TLC32044C Datasheet, PDF (30/39 Pages) Texas Instruments – VOICE-BAND ANALOG INTERFACE CIRCUITS

TLC32044C, TLC32044E, TLC32044I, TLC32044M, TLC32045C, TLC32045I
VOICE-BAND ANALOG INTERFACE CIRCUITS
SLAS017F – MARCH 1988 – REVISED MAY 1995
correction results
Table 5 shows the optimum p values and the corresponding correction results for 8000-Hz and 9600-Hz
sampling rates.
Table 5. Optimum P Values
f (Hz)
300
600
900
1200
1500
1800
2100
2400
2700
3000
ERROR (dB)
fs = 8000 Hz
p1 = – 0.14813
p2 = 0.9888
– 0.099
– 0.089
– 0.054
– 0.002
0.041
0.079
0.100
0.091
– 0.043
– 0.102
ERROR (dB)
fs = 9600 Hz
p1 = – 0.1307
p2 = 0.9951
– 0.043
– 0.043
0
0
0
0.043
0.043
0.043
0
– 0.043
TMS(SMJ)320 software requirements
The digital correction filter equation can be written in state variable form as follows:
Y = k1 × Y + k2 × U
where
k1 = p1
k2 = (1 – p1) × p2
Y = filter state
U = next I/O sample
The coefficients k1 and k2 must be represented as 16-bit integers. The SACH instruction (with the proper shift)
yields the correct result. With the assumption that the TMS(SMJ)320 processor page pointer and memory
configuration are properly initialized, the equation can be executed in seven instructions or seven cycles with
the following program:
ZAC
LT K2
MPY U
LTA K1
MPY Y
APAC
SACH (dma), (shift)
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