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    參數(shù)資料
    型號: SAA7108
    廠商: NXP Semiconductors N.V.
    元件分類: Codec
    英文描述: PC-CODEC
    中文描述: PC的編解碼器
    文件頁數(shù): 51/202頁
    文件大?。?/td> 983K
    代理商: SAA7108
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    2004 Mar 16
    51
    Philips Semiconductors
    Product specification
    PC-CODEC
    SAA7108E; SAA7109E
    9.1.3.1
    Chrominance path
    The 9-bit CVBS or chrominance input signal is fed to the
    input of a quadrature demodulator, where it is multiplied by
    twotime-multiplexedsubcarriersignalsfromthesubcarrier
    generation block 1 (0 and 90
    °
    phase relationship to the
    demodulator axis). The frequency is dependent on the
    chosen colour standard.
    The time-multiplexed output signals of the multipliers are
    low-pass filtered (low-pass 1). Eight characteristics are
    programmable via LCBW3 to LCBW0 to achieve the
    desired bandwidth for the colour difference signals (PAL,
    NTSC) or the 0
    °
    and 90
    °
    FM signals (SECAM).
    Thechrominancelow-pass 1characteristicalsoinfluences
    the grade of cross-luminance reduction during horizontal
    colour transients (large chrominance bandwidth means
    strong suppression of cross-luminance). If the Y comb
    filter is disabled when YCOMB = 0 the filter directly
    influences the width of the chrominance notch within the
    luminance path (large chrominance bandwidth means
    wide chrominance notch resulting to lower luminance
    bandwidth).
    The low-pass filtered signals are fed to the adaptive comb
    filter block. The chrominance components are separated
    from the luminance via a two-line vertical stage (four lines
    forPAL standards)andadecisionlogiccircuitbetweenthe
    filtered and the non-filtered output signals: this block is
    bypassed for SECAM signals. The comb filter logic can be
    enabled independently for the succeeding luminance and
    chrominance processing by YCOMB (subaddress 09H,
    bit 6) and/or CCOMB (subaddress 0EH, bit 0). It is always
    bypassed during VBI or raw data lines, programmable by
    the LCRn registers (subaddresses 41H to 57H);
    see Section 9.2.
    The separated C
    B
    -C
    R
    components are further processed
    by a second filter stage (low-pass 2) to modify the
    chrominance bandwidth without influencing the luminance
    path. It’s characteristic is controlled by CHBW
    (subaddress 10H, bit 3). For the complete transfer
    characteristic of low-pass filters 1 and 2 see
    Figs 18 and 19.
    The SECAM processing (bypassed for QAM standards)
    contains the following blocks:
    Baseband ‘bell’ filters to reconstruct the amplitude and
    phase equalized 0
    °
    and 90
    °
    FM signals
    Phase demodulator and differentiator
    (FM demodulation)
    De-emphasis filter to compensate the pre-emphasized
    input signal, including frequency offset compensation
    (DB or DR white carrier values are subtracted from the
    signal, controlled by the SECAM switch signal).
    The succeeding chrominance gain control block amplifies
    or attenuates the C
    B
    -C
    R
    signal according to the required
    ITU 601/656 levels. It is controlled by the output signal
    from the amplitude detection circuit within the burst
    processing block.
    The burst processing block provides the feedback loop of
    the chrominance PLL and contains the following:
    Burst gate accumulator
    Colour identification and killer
    Comparisonnominal/actualburstamplitude(PAL/NTSC
    standards only)
    Loop filter chrominance gain control (PAL/NTSC
    standards only)
    Loop filter chrominance PLL (only active for PAL/NTSC
    standards)
    PAL/SECAM sequence detection, H/2-switch
    generation.
    The increment generation circuit produces the Discrete
    Time Oscillator (DTO) increment for both subcarrier
    generation blocks. It contains a division by the increment
    of the line-locked clock generator to create a stable
    phase-locked sine signal under all conditions (e.g. for
    non-standard signals).
    The PAL delay line block eliminates crosstalk between the
    chrominance channels in accordance with the PAL
    standard requirements. For NTSC colour standards, the
    delay line can be used as an additional vertical filter.
    If desired, it can be switched off by DCVF = 1. It is always
    disabledduring VBIor rawdatalinesprogrammable bythe
    LCRn registers (subaddresses 41H to 57H), see
    Section 9.2. The embedded line delay is also used for
    SECAM recombination (cross-over switches).
    相關(guān)PDF資料
    PDF描述
    SAA7109 PC-CODEC
    SAA7108E PC-CODEC
    SAA7109E PC-CODEC
    SAA7108AE HD-CODEC
    SAA7109A HD-CODEC
    相關(guān)代理商/技術(shù)參數(shù)
    參數(shù)描述
    SAA7108AE 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:HD-CODEC
    SAA7108E 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:PC-CODEC
    SAA7109 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:PC-CODEC
    SAA7109A 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:HD-CODEC
    SAA7109AE 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:HD-CODEC