K3: honest question re Audio Peak Filter
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K3: honest question re Audio Peak Filter
 
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RE: Audio Peak Filter requests
A number of folks have asked for this, including some who have not commented here. Many of these guys obviously used a "audio peak filter" before, found it useful, and now miss it. As before, I have no issues with any requests, as long as they are user-selectable as OPTIONS and not mandatory. But I have to ask why for this one. It has been my experience that one uses an audio peak filter when the IF filtering is inadequate...it is "another layer" of support (rejecting "unwanted" signals). But hey guys...the stock K3 goes down to a 50hz bandwidth...at IF and AF (if I understand the DSP correctly). Fifty HERTZ! I think that is a just as narrow (if not much narrower) and with as steep skirts (if not steeper) than you will ever find on the Audio Peak Filtering on any past or current radio. Not only can you narrow down the DSPs to 50hz, but you can also set the "pitch" to whatever you like. Doesn't that do the same thing (only better)? QUESTIONS: Are you sure that you actually need this? Have you tried the method cited above? Why/how would an audio peak filter be "better" or a further enhancement? Thanks and Happy New Year! de Doug KR2Q PS...recently I posed another such comment on a different topic and I got some very good answers which taught me at least one new trick...so this is definitely not a sarcastic question. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3: honest question re Audio Peak Filter
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______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3: honest question re Audio Peak Filter
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In reply to this post by DOUGLAS ZWIEBEL
Sorry for the seemingly blank post...have changed the mail so it is plain text instead of
HTML...let's see if this makes it through this time... Doug -- I use it all the time on my FT-1000D. If you're listening to a weak signal, you may or may not have it centered in the passband where when you reduce the bandwidth to 50 hz you still hear the signal. Yes, you can retune but that is an additional step... Also with an APF you may choose to peak the audio at a pitch different from what you typically use. Most people typically set the pitch on the K3 for 500 - 600 hz and forget it...but sometimes -- especially on weak signal, low band stuff -- you may want to listen to a really low tone which -- because of QRM or because it just happens to be more intelligible at the specific time you're listening. Yes, you can change the pitch and retune -- but all require more steps...when you may have a short window of opportunity on 160 meters...It may be just my personal preference...but it I think it is "doable" and could be made "software optional" for those who don't want it or prefer to operate in a different manner. 73 de Greg-N4CC On Thu Dec 31 11:24 , DOUGLAS ZWIEBEL sent: >RE: Audio Peak Filter requests > >A number of folks have asked for this, including some who have not >commented here. Many of these guys obviously used a "audio peak >filter" before, found it useful, and now miss it. > >As before, I have no issues with any requests, as long as they are >user-selectable as OPTIONS and not mandatory. > >But I have to ask why for this one. It has been my experience that >one uses an audio peak filter when the IF filtering is inadequate...it >is "another layer" of support (rejecting "unwanted" signals). But hey >guys...the stock K3 goes down to a 50hz bandwidth...at IF and AF (if I >understand the DSP correctly). Fifty HERTZ! > >I think that is a just as narrow (if not much narrower) and with as >steep skirts (if not steeper) than you will ever find on the Audio >Peak Filtering on any past or current radio. > >Not only can you narrow down the DSPs to 50hz, but you can also set >the "pitch" to whatever you like. Doesn't that do the same thing >(only better)? > >QUESTIONS: Are you sure that you actually need this? Have you tried >the method cited above? Why/how would an audio peak filter be >"better" or a further enhancement? > >Thanks and Happy New Year! >de Doug KR2Q >PS...recently I posed another such comment on a different topic and I >got some very good answers which taught me at least one new trick...so >this is definitely not a sarcastic question. >______________________________________________________________ >Elecraft mailing list >Home: http://mailman.qth.net/mailman/listinfo/elecraft >Help: http://mailman.qth.net/mmfaq.htm >Post: [hidden email]','','','')">[hidden email] > >This list hosted by: http://www.qsl.net >Please help support this email list: http://www.qsl.net/donate.html ---- Msg sent via CableONE.net MyMail - http://www.cableone.net ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3: honest question re Audio Peak Filter
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In reply to this post by DOUGLAS ZWIEBEL
I concur 100%. I have a pair of Datong FL-3 audio filters that I used for years to give me peak filtering for CW and RTTY. Fabulous units, among the best audio filters ever made and much needed in the old days when I used analog JRC and Kenwood radios with IF filters no narrower than 500 Hz. Since getting the K3 they've been in the closet.
