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Why predistortion ?

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IK4EWX

Re: Why predistortion ?

Why it seem so difficult thing for the great Elecraft rigs?
Apache Labs Anan rigs, from 2.700 to 4.400 $, all have predistortion
included.
Are their power supply with higher voltages than the 12V of Elecraft?
Ian Ik4EWX

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Jim Miller

Re: Why predistortion ?

I ordered my K3 in 2008. The K3s was a modest upgrade. The processing power to accomplish predistortion has only become affordable in the last few years and is far beyond the capacity remaining in the 12 year old K3.

Jim abt

On Sep 14, 2020, at 4:44 PM, IK4EWX <[hidden email]> wrote:

Why it seem so difficult thing for the great Elecraft rigs?
Apache Labs Anan rigs, from 2.700 to 4.400 $, all have predistortion
included.
Are their power supply with higher voltages than the 12V of Elecraft?
Ian Ik4EWX

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Phil Kane-2

Re: Why predistortion ?

In reply to this post by Elecraft mailing list

On 9/14/2020 9:52 AM, Dave B via Elecraft wrote:

> Pre-distortion is often used in modern cellular base-station
> transmiters, and perhaps digital broadcast systems where they have to
> handle multiple carriers simultaneously, "at power".

At the beginning of this discussion I was confusing "predistortion" with
"pre-emphasis" which in the FM broadcast field refers to the intentional
introduction of nonlinear audio frequency response of the transmission
chain, recovered by "de-emphasis" in the receivers. Now I understand
better what the discussion is all about.

73 de K2ASP - Phil Kane
Elecraft K2/100 s/n 5402

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon
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Wes Stewart-2

Re: Why predistortion ?

In reply to this post by Joe Subich, W4TV-4

Yes.

On 9/14/2020 9:10 AM, Joe Subich, W4TV wrote:

> On 2020-09-14 7:29 AM, Charlie T wrote:
> >
>> However, implementing the pre-distortion function IS probably a
>> better long-term solution.
>
> Pre-distortion on a 12V rig only hides the problem. Any "home
> station" rig should have 28/50 V finals *and* then one can make
> it even cleaner with pre-distortion. If necessary, use 50V
> capable finals at 50W maximum output for 12V operation and
> 150-200 W output when a 48V supply is available.
>
> 73,
>
> ... Joe, W4TV

ANDY DURBIN

Why predistortion ?

In reply to this post by JHRichards

" Now I understand better what the discussion is all about."

Who ever coined the term "predistortion" should be taken behind the bicycle shed and introduced to a 2x4. The terminology is the epitome of obfuscation!

Andy, k3wyc
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wayne burdick

Re: Why predistortion ?

Administrator

Here on the ranch we call it "IMD optimization."

Wayne

> On Sep 15, 2020, at 3:55 PM, Andy Durbin <[hidden email]> wrote:
>
> " Now I understand better what the discussion is all about."
>
> Who ever coined the term "predistortion" should be taken behind the bicycle shed and introduced to a 2x4. The terminology is the epitome of obfuscation!
>
> Andy, k3wyc

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Joe Subich, W4TV-4

Re: Why predistortion ?

In reply to this post by ANDY DURBIN

> The terminology is the epitome of obfuscation!

Not at all ... "predistortion" has been used in TV broadcasting for
more than 40 years - even back in analog TV. It started as simple
non-linear amplifiers ("proc amps") perhaps 75 years ago to adjust
for the different levels of compression in the amplifier chain with
differing signal levels. However, with the advent of solid state
amplifiers at VHF and MSDC klystrons/IOTs at UHF additional levels
of "predistortion" were employed to cancel the regeneration of the
lower sideband from to *IMD* due to operating well beyond the 1 dB
compression point.

Of course those techniques carried over into digital (HD) TV and
were employed by the cellular industry with the conversion from
analog to digital.

