mc44c402 Freescale Semiconductor, Inc, mc44c402 Datasheet - Page 6

• Manufacturer Part Number: mc44c402
• Description: Mts Stereo Encoder
• Manufacturer: Freescale Semiconductor, Inc

Encoder, the user can significantly improve the performance
by following the suggestions below:
1.
2.
3.
Equipment suggestions
Demodulator:
Decoder:
MC44C402
6
When developing application using the MC44C402 Stereo
Disable the pre-emphasis on the modulator
There must be a 4.5 MHz notch in the video because
Video spectra that fall into the 4.5 MHz range will
severely impact the audio performance. See the notch
filter shown in
Measurements must be made with a precision
demodulator followed by a precision decoder,
measuring audio performance using mono or wide band
output will give erroneous results. We suggest the setup
as described below
DESIGN CONSIDERATIONS
Tektronix
Modulation Sciences
Figure
7.
14k
20
TV1450
SRD-1
50
14.5k
SYSTEM APPLICATION NOTES
100
Figure 5. Amplitude Ripple
Figure 6. Amplitude-Notch
15k
200
500
15.5k
Hz
Hz
1k
4.
5.
16k
A low pass filter is required on the CA (baseband)
output. The filter shown in
recommended. It is a Bessell filter with uniform group
delay to 50 kHz and an input impedance of 500Ω and
high output impedance.
Crystal frequency is critical. It MUST be within +/- 2 kHz
(100 PPM) under all conditions. Recommend 30 PPM
or better at room temperature. Measure the frequency,
being careful not to load the crystal oscillator pins or
alternatively the frequency can be determined by
measuring the 4 MHz using (spectrum analyzer), being
careful not to load the crystal oscillator pins, or with a
frequency counter on the 4 MHz port to +/- 400 Hz max
or 100 Hz at room temp. A symptom of the crystal being
off frequency is stereo separation changing at about a
1 Hz rate (Pulsing).
2k
16.5k
5k
10k
T T
17k
T
+5
+0
-5
-10
-15
-20
-25
-30
-35
-40
-45
-50
+5
+4
+3
+2
+1
+0
-1
-2
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-4
-5
B
A
d
r
Figure 7
B
A
d
r
Freescale Semiconductor
note 1 is