MXPA98002211A - Rotating visual deployment screen for vi test - Google Patents

Abstract

The present invention relates to a method and apparatus for testing the operation of a videophone (102), wherein a rotating body (109) having a visual pattern of contrasting visual forms is placed within the visual field of the videophone (102). The videophone (102) is connected to a communication path (105, 106, 107), which in turn is connected to a display screen (101). A control device (108) varies at least one of the rotary speeds of the rotating body (109) and the characteristics of the communication path (105, 106, 107), while an image of the rotating body (109) is observed on the display screen (10

Description

ROTATING VISUAL DEVICE DISPLAY SCREEN FOR VIDEO TEST FIELD OF THE INVENTION The present invention relates to an apparatus and method for testing video communications equipment, more particularly, an inexpensive method and apparatus for testing videophones in the field. BACKGROUND OF THE INVENTION The speed of data transmission of videotelephones is limited by the requirement that the modems of such devices compress the video data in such a way that they can be transmitted within the narrow bandwidth available in the telephone lines. In other words, if an increase in bandwidth were possible, continuous motion could be displayed for higher velocities of the observed motion. In order to carry out the video data compression, a compression algorithm is incorporated into a platelet inside the codec of the videophone and is used by the codec to compress the video data in such a way that they can be compressed. sent over the narrow bandwidth of a telephone line. Therefore, the better the compression algorithm, the higher the compression ratio and the better the transmission of video movement data. A typical videophone terminal includes a video camera or other image player and a display screen in combination with the codec to compress the local video image before transmission to a remote location and to expand the remote video image after your reception from the remote location. It is often necessary to test the operation of such videophones in the field. For this test, it is desirable to provide a repeatable and controlled optical excitation of the visual field as observed by the videophone. In the past, such a test has been performed by using a mechanical metronome as a visual source observed by a video camera to generate video test signals. Although a metronome provides repeatable action, it only produces a minimal change in the visual field. If the majority of the field of the observed camera remains static, minimal interference, such as that generated by the oscillatory movement of a metronome, can be transmitted as a smooth action in cases where actual movement results in a very deteriorated performance. Therefore, such a test with a metronome does not give adequate importance to the operation of the entire system. Although a repairman may wave a sheet of paper or some other object within the visual field, such a method would produce an uncalibrated and unsystematic optical excitation of the video system, instead of a repeatable and controlled optical excitation. Other systems of the prior art have employed test video signals, such as the method and apparatus described in US Pat. No. 5,313,280 to M.Straus, the entire contents of which are incorporated herein by reference. This patent describes the use of a video disc player to play discs containing computer generated images, such as the image of a rotating color wheel, to provide video signals to test the operation of a codec. However, such electrically generated signals bypass the original camera and its associated circuitry, and therefore do not exercise the complete video system. In addition, the output signals from the video camera of a videophone are difficult to simulate as they often have proprietary video formats. Other systems of the prior art employ video test patterns that are displayed on a video screen placed in the visual field of the videophone to be tested. However, inappropriate synchronization of the videophone and the scanning phase of the video signal that produces the pattern may introduce scan mismatch artifacts, obscuring the test results thereby. FinallyMany prior art systems ey static test patterns or diagrams to test the operation of a video camera or display screen. However, the static test patterns and diagrams are unable to test the codec's moving compression algorithms and therefore are unsuitable for testing the entire video system. SUMMARY OF THE INVENTION When video data transmissions deteriorate, "artefacts" (abnormalities) are induced in the displayed image. The present invention can be used to correlate different movement rates with the number of observable artifacts displayed on a video display screen to reproduce the movement. These artifacts may include average apparent increases by repetition of movement, distortion per block, edge activity, error blocks, and inequality. It is therefore an object of the present invention to provide an economical method and apparatus for reliably testing videophone equipment, especially in the field, for displayed artifacts induced by observed movement.

