Hi,
I'm working on a Nicam modulator in fpga,and such a system is
required
to perform pre-emphasis on the audio channels.Pre-emphasis filter
specified
in the CCITT J.17 recommendation.
Has anybody implemented this pre-emphasis filter and could you give me
some
tips on how you generated the coefficients?
The pre-emphasis attenuation curve is given by the followingformula:
Insertion loss between nominal impedances =
10 log10 ( (75 + (w/3000)^2) / (1 + (w/3000)^2) ) dB
where 'w' is the angular frequency corresponding to frequency 'f'.
Some values are given .
f (kHz) Insertion loss (dB)
0 18.75
0.05 18.70
0.2 18.06
0.4 16.48
0.8 13.10
2 6.98
4 3.10
6.4 1.49
8 1.01
10 0.68
Thank you for your help!
huhu