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three options can be used individually or together. Decimation cannot be used with the adaptive
and multichannel mode options
10.3.3.1.2 Complex Mode
Complex mode performs FIR type filtering with complex data based on the following equations:
Re F n ( )
(
Im F n ( )
(
where H(n) is the coefficients, D(n) is the input data, and F(n) is the output data at time n. Two
samples, the real part then the imaginary part of the input, are written to the FDIR. The EFCOP
processes the data, and then two samples—the real and then the imaginary part of the output—are
read from the FDOR.
Complex mode is selected by setting the FCSR[FOM] bits to 01. In Complex mode, the number
written to the FCNT register should be twice the number of filter coefficients. Also, the
coefficients are stored in the FCM with the real part of the coefficient in the memory location
preceding the memory location holding the imaginary part of the coefficient. Complex mode can
be used with the decimation option.
10.3.3.1.3 Alternating Complex Mode
Alternating Complex mode performs FIR type filtering with complex data, providing alternating
real and complex results based on the following equations
(
(
Re F n
even
(
(
Im F n
odd
where H(n) is the coefficients, D(n) is the input data, and F(n) is the output data at time n. Two
samples, the real part then the imaginary part of the input, are written to the FDIR. The EFCOP
processes the data. Then one sample, alternating between the real part and the imaginary part of
the output, is read from the FDOR.
Alternating Complex mode is selected by setting the FCSR[FOM] bits to 10. In Alternating
Complex mode, the number written to the FCNT register should be twice the number of filter
Freescale Semiconductor
N 1
–
∑
)
Re H i ( )
(
)
⋅
=
Re D n i –
i
=
0
N 1
–
∑
)
Re H i ( )
(
)
⋅
=
Im D n i –
i
=
0
N 1
–
∑
)
)
Re H i ( )
(
)
⋅
=
i
=
0
N 1
–
∑
)
)
Re H i ( )
(
)
⋅
=
i
=
0
DSP56311 Reference Manual, Rev. 2
(
(
)
)
Im H i ( )
(
–
(
(
)
)
Im H i ( )
(
+
(
(
)
)
Im H i ( )
(
Re D n i –
–
(
(
)
)
Im H i ( )
(
Im D n i –
+
EFCOP Operation
)
⋅
(
(
)
)
Im D n i –
)
⋅
(
(
)
)
Re D n i –
)
⋅
(
(
)
)
Im D n i –
)
⋅
(
(
)
)
Re D n i –
10-9
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