If the K3 automatically matches the AF and IF passbands, what would be the purpose or advantage of having manual control over this function? Maybe I'm missing something, too? 73 & HNY, Paul WW2PT
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Re: K3: honest question re Audio Peak Filter
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It works like this....
After filtering the cw signal down to 50hz and you kick in an audio filter that has unity gain, no difference is noticed and you put the AF filter back in the closet. After filtering the cw signal down to 50hz and you kick in an audio filter that has 10db or gain, your jaw drops, your eyes glaze over and you immediately start slobbering about how signals POP OUT OF THE NOISE. Steve N4LQ [hidden email] ----- Original Message ----- From: "Paul - WW2PT" <[hidden email]> To: <[hidden email]> Sent: Thursday, December 31, 2009 1:55 PM Subject: Re: [Elecraft] K3: honest question re Audio Peak Filter > > I concur 100%. I have a pair of Datong FL-3 audio filters that I used for > years to give me peak filtering for CW and RTTY. Fabulous units, among the > best audio filters ever made and much needed in the old days when I used > analog JRC and Kenwood radios with IF filters no narrower than 500 Hz. > Since > getting the K3 they've been in the closet. > > If the K3 automatically matches the AF and IF passbands, what would be the > purpose or advantage of having manual control over this function? > > Maybe I'm missing something, too? > > 73 & HNY, > Paul WW2PT > > > > DOUGLAS ZWIEBEL wrote: >> >> But I have to ask why for this one. It has been my experience that >> one uses an audio peak filter when the IF filtering is inadequate...it >> is "another layer" of support (rejecting "unwanted" signals). But hey >> guys...the stock K3 goes down to a 50hz bandwidth...at IF and AF (if I >> understand the DSP correctly). Fifty HERTZ! >> >> I think that is a just as narrow (if not much narrower) and with as >> steep skirts (if not steeper) than you will ever find on the Audio >> Peak Filtering on any past or current radio. >> >> Not only can you narrow down the DSPs to 50hz, but you can also set >> the "pitch" to whatever you like. Doesn't that do the same thing >> (only better)? >> >> QUESTIONS: Are you sure that you actually need this? Have you tried >> the method cited above? Why/how would an audio peak filter be >> "better" or a further enhancement? >> > > -- > View this message in context: > http://n2.nabble.com/K3-honest-question-re-Audio-Peak-Filter-tp4237359p4237481.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html -------------------------------------------------------------------------------- No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.725 / Virus Database: 270.14.123/2595 - Release Date: 12/31/09 03:52:00 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3: honest question re Audio Peak Filter
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I'm with you so far, I'm all about the slobbering.... but if the AF and IF bandwidths are already identical, a 10dB boost in audio gain is pretty much the same thing as simply turning up the volume, no? Unless the AF bandwidth is even tighter than the IF bandwidth... maybe that's how the APF works in other radios?
Paul WW2PT
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Re: K3: honest question re Audio Peak Filter
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In reply to this post by DOUGLAS ZWIEBEL
Indeed!, Doug got this right.
