Re: W-FM

Calder Latham

    Not to throw water on the parade, but why would a HAM receiver need to have the capability of FM broadcast listening?? FWIW.
    Keep up the good work Simon and us new build nuts are waiting for the next kit.

All the Best
Cal, W1HHO
Fraternity Village ME.

Sent: Thursday, January 06, 2011 06:42 PM
Subject: Re: [sdr-radio-com] W-FM

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.


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:

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?


Join { to automatically receive all group messages.