70.0
-80.0
-90.0
-100.0
-110.0
-120.0
-120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0
Input pow er [dBm]
2.4 kbps
10 kbps
250 kbps
250 kbps, reduced current
500 kbps
Figure 48: Typical RSSI value vs. input power level for some typical data rates
15.10.4 Carrier Sense (CS)
The Carrier Sense flag is used as a sync
word qualifier and for CCA. The CS flag
can be set based on two conditions, which
can be individually adjusted:
• CS is asserted when the RSSI is
above a programmable absolute
threshold, and de-asserted when
RSSI is below the same threshold
(with hysteresis).
• CS is asserted when the RSSI has
increased with a programmable
number of dB from one RSSI sample
to the next, and de-asserted when
RSSI has decreased with the same
number of dB. This setting is not
dependent on the absolute signal level
and is thus useful to detect signals in
environments with time varying noise
floor.
Carrier Sense (CS) can be used as a sync
word qualifier that requires the signal level
to be higher than the threshold for a sync
word search to be performed. The signal
can also be observed in the status register
bit PKTSTATUS.CS.
Other uses of Carrier Sense include the
TX-If-CCA function (see section 15.10.7
on page 206) and the optional fast RX
termination (see section See section
15.12.3 on page 210 for details.).
CS can be used to avoid interference from
e.g. WLAN.
15.10.5 CS Absolute Threshold
The absolute threshold related to the RSSI
value is given by:
THR_RSSI = MAGN _ TARGET +
CARRIER _ SENSE _ ABS _ THR − GAIN_MAX
The maximum possible gain can be
reduced
using
the
AGCCTRL2.MAX_LNA_GAIN
and
AGCCTRL2.MAX_DVGA_GAIN register
fields. CARRIER_SENSE_ABS_THR is
programmable in 1 dB steps from -7 dB to
+ 7dB. Table 64 and Table 65 show the
RSSI readout values at the CS threshold
at 2.4 kbps and 250 kbps data rate
respectively.
The
default
CARRIER_SENSE_ABS_THR = 0 (0 dB)
and MAGN_TARGET = 3 (33 dB) have
been used.
CC2510Fx/CC2511Fx PRELIMINARY Data Sheet (Rev. 1.2) SWRS055A Page 205 of
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