"Predistortion" is a perfectly understandable term to anyone who
has a passing familiarity with the behavior of amplifiers in
compression.

73,

... Joe, W4TV

On 2020-09-15 6:55 PM, Andy Durbin wrote:
> " Now I understand better what the discussion is all about."
>
> Who ever coined the term "predistortion" should be taken behind the bicycle shed and introduced to a 2x4. The terminology is the epitome of obfuscation!
>
> Andy, k3wyc

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k6dgw

Re: Why predistortion ?

In reply to this post by ANDY DURBIN

Didn't the term "pre-distortion" originate in the astronomy world where
one creates an artificial star with a powerful laser, and then distorts
the telescope mirror in real time to minimize atmospheric effects
[twinkling]? That also reduces the twinkle on real nearby stars too.
Maybe that's something else. Pre-emphasis/De-emphasis in FM broadcast
[and analog land mobile FM] is sort of pre-distortion too.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 9/15/2020 3:55 PM, Andy Durbin wrote:
> " Now I understand better what the discussion is all about."
>
> Who ever coined the term "predistortion" should be taken behind the bicycle shed and introduced to a 2x4. The terminology is the epitome of obfuscation!
>
> Andy, k3wyc
>

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Jim Brown-10

Re: Why predistortion ?

In reply to this post by ANDY DURBIN

On 9/15/2020 3:55 PM, Andy Durbin wrote:
> Who ever coined the term "predistortion" should be taken behind the bicycle shed and introduced to a 2x4. The terminology is the epitome of obfuscation!
>

Hmmm. My EE degree is 56 years old, but the term seems quite clear and
descriptive to an old fart like me!

It's been done in audio systems for at least four decades, where it uses
motional feedback from the loudspeakers to which the systems were
carefully matched. The implementation was intended to correct for
non-linearities in the loudspeakers, which are far greater than in the
electronics.

73, Jim K9YC
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Drew AF2Z

Re: Why predistortion ?

In reply to this post by k6dgw

That's funny, I was also thinking of astronomy-- the Schmidt-Cassegrain
telescope where the inherent aberrations of the relatively simple
spherical mirror is corrected (pre-distorted?) with a lens...

73,
Drew
AF2Z

On 09/15/20 18:39, Fred Jensen wrote:

> Didn't the term "pre-distortion" originate in the astronomy world where
> one creates an artificial star with a powerful laser, and then distorts
> the telescope mirror in real time to minimize atmospheric effects
> [twinkling]? That also reduces the twinkle on real nearby stars too.
> Maybe that's something else. Pre-emphasis/De-emphasis in FM broadcast
> [and analog land mobile FM] is sort of pre-distortion too.
>
> 73,
>
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County
>
> On 9/15/2020 3:55 PM, Andy Durbin wrote:
>> " Now I understand better what the discussion is all about."
>>
>> Who ever coined the term "predistortion" should be taken behind the
>> bicycle shed and introduced to a 2x4. The terminology is the epitome
>> of obfuscation!
>>
>> Andy, k3wyc
>>
>
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k6dgw

Re: Why predistortion ?

Isn't that what they did to Hubble originally?

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 9/15/2020 5:41 PM, Drew AF2Z wrote:

> That's funny, I was also thinking of astronomy-- the
> Schmidt-Cassegrain telescope where the inherent aberrations of the
> relatively simple spherical mirror is corrected (pre-distorted?) with
> a lens...
>
> 73,
> Drew
> AF2Z
>
> On 09/15/20 18:39, Fred Jensen wrote:
>> Didn't the term "pre-distortion" originate in the astronomy world
>> where one creates an artificial star with a powerful laser, and then
>> distorts the telescope mirror in real time to minimize atmospheric
>> effects [twinkling]? That also reduces the twinkle on real nearby
>> stars too. Maybe that's something else. Pre-emphasis/De-emphasis in
>> FM broadcast [and analog land mobile FM] is sort of pre-distortion too.
>>
>> 73,
>>
>> Fred ["Skip"] K6DGW
>> Sparks NV DM09dn
>> Washoe County

Paul Van Dyke

Re: Why predistortion ?

