Fw: ESSB

[riese-k3djc]

Try to make me understand why you would use ESSB

Bob K3DJC>
 
Using several different K3 and P3 combinations in over the air test, it
appears that when running the K3  in ESSB mode and set to 3KHZ the actual
bandwidth for a full audio range SSB signal is about 3.5 to 3.6 KHz in
width. Set for 4Khz the bandwidth is about 4.6 Khz.  If this is not true
then it appears that the P3 is improperly showing the bandwidth.  In all
the test the K3 receivers were set a 4 Khz  bandwidth.
 
These same set ups show the standard 2.8 Khz k3 signal to be 2.8 Khz.
 
Can someone with a white noise generator and a good spectrum analyzer
take a look at a K3 in ESSB mode. I dont want to be using ESSB if I cant
limit my signal width to 3.2 Khz.
When listening to the 2.8 vs the K3  in ESSB set at 3khz there is far
more difference in the quality than I think there should be for just 200
cycles more in bandwidth width the same audio input.
 
Hope to have someone give it a try and report. Thanks Van W4GIW
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[wayne burdick]

Hi Bob,

I'm mostly a CW guy, but even I like using ESSB once in awhile. I only  
use it when a band is sparsely populated, so there's no issue with  
consuming a bit of extra bandwidth. It's a nice change to hear the  
lows and highs a bit better during casual conversation.

Of course I'd never use it during contests, or anytime that I'm after  
"punch" rather than the ultimate in fidelity.

73,
Wayne
N6KR

On Apr 25, 2011, at 6:08 PM, [hidden email] wrote:

> Try to make me understand why you would use ESSB
>
> Bob K3DJC
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[Alan Bloom]

On Mon, 2011-04-25 at 21:08 -0400, [hidden email] wrote:
> Try to make me understand why you would use ESSB
>
> Bob K3DJC>

I use it with the bandwidth set to minimum (3 kHz) and the TX equalizer
set to limit the transmitted bandwidth to about what it would be using
regular SSB.  I do that to get better, more natural-sounding transmitted
audio.

Audio quality is not only, or even mainly, determined by the bandwidth
and amplitude flatness.  The phase response is critical.  If you look at
a crystal filter on a vector network analyzer you can easily see that
the phase response is very non-linear.  A "good" crystal filter with a
small shape factor (large number of poles) is worse in this respect than
a cheaper filter with a poorer shape factor.

I believe the un-natural sound of most SSB signals is primarily due to
the non-linear phase of the crystal filters.

ESSB uses the 6 kHz crystal filter, which has a smoother phase response.
The transmitted bandwidth is limited by the digital filter, which is
inherently linear-phase and contributes no additional phase distortion.

Alan N1AL


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[Rick Prather-2]

Alan,

You make an interesting point!

How do you have your EQ set in the setup you describe?

Rick
K6LE


On 4/25/2011, at 8:38 , Alan Bloom wrote:

> and the TX equalizer
> set to limit the transmitted bandwidth to about what it would be using
> regular SSB.

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[Alan Bloom]

I have the TX equalizer set to suppress the lows and emphasize the highs
to get a reasonably-flat RF spectrum with my voice.  Also I notch out
around 800 Hz since those frequencies are not important for voice
communications:

1   50 Hz -16 dB
2  100 Hz -16 dB
3  200 Hz -16 dB
4  400 Hz -10 dB
5  800 Hz -16 dB
6 1600 Hz   0 dB
7 2400 Hz  +3 dB
8 3200 Hz  -6 dB

With those settings my voice looks flat on a spectrum analyzer except
for the notch at 800 Hz.  I should point out that I'm using a
computer-type mic/headset which has flat frequency response.  With a
communications-type microphone you wouldn't need that extreme treble
boost.

The settings for non-ESSB SSB are the same except that #8 3200 Hz is +6
dB instead of -6 dB.  With those settings the ESSB and SSB spectra look
very similar.

Alan N1AL



On Mon, 2011-04-25 at 21:41 -0700, Rick Prather wrote:

> Alan,
>
> You make an interesting point!
>
> How do you have your EQ set in the setup you describe?
>
> Rick
> K6LE
>
>
> On 4/25/2011, at 8:38 , Alan Bloom wrote:
>
> > and the TX equalizer
> > set to limit the transmitted bandwidth to about what it would be using
> > regular SSB.
>

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[Alan Bloom]

On Mon, 2011-04-25 at 23:30 -0700, Alan Bloom wrote:

> I have the TX equalizer set to suppress the lows and emphasize the highs
> to get a reasonably-flat RF spectrum with my voice.  Also I notch out
> around 800 Hz since those frequencies are not important for voice
> communications:
>
> 1   50 Hz -16 dB
> 2  100 Hz -16 dB
> 3  200 Hz -16 dB
> 4  400 Hz -10 dB
> 5  800 Hz -16 dB
> 6 1600 Hz   0 dB
> 7 2400 Hz  +3 dB
> 8 3200 Hz  -6 dB

I meant -16 dB for 3200 Hz.


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[Andy Faber]

Just to whet everyone's appetites further, here's a one week report on my
new KPA500 (ser. 077, almost matches my K3, ser. 076), built as a Field Test
kit.
  The assembly was very straightforward, easier than the K3.  It was speeded
up by the fact that the parts inventory was missing from the preliminary kit
manual, so no time was spent checking for completeness -- I just kept
building, waiting to see if anything crucial had been omitted (nothing was).
There was a pre-production glitch with a ribbon cable, but that was quickly
remedied by Bob Wolbert, K6XX, the project manager, and the finished kit
works great.
  Although this may not bear management's approval, I gave it several hours
of workout in the All Asian contest this weekend, running JA's at a steady
600 watts on my wattmeter.  Nary a problem, and the temperature readout
never went above 60 degrees C. (it's rated for 90 degrees C.).
  The integration with the K3 is delightful.  The amp and radio follow each
other's band changes, and the K3 remembers two power levels, the standby and
operate levels, and switches automatically.  The KPA500 also comes on when
you turn on the K3 (provided the main power switch on the back of the amp is
on), so it's just like having a more powerful radio.  All in all, operation
is really seamless with the K3.  I imagine it would be almost as good with
any other radio, as the amp, when not connected to the K3, switches bands
with the first dit due to rf sampling.
  Anyway, I'm one happy camper with the KPA500, and wanted to share my
experience.
  73, andy ae6y

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