数据搜索系统,热门电子元器件搜索 |
|
STV8207 数据表(PDF) 22 Page - STMicroelectronics |
|
STV8207 数据表(HTML) 22 Page - STMicroelectronics |
22 / 149 page Digital Demodulator STV82x7 22/149 3.2 Demodulation The demodulation system operates by default in Automatic mode. In this mode, the STV82x7 is able to identify and demodulate any TV sound standard including NICAM and A2 systems (see Table 4) without any external control via the I²C interface. It consists of the two demodulation channels (Channel 1 = Mono Left and Channel 2 = Mono Right/Stereo) to simultaneously process two sound carriers in order to handle all transmission modes (stereo and up to three mono languages). The built-in Automatic Standard Recognition System (Autostandard) automatically programs the appropriate bits in the I²C registers which are forced to Read-only mode for users (see Section 12.1). The programming is optimized for each standard to be identified and demodulated. Each mono and stereo standard can be removed (or added) from the List of Standards to be recognized by programming registers AUTOSTD_STANDARD_DETECT and AUTOSTD_STEREO_DETECT, respectively. The identified standard is displayed in register AUTOSTD_STATUS and any change to standard is flagged to the host system via pin IRQ. This flag must be reset by re-programming the MSBs of register AUTOSTD_CTRL while checking the detected standard status by reading registers AUTOSTD_STATUS, NICAM_STAT and ZWT_STAT. Moreover, the detection of Stereo mode during demodulation is also flagged in register AUTOSTD_STATUS. Important: L/L’ and D/K standards cannot be automatically processed because the same frequency is used for the MONO carrier. An exclusive L/DK selection must programmed in register AUTOSTD_CTRL. This may be externally controlled by detecting the RF modulation sign, which is negative for all TV standards except L/L’. To recover out-of standard FM deviations or the Sound Carrier Frequency Offset, additional I²C controls are provided without interfering with the Automatic Standard Recognition System (Autostandard). DK-NICAM Overmodulation Recovery: Four different FM deviation ranges can be selected (via register AUTOSTD_CTRL) for the DK standard while the Autostandard system remains active. The maximum FM deviation is 500 kHz in DK Mono mode and 350 kHz in DK NICAM mode (limited by overlapping FM and NICAM spectrum values). The demodulated signal peak level (proportional to the FM deviation) is detected by the Peak Detector and written to registers PEAK_DET_L and PEAK_DET_R. This value is used to implement Automatic Overmodulation Detection via an external I²C control. Important: Only the selection of the 50 kHz FM deviation standard is compatible with the other DK- A2* standards (DK1, DK2 or DK3). These standards must be removed from the list of standards (registers AUTOSTD_STANDARD_DETECT and AUTOSTD_STEREO_DETECT) when programming larger FM deviations reserved only for DK-NICAM standards. Table 4: Recognized Standards System Sound Type Type Name Carrier 1 (MHz) Carrier 2 (MHz) FM Deviation De- emphasis Roll -off (%) Pilot Frequency (kHz) Nom. Max. Over B/G FM Mono 5.5 FM/NICAM 5.5 5.850 27 50 80 J17 40 FM 2-Carrier A2 5.5 5.742 27 50 80 50 µs 54.6875 D/K FM Mono 6.5 FM/NICAM 6.5 5.850 27 50 80 J17 40 D/K1 FM 2-Carrier A2* 6.5 6.258 50 µs 54.6875 |
类似零件编号 - STV8207 |
|
类似说明 - STV8207 |
|
|
链接网址 |
隐私政策 |
ALLDATASHEETCN.COM |
ALLDATASHEET是否为您带来帮助? [ DONATE ] |
关于 Alldatasheet | 广告服务 | 联系我们 | 隐私政策 | 链接交换 | 制造商名单 All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |