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16.3.4.8.1 Modulation Table, Sample Data Buffers, and AGC Constant. The
modulation table is composed of 16-bit cosine and sine pairs that occupy K +1 bytes in
memory. The samples input buffer is a cyclic buffer containing M+1 bytes. Each sample is
a 16-bit half-word and the new sample is stored in the address that follows the previous
sample. The output buffer is a cyclic buffer that contains N+1 bytes and the new output is
stored in the address that follows the previous output. The AGC constant is in the range
-1≤ AGC≤1.
MODULATION TABLE
sin q
cos q
sin q
cos q
*
*
sin q
cos q
K + 1 bytes
Figure 16-27. DEMOD Modulation Table and Sample Data Buffers
16.3.4.8.2 DEMOD Function Descriptor. The DEMOD function descriptor bit table is
described below.
0
1
2
S
RES
W
OFFSET + 0
OFFSET + 2
OFFSET + 4
OFFSET + 6
OFFSET + 8
OFFSET + A
OFFSET + C
OFFSET + E
MOTOROLA
INPUT SAMPLES
*
1
*
1
*
2
*
2
x(n-k+1)
*
*
n
x(n-2)
n
x(n-1)
x(n)
M + 1 bytes
3
4
5
6
I
MPC823e REFERENCE MANUAL
Communication Processor Module
OUTPUT (COMPLEX)
imag{Y(n-k+1)}
real{Y(n-k+1)}
imag{Y(n-2)}
real{Y(n-2)}
imag{Y(n-1)}
real{Y(n-1)}
imag{Y(n)}
real{Y(n)}
N + 1 bytes
7
8
9
10
11
RES
I
K
DPTR
M
XYPTR
N
RESERVED
*
*
*
*
*
12
13
14
15
OPCODE
16-63
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