Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes

2009-02-26 Thread Dick Green WC1M
I did that FT-1000MP mod and the improvement was marginal. It didn't correct
the problem of AGC "mush" in the passband with big pileups. Lots of IMD in
big contests with that radio, too.

73, Dick WC1M

> -Original Message-
> From: Bill W4ZV [mailto:btipp...@alum.mit.edu]
> Sent: Thursday, February 26, 2009 6:32 AM
> To: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes
> 
> 
> 
> 
> Jan Erik Holm wrote:
> >
> > Don Rasmussen wrote:
> >> Anyone care to take a guess as to how long an anomoly like this
> would
> >> live in any other mass produced HF transceiver?
> >>
> >> My guess - the life of the radio.
> >>
> >> Maybe the Flex guys would get to it.
> >>
> >> With Elecraft, the issue was identified on the weekend, and here it
> is
> >> Wednesday of the same week, the engineers understand the effect and
> offer
> >> test software for it.
> >>
> >> Kudos!
> >>
> > Indeed! Just one example. As I understand this problem the Yaesu
> > FT-1000MP suffers from the same (lets call it) AGC IMD. On the
> > MP I have noticed it myself and others too but it is not widely
> > written about.
> > Very glad to see that it possibly can be fixed on the K3.
> >
> >
> > 73 Jim SM2EKM
> >
> 
> Like everything else about the nasty key-click generator FT-1000MP,
> it's
> left to the customer to find and fix any problems.  Yaesu did nothing
> about
> the key clicks for at least 13 years (beginning with FT-1000D until a
> production change for the MP in 2003)...and Yaesu is now reliving
> design
> problems with the roofing filters in the FT-2000.
> 
> BTW Inrad did implement fixes for both the MP's clicks and the AGC
> problem
> (the customer must pay for all Yaesu design errors, of course):
> 
> "FT-1000MP AGC Improvement Mod
> 
> Some operators on major DX-peditions have complained about poor
> readability
> in large pile ups. From a joint effort between Inrad and some of these
> operators, we are now offering the AGC mod which improves readability
> somewhat for both CW and SSB. Details of the history is included in
> the mod
> instruction sheets.
> 
> This new mod increases the decay time, which in the FT-1000MP is so
> fast
> that weaker signals can come up to full output between dots and dashes
> (or
> speech peaks), causing poor readability in pile ups. It also uses a
> damping
> resistor to eliminate a slight over shoot. Please be aware that under
> "normal" or "average" operating conditions, this mod will make very
> little
> discernible difference."
> 
> The AGC mod is not applicable to the Mark V."
> 
> http://www.inrad.net/product.php?productid=86&cat=10&page=1
> 
> What a horrible contrast Yaesu was to my very pleasant experience with
> Elecraft!
> 
> 73,  Bill
> --
> View this message in context: http://n2.nabble.com/New-K3-Firmware%3A-
> Pileup-inspired-AGC-changes-tp2387110p2389115.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> 


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Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes

2009-02-26 Thread Jim Brown
On Thu, 26 Feb 2009 07:32:03 -0800 (PST), Wes Stewart wrote:

>But I must say that having to turn off the AGC and ride the rf gain
>control in a modern whiz-bang super-duper multi-kilobuck radio 
>seems oxymoronic to me. 

Some do like to run the radio that way (W1UE guested at my QTH for 
CW Sprint a few weeks ago and that's how he did it), but I've never 
liked what I heard with the AGC off. But I DO like what I hear when 
I properly set RF and AF gains for the band conditions, in EXACTLY 
the same way that I would set the gains in the most modern and 
sophisticated audio mix console I use to do live recording! In the 
console, I set those gains for the mic I'm using on each input, what 
instrument/voice it will be picking up, how the musician plays (or 
speaker talks), how far they will be from the mic, etc. I do this to 
optimize that mix channel for the signal that I'm feeding it. 

