> I learned last week after experiencing less than optimal > FM audio quality on receive that the Rx EQ is enabled > on all modes. I've never seen that on FM.
The Rx EQ is for the receiver. It currently applies to all modes. > The complicating factor is that the 8 equalizer sound > band values vary from the K3 documentation whenever the > filter width changes (this always happens with > mode changes). There is but one Rx EQ routine in the DSP and it has but one set of parameters. It does not vary by mode; it is completely independent. Note that the way the EQ works is that it creates, or attempts to create, a smooth slope from the indicated frequency (say, 1.60 kHz, EQ band 6) to halfway to the next indicated frequencies (in this case, halfway to the 0.80 kHz band (thus 1200 Hz), band 5) and halfway to the 2.40 kHz band (thus 2.00 kHz), band 7). The Tx EQ works the same way. This is similar to the way the W2IHY equalizer works,or the formerly-common "graphic equalizer" sliders on stereo equipment. The indicated frequency is the "center" of the band of frequencies over which it operates. (I put "center" in quotes as you may not consider 1600 Hz to be the center frequency between 1200 Hz and 2000 Hz as explained above.) Finally, the upper frequency correction value (3200 Hz, band 8) extends to the top of the audio passband. If you set it for - 4 dB, for example, the -4 dB correction will be applied from 3.20 kHz to 4 kHz, or 4.2 kHz, or whatever the audio frequency cutoff happens to be for the mode you have selected. The net result is that you can create a smooth frequency roll off characteristic. While on the topic of the ERQ, some people have asked me if the DSP delay can be reduced if the EQ is set to OFF (flat). The answer is no. The Rx EQ is *not* a separate process added to the audio path. The EQ parameters are used when building the AF filter response for the radio. There is *one* DSP AF filter, which includes the effects of SHIFT/WIDTH/MANUAL NOTCH *and* Rx EQ. The Auto notch, and noise reduction, are additional processes in the path. So is AFX in the right channel. 73, Lyle KK7P ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
