U.S. patent application number 09/740065 was filed with the patent office on 2001-05-03 for method of evaluating degradation of electrical signals.
Invention is credited to Gershfeld, Jack.
Application Number | 20010000673 09/740065 |
Document ID | / |
Family ID | 25399825 |
Filed Date | 2001-05-03 |
United States Patent
Application |
20010000673 |
Kind Code |
A1 |
Gershfeld, Jack |
May 3, 2001 |
Method of evaluating degradation of electrical signals
Abstract
Method of evaluating degradation of electrical signals is
disclosed. The method involves visually comparing a visual
representation of a reference signal generated by a test signal
source, which can be made identical to an original signal, and a
degraded signal generated by another test signal source after
passing through a video system.
Inventors: |
Gershfeld, Jack; (Fullerton,
CA) |
Correspondence
Address: |
LAW OFFICES OF VLADIMIR KHITERER
2102 BUSINESS CENTER DR
SUITE 130
IRVINE
CA
92612
US
|
Family ID: |
25399825 |
Appl. No.: |
09/740065 |
Filed: |
December 20, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09740065 |
Dec 20, 2000 |
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08892347 |
Jul 14, 1997 |
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Current U.S.
Class: |
348/184 ;
348/E17.001 |
Current CPC
Class: |
H04N 17/00 20130101 |
Class at
Publication: |
348/184 |
International
Class: |
H04N 017/00 |
Claims
What is claimed is:
1. A method of evaluating degradation of an electrical signal
caused by a circuit comprising the steps of: (a) placing a first
electrical signal in communication with an input of the circuit;
(b) passing said first electrical signal through the circuit
thereby causing the circuit to output a degraded electrical signal;
(c) providing a means of synchronizing and combining electrical
signals having at least a first and a second input and one output,
placing said degraded electrical signal in communication with the
first input of said means of synchronizing and combining electrical
signals; (d) placing a second electrical signal, identical to said
first electrical signal, in communication with the second input of
said means of synchronizing and combining electrical signals; (e)
placing the output of said means of synchronizing and combining
electrical signals in communication with a plurality of means for
creating visual representations of electrical signals in a way that
the visual representation of said degraded electrical signal and
the visual representation of said second electrical signal are
presented separate from each other and each representation is not
altered by the representation of any other signal; and (f)
comparing said visual representation of said degraded image and
said visual representation of said second electrical signal.
2. A method of evaluating the degradation of an electrical signal
caused by a circuit as recited in claim 1 wherein one of the
plurality of means for creating visual representations recited in
step e is an oscilloscope.
3. A method of evaluating the degradation of an electrical signal
caused by a circuit as recited in claim 1, in which the electrical
signal further comprises a video signal.
4. A method of evaluating for the degradation of an electrical
signal caused by a circuit as recited in claim 1, in which the
video signal further comprises a signal selected from a group
consisting of NTSC, PAL, SECAM, or video signals generated by a
computer.
Description
REFERENCE TO THE RELATED APPLICATION
1. This application is filed under 37 CFR 1.53(b) and is a
continuation application of the prior application Ser. No.
08/892,347. No new matter has been added to this application.
Claims 1 through 4 are identical to the claims 1 through 4 in the
application Ser. No. 08/892,347, with the exception of the
following amendments:
2. 1. In claim 1, step (d), the word "substantially" before the
word "identical" is deleted.
3. 2. In claim 1, the word "for" in the phrase "method for
evaluation" is deleted and the word "of" is added in its place.
4. 3. In claim 2, the word "for" in the phrase "method for
evaluation" is deleted and the word "of" is added in its place.
5. 4. In claim 3, the word "for" in the phrase "method for
evaluation" is deleted and the word "of" is added in its place.
6. 5. In claim 4, the word "for" in the phrase "method for
evaluation" is deleted and the word "of" is added in its place.
BACKGROUND
7. The present invention is in the field of computer video systems.
More particularly, the present invention relates to the method of
visually testing video systems for degradation of video signals
that pass through video systems.