In the K3, I'm optimizing the signal path for the range of signals 
it is seeing. No electronic product, and no AGC, can handle an 
INFINITE range -- if we want optimum performance from the radio, we 
must set the radio's gains to match signal conditions to the optimum 
range of the radio. That's nothing more than "Electronics 101!" To 
expect otherwise is to deny the laws of physics. 

73,

Jim Brown K9YC


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Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes

2009-02-26 Thread Joe Subich, W4TV


> #  I'm seeing 5 to 6 dB of increase in meter reading between 
> no modulation and modulation peaks. I guess I'm old fashioned 
> but I thought that the AM carrier strength should set the AGC 
> level. 

It seems to me that this is exactly what one would expect.  AM 
PEP = 4 x carrier (e.g. 6 dB).  If an S-meter did not respond 
to peaks but rather responded to the "no modulation" signal level, 
it would be completely useless for CW or SSB. 

73, 

   ... Joe, W4TV 
  



> -Original Message-
> From: elecraft-boun...@mailman.qth.net 
> [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Wes Stewart
> Sent: Thursday, February 26, 2009 10:32 AM
> To: elecraft@mailman.qth.net; Jim Brown
> Subject: Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes
> 
> 
> 
> 
> --- On Wed, 2/25/09, Jim Brown  wrote:
> 
> > 
> > Someone just posted that they had trouble in pileups during the 
> > contest last weekend, but the radio worked better when they turned
> > on the 
> > attenuator and turned down the RF gain. DUH!  I learned
> > that in 1957 -- 
> > but younger operators never learned it, since modern radios
> > depend so 
> > heavily on AGC. 
> 
> Nothing personal Jim, but your post is a handy one to add to.
> 
> I've been licensed for over 50 years so I've been through all 
> of the turn off the AVC (dating myself) and ride the rf gain 
> control business.  
> 
> But I must say that having to turn off the AGC and ride the 
> rf gain control in a modern whiz-bang super-duper 
> multi-kilobuck radio seems oxymoronic to me.  Why should I 
> have to ride the gain?  I thought all of this DSP stuff was 
> supposed to be smarter than I am.  Shouldn’t the radio be 
> smart enough to know when a signal is so strong that the 
> attenuator needs to be inserted to "protect" the DSP or the 
> second mixer, for example?   
> 
> Besides the K3 AGC appears to never be "off" despite what the 
> display reports.  For example while listening to a strong AM 
> broadcast station, if I reduce the RF Gain* with the AGC on 
> so that the S-meter stops peaking# and adjust the audio gain 
> for comfortable listening and then turn the ACG off, the 
> signal practically disappears.  If the AGC was truly off then 
> there shouldn't be any change.  Adjusting the RF Gain higher 
> to bring back the signal level will also result in the 
> S-meter following the signal peaks.
> 
> Running this experiment also seems to demonstrate a problem 
> with the gain distribution in this radio.  If I reduce the RF 
> Gain to the point that the S-meter is just beginning to be 
> affected, there is a distinct reduction in the SNR.  It's 
> quite disconcerting to have a S9+50 dB, interference-free 
> signal that sounds noisy.
> 
> Comparing to my TS870 with the same signal, I can decrease 
> the gain (increase the S–meter reading) by at least 20 dB 
> without noticing any reduction in SNR.
> 
> *  RF Gain seems to be a misnomer; unless I'm mistaken 
> (always a possibility) there isn't a gain-controlled RF 
> amplifier in the radio.  The only hardware that is obviously 
> gain-controlled is the second stage in the first i-f amplifier.
> 
> #  I'm seeing 5 to 6 dB of increase in meter reading between 
> no modulation and modulation peaks. I guess I'm old fashioned 
> but I thought that the AM carrier strength should set the AGC 
> level.  This peak-reading AGC may also be a contributor to 
> the distorted audio that has been widely reported. 
> 
> Wes Stewart, N7WS
> 
> 
> 
>   
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Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes

2009-02-26 Thread Wes Stewart


--- On Wed, 2/25/09, Jim Brown  wrote:

> 
> Someone just posted that they had trouble in pileups during
> the contest 
> last weekend, but the radio worked better when they turned
> on the 
> attenuator and turned down the RF gain. DUH!  I learned
> that in 1957 -- 
> but younger operators never learned it, since modern radios
> depend so 
> heavily on AGC. 

