Re: [Elecraft] Final K3 APF Lab Test Results
The APF engages. I measured it in 4.22. It is no different than in 4.17. Of course, you must set the feature to operate, or it will indeed be the old DUAL PB algorithm. CONFIG:DUAL PB must be set to APF and not set to NOR. 73, Lyle KK7P > My intuition says that the problem is not in the filter algorithm. Could be > that the APF just not engages in 4.22? Could be that instead of APF it is > still does Dual PB or something? __ 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
Re: [Elecraft] Final K3 APF Lab Test Results
Wayne, My intuition says that the problem is not in the filter algorithm. Could be that the APF just not engages in 4.22? Could be that instead of APF it is still does Dual PB or something? Can you try to listen to the weak CW with 2 rigs - one with 4.17 and one with 4.22? When I engage 4.22 APF I hear high pitch noise at frequency range close to the CW pitch, which makes hearing CW signal very hard. The 4.17 (and 4.18) did not have this. I have 400Hz 8-pole and 250 Hz 8-pole filters, I tried with both - same problem. 73, Igor, N1YX -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Wayne Burdick Sent: Saturday, November 20, 2010 3:44 PM To: elecraft@mailman.qth.net Subject: [Elecraft] Final K3 APF Lab Test Results We just did a *very* accurate sweep of the APF passband from the original (4.17) and new (4.22) beta releases. Lyle has the data in spreadsheet form and will send it out on request. It's too big to attach to a reflector posting. Bottom line: There is no difference between the two. This is not surprising, since we did not change the filter algorithm. Any difference must be attributed to noise and signal conditions, filter bandwidth settings, or APF tuning vs. actual signal pitch. This is the nature of APF; it is most effective under specific conditions. Try turning it on, and if it doesn't help, leave it off. 73, Wayne N6KR http://www.elecraft.com On Nov 20, 2010, at 12:16 PM, John Seney wrote: > Hi All: > > I have the same experience as Igor. There is an APF sweet spot that either moved or > disappeared. > > Would it be helpful if there was a GUI that let us save, load, share, and see all of > the various K3 parameter settings that we are adjusting? > > On Nov 17, 2010, at 11:53 PM, Igor Kosvin wrote: > >> Sure, you are right, but you would not deny that using same set of >> parameters (NR/NB, WIDTH, PITCH, RF, etc) the APF circa 4.17 and 4.22 should >> give very similar results since the code of APF remains the same. After >> playing few days with 4.22 I find myself having to turn off APF to better >> receive weak CW stations. I don't have explanation for this. With APF on I >> find it difficult to distinguish dits and dahs of weak signals. With 4.17 it >> was much better for me. That should be apples-to apples comparison, I think. >> I don't claim to be expert though, listening is very subjective IMHO. >> >> Regards, >> >> Igor, N1YX > > > 73, > > John Seney > ARS WD1V (fn42gw) > 603 785-2413 > > > __ > 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 __ 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 __ 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
Re: [Elecraft] Final K3 APF Lab Test Results
On Nov 20, 2010, at 12:43 PM, Wayne Burdick wrote: > Any difference must be attributed to noise and signal conditions, filter > bandwidth settings, or APF tuning vs. actual signal pitch. This is the nature > of APF; it is most effective under specific conditions. Try turning it on, > and if it doesn't help, leave it off. Those running Mac OS X 10.6 (Snow Leopard) on your computers might want to play with this application to hear what changing filter parameters does to an "APF": http://homepage.mac.com/chen/w7ay/cocoaFilter/index.html The "stock" IIR filter in the program has adjustable Q and center frequencies, with a GUI so you can see the transfer function and compare different settings with what you "hear." There is also an experimental FIR filter in it that attempts to achieve better SNR than the IIR without introducing the "hollow" flat-topped narrow bandpass DSP sound. The IIR that is in the program is just a simple analog second order bandpass filter that is transformed into the digital domain. But you can change both the FIR and IIR filters with just a few lines of C code to experiment with something other than the "stock" filters. cocoaFilter is not intended as an end-user program, but as a sandbox for people to try other filter ideas without having to learn all of Cocoa and Core Audio. if you are familiar with DSP but don't want to deal with the Mac OS Core Audio or the Cocoa user interface, this framework should make it easy -- you only need to modify a few lines of the filter code. Just think of the "stock" filters as a starting point. Go build your own "INRADS" :-). Modern computers are so fast that you don't need a DSP chip to experiment with real time audio filters -- the "stock" filters in cocoaFilter use only about 2% of the processor load of *one* core of my Nehalem-based MacPro, and I didn't attempt *any* optimization (audio is filtered one sample at a time with the dynamic messaging of Objective-C; that is as inefficient as you can get). Only when you start building audio filters that are 10 times more complex, will you need to use Mac OS X's Grand Central Dispatch in your filters to spread the work among the cores of your processor. Audio Units and the AU Lab program in the Mac OS X Developer disk (it is on every Mac OS X Installer DVD) is another platform you can use to experiment with filters. It is probably a bit more complex than changing a few lines of code in cocoaFilter. cocoaFilter uses Audio Unit calls but you don't *need* to understand that code to experiment with other filters :-). 73 Chen, W7AY __ 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
