+++++++++++++++++++++ See also K2_KK7P_DSP2_Info KDSP2_Info KDSP2_Notes KDSP2_Experiences Note that KK7P developed the KDSP2 module that elecraft is marketting... +++++++++++++++++++++ From: "Bozidar Benc" To: "barry" , "Pat n8vw" Cc: Subject: RE: [Elecraft] DSP... Date: Sun, 16 Mar 2003 13:06:12 +0100 I've found that device in "DSP-Speakers" on http://www.wimo.com (you must navigate to the "Radio accessories" page). They have demo sound files (20m and 40m CW). Here is a link to one I tried (sounds promising): http://home.tiscalinet.de/wimodata/40mcwlong.wav A link to the RadCom review: http://home.tiscalinet.de/wimodata/bhi%20radcom%20review.pdf I've made some tests tonight with EZKIT-LITE (Analog Devices ADSP2181 evaluation board) and DSP-10 (2-meter transceiver, http://www.proaxis.com/~boblark/dsp10.htm) software. The software can be used with the bare EZKIT (no RF hardware needed) and is quite capable. It has various band-pass filters, de-noiser and, what was the most interesting for me, binaural mode. In binaural mode one channel is delayed by 20ms (user settable). The result is that the noise appears all around you (not in your head) and the signal is in front of you (not in your head), halfway between the center and the right side (or left side, depends on how your earphones are connected). It's quite an experience, but one must get used to it (which I did tonight during the RU DX contest). De-noiser is useful, but I guess that it's much more useful on VHF and UHF where the noise is more uniform. 73, Bole, 9A3RR > On Thursday, Mar 13, 2003, at 17:22 US/Eastern, Pat n8vw wrote: > > > On Thu, Mar 13, 2003 at 09:25:35PM +0000, ray satel wrote: > > That's www.bhinstrumentation.co.uk > > > > Pat > > Hi Friends, > Does anyone know how well this unit works with CW? > Barry, W2BJ ++++++++++++++++++ Date: Mon, 24 Mar 2003 22:43:04 -0700 From: "James R. Duffey" Subject: Re: [Elecraft] K2 with DSP, big NO NO! To: daniel-k2 at juno.com Cc: elecraft at mailman.qth.net Daniel - I disagree with you that the DSP is not needed or useful with Elecraft radios. The frequency response of a series of circuits, such as comprise a receiver, is the frequency response of each individual unit concatinated together, assuming that each unit is linear. So, if the DSP has a better frequency response than the circuits that preceed it, the frequency of the whole will be improved by the addition of a DSP. Again, assuming all the circuits are operating in a linear region. For the K-2 with AGC off this is a good assumption under most operating conditions. In fact, since the K-2 is less subject to the non linear effects of second and third order intermodulation, a good DSP unit will be more useful with it than with other receivers. I do not have a K-2, but I do have a K-1, and have played around with it a good deal on a spectrum analyzer with various audio filters. The frequency response of the K-1 has a very gentle slope on the high side and, on the wide settings is somewhat ragged to boot. Rod, N0RC, had some good spectrograms on his web site that demonstrate this quite vividly. I think the extraneous bumps on the high side are due to IMD in the audio output. An audio filter, either analog or DSP cleans these up very nicely, and makes a dramatic difference both to the ear and the spectrum analyzer. Your mileage may vary, but a good audio filter is a useful adjunct to nearly every receiver, assuming, of course, that good narrow IF filters have already been fitted. Selectivity early in the receive chain is preferable due to potential non linearity problems. But if the early stages have been taken care of, audio filters can be of great utility. - Dr. Megacycle KK6MC/5 ______________________ James R. Duffey KK6MC/5 Cedar Crest NM 87009 DM65 ++++++++++++++++++ From: "David Gropper" To: "James R. Duffey" , Cc: Subject: Re: [Elecraft] K2 with DSP, big NO NO! Date: Tue, 25 Mar 2003 07:46:57 -0800 Dear Dr. Megacycle James - My humble opinions are in line... Just playing "Devils' Advocate!"" > So, if the DSP has a better frequency response than the circuits that > preceed it, the frequency of the whole will be improved by the addition of a > DSP. If the frequency response of the audio amp is ,say, 400-3000 Hz then the addition of an ADSP unit will not usually make it Hi-Fi. > An audio filter, either analog or DSP cleans these up very nicely, and makes a > dramatic difference both to the ear and the spectrum analyzer. Agreed... > Selectivity early in the receive chain is preferable > due to potential non linearity problems. But if the early stages have been > taken care of, audio filters can be of great utility. Well said !! Addendum: However, IMHO, the utility of putting something like the SGC ADSP2 unit into a K2 (I don't know about a K1) is the ability to 'notch' out the heterodynes, removes 'crashes', 'clicks', etc.. and generally decrease the harshness on the ears.. there is very little, if any, artifacting from that unit. I have the (possible) advantage of being able to put my K2 and my SGC-2020 ADSP side by side on the same (poor) antennas and compare them under real life conditions as opposed to being in the ARRL lab!! With my far from ideal operating conditions there are definitely times when I switch to the SGC-2020 although the K2 is the favorite child :-) The poor old ICOM 746's built in DSP cannot compete!! I use the Am-Comm ClearSpeech with that... but the ClearSpeech produces to many artifacts.. "Steps down from the dais, bows, takes tomato in face !!" Dave KK7SS K2 #3003 ++++++++++++++++++++ From: "Lyle Johnson" To: Cc: "self" Date: Tue, 25 Mar 2003 14:57:14 -0800 Subject: [Elecraft] K2 with DSP, big YES YES! Hmm, I've looked over the posting rules, and with the recent discussion about the SGC ADSP2 module and hacking it into the K2, I thought there might be some interest in seeing another way to mount a DSP module inside a K2... http://www.fidalgo.net/~wa7gxd/kdsp2.html Enjoy! 73, Lyle KK7P +++++++++++++++++++++ Date: Tue, 25 Mar 2003 22:22:46 -0700 From: "James R. Duffey" Subject: Re: [Elecraft] K2 with DSP, big NO NO! To: David Gropper , daniel-k2 at juno.com Cc: elecraft at mailman.qth.net David - I agree with your comments. By better frequency response, I meant narrower bandwidth and steeper skirts. Not Hi-Fi. :^) I agree with your comments. I think that most SSB operators would be quite pleased with the addition of an automatic notch filter either outboard or internal. - Dr. Megacycle KK6MC/5 ______________________ James R. Duffey KK6MC/5 Cedar Crest NM 87009 DM65 +++++++++++++++++++++++ Date: Wed, 26 Mar 2003 07:10:31 -0500 From: Kotarak Subject: Re: [Elecraft] K2 with DSP, big YES YES! To: la3za at qsl.net, 'Lyle Johnson' Cc: elecraft at mailman.qth.net Well, SGC should look at this page to see (learn) how the things should be done the right way. Very elegant solution. Good job on the design Lyle! This is the kind of DSP i wouldnt hesitate to build and try in my K2. I can't speak for Lyle, but looking at the scematics i think he uses an Atmel chip with a firmware to access the K2's AuxBus and emulate the AFIL interface, so the things are transperant for the K2 and K2 acts as if a AFIL module is installed. I might be wrong of course! Very cool and professionally done. 73s KB1FZA ++++++++++++++++++++ From: "Robert Parker" To: "Elecraft" Date: Wed, 26 Mar 2003 22:23:46 -0500 Subject: [Elecraft] Effective add-on for your K1 or K2 Hi All; I recently purchased a kit called the SCAF-1. I built it in 4hrs and tried it out with my K2 and K1 and am really impressed with the results. The SCAF-1 is essentially a variable audio filter similar to the internal audio board option in the K2 which I also have installed in my K2. The Elecraft Audio option is truly a great thing to have and is very effective. The only drawback is that it's not adjustable. The SCAF-1 is an outboard audio filter that has a pot for adjusting the BW of the audio with at least 90dB skirts. I use it with or without the Elecraft audio option depending on the noise level. The SCAF-1 virtually eliminates white noise and most hetrodynes as well as narrows the BW of the signal to eliminate interfering