TLC32044C, TLC32044E, TLC32044I, TLC32044M, TLC32045C, TLC32045I

VOICE-BAND ANALOG INTERFACE CIRCUITS

SLAS017F − MARCH 1988 − REVISED MAY 1995

30

POST OFFICE BOX 655303

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)

ERROR (dB)

p1 = − 0.14813

ERROR (dB)

p1 = − 0.1307

f (Hz)

p1 = − 0.14813

p2 = 0.9888

p1 = − 0.1307

p2 = 0.9951

300

− 0.099

− 0.043

600

− 0.089

− 0.043

900

− 0.054

0

1200

− 0.002

0

1500

0.041

0

1800

0.079

0.043

2100

0.100

0.043

2400

0.091

0.043

2700

− 0.043

0

3000

− 0.102

− 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)