In a previous msg I did say why not but thinking more about it, after reading this, I will agree that it´s not needed. Too many darn functions to fiddle with anyway, enough is enough. As I stated in a previous message, fix the flaws and get done with it, the K3 is a very nice product as is but a few bits and pieces needs fixing. Anyway,......happy new year / Jim SM2EKM ................................................ DOUGLAS ZWIEBEL wrote: > RE: Audio Peak Filter requests > > A number of folks have asked for this, including some who have not > commented here. Many of these guys obviously used a "audio peak > filter" before, found it useful, and now miss it. > > As before, I have no issues with any requests, as long as they are > user-selectable as OPTIONS and not mandatory. > > But I have to ask why for this one. It has been my experience that > one uses an audio peak filter when the IF filtering is inadequate...it > is "another layer" of support (rejecting "unwanted" signals). But hey > guys...the stock K3 goes down to a 50hz bandwidth...at IF and AF (if I > understand the DSP correctly). Fifty HERTZ! > > I think that is a just as narrow (if not much narrower) and with as > steep skirts (if not steeper) than you will ever find on the Audio > Peak Filtering on any past or current radio. > > Not only can you narrow down the DSPs to 50hz, but you can also set > the "pitch" to whatever you like. Doesn't that do the same thing > (only better)? > > QUESTIONS: Are you sure that you actually need this? Have you tried > the method cited above? Why/how would an audio peak filter be > "better" or a further enhancement? > > Thanks and Happy New Year! > de Doug KR2Q > PS...recently I posed another such comment on a different topic and I > got some very good answers which taught me at least one new trick...so > this is definitely not a sarcastic question. > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3: honest question re Audio Peak Filter
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In reply to this post by Paul - WW2PT
Exactly! But many are dazzled at how one button can make things louder.
Steve N4LQ [hidden email] ----- Original Message ----- From: "Paul - WW2PT" <[hidden email]> To: <[hidden email]> Sent: Thursday, December 31, 2009 2:18 PM Subject: Re: [Elecraft] K3: honest question re Audio Peak Filter > > I'm with you so far, I'm all about the slobbering.... but if the AF and IF > bandwidths are already identical, a 10dB boost in audio gain is pretty > much > the same thing as simply turning up the volume, no? Unless the AF > bandwidth > is even tighter than the IF bandwidth... maybe that's how the APF works in > other radios? > > Paul WW2PT > > > > Steve Ellington wrote: >> >> After filtering the cw signal down to 50hz and you kick in an audio >> filter >> that has 10db or gain, your jaw drops, your eyes glaze over and you >> immediately start slobbering about how signals POP OUT OF THE NOISE. >> > > -- > View this message in context: > http://n2.nabble.com/K3-honest-question-re-Audio-Peak-Filter-tp4237359p4237558.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html -------------------------------------------------------------------------------- No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.725 / Virus Database: 270.14.123/2595 - Release Date: 12/31/09 03:52:00 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Steve Ellington
I've never had an FT-1000D but I know some who do swear by the APF. We had a previous thread about this which resulted in a circuit simulation analysis by Al W6LX. This is using the **EXACT** circuit in the FT-1000D which I found sent to Al. Al's analysis is below (in PowerPoint): http://sites.google.com/site/ft1000apf/w6lxanalysisoftheapfcircuitintheft-1000 You can see the APF has a 6 dB BW of ~50 Hz and ~8.5 dB gain. So how do I emulate that in the K3? I have both the 500 Hz 8-pole and 200 Hz 5-pole filters in my main RX. Normally I set the filter gain to 1 dB for the 500 and 2 dB for the 200, based on Wayne's recommendations. However, you can emulate the APF by setting the gain for the 200 Hz to 8 dB. Now my rig transitions from 1 dB to 8 dB gain as I go to 200 Hz BW or lower, and I have ~7 dB gain over the 500 Hz filter at DSP BW = 50 Hz, which is very close to the FT-1000D APF's characteristics. By pure coincidence I had my rig set to 1822.5 as I was doing this. Lo and behold, at 2:45 PM here I just heard G3FPQ very weak here at 2.5 hours before sunset. Indeed this emulated APF did seem to help, but I'm going to do much more listening before I draw any conclusions. If you have a 200 Hz filter, you might want to give this a try. 73, Bill |
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An APF is a tool that I would like to see on the K3. I liked it on my FT1000D.