stations in the same passband. Super on CW! There was an older version of this called the Super SCAF and although very effective, used BCD wheels making quick adjustment more of a chore. The SCAF-1 is as easy as turning the pot to your desired BW. It's extremely sharp and IMHO complements not only the Elecraft Audio options but the top cover is close in color to the K2. My recommendation is to get the Elecraft audio filter option and build or buy prebuilt the SCAF-1. This is really an effective combination. For a non-DSP filter, it's really hard to beat. I have no affiliation with this company other than being a happy customer and just commenting on my experience. Here is the website to read more if interested: http://www.idiompress.com/scaf-1.html Regards, Robert VE3RPF ++++++++++++++++++ From: "Jerry T Dowell" To: Date: Thu, 27 Mar 2003 05:28:48 -0800 Subject: [Elecraft] Re: Effective add-on for your K1 or K2 It should be noted that the SCAF-1 is a low-pass filter with variable cut-off frequency, not a bandpass filter. The minimum bandpass is 450 Hz, since that is the minimum cut-off frequency. That is not to say that it will not be effective. I use a Timewave DSP-599zx occasionally with my K2. It works well in many types of tough QRM/QRN conditions. It also has the advantage of flexibility and offers RTTY, etc. IMHO, however, DSP is not all it is touted to be, at least insofar as CW is concerned. Dynamic range can be a problem with all DSP. Noise reduction seems to be good on SSB, but not always useful on CW. However, if one can get a unit for a decent price used, it might be a better choice than the SGC or other DSP units looming on the horizon for the K2. Jerry AI6L +++++++++++++++++++ From: To: "Jerry T Dowell" , Date: Thu, 27 Mar 2003 10:03:19 -0500 Subject: [Elecraft] Effective add-on for your K1 or K2 Hi folks - Another unit that I think works fairly well is the Clearspeech base unit (not the speaker unit). It's relatively small and seems to have a good algorithm - however, its primary benefit is on SSB - does not work so well on cw. I have a huge amount of respect for Idiom Press's Logikey as well as his service - great folks. On that alone I will order the SCAF filter just to see how it does. The old Index Labs QRP+ used a SCAF - it was interesting, but very hard to tell it's usefulness when it's on a rig like the QRP+. 73/Tim NZ7C +++++++++++++++++ From: "Wallace, Andy" To: "'Lyle Johnson'" , elecraft at mailman.qth.net Date: Thu, 27 Mar 2003 12:26:53 -0500 Subject: [Elecraft] KK7P KDSP2 module > -----Original Message----- > From: Lyle Johnson [mailto:wa7gxd at fidalgo.net] > > Hmm, I've looked over the posting rules, In my view, there should be no problem posting this sort of announcement. You're not taking money AWAY from Elecraft with your product, because to use it someone needs a K2...! > and with the recent > discussion about the SGC ADSP2 module and hacking it into the K2, I > thought there might be some interest in seeing another way to mount a DSP module > inside a K2... > > http://www.fidalgo.net/~wa7gxd/kdsp2.html Beautiful job, Lyle. I'm assuming that you were able to reverse engineer the AUXBUS commands to do this -- not impossible, given a logic analyzer and a KAF2 to pass commands back and forth to monitor. No need to make that public to anyone, and I agree completely with Elecraft's reasons for not making it public. It will be interesting to hear further details as things progress. I bet you got a pile of emails about this. I am sure a lot of people who were on the fence about a K2 because it lacked DSP would consider this very exciting news. The list of birdies was enlightening. You may want to do some sort of spectrum analyzer trace on the audio out to see how that is affected, using a signal or sweep generator, too. Bravo. Andy +++++++++++++++++ From: "Guy Olinger, K2AV" To: "Wallace, Andy" , "'Lyle Johnson'" , elecraft at mailman.qth.net Subject: Re: [Elecraft] KK7P KDSP2 module Date: Thu, 27 Mar 2003 13:08:29 -0500 Probably the biggest reason for keeping the aux bus tightly held, is that if it