Another object of the invention is to provide an apparatus and method for producing a variety of controlled visual movement effects for the repeatable and systematic testing of videophone systems. Still another object of the invention is to provide a source of dynamic test signals suitable for end-to-end testing of a pair of interconnected videophones. A further object of the invention is to provide a visual source of movement that covers a sufficiently large field of view to give full importance to the videophone's video system's ability to transmit rapid movement. Still a further object of the invention is to provide a visual source of motion that is controlled and repeated enough to accurately test and compare the entire videophone systems, including the camera. These and other advantages of the invention are carried out by a portable videophone test device comprising a variable speed controlled electric motor and a disk having one or more test patterns. The disc is rotated by the motor in such a way that when placed in the visual field of the videophone, the complete video system, including the video camera, can be tested accurately and reliably. In this way the invention provides a physical system comprising a rotating disk having a test pattern on the face thereof, said test pattern comprising circular segments formed in black and white. The rotating disc is observed by the camera of the videophone system and its rotational speed is varied to test the ability of the system to transmit movement. The pattern on the rotating disc constitutes a measurable and repeatable visual excitation that serves as a signal source for testing videophones. This standard signal source or "reference" allows intelligent comparisons to be made between video systems that have different characteristics. In the context of this specification, the term "videophone" is used in a generic sense to describe any combination of devices for transmitting both audio and video signals over telephone lines. Such devices include video cameras, CRT's and television display screens that respond to video signals, audio system components, and modems and codecs under the control of a microprocessor. In this way, the display screen can be a computer monitor, and the other components can be provided by cards placed in the computer housing in conjunction with a CPU, or the display screen can be a television receiver with the other components housed in a box placed on or inside the television receiver housing. Another alternative is to have a dedicated videophone unit of compact design. BRIEF DESCRIPTION OF THE DRAWINGS A more complete understanding of the present invention can be obtained by considering the following more detailed description in conjunction with the accompanying drawings, in which: Figure 1 shows a typical test installation using the rotating disc of the present invention; Figures 2 and 3 show rotating discs with typical test patterns that can be employed in the present invention; Figure 4 is a schematic diagram of the electrical components for rotating the disc and controlling the rotation speed of the disc; and Figure 5 shows details of several of the components of Figure 4. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES Figure 1 shows an installation of the invention for testing videophones, first and second, 101 and 102, respectively, which are linked by a simulated transmission link 107 and two simulated transmission lines 105 and 106. In this installation, the first videophone 101 is focused on a static test pattern 103, while the second videophone 102 is focused on a physically rotating test pattern, provided by an assembly 104. A test controller 108 connects to the transmission link 107, to the line simulators 105 and 106, and to the assembly of test pattern 104. The line simulators 105 and 106 and the transmission link 107 are preferably provided by a Transmission Analysis System of a type commercially currently available for test video transmissions. Such a system is known as a Simulator of the Central Office 1040-A of Innovations of the Northeast. Such systems can be provided as many as 168 different sets (sets) of transmission impairments. Because a set of deteriores may involve changing values of distortion, line loss and the like, the reception of video signals by the videophone 101 may be lost during the test due to damage to the simulated line. It can be said that the lost video signals have "fallen". Examples of the characteristics of the impairments to test video systems are established in publication No. TSB-37A issued by TIA / EIA. When the videophone 101 comprises a computer capable of running the required software, the software can be used to determine the link-up rate between the videophone modems 101 and 102. This link-up rate can be displayed on a monitor associated with the computer . The rotating test pattern assembly 104 comprises a test pattern 112 or 144 printed on a disc 109, which is driven in rotation by a speed-controlled motor 110. The speed of the motor 110 can be controlled automatically by the controller. of test 108, or can be manually controlled by a human test operator manipulating a speed controller 116 (Fig 4). The pattern 112 comprises segments in the form of alternating dark and light circles 111 and 113, respectively. The pattern 114 comprises, on a light background, multiple dark asymmetric shapes 117, 118 and 119, each having a different configuration. The rotating disc 109 may comprise any of a variety of test patterns other than the symmetric color wheel 112 of Figure 2, or the asymmetric pattern 114 of Fig 3. Although black and white patterns are preferred for contrast, a plurality of other colors are used instead, since the required contrast is provided between the adjacent colors. The number of segments in the form of circles in the disk pattern 112 and the number of dark shapes in the disk pattern 114 may vary from at least 3, preferably 6 to 20, and more preferably 8 to 16. The segments in the form of circle are preferably in alternating colors in such a way that there is a sharp contrast between adjacent segments. The preferred colors are black and white. A reference mark 115, 120 resides in front of each disk pattern 112 and 114 respectively. This mark is particularly important where the disc pattern is symmetrical, as with the circle-shaped segments of the pattern 112, so that each full revolution of the disc can be observed, thus allowing the count of the number of incremental jumps in the image to be observed. of the video film by revolution of the disc. A colored band 124, preferably black, which is on a clear contrasting background, preferably white, and aligned with the reference mark 115 or 120 on the front of the disk could also be placed on the back of the disk. A light detector 126 is then installed on the back side of the disk and combined with an audio system 128 to provide a sound pulse each time the disk makes a complete revolution. Both the visual pattern and the sound pulse are then shielded by the videophone 102 to provide an image test and sound synchronization as transmitted by the videophone 102 and received by the videophone 101. The pulse frequency can also be used to determining the speed of the rotating disk 109. The size of the rotating disk pattern should be sufficient to substantially fill the entire field of view of the video camera or other image player. For conventional cameras, the diameter of the disc pattern is preferably 10 to 15 inches, more preferably 20 to 40 inches, and more preferably about 30 inches. In the basic operation, the test controller 108 is first adjusted to provide maximum performance for the line simulators 105 and 106 and the transmission link 107, such that the videophone 101 is optimized for resolution and the videophone 102 is optimized for the transmission of movement. The video signal for optimizing the resolution is generated by the camera of the videophone 101 observing the still image of the eye diagram 103, and this signal is shown on the visualization screen of the videophone 102. In this aspect, the resolution of an image of the Videophone usually decreases by increasing the observed movement speed. In other words, the resolution deteriorates (decreases) by increasing the amount of movement observed. The video signal for optimizing motion transmission is generated by the videophone camera 102, observing the rotating disc 109, and this signal is displayed on the videophone 101 display screen. With both videophones in operation, the speed of the rotating disc 109 is set low enough to provide continuous movement on the display screen of the videophone 101. The speed gradually increases while the resulting image is observed. Two criteria are judged, the modem speed, at which the videotelephones are linked, and the free input of the image received from the induced artifacts, such as the incremental intermittent motion. In a further test, the speed controller 116 is set to rotate the disk 109 at a designated angular velocity, and the line parameters of the line simulators 105 and 106 and / or transmission link 107 are adjusted to increasingly simulate insufficient transmission quality.

