EN 1409.FM23, FM24, FM33Circuit Descriptions, List of Abbreviations, and IC Data Sheets
9.4.3 Audio processing (Diagrams SC13, 14 and 15)processing and audio delay. It also matches the output signals
for the Audio Amplifier panel.
This chapter describes the audio processing on the SCAVIO The sound-related electronics are very straight forward, and
board. The circuit enables to connect several audio sources, consists of a Micronas MSP3415G sound processor, an active
selects the source on the desired input, and performs audio high pass, and low pass filter, and separate Class-D amplifiers
for the woofers and tweeters.
(Basic only)7880
Digital Audio
7798Delay Line
(Enhanced only)
MatrixT1T2
Switch
TEA6422
Audio2* Differential
inputs7812I2CI2SI2S0388Amplifier
VGA1PRE-out1 (L)-4dBIn 4Out 1SCART1-in7841L-NEG
Audio-VGA-in
DACM-L+4.9dBL-POS
VGA2-4dBIn 5(Enhanced only)I2S-DA-OutII2S-DA-In1I2S-DA-In2
Audio-Flex-VGA
DVI-D-4dBIn 6(Enhanced only)(Enhanced only)
Audio-DVIPRE-out2 (R)7851
R-NEG
Out 2SCART2-in
AV1-4dBIn 2(Enhanced only)(Enhanced only)AUDIO DSPDACM-R+4.9dBL-NEG
Audio-CVBSMSP3415
AV2(Enhanced only)(Enhanced only)-4dBIn 3
Audio-YC
AV3-4dBIn 1Out 3(Enhanced only)(Enhanced only)SC1-OUT+3.0dBAudio out (to Audio Amplifier)
Audio-YPbPr
Audio Enable
I2C-SCLI2C-SDA(Basic only)D-CTRL-0D-CTRL-1I2C-SCLI2C-SDAMSP-Reset
7801 : 7808
(Enhanced only)
Switch
Mute
7800
Power-okLogic
&
MSP-Reset
I2C-SDA
I2C-SCL
= Only for Basic configuration.
CL 26532038_012.eps
280302
Figure 9-15 Audio Path
Audio delay
The processing part consists mainly of the following To compensate for "lip sync error" (the difference in time
components:between the aural and visual perceptions), two different audio
MSP3415G: a DSP sound processor from Micronas. This delays are selectable via the customer's menu (one for the
component is able to do all kinds of digital signal Receiver box and one for the Monitor).
processing like volume, bass/treble, Ultra Bass, and This is done at the audio processor IC7812 via an I2S bus and
balance. It has analogue inputs and outputs, as well as an an additional delay circuit (IC7880 - 7882).
I2S in/output used for digital audio delay.One can select delays of 24 ms (I2S_DATA_IN1) and 40 ms
RAM with its logic to be able to store the I2S information for (I2S_DATA_IN2), or no delay.
audio delay.In case of a delay, the AUDIO_L/R_IN is re-routed as
Anti-plop/ mute circuit: which is necessary to prevent I2S_DATA_OUT to the audio delay circuit and, depending on
disturbances on the audio lines during start-up or the selected delay, returned as I2S_DATA_IN1 or
switching.I2S_DATA_IN2, resulting in AUDIO_L/R_OUT.
TEA6422: a matrix switch of ST. This component is able to
switch six inputs to three different outputs (only used in the Anti-plop/Mute
Enhanced version).In several cases, it is necessary to mute the sound output. This
muting is handled by the MSP sound processor, or by the
MSP3415GReceiver box in case of TV-mode.
In Monitor mode:
Ultra Bass- During switch "on/off" of the monitor.
Because of the closed box implementation in this FM-chassis, - During source change.
a common DBE solution will not give an optimal bass - During video or sync loss, or
performance. A closed box needs a substantial boost over a - By a user action (A/V-mute or mute).
wide frequency range, while DBE operates in a limited In TV mode:
frequency region. - During switch "on/off" of the Monitor/Receiver box.
Adaptive Ultra Bass 2 (UB2) is a suitable alternative. This - During source change in the Receiver box.
feature is based on the psycho-acoustic effect of the missing - During video or sync loss, or
fundamental, and gives the impression of a deep bass, while - By a user action (mute).
the loudspeakers do not reproduce these low frequencies. This
feature is implemented in the MSP3415G. In the FM-chassis,
this feature is always switched "on". |
ACEC
PHILIPS
