Thanks Don!
73,
Joe kk0sd
-----Original Message-----
From: RFI <rfi-bounces+gary_mayfield=hotmail.com@contesting.com> On Behalf Of
Don Kirk
Sent: Wednesday, March 24, 2021 2:21 PM
To: jim@audiosystemsgroup.com
Cc: RFI <rfi@contesting.com>
Subject: Re: [RFI] New Interference at kk0sd
Hi Jim,
I just went back and looked at the audio on Garys recording using a real
benchtop oscilloscope instead of a software based audio scope. I'm seeing an
obvious burst of noise at a rate of 60 Hz, and intermittently the bursts
disappear, sometimes for 1 or 2 cycles, sometimes 5 cycles, etc. When I
originally looked at it using a software based audio scope I thought there was
sometimes bursts at a frequency of 120 Hz, but I'm not seeing that using a
benchtop oscilloscope connected right to the audio jack on my laptop listening
to Garys recording when he is not talking or changing frequency (I even looked
at both the Left and Right channel signal at the same time to make sure I was
not missing something). It's possible that I originally got tricked when using
the software based scope when Gary was constantly changing frequency or
possibly talking and today I was careful to avoid both those times on his
recording.
A great example of where to grab the audio on his recording is starting at the
1:16 mark or 1:37 mark just for a second.
I promised myself I was not going to post anymore today, but your recent post
made me dig my scope out :)
Just FYI, and 73,
Don (wd8dsb)
On Wed, Mar 24, 2021 at 2:26 PM Jim Brown <jim@audiosystemsgroup.com> wrote:
> There is a LOT of great advice in this post, but I'll zero in on this
> one, on the basis of my professional background in psychoacoustics
> (the science of how our brains process what we hear). There's a
> fundamental property of human hearing behind the success of what Ed
> describes. Human hearing is FAR more able to hear differences in the
> loudness of one sound compared to the other when they are more nearly
> equal. The two sounds here were the arcing sound and the broadband circuit
> noise.
>
> Also, we humans have very poor sensitivity to the loudness of a sound.
> It takes a change of 6-10 dB for us to perceive a sound as twice as
> loud (or half as loud), but a change of only 1-2 dB in the strength of
> a signal that is very close to the noise level can be the difference
> copy or no copy. And when I was recording mixing live sound for a jazz
> band, I rarely needed to move faders more than a dB or two once I had
> the mix "right" musically.
>
> 73, Jim K9YC
>
> On 3/23/2021 11:27 PM, Hare, Ed, W1RFI wrote:
> > I had a step attenuator, so I decided to try a trick. I drove to
> > about
> where I thought it was strongest. I listended to the raucous buzz (120
> Hz) and cranked in attentuation until the buzz dissapeared and all I
> heard was white noise from the receiver. I cranked back until I could
> JUST barely hear the buzz over the white noise of the receiver. My
> ear was pretty good at that. I again drove the line and heard it
> louder as I drove past a
>
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>
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