CC2400 Chipcon AS, CC2400 Datasheet - Page 40

• Manufacturer Part Number: CC2400
• Description: 2.4 GHz RF Transceiver
• Manufacturer: Chipcon AS

Automatic Frequency Control
CC2400
called
Control). This feature can be used to
measure and compensate for frequency
drift.
The average frequency offset of the
received signal (from the nominal IF) can
be
FREQEST.RX_FREQ_OFFSET[7:0]
register. This is a signed (2’s-complement)
8-bit
compensate for frequency offset between
an external transmitter and the receiving
device. The frequency offset is given by:
∆F= RX_FREQ_OFFSET x 5.2
The receiver can be calibrated against an
external transmitter (another
external test signal) by changing the
Chipcon AS
value
has a built-in optional feature
AFC
read
SmartRF
that
(Automatic
Table 8. Minimum number of bits for the averaging filter
®
can
CC2400 PRELIMINARY Datasheet (rev. 1.1), 2003-10-02
AFC settling time
MDMTST0.AFC_SETTLING[1:0]
in
be
CC2400
Frequency
used
[kHz]
00
01
10
11
or an
the
to
SmartRF
operating frequency according to the
measured offset. The new frequency must
be calculated by the microcontroller and
written to the FSDIV.MOD_OFFSET[5:0]
register. After this compensation the
center frequency of the received signal will
match better the digital channel filter
bandwidth.
described
compensates the transmitter, i.e. the
transmitted signal will match the ‘external’
transmitter’s signal.
This feature reduces the requirement to
the crystal accuracy, which is important
when
bandwidths. See also further description of
this feature on page 49 under (Crystal drift
compensation).
using
Bits
16
2
4
8
above,
The
the
®
compensation,
also
narrower
CC2400
automatically
Page 40 of 73
channel
as