Texas Instruments DEM-DAI3793A User Manual
www.ti.com
3D Effect Options
3D Effect Options
By implementing a 3D effect in this option box, the PCM3793A is enabled to provide 3D sound to the
headphone and speaker outputs with low power consumption during either ADC or DAC operation. Check
the 3D effect, then select an Effect type and an Efficiency drop-down menu to obtain the desired 3D
enhancement.
headphone and speaker outputs with low power consumption during either ADC or DAC operation. Check
the 3D effect, then select an Effect type and an Efficiency drop-down menu to obtain the desired 3D
enhancement.
Effect type means the selection of a band-pass filter (BPF); the BPF filters the sound, and enables a high
percentage of heavy 3D enhancements to be applied to the signal.
percentage of heavy 3D enhancements to be applied to the signal.
Effect type and efficiency are controlled through the use of checkboxes.
Notch Filter 1 Coefficient, Notch Filter 2 Coefficient Options
In some applications, incoming noise such as motor control noise, CCD noise and other mechanical noise
may not be negligible. The PCM3793A provides a very useful function to reduce such interference with the
notch filter function.
may not be negligible. The PCM3793A provides a very useful function to reduce such interference with the
notch filter function.
When the checkbox of Notch Filter 1 Coefficient or Notch Filter 2 Coefficient is checked, coefficient a
1
and
a
2
of the notch filter can be programmed at each edit box.
Load the values of f
c
, f
b
and f
S
into the Filter Calculator group box.
Click Apply to Filter 1 or Apply to Filter 2. The calculated coefficient will then appear in the a
1
and a
2
edit
box.
Finally, click the Update button for each Notch filter coefficient. To complete the notch filter operation, the
Update button must be clicked.
Update button must be clicked.
Note that Update step is required each time new or different parameters are loaded to the dialog box.
Follow these steps to update the notch filter coefficient:
Step 1.
Click the checkbox of Notch Filter 1 Coefficient or Notch Filter 2 Coefficient.
Step 2.
Input the parameter values f
c
, f
b
and f
S
.
Step 3.
Click Apply to Filter 1 or Apply to Filter 2.
Step 4.
Update for each notch filter coefficient.
Each coefficient is calculated using the following equations.
a
1
= –(1 + a
2
)cos(
ω
o
)
a
2
= [1 – tan(
ω
b
/2)] / [1 + tan(
ω
b
/2)]
where:
•
f
S
= sampling frequency
•
f
c
= center frequency
•
f
b
= bandwidth
•
ω
o
= 2
π
f
c
/f
S
represents the angular center frequency
•
ω
b
= 2
π
f
b
/f
S
is the parameter to adjust bandwidth
Here are several example coefficient calculations using
and
. These
measurements are also shown in
.
Given: f
S
= 16kHz, f
c
= 0.5kHz, f
b
= 0.2kHz
a
2
= 0.924390492 (converted decimal to hex: 3B29h)
a
1
= –1.887413868 (converted decimal to hex: 8735h)
a
2
: F[215:208] = 3Bh, F[207:200] = 29h
a
1
: F[115:108] = 87h, F[107:100] = 35h
32
Set-Up Guide
SBAU127 – July 2007