Philips msp34xx Service Manual

APPLICATION NOTE IC

Micronas

MSP 34xx Family
Recommendations for

Applications with

Intercarrier IF-Signals

Edition March 15, 2000
6251-495-2AN

MICRONAS

APPLICATION NOTE IC MSP 34xx Family

Recommendations for Applications
with Intercarrier IF-Signals

In order to avoid clipping effects at the IF-A/D con­verter of the MSP, the video, chroma, and sync signal
components, which are included in the intercarrier
sound-IF-signal (see Fig. 1, left), should not exceed
300 mVpp at the ANA_IN1/2+ MSP IF-input. Such clip­ping can cause a high NICAM error rate and loss of
SNR performance with FM signals.

Basic Recommendations

1. If an intercarrier IF-input signal is used (see Fig. 1,
left) for the IF-input of the MSP family, it is recom­mended to use a simple IF-amplifier and a band­pass- or highpass-filter in front of the MSP IF-input
to attenuate the video, chroma, and sync signal
components.

2. For the European market, a bandpass ranging from

5.3 MHz to 6.7 MHz should be used to eliminate the
video and chroma signal components.

3. For the M-standards, a bandpass ranging from

4.3 MHz to 4.7 MHz is recommended. Instead of a
bandpass filter, a highpass filter at 5.3 MHz (or at

4.3 MHz for standard M) can also be used.

4. Due to the filter loss and additional tolerances of the
sound carrier (normally 100 mVpp with a 1 Vpp
intercarrier signal), an analog gain of about +9 dB or
more is required as well. Tests have shown that the
filter attenuation at the chroma carrier frequency
should be about −12 dB or mor e re lat iv e to t he m ain
sound carrier.

5. The filtered IF-signal (sound carrier) at the MSP
input should have a minimum level of 100 mVpp.

6. For standard NICAM-L, with a 6.5 MHz AM sound­carrier, a Quasi Split Sound (QSS) IF-Demodulator
is recommended to avoid loss of AM-performance
caused by the video and chroma signal compo­nents.

Examples for Bandpass Filter Circuits

The diagrams on the following pages show examples
for the IF-spectrum, for the circui t, and the frequency
characteristic of such bandpass filters.

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MSP 34xx Family APPLICATION NOTE IC

Fig. 1: Spectrum of typical intercarrier IF-signal (left) and

Quasi Split Sound (QSS) IF (right) for PAL, NICAM B/G

Fig. 2: Measured input-spectrum (left) and

output-spectrum (r i ght )
with the bandpass for the European Market (PAL, NICAM B/G)

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APPLICATION NOTE IC MSP 34xx Family

Fig. 3: Bandpass filter circuit for the European Market

Fig. 4: Bandpass characteristic for the European Market

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MSP 34xx Family APPLICATION NOTE IC

Fig. 5: Bandpass filter circuit for standard-M

Fig. 6: Bandpass characteristic for standard-M

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APPLICATION NOTE IC MSP 34xx Family

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MSP 34xx Family APPLICATION NOTE IC

1. Application Note History

1. Application Note IC: “MSP 34xx Family Recommen­dations for Applications with Intercarrier IF-Signals”,
March 15, 2000, 6251-495-2AN. First release of the
application note IC.

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P.O. Box 840
D-79008 Freiburg (Germany)
Tel. [phone]
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Internet: www.micronas.com

Printed in Germany
Order No. 6251-495-2AN

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