Hi Simon,

Would it not be smarter to have the WB FM demodulator with a flat response and make the de-emphasis a selectable option to suite different requirements, as wide band data modes don't use pre -emphasis.

Paul
VK4ZBV.



jose maria trueba wrote:

 

For FM de-emphasis just make frequency response at receiver flat up to 1KHz, and slope down 2dB@2KHz, 4dB@4KHz and then 9dB@8KHz and 14dB@16KHz. Instead of a fix value per octave as said too often.

For U.S. transmitters values are slightly higher with 3dB@2KHz, 6dB@4KHz, 12dB@8KHz and 18@16KHz.

This can be a good way to compensate the pre-emphasis at transmitter side, as shown here:
http://www.radiomuseum.org/forumdata/users/4644/Deemphasis_Comp.png

I think is better to think about it this way, instead of naming delays of the RC time constant of the low pass filter made this way at regular FM receivers.

2011/1/4 Rob M0TFO <robpegs@...>

 

I may of just missed it,but does sdr-radio support Wide FM?
Rob