++++++++++++++++++ Date: Mon, 5 May 2003 11:23:41 -0100 From: "Julian (G4ILO)" Subject: Re: [Elecraft] To: "Elecraft List" The K2 is a superb radio making the most of analog technology and one might question whether much of the "need" for DSP comes simply from wanting to have the latest gizmos. If I decide to break the bank and buy this option I think that will be the main reason, not any real requirement. For digital mode operation a DSP filter is completely redundant because the computer ignores everything it isn't interested in. In fact wonder whether it might actually be a bad idea to have the signal pass through an audio filter before it reaches the sound card? For CW, I think I'll await the comments of the far more experienced CW operators than me here who have previously stated that the K2 with KAF2 is much better at hearing weak signals than any existing DSP-equipped radio. It could be that for those who mostly use CW, the KAF2 will remain the better option. 73, -- Julian, G4ILO. (RSGB, ARRL, G-QRP, K2 #392) G4ILO's Shack: http://www.qsl.net/g4ilo ++++++++++++++++++++ From: "Robert Parker" To: "Daniel Reynolds" , "Julian (G4ILO)" , "Elecraft List" Subject: Re: [Elecraft] DSP vs KAF2 for CW/SSB? Date: Mon, 5 May 2003 11:16:27 -0400 Well I have a KAF2 in each of my K2s and I can say it works very well on CW. The CW filters in the K2 do a great job at reducing noise but the KAF2 gives the K2 an added edge in that it really tightens up even more. A weak signal will come right up from the noise. Plus on SSB, the KAF2 positon 1 really reduces noise further making operating even more pleasurable. Regards, Robert VE3RPF ----- Original Message ----- From: "Daniel Reynolds" To: "Julian (G4ILO)" ; "Elecraft List" Sent: Monday, May 05, 2003 10:37 AM Subject: [Elecraft] DSP vs KAF2 for CW/SSB? > --- "Julian (G4ILO)" wrote: > > For CW, I think I'll await the comments of the far more experienced CW > > operators than me here who have previously stated that the K2 with KAF2 is > > much better at hearing weak signals than any existing DSP-equipped radio. > > It could be that for those who mostly use CW, the KAF2 will remain the > > better option. > > I would be curious to know what most folks think about the DSP vs KAF2. Are > they getting the DSP for SSB use only? I intend on using CW only for quite a > while. Is the DSP going to help me that much more than the KAF2? > > BTW - FWIW... I bought the KAF2 thinking that I might use the audio filter but > I really wanted it for the clock (what's a station without a clock!?)... and > after seeing how configurable the IF filtering is on the K2, I wonder if I'll > ever really need the KAF2 for anything except the clock? My KAF2 is still > unbuilt - it is patiently waiting in line behind the KAT2 and KNB2. > > - Daniel/AA0NI ++++++++++++++++ Date: Mon, 05 May 2003 08:21:51 -0700 From: Vic Rosenthal Organization: Transparent Software To: "Julian (G4ILO)" Cc: Elecraft List Subject: Re: [Elecraft] KI02?? Julian (G4ILO) wrote: > For CW, I think I'll await the comments of the far more experienced CW > operators than me here who have previously stated that the K2 with KAF2 is > much better at hearing weak signals than any existing DSP-equipped radio. > It could be that for those who mostly use CW, the KAF2 will remain the > better option. Although I saw the DSP in action this weekend, I didn't get a chance to play with it under real conditions. For me, the test will be to see how much it enhances reception of weak signals in the presence of noise (especially the manmade garbage that surrounds my QTH). The KAF2 has what seems to me to be just about the maximum usable selectivity for copying CW by ear. My experience has been that it's the kind of noise that's present that determines whether or not the KAF2 will improve my ability to copy a given signal. What we really need to do is get one of those guys who has two K2's and is a good CW operator (are you listiening, K1JD?) to install the DSP in one of them and the KAF2 in the other, and then do an A/B comparison. 73 Vic K2VCO ++++++++++++++++++ Date: Mon, 05 May 2003 08:44:38 -0700 From: Vic Rosenthal Organization: Transparent Software To: Andrew Moore Cc: Elecraft Subject: Re: [Elecraft] DSP improves K2?: Andrew Moore wrote: > Isn't it conceivable that the audio DSP would actually do the > job of the KAF2 plus more? That is the intention, since one of its functions is a simple bandpass filter. But it's much more flexible since you can change the bandwidth and center frequency from the menu, plus having an automatic notch filter for SSB, and at least one noise reduction algorithm. I didn't notice if it had lowpass/highpass modes, but I wouldn't be surprised if it does. One of the problems with DSP filters is that they can introduce 'artifacts' (noise and distortion) into processed signals. I didn't hear anything obvious in the few moments that I listened to it, but that is one reason someone might prefer an analog filter. If they did a good job on the design, that won't be an issue. For best performance, the input level of a DSP filter is more critical than an analog filter, but I presume that this is much less of a problem with an integrated DSP such as this than outboard filters like the Timewave units. 