Fast Fourier Transforms on Motorola's Digital Signal Processors

where:
and
H1 r
H1 i
H2 r
H2 i
′
A
r
′
B
r
′
A
i
′
B
i
=
=
=
=
( A
r
+ B
r
) ⁄ 2
( A
i
– B
i
) ⁄ 2
( A
i
+ B
i
) ⁄ 2
( B
r
– A
r
) ⁄ 2
= H1
r + ( W
r
H2
r
– W
i
H2
i
)
=
=
H1
r – ( W
r
H2
r
– W
i
H2
i
)
H1
i + ( W
i
H2
r
– W
r
H2
i
)
= – ( H1
i)
+ ( W
i
H2
r
– W
r
H2
i
)
W
r
= cos(
( 2πk ) ⁄ N)
W
i
= – sin(
( 2πk ) ⁄ N)
A
r
= realZ ( k )
B
r
= realZ ( N – k )
A
i
= imagZ ( k )
B
i
= imagZ ( N – k )
6.2.3 Performance Estimation
Eqn. 6-11
k=0,...(N/4-1)
k=0,...(N/4-1)
k=0,...(N/4-1)
k=0,...(N/4-1)
In the following paragraph, we will discuss the computational
complexity of Eqn. 6-10 and the
implementation constraints on the architecture of
Motorola’s DSP. For detailed implementation,
please refer to the programs RFFT96.ASM and
RFFT56.ASM in APPENDIX A.
MOTOROLA 6-13