is published, then it has to be maintained. If company x designs a product on the aux bus protocol being just so, then it has a grievance if elecraft changes it. As it stands now, if elecraft wants to change it, it is a matter of its own firmware, and upgrades that its own customers apply. Anyone who reverse engineers it and bases a product on it does so at their own risk, and elecraft does not have to worry about keeping them happy. Based on their excellent track record, I'd want them to keep the new stuff in-house (and the revenue to keep them perking along). They decide themselves to publish it, then fine. Just my .02 & 73, Guy, K2AV. ++++++++++++++++++ From: "Mike" To: Cc: Date: Sat, 29 Mar 2003 07:36:41 -0600 Subject: [Elecraft] Re: Effective add-on for your K1 or K2 > I use a Timewave DSP-599zx occasionally with my K2. It works well in = many > types of tough QRM/QRN conditions. -- snip -- > > Jerry AI6L > > I too use a 599ZX with my K2 and I guess the operative words are 'your = mileage may vary' (YMMV) since I find it extremely useful for all modes, = CW, SSB & digital. Does your Timewave have the latest (5.0) firmware? I cannot begin to list all the features/capabilities of this unit here = but suffice to say I am so impressed with it I have two of them (even = though a single DSP-599ZX has 2 independent A & B in/out channels to = support two seperate rigs). For a digital audio DSP unit my opinion is = it surpasses the capabilities of any other outboard DSP I've used (and = seen) by at least a factor of 10. YMMV ;)=20 My only 'complaint' is it's almost TOO sophisticated & feature rich. I'd = venture to say it probably requires more time/effort to master all the = things this device is capable of providing than the rig it supports. Well, that and its current consumption (1+ amp) which is not an issue in = the 'shack' but precludes K2 portable/field/batt operation. That's why = I'm so interested in the progress of KK7P's internal KDSP2 DSP Module. 73, Mike K5PU +++++++++++++++++++ From: "Andrew Catanzaro" To: Date: Thu, 8 May 2003 06:41:04 -0500 Subject: [Elecraft] DSP value? All those people who write about the limited utility of an audio DSP unit compared to the KAF2 have a point. I've had Timewave's best DSP filter hung on the output of my K2 and the only DSP function I've used is the autonotch about five times since October. The analog filter in the K2 is more than adequate for huge CW pileups where I have been the DX (PJ4/W9NJY), and I haven't found digital noise reduction to improve intelligibility on SSB. I have my K2 SSB filters set with different IF bandpass frequencies so it operates like passband tuning, and that arrangement works well. The word "digital" in ham radio is like the word "laser" in medicine. It's a marketing tool that sells products and services. The best thing about the Timewave is that it accepts inputs from two rigs and outputs tons of audio to one speaker and the headphone jack all at the same time. I never have to worry about wearing out the headphone jack on the K2. 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. It's a great filter that doesn't ring, and there's no digital bandwidth that's narrower that's more useful! Andy W9NJY Milwaukee WI +++++++++++++++++ Date: Fri, 09 May 2003 19:07:28 -0600 From: "James R. Duffey" To: elecraft at mailman.qth.net, aa4lr at arrl.net Subject: [Elecraft] Quantization noise and DSPs Bill - I have one of the original W9GR DSPs. In my experience, it is not possible to hear the quantization noise of the analog to digital (A/D) converter. There are other digital artifacts though, some clock feed throug= h is noticeble on very quiet bands and the artifacts from the noise reduction and voice enhancement are also evident in an A/B comaprison. The noise introduced by quantization in a perfect analog to digital converter is the least siginificant bit (lsb) divided by the square root of=A012. In practical use without AGC, one tends to put the noise level at several bits, which is far above the quantization noise introduced by the A/D converter.