73 Vic K2VCO +++++++++++++++++ From: "Michael Harris" To: "Elecraft List" Subject: Re: [Elecraft] DSP vs KAF2 for CW/SSB? Date: Mon, 5 May 2003 11:35:27 -0300 G'day, It's worth building the KAF2 just for the always in-line low pass filter slicing off the high frequency audio hiss. Regards, Mike VP8NO #1400 +++++++++++++++++++ From: "Andrew Catanzaro" To: "Dale Boresz" Cc: Subject: Re: [Elecraft] DSP value? Date: Thu, 8 May 2003 21:13:25 -0500 Dale, I understand what you are saying below. I have never run into a DSP unit, however, that ever left a CW element untainted. It takes a finite length of processing time for the signal to be identified as such and passed through the output of the filter. This tiny fraction of a dit may make no difference at 20 WPM, but at higher speeds that rolloff of the leading edge becomes a larger part of the same dit.. I find the effect to be a deterrent to comfortable copy. At really high speeds, it subtracts from intelligibility regardless of how high or low the unprocessed S/N ratio is. With all the traffic on this reflector in the past couple weeks about the waveform of the transmitted K2 signal, I would think most ops would be more concerned about the shape of the waveform hitting their ears on the receiving end. I do not own a storage oscilloscope, but I'm pretty sure my point could be effectively displayed in a measurable format. I have found that relatively tight analogue filtering to be superior at increasing the S/N ratio compared to digital noise subtraction or SCAF filtering. If there are too many poles of Butterworth, Chebyshev, or whatever filtering, there can be time domain smearing of the CW elements, and the benefit of even this filtering goes away. The KAF2 is just right! BUT, I know the guys at Elecraft make superior products and it would be stupid of me judge anything they make before hearing it. And of course, to really analyze the KDSP2, I'll have to buy one. Besides, I need something to build, and more important than that, I have to support Elecraft so they keep producing wonderful radios. 73, Andy W9NJY Milwaukee WI ----- Original Message ----- From: "Dale Boresz" To: "Andrew Catanzaro" Sent: Thursday, May 08, 2003 8:13 AM Subject: Re: [Elecraft] DSP value? > Andrew Catanzaro wrote: > > >Headphones are absolutely necessary for good CW copy because putting the source of the CW at the ear eliminates multipart distortion that causes the brain to work overtime in copying even in-the-clear signals. So when I hear something on the speaker I want to hear better, I just put the cans on my head. I leave the filtering wide-open on the TimeWave and use the KAF2 when needed. > > > I agree completely. However, when you put on the headphones, you are > also able to hear the noise surrounding the signal that much clearer as > well. This is where the noise-reduction of the KDSP2 really helps; it > reduces that surrounding noise to a level that makes it much less > distracting, without changing the level of the desired signal. The > result is that your ear/brain doesn't have to work as hard to separate > the signal from the noise, and copy is far more enjoyable. > > >It's a great filter that doesn't ring, and there's no digital bandwidth > >that's narrower that's more useful! > > > I have been a long-time fan of the KAF2 (being primarily a cw op), and > being one of the KDSP2 field testers, I have also had the opportunity to > work with the KDSP2 on the air for some weeks now. While I've always > liked the character of the audio with the KAF2 filter engaged, it > accomplishes this at the expense of reduced bandwidth - whether the > reduction is needed or not. Many times I have engaged the KAF2's filter > only to help lift a weak signal out of the noise, even when there were > no other signals around. Being one who prefers a wider bandwidth for > general operation, I find the ability of the KDSP2 to reduce noise > independently of bandwidth, to be one of it's most appreciated features. > > In short, the KAF2 is a wonderfully elegant and effective product, but > the versatility and effectiveness of the KDSP2 is what keeps it firmly > attached to my K2. :-) > > 73, Dale - WA8SRA +++++++++++++++++ Date: Fri, 09 May 2003 10:11:48 -0400 From: Dale Boresz To: elecraft at mailman.qth.net Subject: Re: [Elecraft] DSP value? Hi David, Leonard, David wrote: >Dale: > >Since you field tested the DSP unit, I have a quick question. > >Can you still have the KAF2 in the unit with the DSP at the same time? > No; they each interface to the K2 via the same connectors, so you can certainly install *either*, but not both. >I too love my KAF2. So the ideal scenario (to me) would be to be able to >switch back and forth from time to time. > You can, but once you've beaten KAF2 withdrawall, you won't look back! >Or is the DSP so far superior that you don't "miss" the KAF2 (if they are >mutually exclusive)? > Seriously, the wealth of adjustments available - including the 'soft' CW filters, along with the bandwidth-independent Noise Reduction, enable you to tailor it to your particular hearing and operating preferences - which may even change over time. At first, I found that I preferred a less aggressive NR, but then as I used it more, and discovered that a more aggressive NR seems to improve readability - regardless of whether there is QRN at the moment or not - I kept with the more aggressive settings. But the beauty of it, is that I can alter those settings whenever I want, with just a couple of button pushes. Also, you'll find that by playing with the filter bandwidth adjustment, particularly with the 'soft' cw filters, you'll be able to achieve the 'sound' of the good 'ole KAF2 - along with the added benefit of noise reduction. 73, Dale +++++++++++++++++