Hi,all,
De-emphsis filter with (15us/50us) is included in many digital audio DAC
chips. My question is why we need de-emphasis filter, what emphasis filter is. Can you provide detailed specification about de-emphasis filter?
If it is defined in some standard,can you share me the document?
Emphasis filter are used to give emphasis in the higher frequency components on filtering process.
This filters (Pre-emphasis and De-emphasis) are used in systems in which the power spectral density of the signal decreases more rapidly than the noise power spectral density; Increasing the SNR (signal to noise ratio).
(This is the case of an DAC.)
Take a look in the graphics in the attach.
This pages (attached) are of the book "Telecommunications Engineering" J. Dunlop and D. G. Smith, by Chapman & Hall. (Good book!)