=20 8 bits are enough dynamic range for CW signals, but without AGC, it does require some riding of the volume control. I also have DSPs with 12, 16, an= d 24 bit A/Ds as well, some with AGC, but only the 24 bit DSP can ignore the volume control.=20 All in all I have more audio filters than I can recall; collecting them is = a bad habit of mine. My favorite CW filter is an analog one, the DaTong FL-3. My favorite DSP for CW is made by Zim, VK3GJZ, with 24 bit CODEC it sounds like an analog filter with no detectable digital artifacts. See: < for more information on Zim's filter. My favorite overall DSP is the Timewave 59+, but the DaTong is a close second. In my experience, DSP is no= t of as great a utility in CW as it is for voice or data. I have not noticed the delay mentioned by Andrew on the 59+ or Zim's filter, but I do not operate high speed CW except on contests. I have noticed it on the NIR-12 though, which was unexpected. I have not seen or heard the K-2 DSP, so I cannot comment on it. I expect that its greatest utility will probably be to eliminate heterodynes on SSB and as a filter for data signals. I have heard and used the K2 with the KAF2, which is a good sounding combination on CW, even at the narrow setting. I suspect that most K-2 CW only ops will think the DSP overkill. Now, if you operate SSB on 40 M after dark, the DSP will be a godsend. - Dr= . Megacycle KK6MC/5 ______________________ James R. Duffey KK6MC/5 Cedar Crest NM 87009 DM65 +++++++++++++++++ Reply-To: From: "Jerry Hancock" To: Subject: RE: [Elecraft] Quantization noise and DSPs Date: Sat, 10 May 2003 09:26:17 -0700 For those interested in DSP, the following link from Analog Devices is a very good primer on the technology: http://www.analog.com/Analog_Root/static/technology/dsp/beginnersGuide/intro duction.html In reference to quantization noise, there are more serious limiting factors once you reach a true 16bits in the codec. External noise, grounding, cabling, resistive thermal noise, external audio transducers, etc all come into play. There are other papers on Analog's website that discuss DSP limitations like 24 vs 16 bit codecs and 32bit vs 24bit processors (internal floating point significant digits). I also found some papers on Dolby SR noise reduction that demonstrate wider dynamic range (in recording) using analog tape than DAT 48khz 16bit. If you have a copy of MATLAB, the filter design tool enables you to graph the quantization effects of 16, 24 etc. bits. Jerry Hancock, KG6KGP -----Original Message----- From: elecraft-admin at mailman.qth.net [mailto:elecraft-admin at mailman.qth.net]On Behalf Of James R. Duffey Sent: Friday, May 09, 2003 6:07 PM To: elecraft at mailman.qth.net; aa4lr at arrl.net Subject: [Elecraft] Quantization noise and DSPs Bill - I have one of the original W9GR DSPs. In my experience, it is not possible to hear the quantization noise of the analog to digital (A/D) converter. There are other digital artifacts though, some clock feed through is noticeble on very quiet bands and the artifacts from the noise reduction and voice enhancement are also evident in an A/B comaprison. -- snip -- I suspect that most K-2 CW only ops will think the DSP overkill. Now, if you operate SSB on 40 M after dark, the DSP will be a godsend. - Dr. Megacycle KK6MC/5 ______________________ James R. Duffey KK6MC/5 Cedar Crest NM 87009 DM65 +++++++++++++++++ From: "Lyle Johnson" To: Subject: RE: [Elecraft] Quantization noise and DSPs Date: Sun, 11 May 2003 21:25:38 -0700 Hello Jerry! > ...In reference to quantization noise, there are > more serious limiting factors once you reach a > true 16bits in the codec. External noise, grounding, > cabling, resistive thermal noise, external audio > transducers, etc all come into play. It may not be clear in the photographs, but great care was taken in the PCB layout of the KDSP2 to divide power and signal ground at the location where the connectors plug into the K2 control board. The DSPx module also has carefully isolated analog and digital sections including separate analog and digital section voltage