8. Video systems may include a variety of video sources, including
but not limited to computers, video cassette recorders, video
cameras, and a variety of display devices, including but not
limited to CRT monitors, CRT projectors, LCD projectors, DLP
projectors, or other video display devices. The video sources can
generate video signals of many types, including but not limited to
NTSC, PAL, SECAM, as well as the types produced by computers, such
as composite, monochrome analog, RGB, RGBS, RGBHV, RGsB, RsGsB, and
any additional video standards developed by IBM for personal
computer compatible technology, including but not limited to CGA,
EGA, VGA, and SVGA type signals and any other standards developed
by industry associations like VESA.
9. Regardless of the specific types of video signals produced,
video signals frequently require processing and manipulation before
they reach video display devices. To this end, video switchers,
video distribution amplifiers and other equipment, as well as
various types of interconnecting cables, are frequently installed
between video signal sources and video display devices.
10. Those ordinarily skilled in the pertinent arts will recognize
that after video signals pass through such video system and reach
video display devices, the quality of the video signals frequently
degrade. The degree and type of degradation of a video signal
depends upon the characteristics of components of the circuits
through which the video signal is passing. The number of components
and the individual characteristics of these components, as well as
the characteristics and length of interconnecting cables used to
connect said devices together determine the video signal
degradation level.
11. In order to determine the extent to which a particular circuit
degrades a video signal, as well as to determine how to compensate
for the degradation, it is necessary to compare the original video
signal generated by the source, with the video signal received by a
video display device after the video signal has passed through such
circuit.
12. Conventionally, this is done by connecting a video display
device to a video signal source and observing the original image
generated by the original video signal on the screen of the video
display device. The video display device can then be connected at
the output of the video system and the degraded image generated by
the video signal after passing through the video system can be
compared to the original image before passing through the video
system. A troublesome shortcoming of this method is that a person
comparing these two images has to remember what the original image
looked like because only one image is viewed at a time, and the
original image is not displayed while the degraded image is
observed.
13. It is also possible to use two monitors, one connected to the
original video signal and displaying the original image and one
connected at the output of the video system and displaying the
degraded image. However, those skilled in the pertinent arts will
recognize that this method requires close proximity between video
signal sources and video display devices, which in many cases is
not possible. In addition, different display characteristics of
each monitor may provide inaccurate results. Alternatively, one can
employ network analyzers which test video systems by measuring
various bandwidth characteristics. However, those skilled in the
pertinent arts will recognize that network analyzers, aside from
being expensive, also require close proximity between video signal
sources and video display devices, which in many cases is not
possible. In addition, specially trained personnel are required to
operate complex network analyzers, who are often in short supply,
and expensive.
14. Accordingly, a clear need exist for an inexpensive and simple
method of testing video systems for degradation of video signals
that pass through video systems, as well as compensating for the
degradation of the video systems in order to provide the highest
quality image possible.
OBJECT AND SUMMARY OF THE INVENTION
15. The present invention is directed to the method of testing
video systems for degradation of video signals after passing
through video systems, in which the method meets the needs
discussed above.
16. An additional object of the present invention is to provide a
novel enhanced means of testing for degradation of signals, which
overcomes the drawbacks of the prior art.
17. The method, which is the subject matter of this invention,
comprises the steps of applying a first test video signal to an
input of a video system (where computers, video cassette recorders,
video cameras, or any other video signal sources are connected to
the video system) in a way that images generated by the first test
video signal are displayed only on a portion of a screen of a
display device. This can be accomplished by a generator or any
other means capable of generating signals which produce images only
on portions of the screen, as opposed to images occupying the
entire screen. The first test video signal is then passed through
the video system and the image generated by the first test video
signal, which has been subject to degradation, is displayed only on
a portion of the screen of the video display device.
18. A second test video signal, acting as a reference signal, is
generated identical to the first test video signal. The second test
video signal is designed so that the image it produces will be
displayed on a portion of the screen not occupied by the signal
from the first generator. The second test signal, along with the
first test signal are synchronized and combined by a special
circuit and connected to the video display device. Those ordinarily
skilled in the pertinent arts will recognize that in order for the
second test video signal to be identical to the first test video
signal, same can be, for example, calibrated to the first test
video signal.