Transmission impairments may include, for example, various types of noise inputs, signal distortions, and line losses. By increasing the rotary speed of the disk 109, and / or by reducing the quality of the line transmissions, the modems associated in the videophones can successively decrease the baud rate of the transmission line, and the videophones can also alter their compression modems. in order to try to accommodate the reduction in transmission capacity to the videophone 101 or to some other display screen connected to the line simulator 105. The resulting image is seen on the videophone 101 or the other display screen connected to the line simulator 105. Since the link decreases, generally the frame rate of the video image will also decrease, so that the angle of rotation between successive video images on the display screen increases. At lower frame rates, the displayed movement increases. The standard or "reference", by which a videophone will be judged, can be provided by an independent video camera that observes the rotating disc and transmits its output directly to a display screen that has split screens, a side which displays the output of the independent camera, and the other side displays the input of the video signals to the videophone 101. The split screen display screen can be that of the videophone 101. In other words, the use of a split screen allows a comparison direct visual between the motion execution of a videophone with deterioration, and a display screen of the same movement observed on the basis of video signals without such deterioration, that is, the split screen allows direct visual comparison between video data transmissions deteriorated and without deteriorating based on the same observed movement. In the rotation of the low speed disk, the movement of the disk pattern appears to be substantially continuous, even when there are transmission impairments. By increasing the rotating speed of the disc, the unfolding movement is no longer continuous because it begins to have a large number of small incremental jumps, which can be referred to as oscillatory disturbances. In additional increments in speed, the number of increments decreases, while the size of the increments increases. In this way, at high disk speeds, there is a lower number of large incremental movements.

Referring now to FIG. 4, there is shown a schematic diagram of the components and electrical circuitry of the speed controller 116 for driving and controlling the rotating disk 109. 117 volt power is supplied from C.A. to a variable output transformer 132 through an on / off switch 130 and a 3 amp fuse 131. The output of the transformer 132 is rectified midway and filtered, and is adjustable to provide 10 volts of C.D. at the minimum disk speed, and 75 voliots of C.D. at the maximum disk speed. A switch 134 allows the direction of a drive motor 136 to be turned, so that the disk 109 can be turned in any direction. The motor 136 is connected to the disk 109 through a gearbox 138 having a speed reduction ratio of 200 to 1. The motor 136 may be a speed reduction motor, such as the NSH-11-R type made by the Bodine Electric Company, and preferably it is a 1/150 motor capable of 2,000 RPM at a rated input voltage maximum of 75 volts of CD, and 280 milliamps. The speed measurements are provided by a meter 142 having a scale with signs indicating from 0 to 10. The meter 142 is calibrated to read from 0 to 100 volts of C.D. by means of a calibration potentiometer having a variable resistor 140 connected through the power lines to the motor in series with the meter. Under this establishment, the minimum disc speed is approximately 0.5 revolutions per minute (RPM), and the maximum disc speed is approximately 10 RPM. A neon indicator lamp 144 may be provided to indicate the condition of the on / off switch 130. A second transformer 148 may be provided to supply 12 volt power of C.A. to an auxiliary module 150 containing the components and circuitry for operating the light detector 126 and the horn 128 to provide a tone signal at the start of each revolution of the disk 109, as previously described. The auxiliary module 150 can also provide TTL output to an oscilloscope to determine the synchronization of the output of visual and audio signals by the videophone 102. An instrument panel 151 for operating the motor 136 and includes a device is shown in FIG. selection 152 having signs 154 and a needle 156 to indicate the rotating speed (RPM) of disk 109. The rotary speed of disk 109 can be determined by the audio pulse frequency omitted by the horn 128, or by the rotation frequency of the reference mark 115 or 120 as determined with a chronograph or the like. The position of the needle 156 along the signs 154 is then calibrated relative to the different rotary speeds of the disc 109 by adjusting the variable resistance of the calibration potentiometer 140. The selection device 152 may have a scale of 0 to 10. , calibrating the meter 142 to read from 0 to 100 volts of CD The speed of the motor 136 can be varied manually by using a setting button 158 of the variable transformer 132. Also installed on the instrument panel 150 are the on / off switch 130, the forward / reverse switch 134, the indicator lamp 114, and the lid of the fuse holder 131, all as shown in Fig 5. Although the present invention has been described in terms of specific preferred embodiments of the invention, it should be clear that variations of the preferred embodiments can be planned by those skilled in the art when they learn of the invention. In this way, the present invention is only defined by the claims set forth below.