regulators, and grounding that ties analog and digital together at the CODEC chip. The results of this care are such that, in the DSP-10 Software Defined Radio project, the DSPx module has about 10 dB better analog-to-digital dynamic range performance (primarily due to reduced noise floor) over the Analog Devices EZ Kit Lite product around which the radio was originally designed! > ...If you have a copy of MATLAB, the filter design > tool enables you to graph the quantization effects > of 16, 24 etc. bits. You can also download a free evaluation copy of scopeFIR from www.iowegian.com, design a filter and then look at the quantization effects. Yes, the commercial version of this product was used to design the filters used in the KDSP2's DSP code. No, I have no pecuniary interest in Iowegian. 73, Lyle KK7P +++++++++++++++ Date: Thu, 22 May 2003 07:45:24 -0700 From: Phil Wheeler Organization: Outstanding To: Kevin Cozens Cc: elecraft at mailman.qth.net Subject: Re: [Elecraft] KDSP is done Kevin Cozens wrote: > At 09:34 PM 05/21/2003 -0400, gwlillie wrote: > >> Just finished dsp and everything works fine. No problems so far and >> it was a perfect fit. Noise reduction is great but as you know it >> will affect rec audio in the form of distortion. Its a little like >> having your speaker under water. > > > Can you please clarify your statements about the KDSP and it causing > distortion in the audio. Are you speaking from experience of using the > KDSP in noise reduction mode or are you speculating about expected > distortion based on other inexpensive DSP units? > > I have used a JPS Communications NIR-10 DSP unit for several years. It > was an expensive purchase at one of my trips to Dayton. On a band like > 10m or 15m where band noise is fairly low, the NIR-10 in noise > reduction mode would almost make you think the band was dead as it > would take out all the background noise. When you tuned in a signal, > it would just pop right out at you. It was a pleasure to work stations > with little to no background noise and there was no audio distortion. > I would expect the KDSP2 would behave in a similar fashion. PMFJI, Kevin. I do not yet have a KDSP (couldn't make it to Dayton, alas .. so I am waiting for mine to arrive in late June or so). But I have used numerous commercial audio DSP units such as the JPS NIR-12, DSP in my TS-570DG, Timewave 599ZX (or whatever that model is), etc. I've found all to produce artifacts on an SSB audio signal, including the NIR-12 (which is an improved NIR-10). But in most cases the overall result was improved intelligibility and reduced noise. The "having your speaker under water" may be a good characterization. of the artifacts, particularly with aggressive processing; I've always thought of it as a "watery signal". It seems inevitable that shoving any signal through a filter will "distort" it by removing some part of it. But usually you can temper that by choosing how aggressive to make the digital signal processing. Based on the technical discussion ("Design Notes"?) written by Lyle and posted at the website, I expect the KDSP to outshine any I've used in the past, because of the way the design is integrated into the K2 and the excellent (and adjustable) xtal filters ahead of the DSP. 73, Phil +++++++++++++++++++ From: WJuergens at t-online.de (Wolf-Ruediger Juergens) Organization: privat To: elecraft at mailman.qth.net Date: Thu, 22 May 2003 20:27:28 +0200 Subject: [Elecraft] If you cant wait for the KDSP2... Hi, For all OM's waiting for the KDSP2 shipped, like me ;-), there is a toy. You can try the DSP software from JE3HHT, Makoto Mori. His PC DSP program has similar features like the KDSP2, cw filter, noisereduction and so on. You can download the software on http://www.qsl.net/mmhamsoft/dsp/index.htm I dont know how it really compares to the KDSP2 but I assume that there is not so much difference. 