19. The image generated by the second test video signal, which has
not passed through the circuitry that the first test signal has,
therefore functions as a reference signal. The image of the second
test video signal is then displayed only on a portion of the screen
of the display device, other than that portion of the display
device on which said degraded image is displayed. It is most
convenient, but not necessary, to display the degraded image and
the reference image side by side on the screen of the video display
device. For example, the reference image can occupy the left side
of the screen, and the degraded image can occupy the right side of
the screen of the video display device. (Alternatively, the
degraded image and the reference image can be displayed on top and
bottom of the video display device.) By visually comparing the two
images simultaneously displayed on different portions of the screen
of the video display device, it is easy and convenient to determine
the extent to which the video signal degraded after passing through
the video system. It should be apparent to those skilled in the
pertinent arts that both generators of test video signals used for
this type of testing can have the ability of adjusting positions
and sizes of images used for comparison.
BRIEF DESCRIPTION OF THE DRAWINGS
20. The advantages of the present invention will become better
understood with reference to the following description of preferred
embodiments of the invention, appended claims, and accompanying
drawing figures in which the same reference numeral indicates the
same feature, or features which are analogous in structure or
function.
21. FIG. 1 provides a schematic presentation of a video system to
which the method embodying the present invention are applied.
22. FIG. 2 provides a schematic presentation of the steps of
testing video systems for degradation of signals by comparing
reference and degraded images according to the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE PRESENT
INVENTION
23. Throughout the following detailed description, it should be
understood by those skilled in the pertinent arts, that references
to electrical communication shall not be limited to communications
performed entirely by electrical means, but shall be understood
that some portions of the overall communications of the electrical
signals may be performed by other means, including but not limited
to optical, RF, ultrasound, magnetic, microwave, acoustic and other
signals and means now known to those skilled in the pertinent arts
or later developed.
24. The initial discussion of the preferred embodiment shall be
made by reference to FIG. 1. Starting on the left hand portion of
FIG. 1, there is initially provided a Video Signal Source 10 which
is placed in electrical communication with the first end of Cable
30 at Junction A. Video Signal Source 10, which in this embodiment
is shown as a computer, could be any number of other video sources
producing a wide variety of types of video signals.
25. For example, Video Signal Source 10 could be a video camera, a
video cassette recorder (VCR), a video tape recorder, a video disc
player, a DVD, and any number of other video signal sources which
are known to those ordinarily skilled in the pertinent arts. Cable
30 represents any number of possible means for conducting a video
signal, including but not limited to a coaxial, fiber optic, and
twisted pair cable. Cable 30 conducts the video signal from Video
Signal Source 10 to Intermediary Circuit 20 which comprises any
number of possible circuit elements. Intermediary Circuit 20 is
generally composed of devices for processing and manipulating video
signals, which may include distribution amplifiers, matrix
switchers, interfaces and any number of other devices which are
known to those ordinarily skilled in the pertinent arts.
26. The output of Intermediary Circuit 20 is placed in electrical
communication with a second Cable 30, which conducts the video
signal to Junction B which is in electrical communication with
Video Display Device 40. The video signal generated by Video Signal
Source 10 is displayed in some visual manner by Video Display
Device 40. As shown in FIG. 1, Video Display Device 40 is a
computer monitor, although other video display devices, such as TV
monitors, projectors, LCD displays, DLP projectors, and a number of
other devices are possible.
27. Junction A is usually located in close proximity to the Video
Signal Source 10. Junction B is usually located in close proximity
to the Video Display Device 40. All of the circuitry and cables
located between Junction A and Junction B represent the circuit
that is being evaluated. No electronic circuitry can perfectly
duplicate or process a video signal. Thus the video signal present
at Junction B will be in some manner degraded or inferior to the
signal at Junction A which was generated by Video Signal Source 10.
The method of the instant invention is used in conjunction with the
circuitry, components and cables of the system shown in FIG. 1 and
enable a person to visually estimate a level of degradation and
compensate for the degradation and alteration of a video signal
after passing through Intermediary Circuit 20.
