HFA3863IN96 Intersil Corporation, HFA3863IN96 Datasheet - Page 16

• Manufacturer Part Number: HFA3863IN96
• Description: Processor, Direct Sequence Spread Spectrum Base band Processor with Rake Receiver and Equalizer, Tape And Reel
• Manufacturer: Intersil Corporation

Channel Matched Filter (CMF) Description
The receive section shown in Figure 13 operates on the
RAKE receiver principle which maximizes the SNR of the
signal by combining the energy of multipath signal
components. The RAKE receiver is implemented with a
Channel Matched Filter (CMF) using a FIR filter structure
with 16 taps. The CMF is programmed by calculating the
Channel Impulse Response (CIR) of the channel and
mathematically manipulating that to form the tap coefficients
of the CMF. Thus, the CMF is set to compensate the channel
characteristics that distort the signal. Since the calculation of
the CIR is inaccurate at low SNR or in the presence of strong
CW interference, the chip has thresholds (CR 36 to 39) that
TX_AGC_IN (18)
TX_IF_AGC (35)
ANTSEL (39)
ANTSEL (40)
V
I
REF
REF
(21)
(16)
6-BIT
6-BIT
DAC
16
ADC
V
(12, 17, 22, 31)
DD
(62) TX_PE
FIGURE 11. DSSS BASEBAND PROCESSOR, TRANSMIT SECTION
(ANALOG)
GENERATOR
TIMING
MCLK
REGISTER
CONTROL
TX AGC
MCLK
(42)
(9, 15, 20, 25, 28)
GND (ANALOG)
HFA3863
MODULATOR,
BARKER/CCK
TRANSMIT
FILTER
CONTROL
are set to substitute a default CMF shape under those
conditions. This default CMF shape is designed to
compensate only the known transmit and receive non
linearity.
PN Correlators Description
There are two types of correlators in the HFA3863 baseband
processor. The first is a parallel matched filter correlator that
correlates for the Barker sequence used in preamble,
header, and PSK data modes. This Barker code correlator is
designed to handle BPSK spreading with carrier offsets up
to ±50ppm and 11 chips per symbol. Since the spreading is
BPSK, the correlator is implemented with two real
STATE
(2, 8, 37, 41, 57)
V
TX
DD
(DIGITAL)
(44)
PREAMBLE/HEADER
(45)
SCRAMBLER
GENERATOR
TX_DATA
CRC-16
TEST PORT
(46) (47) (48) (49) (50) (51)
(1, 7, 36, 43, 56)
GND (DIGITAL)
DAC
DAC
TXI (23, 24)
TXQ (29, 30)
(59) TX_RDY
(55) TXCLK
(58) TXD
(3) SD
(4) SCLK
(64) SDI
(5) R/W
(6) CS
(52) RXCLK
(60) CCA