Nothing personal Jim, but your post is a handy one to add to.

I've been licensed for over 50 years so I've been through all of the turn off 
the AVC (dating myself) and ride the rf gain control business.  

But I must say that having to turn off the AGC and ride the rf gain control in 
a modern whiz-bang super-duper multi-kilobuck radio seems oxymoronic to me.  
Why should I have to ride the gain?  I thought all of this DSP stuff was 
supposed to be smarter than I am.  Shouldn’t the radio be smart enough to know 
when a signal is so strong that the attenuator needs to be inserted to 
"protect" the DSP or the second mixer, for example?   

Besides the K3 AGC appears to never be "off" despite what the display reports.  
For example while listening to a strong AM broadcast station, if I reduce the 
RF Gain* with the AGC on so that the S-meter stops peaking# and adjust the 
audio gain for comfortable listening and then turn the ACG off, the signal 
practically disappears.  If the AGC was truly off then there shouldn't be any 
change.  Adjusting the RF Gain higher to bring back the signal level will also 
result in the S-meter following the signal peaks.

Running this experiment also seems to demonstrate a problem with the gain 
distribution in this radio.  If I reduce the RF Gain to the point that the 
S-meter is just beginning to be affected, there is a distinct reduction in the 
SNR.  It's quite disconcerting to have a S9+50 dB, interference-free signal 
that sounds noisy.

Comparing to my TS870 with the same signal, I can decrease the gain (increase 
the S–meter reading) by at least 20 dB without noticing any reduction in SNR.

*  RF Gain seems to be a misnomer; unless I'm mistaken (always a possibility) 
there isn't a gain-controlled RF amplifier in the radio.  The only hardware 
that is obviously gain-controlled is the second stage in the first i-f 
amplifier.

#  I'm seeing 5 to 6 dB of increase in meter reading between no modulation and 
modulation peaks. I guess I'm old fashioned but I thought that the AM carrier 
strength should set the AGC level.  This peak-reading AGC may also be a 
contributor to the distorted audio that has been widely reported. 

Wes Stewart, N7WS



  
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Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes

2009-02-26 Thread Bill W4ZV



Jan Erik Holm wrote:
> 
> Don Rasmussen wrote:
>> Anyone care to take a guess as to how long an anomoly like this would
>> live in any other mass produced HF transceiver?
>> 
>> My guess - the life of the radio.
>> 
>> Maybe the Flex guys would get to it. 
>> 
>> With Elecraft, the issue was identified on the weekend, and here it is
>> Wednesday of the same week, the engineers understand the effect and offer
>> test software for it. 
>> 
>> Kudos!
>> 
> Indeed! Just one example. As I understand this problem the Yaesu
> FT-1000MP suffers from the same (lets call it) AGC IMD. On the
> MP I have noticed it myself and others too but it is not widely
> written about.
> Very glad to see that it possibly can be fixed on the K3.
> 
> 
> 73 Jim SM2EKM
> 

Like everything else about the nasty key-click generator FT-1000MP, it's
left to the customer to find and fix any problems.  Yaesu did nothing about
the key clicks for at least 13 years (beginning with FT-1000D until a
production change for the MP in 2003)...and Yaesu is now reliving design
problems with the roofing filters in the FT-2000.

