CC2510FX Datasheet, PDF (197/253 Pages) List of Unclassifed Manufacturers – True System-on-Chip with Low Power RF Transceiver and 8051 MCU

CC2510Fx / CC2511Fx
15.6 Receiver Channel Filter Bandwidth
In order to meet different channel width
requirements, the receiver channel filter is
programmable. The MDMCFG4.CHANBW_E
and MDMCFG4.CHANBW_M configuration
registers control the receiver channel filter
bandwidth, which scales with the crystal
oscillator frequency. The following formula
gives the relation between the register
settings and the channel filter bandwidth:
BW_channel
=
f _XOSC
8 ⋅ (4 + CHANBW _ M )·2^{CHANBW_ E}
The CC2510Fx/CC2511Fx supports channel
filter bandwidths shown in Table 58.
MDMCFG4.
CHANBW_M
00
01
10
11
MDMCFG4.CHANBW_E
00 01 10 11
812 406 203 102
650 325 162 81
541 270 135 68
464 232 116 58
Table 58: Channel filter bandwidths [kHz] (26 MHz crystal)
For best performance, the channel filter
bandwidth should be selected so that the
signal bandwidth occupies at most 80% of
the channel filter bandwidth. The channel
centre tolerance due to crystal accuracy
should also be subtracted from the signal
bandwidth. The following example
illustrates this:
With the channel filter bandwidth set to
600 kHz, the signal should stay within 80%
of 600 kHz, which is 480 kHz. Assuming
2.44 GHz frequency and ±20 ppm
frequency uncertainty for both the
transmitting device and the receiving
device, the total frequency uncertainty is
±40 ppm of 2.44 GHz, which is ±98 kHz. If
the whole transmitted signal bandwidth is
to be received within 480 kHz, the
transmitted signal bandwidth should be
maximum 480 kHz–2·98 kHz, which is 284
kHz.
15.7 Demodulator, Symbol Synchronizer and Data Decision
CC2510Fx/CC2511Fx contains an advanced
and highly configurable demodulator.
Channel filtering and frequency offset
compensation is performed digitally. To
generate the RSSI level (see section
15.10.3 for more information) the signal
level in the channel is estimated. Data
filtering is also included for enhanced
performance.
15.7.1 Frequency Offset Compensation
When using FSK or MSK modulation, the
demodulator will compensate for the offset
between the transmitter and receiver
frequency, within certain limits, by
estimating the centre of the received data.
This value is available in the FREQEST
status register.
By issuing the SAFC command strobe, the
measured
offset,
FREQEST.FREQOFF_EST,
can
automatically be used to adjust the
frequency offset programming in the
frequency synthesizer. This will add the
current RX frequency offset estimate to
the value in FSCTRL0.FREQOFF, which
adjust the synthesizer frequency. Thus,
the frequency offset will be compensated
in both RX and TX when the SAFC
command strobe is used.
CC2510Fx/CC2511Fx PRELIMINARY Data Sheet (Rev. 1.2) SWRS055A Page 197 of
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