28. Referring now to FIG. 2, a method will now be explained which
permits the basic circuit as shown in FIG. 1, to be evaluated. As
part of the evaluation method described for FIG. 2 and all other
figures, the normal video source is removed and a test signal is
used for evaluation. Once the evaluation has been completed, the
usual video source can be returned to the circuit.
29. Starting at the left side of FIG. 1, there is provided a Video
Signal Source 10. However, in this test situation, Video Signal
Source 10 has been removed from electrical communication at
Junction A during the evaluation steps. Instead, First Test
Generator 50, is placed in electrical communication with Junction
A. First Test Generator 50 is capable of generating video signals
which produce images only on selected portions of a video display
screen, as opposed to producing images which occupying the entire
screen. In addition, First Test Generator 50 is designed to
produce-signals that have characteristics identical to those
produced by Video Signal Source 10.
30. The circuitry as shown in FIG. 2, between Junction A and
Junction B, is identical to the circuitry between Junction A and
Junction B as shown in FIG. 1.
31. However, in the circuit as shown in FIG. 2, Junction B is not
placed in electrical communication with a video display device, but
rather with Video Synchronizer 70. A Second Test Generator 60 is
also placed simultaneously in electrical communication with Video
Synchronizer 70.
32. Video Synchronizer 70 receives input directly from Second Test
Generator 60 and indirectly from First Test Generator 50, after the
video signal has been processed by the circuitry between Junction A
and Junction B. Because the video signals generated are from
different sources, they will not be synchronized when generated.
The purpose of Video Synchronizer 70 is thus to not only combine
the video signals but to synchronize them as well, so that they can
be properly displayed on Video Display Device 40. However, as
should be apparent to those knowledgeable in the pertinent arts, it
is simply more convenient, but not necessary to use one device,
such as Video Synchronizer 70, for both synchronizing and combining
video signals. Synchronizing can be accomplished by a variety of
means. For example, First Test Generator 50 and Second Test
Generator 60 can be connected to a separate means of synchronizing
the video signals.
33. The output of Video Synchronizer 70 is placed in electrical
communication with Video Display Device 40. First Test Generator 50
and Second Test Generator 60 are designed so that the signal from
each of them is displayed on separate portions of Video Display
Device 40. In FIG. 2, the signal that originated from First Test
Generator 50 is shown as Image 50a. Image 50a represents a signal
that has been degraded or altered by passing through the circuitry
located between Junction A and Junction B. The signal that
originated form Second Test Generator 60 is shown in the figure as
Image 60A and represents an unaltered or reference image.
34. It is within the scope of the invention, that the video signals
coming from First Test Generator 50 and Second Test Generator 60,
can be modified so that each image that results from each signal,
can be displayed in a plurality of sizes and in any possible
position on the video display screen.
35. By observing Image 50a and Image 60a on Video Display Device
40, it is easy and convenient to determine the extent to which the
video signal degrades after passing through the video system
represented by the circuitry between Junction A and Junction B.
Those ordinarily skilled in the pertinent arts will recognize that
additional monitors, oscilloscopes or a number of other devices
capable of displaying images generated by video signals can be
connected instead of or in addition to the Video Display Device 40,
for the purpose of observing and comparing the Image 50a and the
Image 60a.
36. In short, FIG. 2 shows how the basic system as described in
FIG. 1 can be modified to permit the visualization of a degraded
video signal and a reference video signal simultaneously on the
same video display device.
37. While the present invention has been described and defined by
reference to the preferred embodiment of the invention, such
reference does not imply a limitation on the invention, and no such
limitation is to be inferred. The invention is capable of
considerable modification, alteration, and equivalents in form and
function, as will occur to those ordinarily skilled in the
pertinent arts.
38. The depicted and described preferred embodiment of the
invention is exemplary only, and is not exhaustive of the scope of
the invention. Consequently, the invention is intended to be
limited only by the spirit and scope of the appended claims, giving
full cognizance to equivalents in all respects. Specifically, those
ordinarily skilled in the pertinent arts will recognize that the
present invention, or its equivalents, is not limited to video
signals, but can be used with any type of signals that can be
visually represented and which degrade due to passing through
components of a system.
* * * * *