Claims (20)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and therefore the property described in the following claims is claimed as property. A method for testing the operation of a videophone, comprising: placing a rotating body within the visual field of said videophone, said rotating body having a visual pattern comprising a plurality of contrasting visual forms; connecting said videophone to a communication path; connecting said communication path to a deployment apparatus; and varying at least one of the rotary speeds of said rotary body and the characteristics of the communication path, while an image of said rotating body is observed on said deployment apparatus. The method, according to claim 1, for testing the operation of a videophone, characterized in that said display apparatus comprises the display screen of a videophone. The method, according to claim 1, for testing the operation of a videophone, characterized in that said step of variation comprises, changing the rotational speed of said rotating body. The method, according to claim 1, for testing the operation of a videophone, characterized in that said variation step comprises changing the transmission impairments of said communication path. The method, according to claim 1, for testing the operation of a videophone, characterized in that said body is a disk and said visual pattern is on one face of said disk. The method, according to claim 1, for testing the operation of a videophone, characterized in that said visual forms are dark objects of irregular shape on a light background. The method, according to claim 1, for testing the operation of a videophone, characterized in that said visual forms are segments in the form of a circle of alternate light and dark colors. The method, according to claim 7, for testing the operation of a videophone, characterized in that said visual pattern comprises segments in the form of white circles alternating with segments in the form of black circles. The method, according to claim 1, for testing the operation of a videophone, characterized in that said visual pattern includes a reference mark for determining a complete rotation of said body without regard to said contrasting visual forms. The method, according to claim 1, for testing the operation of a videophone, characterized in that said method further comprises the step of determining the rotational speed of said body with reference to a sound pulse emitted each time said body makes a revolution. complete rotation. 11. An apparatus for testing a videophone, comprising: a body having a visual pattern on at least one of its surfaces, said pattern comprising a plurality of contrasting visual forms; an engine for making the rotation of said body with said pattern that faces the front of said videophone; a display screen for detaching an image of the pattern on said rotating body; a communication path for connecting said videophone and said display screen; and, a control device for varying at least one of the speeds, to which said body rotates, and the characteristics of said communication path, while an image of the rotating body is observed on the display screen. The apparatus, according to claim 11, for testing a videophone, characterized in that said body is a disk and said visual pattern is on one face of said disk. 13. The apparatus, according to claim 11, for testing a videophone, characterized in that said visual forms are dark objects of irregular shape on a light background. 14. The device, according to claim 11, for testing a videophone, characterized in that said visual forms are segments in the form of a circle of alternating light and dark colors. 15. The apparatus according to claim 14, for testing a videophone, characterized in that said visual pattern comprises segments in the form of white circles alternating with segments in the form of black circles. The apparatus, according to claim 11, for testing a videophone, characterized in that said visual pattern includes a reference mark for determining a complete rotation of said body without regard to said contrasting visual forms. The apparatus, according to claim 11, for testing a videophone, characterized in that said apparatus further comprises an audio device for emitting a sound pulse each time said body makes a complete revolution of rotation. The apparatus, according to claim 17, for testing a videophone, characterized in that said body has a second visual pattern on at least one of its surfaces, said second visual pattern comprising a visual form of a color contrasted with a background of another color.; and wherein said audio device comprises a sensor that responds to the passage of said contrasted visual form, in such a way that each complete revolution of said body causes said audio device to emit said noise pulse. The apparatus, according to claim 18, for testing a videophone, characterized in that said body is a disk and said visual pattern with multiple visual forms is on a first face of said disk, and wherein said second visual pattern is on another side of said disc. The apparatus, according to claim 11, for testing a videophone, characterized in that said control device causes the speed, at which said body rotates to be varied within the range of approximately 0.5 RPM to approximately 10 RPM, and where said visual forms comprise of 4 to 8 segments in the form of a circle of a light color alternated with an equal number of segments in the form of circles of a dark color.