AN2834 Freescale Semiconductor / Motorola, AN2834 Datasheet - Page 8

• Manufacturer Part Number: AN2834
• Description: AN2834, Packet Telephony Automatic Level Control on the StarCore SC140 Core
• Manufacturer: Freescale Semiconductor / Motorola

Automatic Level Control on StarCore
Table 1 lists the coefficients of the fourth-order polynomial. The MMSE coefficients are optimized for values of y
between –1 and 0 (notice that the exponent of A
Taylor expansion (c
requires three cycles on the SC140 DSP core:
Figure 3 illustrates the typical dynamic behavior of the ALC StarCore DSP implementation.
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•
•
•
Cycle 1: A = y
Cycle 2: D = A
Cycle 3: F = c
–0.5
–0.5
0.5
–1
0.5
–1
1
0
1
0
Coefficients X 2
Packet Telephony Automatic Level Control on the StarCore SC140 Core, Rev. 1
0
0
k
= (ln2)
c
c
c
c
c
0.1
0.1
0
1
2
3
4
Figure 3. Typical Performance of the Proposed ALC Device
0
Table 1. Coefficients of the Polynomial Approximation of 2
E + D
k
y, B = c
/ k!) are included for comparison. The computation of the fourth-order polynomial
B + C, E = A
15
0.2
0.2
1
y + c
0.3
0.3
2
, C = c
A
Send-Out Signal y(n) from ALC
f
is in the range from –1 to 0). The coefficients of the standard
Taylor Coefficients
0.4
0.4
Send-In Signal x(n) to ALC
3
y + c
22713
32767
Time (s)
Time (s)
1819
7872
315
0.5
0.5
4
0.6
0.6
0.7
0.7
MMSE Approximation
0.8
0.8
22709
32767
y
1743
7844
224
0.9
0.9
Freescale Semiconductor
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