BTW Inrad did implement fixes for both the MP's clicks and the AGC problem
(the customer must pay for all Yaesu design errors, of course):

"FT-1000MP AGC Improvement Mod  

Some operators on major DX-peditions have complained about poor readability
in large pile ups. From a joint effort between Inrad and some of these
operators, we are now offering the AGC mod which improves readability
somewhat for both CW and SSB. Details of the history is included in the mod
instruction sheets.

This new mod increases the decay time, which in the FT-1000MP is so fast
that weaker signals can come up to full output between dots and dashes (or
speech peaks), causing poor readability in pile ups. It also uses a damping
resistor to eliminate a slight over shoot. Please be aware that under
"normal" or "average" operating conditions, this mod will make very little
discernible difference."

The AGC mod is not applicable to the Mark V."

http://www.inrad.net/product.php?productid=86&cat=10&page=1

What a horrible contrast Yaesu was to my very pleasant experience with
Elecraft!

73,  Bill
-- 
View this message in context: 
http://n2.nabble.com/New-K3-Firmware%3A-Pileup-inspired-AGC-changes-tp2387110p2389115.html
Sent from the Elecraft mailing list archive at Nabble.com.

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Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes

2009-02-25 Thread Jan Erik Holm
Don Rasmussen wrote:
> Anyone care to take a guess as to how long an anomoly like this would live in 
> any other mass produced HF transceiver?
> 
> My guess - the life of the radio.
> 
> Maybe the Flex guys would get to it. 
> 
> With Elecraft, the issue was identified on the weekend, and here it is 
> Wednesday of the same week, the engineers understand the effect and offer 
> test software for it. 
> 
> Kudos!
> 
Indeed! Just one example. As I understand this problem the Yaesu
FT-1000MP suffers from the same (lets call it) AGC IMD. On the
MP I have noticed it myself and others too but it is not widely
written about.
Very glad to see that it possibly can be fixed on the K3.


73 Jim SM2EKM

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Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes

2009-02-25 Thread wayne burdick
>> Does this new firmware eliminate the need for really narrow roofing
>> filters?

It has nothing to do with roofing filters. The roofing filters are 
critical to the K3's design; they keep large signals from getting into 
the I.F. strip in the first place.

The AGC changes we're testing are intended to reduce the modulation 
effects that DSP AGC creates when multiple, closely spaced signals are 
present within the DSP's passband. Early reports suggest that it's 
working.

73,
Wayne
N6KR

---

http://www.elecraft.com

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Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes

2009-02-25 Thread Jim Brown
On Wed, 25 Feb 2009 14:39:16 -0500, garyhviz...@cfl.rr.com wrote:

> Does this new firmware eliminate the need for really narrow roofing
>filters?  Does it make them even more useful?  Does it not have any 
>bearing?

The benefit of all of this software tweaking and the roofing filters and 
the operator working hard to learn the radio and radios in general are 
all additive! 

Someone just posted that they had trouble in pileups during the contest 
last weekend, but the radio worked better when they turned on the 
attenuator and turned down the RF gain. DUH!  I learned that in 1957 -- 
but younger operators never learned it, since modern radios depend so 
heavily on AGC. 

73,

Jim K9YC 



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[Elecraft] New K3 Firmware: Pileup-inspired AGC changes

2009-02-25 Thread Don Rasmussen
Anyone care to take a guess as to how long an anomoly like this would live in 
any other mass produced HF transceiver?

My guess - the life of the radio.

Maybe the Flex guys would get to it. 

With Elecraft, the issue was identified on the weekend, and here it is 
Wednesday of the same week, the engineers understand the effect and offer test 
software for it. 

Kudos!



[Elecraft] New K3 Firmware: Pileup-inspired AGC changes
wayne burdick n6kr at elecraft.com 
Wed Feb 25 13:45:20 EST 2009 



There's been a lot of discussion recently about what happens to 
multiple closely spaced signals with AGC turned on. We have a new 
field-test firmware revision available that offers a significant 
improvement in such situations by reducing the IMD caused by 
conventional AGC. If you'd like to try it, please send an email to 
n6kr at elecraft.com.