Well part of the problem with the original Hubble lenses where they were
miss ground in the 1st place

Paul KB9AVO

On Tue, Sep 15, 2020, 9:57 PM Fred Jensen <[hidden email]> wrote:

> Isn't that what they did to Hubble originally?
>
> 73,
>
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County
>
> On 9/15/2020 5:41 PM, Drew AF2Z wrote:
> > That's funny, I was also thinking of astronomy-- the
> > Schmidt-Cassegrain telescope where the inherent aberrations of the
> > relatively simple spherical mirror is corrected (pre-distorted?) with
> > a lens...
> >
> > 73,
> > Drew
> > AF2Z
> >
> > On 09/15/20 18:39, Fred Jensen wrote:
> >> Didn't the term "pre-distortion" originate in the astronomy world
> >> where one creates an artificial star with a powerful laser, and then
> >> distorts the telescope mirror in real time to minimize atmospheric
> >> effects [twinkling]? That also reduces the twinkle on real nearby
> >> stars too. Maybe that's something else. Pre-emphasis/De-emphasis in
> >> FM broadcast [and analog land mobile FM] is sort of pre-distortion too.
> >>
> >> 73,
> >>
> >> Fred ["Skip"] K6DGW
> >> Sparks NV DM09dn
> >> Washoe County
>
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Brian Hunt

Re: Why predistortion ?

In reply to this post by k6dgw

Usually called adaptive optics these days. The laser is a "guide star".

73,
Brian, K0DTJ

> On Sep 15, 2020, at 16:39, Fred Jensen <[hidden email]> wrote:
>
> Didn't the term "pre-distortion" originate in the astronomy world where one creates an artificial star with a powerful laser, and then distorts the telescope mirror in real time to minimize atmospheric effects [twinkling]?

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Art Peters

Re: Why predistortion ?

In reply to this post by Jim Brown-10

Hmmmm, my EE degree is only 37 years old and the term also seems clear and descriptive to me too.... hmmm wonder if that also makes me an old fart???

73 es God. bless,

Art/K0ACP

Sent from my iPad

> On Sep 15, 2020, at 8:24 PM, Jim Brown <[hidden email]> wrote:
>
> On 9/15/2020 3:55 PM, Andy Durbin wrote:
>> Who ever coined the term "predistortion" should be taken behind the bicycle shed and introduced to a 2x4. The terminology is the epitome of obfuscation!
>
> Hmmm. My EE degree is 56 years old, but the term seems quite clear and descriptive to an old fart like me!
>
> It's been done in audio systems for at least four decades, where it uses motional feedback from the loudspeakers to which the systems were carefully matched. The implementation was intended to correct for non-linearities in the loudspeakers, which are far greater than in the electronics.
>
> 73, Jim K9YC
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
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Lyn WØLEN

Re: Why predistortion ?

Hmmm ... if my math still works ...

2020 - 1965 = 55 (years)

Mark me down as a "Not quite as old fart as Jim."

73
Lyn, W0LEN

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of Art Peters
Sent: Wednesday, September 16, 2020 5:27 AM
To: [hidden email]
Cc: [hidden email]
Subject: Re: [Elecraft] Why predistortion ?

Hmmmm, my EE degree is only 37 years old and the term also seems clear and descriptive to me too.... hmmm wonder if that also makes me an old fart???

73 es God. bless,

Art/K0ACP

Sent from my iPad

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Jim GM

Re: Why predistortion ?

In reply to this post by JHRichards

Hmmm 2 year degree of 45 years. Old farts are kept in Funkenwagnal Jars to keep the essence in tack, so when opened the sound can reverb within the nostrils. Jim K9TFSent from my T-Mobile 4G LTE Device
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