|
楼主 |
发表于 2012-11-6 17:23
|
显示全部楼层
本帖最后由 new1510 于 2012-11-6 18:43 编辑
【1541条制作经验之一】:了解SAA7220 p/A、B、C有什么不同。
[转载]一个国外网站的介绍,或许能了解。
一、SAA7220P/A
The SAA7220P/A was originally designed for digital audio applications using a sampling rate frequency of 44.1kHz (±10%). It can also be used for 32kHz(±10%) and 48kHz(no tolerance) applications suc as DAT.
度娘译文:“SAA7220P / A最初是专为数字音频应用的使用频率为44.1kHz的采样率(±10%)。它也可以被用于为32kHz(±10%)和48kHz(无公差)应用程序SUC作为DAT。
二、SAA7220P/B
The SAA7220P/B is an improved version of the 'A' device giving 1dB better performance in the passband of the FIR filter, achieved by using different ROM coefficients. The other difference between the two types is that the offset in the accumulator is greatly reduced (+0.05% in the 'B' compared to +5% in the 'A'). The SAA7220P/A required a +5% offset to give optimum performance when used with the TDA1541 dual DAC. However, with the 'B' version this offset is no longer necessary for optimum performance.
度娘译文:SAA7220P / B是一个改进版的'A'给1分贝更好的性能,实现了通过使用不同的ROM系数的FIR滤波器在通带内的设备。在两种类型之间的另一个区别是,在累加器中的偏移量被大大减少(0.05%比5%中的'A'中的'B')。的SAA7220P / A需要一个+5%的偏移,以提供最佳性能时使用的TDA1541双通道DAC。然而,这个偏移量与'B'版本,不再需要以获得最佳性能。
三、SAA7220/C
The SAA7220P/C has been specifically designed for better performance for satellite (32kHz) applications. Again it has a different set of ROM coefficients. They are chosen such that the transition band (0 to -50db) is much sharper than for the 'A' or 'B' versions - 14.6 to 17.0kHz (for the 'C') compared to 14.6 to 17.7kHz (for the 'A' and the 'B') at the 32kHz sampling rate. The SAA7220P/C also has the reduced accumulator offset to +0.05%
度娘译文:SAA7220P / C已经专门设计的卫星(32kHz的)应用程序有更好的表现。同样,它具有一组不同的ROM系数。他们选择了这样的过渡频带(0〜-50dB以下)更清晰的比为'A'或'B'版本 - 14.6〜17.0kHz('C')相比,14.6〜17.7kHz(“ A'和'B'),在32kHz的采样率。 SAA7220P / C也减少累加器偏移+0.05%。
看了这段文字,元芳,你们怎么看?这里面有木有七窍?
(转帖说明)
SAA7220PA是针对TDA1541开发的,插值误差大,性能一般。
SAA7220PB是针对TDA1541A开发的,插值误差小,适于44.1KHz的CD音频解码。
SAA7220PC是针对32KHz音频的卫星接收机开发,采用椭圆滤波器。
B是A的改进版
C是专为卫星信号(32KHZ抽样频率)优化的版本.而且滤波器等效类型与A/B有明显区别(C是契比雪夫的).
|
|