MOTOROLA
Chapter 36. Digital Signal Processing
36-23
Part V. The Communications Processor Module
36.14 DEMODÐReal Sin; Real Cos, Real X, and
Complex Y
Using the values provided in the parameter packet, the DEMOD implements a basic
demodulator function, shown in Figure 36-27, with a modulation table composed of (cos
w
nT, sin
w
nT) pairs, real input samples, and complex outputs. The input data is in a circular
buffer with size (M+1) and the output data is in a circular buffer with size (N+1). The AGC
parameter controls the demodulator gain.
Figure 36-27. DEMOD Function
36.14.1 Modulation Table, Input and Output Buffers, and AGC
Constant
The modulation table consists of 16-bit cosine and sine pairs that occupy (K+1) bytes in
memory. The input sample buffer is a circular buffer containing (M+1) bytes. The next
16-bit sample is stored in the address that follows the previous sample. The output buffer is
a circular buffer that contains (N+1) bytes and the next output is stored in the address that
follows the previous output. The AGC constant is in the range -1
£
AGC
£
S
Ñ
W
I
X
Ñ
Ñ
Ñ
Ñ
Ñ
Ñ
OPCODE
0
S
0
W
I
0
0
0
0
0
0
0
01000
2
I=3 (Three Iterations)
Figure 36-26. MOD Modulation Example
Table 36-21. DEMOD Modulation Table, Input, and Output Buffers
Modulation Table
Input Samples
Output (Complex)
sin q
1
*
*
cos q
1
*
*
sin q
2
x(n-k+1)
imaginary{Y(n-k+1)}
cos q
2
*
real{Y(n-k+1)}
*
*
*
*
x(n-2)
*
sin q
n
x(n-1)
imaginary{Y(n-2)}
cos
w
nT, sin
w
nT, AGC
{Real}
X(n)
Y(n)
{Real}
{Complex}
Real Y n
( )
{
}
1
AGC
+
(
)
X
´
n
( )
w
nT
cos
´
=
Image Y n
( )
{
}
1
AGC
+
(
)
X
´
n
( )
w
nT
sin
Ð
(
)
´
=
Summary of Contents for MPC860 PowerQUICC
Page 3: ...MPC860UM AD 07 98 REV 1 MPC860 PowerQUICC ª UserÕs Manual ...
Page 36: ...xxxvi MPC860 PowerQUICC UserÕs Manual MOTOROLA CONTENTS Paragraph Number Title Page Number ...
Page 78: ...I iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 88: ...1 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 114: ...3 16 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 226: ...8 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
Page 262: ...9 36 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
Page 274: ...III iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Page 320: ...12 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Page 325: ...MOTOROLA Part IV Hardware Interface IV v Part IV Hardware Interface ...
Page 326: ...IV vi MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 352: ...13 26 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 394: ...14 42 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 426: ...15 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 530: ...17 26 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 632: ...21 44 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 660: ...22 28 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 708: ...24 24 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
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Page 948: ...36 34 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 998: ...37 48 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part VI Debug and Test ...
Page 1016: ...A 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1024: ...B 8 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1030: ...C 6 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
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