> "Dual PB" (press and hold XFIL) allows one, as the manual says, to "focus" > on a given signal that is matched to the sidetone frequency while hearing > other callers above and below that frequency at reduced level (the > "context"). Doesn't that do what the waveforms described on AB4OJ's > website > depict?
Icom's use of APF is different than that used in the FT-1000/D. Icom more closely emulates the Dual PB feature in the K3 but without the "context" feature. What's missing is high "Q" of the centered frequency. The FT-1000/D's Q of the audio circuit varies with the tuning control, but it's generally greater than 10. When the Dual PB tuning is enabled on the K3, and with aggressive NR engaged, I don't hear what sounds like a high Q equivalent. The FT-1000/D's APF is more closely associated with a single-channel of a multi-band parametric equalizer where Q, amplitude, and frequency are all variable. In the FT-1000/D, Q is mostly fixed, but amplitude and frequency are variable. Although the FT-1000/D adds amplification of the centered frequency -- and even allows changing the peaking frequency, I think the most desirable attribute of the circuit is the high Q ability. Fixed gain and variable peaking frequency may be a nice added feature to the K3 if APF is implemented, but these are secondary to achieving emulation of the high Q portion of the analog circuit in DSP. Paul, W9AC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