Details:

Some operators described a "merging" of multiple, close-spaced signals 
when listening to pileups, making individual signals hard to copy. 
Assuming that a narrow crystal filter is in use (close to the DSP 
bandwidth), this is not "desense". In most cases, we've discovered, the 
cause is IMD (intermodulation distortion) related to the AGC algorithm.

To simulate what happens under pileup conditions, we combined four 
crystal oscillators with gaps between them of 5, 6, and 7 Hz (a total 
spread of 18 Hz for the four signals). We then injected the signals 
into the K3 at an equal level of about S5 and used spectral analysis to 
examine what happens to the passband. With AGC-F turned on (AGC fast, 
set to the K3's factory defaults), IMD products came up some 20-25 dB 
as compared to AGC OFF. The situation could be far worse in an actual 
on-air situation with more signals, noise, and key clicks. (AGC-S makes 
only a small improvement.) We ran the same test on several other 
radios, and verified the AGC-induced IMD characteristics are similar.

IMD is generated because AGC can cause mixing between the tones and 
their harmonics. The faster the decay rate, in general, the more 
products will be generated. With just one or two signals, most products 
will be outside the DSP's narrow IF or AF passband. But in a pileup, 
where signals are greater in number and can be nearly on top of each 
other, there are many more opportunities for signals to combine. This 
results in IMD products spaced at 1 to 20 Hz, depending on the time 
constants, location of the signals, etc.

Turning AGC off is one strategy that operators have traditionally used 
to combat the effects of AGC modulation. It then becomes necessary to 
"ride" the gain controls. Neither Lyle nor I have that much patience :) 
  So we took a different approach: keep the AGC on, but reduce its 
modulation effects to negligible levels by adding a very long "hold" 
time.

In the field-test firmware, two changes have been made. First, the AGC 
HLD menu setting, which used to apply only to voice modes, now applies 
to CW as well. (It still only affects AGC-S, the slow AGC setting.) 
Second, we increased the range of AGC HLD to facilitate 
experimentation. What we found is that an AGC hold time of about 1 
second, combined with a slower AGC-S decay time, reduces in-band IMD 
with closely spaced signals by 20-25 dB, making it very similar to 
turning AGC off. The *attack* time is unaffected, so there is no 
"thumping" as you might have with audio-derived AGC. Any new signal 
peak above the one that starts the "hold" timer will restart the timer.

This "hold" AGC appears to be useful in many listening situations. It 
can make voice signals sound cleaner, as well; after all, a voice 
signal can have many components, and AGC-induced modulation can add IMD 
products. It also helps with noisy band conditions.

The down side to AGC "hold" is that large signals can charge it up to a 
high level, reducing gain for the duration of the hold time. But in 
many cases this is far preferable to the AGC IMD effects, especially if 
you're listening to many signals at similar amplitudes -- as in a 
pileup.

73,
Wayne, N6KR
Lyle, KK7P


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Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes

2009-02-25 Thread wayne burdick
To those of you who are testing this: Remember that AGC HLD only 
affects slow AGC (AGC-S). So, once you have a long AGC HLD time set up 
(0.3 to 1 sec, let's say), you can go back and forth between fast AGC 
(with no hold), and slow AGC (with a long hold) just by tapping the AGC 
switch.

Long-hold/slow AGC isn't going to be the best choice every situation. 
Some experimentation will be required. Please let me know what settings 
you're using, and what you've listened to (pileups, general QRM, QRN, 
voice signals, etc.).

tnx
Wayne
N6KR


---

http://www.elecraft.com

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Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes

2009-02-25 Thread wayne burdick
We now have plenty of volunteers to try this experimental AGC firmware. 
Thanks!

73,
Wayne
N6KR

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Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes

2009-02-25 Thread garyhvizdak
Wed Feb 25 13:45:20 EST 2009 wayne burdick n6kr wrote ...