Different people find different tools useful. Here's three K3 tools that I have not found useful. The noise blanker, the notch filter, and the AFX feature. But they are tools that might come in handy some day and I'm glad I have them. I'd like to have the APF as well. 73, Mike K2MK from previous posts After filtering the cw signal down to 50hz and you kick in an audio filter that has 10db or gain, your jaw drops, your eyes glaze over and you immediately start slobbering about how signals POP OUT OF THE NOISE. I've never had an FT-1000D but I know some who do swear by the APF. |
Re: K3: honest question re Audio Peak Filter
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In reply to this post by Steve Ellington
AMEN. what APF does is put rare DX in my logbook that most of the
others sit there and cannot pull the callsign out of the noise. I call it receivability, you can have the best specs on the radio in the world but if you cannot pull that weak one out and copy the call your just second class. I can say over and over that my K3 is by far the best radio I own, but it cannot pull the weakest signals out of the noise that the 1000D APF can. So when I have to revert back to the 90s radio to get the job done specs mean nothing., if you never DX on 160 or even other bands at the noise level you will never need APF. Different tools for different uses, no one gripes when you guys ask for scrolling power up banners, now that really helps the K3 receive better eh? Merv KH7C > It works like this.... > > After filtering the cw signal down to 50hz and you kick in an audio filter > that has unity gain, no difference is noticed and you put the AF filter back > in the closet. > > After filtering the cw signal down to 50hz and you kick in an audio filter > that has 10db or gain, your jaw drops, your eyes glaze over and you > immediately start slobbering about how signals POP OUT OF THE NOISE. > > Steve > N4LQ > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3: honest question re Audio Peak Filter
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In reply to this post by Paul - WW2PT
The audio bandwidth is extremely narrow, centered on the tone freq
or some other you set it for, but its 10db of gain at essentially one freq. > I'm with you so far, I'm all about the slobbering.... but if the AF and IF > bandwidths are already identical, a 10dB boost in audio gain is pretty much > the same thing as simply turning up the volume, no? Unless the AF bandwidth > is even tighter than the IF bandwidth... maybe that's how the APF works in > other radios? > > Paul WW2PT > > > > Steve Ellington wrote: > >> After filtering the cw signal down to 50hz and you kick in an audio filter >> that has 10db or gain, your jaw drops, your eyes glaze over and you >> immediately start slobbering about how signals POP OUT OF THE NOISE. >> >> > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3: honest question re Audio Peak Filter
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In reply to this post by Mike K2MK
Okay - hear a simulation of the effect of K3 APF for yourself:
http://n1eu.com/k3/rz0af_apf.wav This is a stereo diversity recording of a fairly weak RZ0AF on a fairly quiet topband night. I switch the APF in and out - it's centered on the 400hz sidetone frequency and is 50hz wide and +10dB. The raw receive selectivity is 250-300hz before applying APF. You'll hear "N1EU" with no APF and then with APF. Then you'll hear "GM UR 579" without and with APF. Just one experiment, but APF seems like it could be a useful tool to have in the dx'ing arsenal. 73/HNY, Barry N1EU
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Re: K3: honest question re Audio Peak Filter
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In reply to this post by Bill W4ZV
Bill W4ZV wrote:
> Steve Ellington wrote: > >> After filtering the cw signal down to 50hz and you kick in an audio filter >> that has 10db or gain, your jaw drops, your eyes glaze over and you >> immediately start slobbering about how signals POP OUT OF THE NOISE. >> >> > > I've never had an FT-1000D but I know some who do swear by the APF. We had > a previous thread about this which resulted in a circuit simulation analysis > by Al W6LX. This is using the **EXACT** circuit in the FT-1000D which I > found sent to Al. Al's analysis is below (in PowerPoint): > > http://sites.google.com/site/ft1000apf/w6lxanalysisoftheapfcircuitintheft-1000 > > You can see the APF has a 6 dB BW of ~50 Hz and ~8.5 dB gain. So how do I > emulate that in the K3? I have both the 500 Hz 8-pole and 200 Hz 5-pole > filters in my main RX. Normally I set the filter gain to 1 dB for the 500 > and 2 dB for the 200, based on Wayne's recommendations. However, you can > emulate the APF by setting the gain for the 200 Hz to 8 dB. Now my rig > transitions from 1 dB to 8 dB gain as I