In my opinion this red screen is not an intentional indication of overload.
Why would a software designer employ such exotic behavior (solid red, then
moving vertical lines, etc.) just to indicate an overload? An overload can
be detected at an A/D converter output usually as an overflow bit or all
one's, depending on the A/D chip. A simple text indicator could then be
displayed to indicate overload. No, this is not a "sound card red screen"
in my opinion. However I do believe it is related somehow to high signal
strengths or possible to high band activity across the spectrum. I used to
write signal processing software when much younger, and these kinds of
anomalies are usually caused when the programmer uses a data value to
calculate an index into a table, and writes a data value into the table, but
fails to check the value of the index first. If the calculated value
exceeds the preallocated size of the table, you end up overwriting other
data or even the software code itself. Most programming languages today
(like C and C++) do a miserable job of preventing programmer error. A
phenomenon known as "memory leak" can happen when one program module does
not manage its memory spaces well and inadvertently writes data on top of
other data as I have described. No, the memory isn't actually leaking, but
the programmer "leaked" data where it shouldn't be. When signal data is
used to calculate indices, or when processed spectral data is similarly
used, as it probably is in the Orion DSP, then you can easily overwrite data
where you shouldn't. The combination of signals and amplitudes probably
happens rarely, so this may not have been detected during factory testing.
Hopefully our input will help. My $.02 worth.
Jim N4BE
-----Original Message-----
From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
On Behalf Of Ron Zond
Sent: Monday, March 09, 2009 5:03 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] NEW Orion II/2.041XL Bug? RedScanWith
VerticalLinePatterns
Hi Stuart and Group
I made the statement, and this is observable even in modern soundcard
software.
Ron
K3MIY
-----Original Message-----
From: tentec-bounces@contesting.com
[mailto:tentec-bounces@contesting.com]On Behalf Of Stuart Rohre
Sent: Monday, March 09, 2009 4:22 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] NEW Orion II/2.041XL Bug? Red ScanWith
VerticalLinePatterns
Didn't someone point out that a type of sound card software uses a red
screen to indicate when there has been an overload in the signal path?
A number of sound card programs work this way. Transient signals have
been reported just before someone notices the red screen. I would say
this is a reasonable warning signal that too much gain, or a very large
transient has been received.
Stuart
K5KVH
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