72 de Wolf, DL2WRJ ++++++++++++++++++ From: "Lyle Johnson" To: "Elecraft" Subject: RE: [Elecraft] DSP question Date: Thu, 22 May 2003 11:48:13 -0700 Hello Vic! > In Lyle's article on the design of the Elecraft DSP, he says "...with > high speed CW the shorter delay may be beneficial." > > Lyle, could you expand on this? What do you hear different as a result > of more or less delay in the filter? There are two aspects of the delay that are of interest: the actual delay, and the time the signal "lives" in the filter. Actual Delay Here, we are interested in how long it takes before you hear the signal. If there is a delay of 50 mSec, for example, then it would take an additional 50 mSec after you have received the dit or dah before you begin to hear it. This is the same as being another 9,300 miles away from the sending station if you think of it in terms of propagation delay. This may affect things if you are doing fast break-in. Or it may not :-) The other issue with delay is hearing your own sidetone. In the case of an external DSP unit, you have to run a keying line to bypass the DSP so your sidetone isn't delayed. Otherwise, your sync between key/paddle and ears gets messed up really fast! The KDSP2 doesn't have this problem due to its method of integration in the radio audio path -- the sidetone bypasses the DSP completely and is injected directly into the LM380 audio amplifier on the K2 control board. Time in Filter The type of filter used in most DSPs, including the KDSP2, is a so-called FIR filter. This type of filter can't oscillate, and has many advantages over feedback-type filters, such as common op-amp based filters. The length of the filter, or number of taps and the sampling rate all play a part in determining how long a signal is in the filter. This gives rise to effects like ringing. In designing the KDSP2, I set the filter lengths to very long and determined how good the filter would be. I then took into account real-world limits, like "coefficient quantization" and looked at how short I could make the filter and achieve the same practical result. The net result is that the filters in the KDSP2 are shorter than found in many external boxes, yet achieve the same real-world results. In the KDSP2, the filters are 128 taps and sampled at a rate of 8 kHz, so the "time to live" is 16 mSec. The peak effect of the signal in the filter occurs at 8 mSec, and would be normally specified as an 8 mSec delay. 73, Lyle KK7P +++++++++++++++ Date: Sun, 25 May 2003 13:56:23 -0700 To: elecraft at mailman.qth.net From: Eric Manning Subject: [Elecraft] JE3HHT FREE software DSP versus the Kdsp2 I downloaded the JE3HHT dsp freeware recently mentioned on this list, and ran it in my Sony Picturebook. The audio from my K2 goes to the Picturebook sound card and I listen to the computer's audio output, the computer running the JE3HHT software acting as a dsp filter. Good news: 1] free 2] VERY effective -- suppresses background [thermal] noise like magic, provides nice rectangular filters. Bad news: 1] It's completely unsuitable for CW operation, because the filter adds noticeable delay to the audio signal path, INCLUDING the transmit sidetone. I cannot send CW when I hear the sidetone only after such a delay. Several OMs I worked using the freeware during the WPX think I'm drunk, or a lid, or both. [The kdsp2 avoids this problem, by injecting sidetone AFTER the filter delay.] 2] The transmeta cpu in my picturebook laptop does not have the necessary oomph, so the audio is interrupted frequently by cpu overload. The freeware might be marginally OK for SSB-only use with a faster cpu, but I doubt it. SO, by all means play with the JE3HHT dsp [www.qsl.net/mmhamsoft/dsp/index.htm ] while you're waiting for your kdsp2, but forget about saving $$ by using it instead of the kdsp2. [JE3HHT says the same thing in his user's guide .] -- Eric Manning VA7DZ VE3DPV K2 #2561 "Pauline" +++++++++++++++ From: "Bob Tellefsen" To: "Elecraft Mail List" Date: Mon, 26 May 2003 08:48:29 -0700 Subject: [Elecraft] QEX DSP articles Lyle mentioned the QEX series on DSP. I found a place where all the articles in the series can be downloaded for free. It is http://www.flex-radio.com/ then click on the SDR Articles menu selection. 73, Bob N6WG +++++++++++++++