go to 200 Hz BW or lower, and I have > ~7 dB gain over the 500 Hz filter at DSP BW = 50 Hz, which is very close to > the FT-1000D APF's characteristics. > > By pure coincidence I had my rig set to 1822.5 as I was doing this. Lo and > behold, at 2:45 PM here I just heard G3FPQ very weak here at 2.5 hours > before sunset. Indeed this emulated APF did seem to help, but I'm going to > do much more listening before I draw any conclusions. If you have a 200 Hz > filter, you might want to give this a try. > > 73, Bill > use wider bandwidths you "spread" the noise level out across more spectrum and hearing is much easier, narrowing the bandwidth down that radical concentrates the noise into a small amount of audio, many times I find that there is not QRM present and with filter width of 2.1KHZ and using the APF signals really do jump out of the noise, narrowing the bandwidth creates more ringing also in the APF due to the concentration of noise at the same freq as the APF. One of those things you have to hear to put a handle on. K3 cannot in any way I have found duplicate this, and the way suggested by Elecraft is to Narrow to .05 with IIR and use the shift to center the signal perfectly in the bandpass, it boosts the signal a small amount but it is not APF and of course cannot be used at wider bandwidths. Merv KH7C > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3: honest question re Audio Peak Filter
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In reply to this post by Mike K2MK
The K3 is the first rig I've used in years that I've not run the audio thru an external audio filter. I have owned and used several, often to eliminated hiss and to peak the signal. On the K3 I've often found the AFX feature helps me to copy signals that are challenging otherwise. This morning I was listening on a noisy band to a weak signal with NR engaged and set to 3-2. I turned it off and the signal disappeared in the mud. In fact, if I'd been tuning the band without NR, I would have missed it altogether. I repeated it several times. This was a first for me.
73, Gary W7TEA <quote author="Mike K2MK"> An APF is a tool that I would like to see on the K3. I liked it on my FT1000D. Different people find different tools useful. Here's three K3 tools that I have not found useful. The noise blanker, the notch filter, and the AFX feature. But they are tools that might come in handy some day and I'm glad I have them. I'd like to have the APF as well.
73,
Gary W7TEA K3 #1001, #5763 |
Re: K3: honest question re Audio Peak Filter
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In reply to this post by Barry N1EU
I did a second experiment that gives another perspective:
http://n1eu.com/k3/ha8bt_apf.wav This time the K3 selectivity was 50hz before applying APF. The conclusion I come to after listening to this recording is by narrowing K3 bandwidth down to 50hz, you gain most of the benefit of the APF. (the APF center frequency was adjusted to match the received signal) 73, Barry N1EU
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I'm confused Barry. What do you mean "before applying APF" since the K3 does not have APF. Did you mean DUAL PB? 73, Bill |
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I've used Bill W4ZV's technique since receiving my K3 a year ago = 50 to 100Hz BW and 8db filter gain on the 200Hz filter. It's sometimes the only way I can hear DX from Interior Alaska. Otherwise, I prefer the Dual PB filter @ 400-800Hz for general CW. APF would be nice only if it were proven to be better. 73 es HNY, Gary NL7Y |
Re: K3: honest question re Audio Peak Filter
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In reply to this post by Bill W4ZV
I made recordings of K3 rx audio and then processed those recordings with filtering equivalent to an APF. I applied a 50hz wide +10dB filter centered on the cw tone. So the filtering was applied after the fact but is completely analogous with an in-line audio filter in real-time. I edited the recording to splice together pre and post APF audio to compare. 73, Barry N1EU |
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In reply to this post by Barry N1EU
Barry N1EU wrote:
> Okay - hear a simulation of the effect of K3 APF for yourself: > > http://n1eu.com/k3/rz0af_apf.wav > > This is a stereo diversity recording of a fairly weak RZ0AF on a fairly > quiet topband night. I switch the APF in and out - it's centered on the > 400hz sidetone frequency and is 50hz wide and +10dB. The raw receive > selectivity is 250-300hz before applying APF. You'll hear "N1EU" with no > APF and then with APF. Then you'll hear "GM UR 579" without and with APF. But is this any different from reducing the K3 DSP bandwidth to 50Hz and turning up the volume? -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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