... We have a new field-test firmware revision available that offers a
significant improvement in such situations by reducing the IMD caused by 
conventional AGC.

--

Wayne,

I just received #2724 yesterday and am still inventorying the parts, and
you've already improved mine and all existing and future K3s?  And all that's
necessary is to download and install new firmware?  And there's no additional
cost to the user?

:>)

73,
Gary  KI4GGX

P.S.  Does this new firmware eliminate the need for really narrow roofing
filters?  Does it make them even more useful?  Does it not have any bearing?
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[Elecraft] New K3 Firmware: Pileup-inspired AGC changes

2009-02-25 Thread wayne burdick
There's been a lot of discussion recently about what happens to 
multiple closely spaced signals with AGC turned on. We have a new 
field-test firmware revision available that offers a significant 
improvement in such situations by reducing the IMD caused by 
conventional AGC. If you'd like to try it, please send an email to 
n...@elecraft.com.

Details:

Some operators described a "merging" of multiple, close-spaced signals 
when listening to pileups, making individual signals hard to copy. 
Assuming that a narrow crystal filter is in use (close to the DSP 
bandwidth), this is not "desense". In most cases, we've discovered, the 
cause is IMD (intermodulation distortion) related to the AGC algorithm.

To simulate what happens under pileup conditions, we combined four 
crystal oscillators with gaps between them of 5, 6, and 7 Hz (a total 
spread of 18 Hz for the four signals). We then injected the signals 
into the K3 at an equal level of about S5 and used spectral analysis to 
examine what happens to the passband. With AGC-F turned on (AGC fast, 
set to the K3's factory defaults), IMD products came up some 20-25 dB 
as compared to AGC OFF. The situation could be far worse in an actual 
on-air situation with more signals, noise, and key clicks. (AGC-S makes 
only a small improvement.) We ran the same test on several other 
radios, and verified the AGC-induced IMD characteristics are similar.

IMD is generated because AGC can cause mixing between the tones and 
their harmonics. The faster the decay rate, in general, the more 
products will be generated. With just one or two signals, most products 
will be outside the DSP's narrow IF or AF passband. But in a pileup, 
where signals are greater in number and can be nearly on top of each 
other, there are many more opportunities for signals to combine. This 
results in IMD products spaced at 1 to 20 Hz, depending on the time 
constants, location of the signals, etc.

Turning AGC off is one strategy that operators have traditionally used 
to combat the effects of AGC modulation. It then becomes necessary to 
"ride" the gain controls. Neither Lyle nor I have that much patience :) 
  So we took a different approach: keep the AGC on, but reduce its 
modulation effects to negligible levels by adding a very long "hold" 
time.

In the field-test firmware, two changes have been made. First, the AGC 
HLD menu setting, which used to apply only to voice modes, now applies 
to CW as well. (It still only affects AGC-S, the slow AGC setting.) 
Second, we increased the range of AGC HLD to facilitate 
experimentation. What we found is that an AGC hold time of about 1 
second, combined with a slower AGC-S decay time, reduces in-band IMD 
with closely spaced signals by 20-25 dB, making it very similar to 
turning AGC off. The *attack* time is unaffected, so there is no 
"thumping" as you might have with audio-derived AGC. Any new signal 
peak above the one that starts the "hold" timer will restart the timer.

This "hold" AGC appears to be useful in many listening situations. It 
can make voice signals sound cleaner, as well; after all, a voice 
signal can have many components, and AGC-induced modulation can add IMD 
products. It also helps with noisy band conditions.

The down side to AGC "hold" is that large signals can charge it up to a 
high level, reducing gain for the duration of the hold time. But in 
many cases this is far preferable to the AGC IMD effects, especially if 
you're listening to many signals at similar amplitudes -- as in a 
pileup.

73,
Wayne, N6KR
Lyle, KK7P


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