CA2102404A1 - Signal quality monitoring system - Google Patents
Signal quality monitoring systemInfo
- Publication number
- CA2102404A1 CA2102404A1 CA002102404A CA2102404A CA2102404A1 CA 2102404 A1 CA2102404 A1 CA 2102404A1 CA 002102404 A CA002102404 A CA 002102404A CA 2102404 A CA2102404 A CA 2102404A CA 2102404 A1 CA2102404 A1 CA 2102404A1
- Authority
- CA
- Canada
- Prior art keywords
- signal
- fourier transform
- video
- head
- transmitted
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N17/00—Diagnosis, testing or measuring for television systems or their details
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/28—Measuring attenuation, gain, phase shift or derived characteristics of electric four pole networks, i.e. two-port networks; Measuring transient response
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/28—Testing of electronic circuits, e.g. by signal tracer
- G01R31/282—Testing of electronic circuits specially adapted for particular applications not provided for elsewhere
- G01R31/2825—Testing of electronic circuits specially adapted for particular applications not provided for elsewhere in household appliances or professional audio/video equipment
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/10—Adaptations for transmission by electrical cable
Abstract
ABSTRACT OF THE DISCLOSURE
A cable television signal for example may be monitored and impairments determined and in many cases classified by grabbing at least portion of a transmitted frame of video information somewhere on the network to provide a video signal, performing a two dimensional Fourier transform on the video signal and analyzing the Fourier transform so obtained to determine the location of areas indicating above average occurrence of specific frequencies to provide an indication of an impairment.
A cable television signal for example may be monitored and impairments determined and in many cases classified by grabbing at least portion of a transmitted frame of video information somewhere on the network to provide a video signal, performing a two dimensional Fourier transform on the video signal and analyzing the Fourier transform so obtained to determine the location of areas indicating above average occurrence of specific frequencies to provide an indication of an impairment.
Description
~ ` 2 ~
SIGNAL QU~LITY MONITORING SYSTEM
Field of the In~vention 1 he present invention relates to a system for signal quali~
monitoring. More particularly the present invention relates to a system for S monitoring a cable television signal using image analyses.
Bacl~ound of the Present Invention The quality of cable t.v. pictures is of great concern to cable companies as well as to their viewers. These cable networks carry dozens of 10 television channel signals a~d programs into millions of homes by transmitting ~he signal along a transmission line, ampli~ying the signal at various locationsalong the system to maintain the strength and quality of the transrnitted signalas close as possible to the signal being transmitted at the head end or transmitting station.
There are many opportunities for extraneous signals to be picked up in line. Such impairment may arise from a variety of different sources. For example, intermodulation problems generally appear on the screen as diagonal bands that may be either narrow or quite broad depending on relationship of the intermodulation frequency with the frequency of the picture carrier. Composite 20 triple beat impalrment has video characteristics of graininess or texture effect over the entire picture. These are generally caused by overdriven cable amplifiers. -Another common problem with television transrnission via cable ~;
networks is snow noise which is generally caused by a weak signal which results 25 in a poor (small~ carrier to noise ratio. Faults in the cable transrnission system itsel~ such as poor cable splices, badly coupled cable connec~ions, or impedancewhish mismatch in the cable system may also result in noise.
Yet another common problem with cable t.v. reception is power line inter~erence which appears as horizontal lines on the television screen.
No automatictelevisionpicture qualitymonitoring systemhas been ava~lable to cable television suppliers and it is believed there is no known adequate system for monitorillg.
The concept of applying a Fourier transform to a signal is not new.
~ 2~ ~2~
ThfiS has been practised ~or many years in a variety of different industries.
Similarly two dimensional Fourier transforms have been used. For example, as taught in U.S. patent 4,f843,631 where it is used for pattern recognition in a pattern recognition process which, in order to locate an image content or a S portion of an original image which is identical with a reEerence pattern, the received reference pattern or a two diminsional Fourier transform thereof is compared to the image content or portion in respect of size and orientation by inverse rotary extension with the ascertained twist angle of enlargement factor to find the position or positions at which the reference pattern when converted in that way has maximum identity with a section of the image.
Brief Descr~fption of the Present Invention It is an object of the present invention to provide a cable television picture monitoring system to detect signal impairment affecting the picture quality receiYed by subscribers.
It is a further object of the present invention to provide an image processing system for analyzing a selected video frame or portion thereof to deterrnine the quality of the signal used to generate the frame at or near the location where the frfame is to be sff-~en.
Broadly the present invention relates to a signal quality monitoring system comprising grabbing at least a portion of a selected transrnitted frame of video informatioll transmitted from a head end at a mornfitoring station away from said head~end to provide a video frame signal performfing a two dimensional Fourier trallsform of at least a selected area of said video frame signal to obtain a two dimensional Fourier trans~orm of video frequencies versusfrequency of occurrence, analyzing said two dimensional Fourier transforrn to determinfe areas ha~ing above average occurrence of specific frefsluencies to provide an indication of signal impairments included in said selected area of said video fraIne signal.
Preferably said steps will be repeated periodically on a routine basis to provide continuing detailed information of the siffgnal at said monitoring station. ~
Preferably said transform is provided at said head end and used f' r ~ 2 1 ~
to alert repairmen as to the signal at the monitoring station.
It is also possible to subtract from the video frame signal, the corresponding video frame signal as transrnitted from the head end to form an impairment signal and then yerform a two dimensional Fourier transform on the S impairment signal to provide indications of impairmen~s and types of impairments.
Brief De~cription of the Dr~wings Further features, objec~s and advantages will be evident from the following detailed description of the preferred embodiments of the present 10 invent;on taken in conjunction with the accompanying drawings in which.
Figure 1 is a schematic illustration of a transm~ssion system for cable television incorporating the present invention.
Figure 2 is a schematic illustration of the monitoring system of the present invention.
Figure 3 is an illustration of a picture or frame impaired by intermodulation with a signal to noise ratio of 40 decibels, and Figure 4 is a two dimensional Fourier transform of impairmen~s of the picture in Figure 3 obtained by subtracting the original image from the impaired image.
Figure S shows the signal with snow noise having a signal to noise -ratio of 33 decibels and Figure 6 is two diminsional Fourier spectra of the impairment obtained by subtracting the original image from the impaired image.
Figure 7 illustra~es a substantially normal image alld Figure 8 is a two dirninsional Fourier transform of the grabbed picture of Figure 7.
Figure 9 is a two diminsional Fourier transform of the actual picture or frame of Figure 3 without the subtraction of the frame as originally transrnitted. '~ -Figure 10 is a two diminsional Fourier transform of the actual picture or frame as shown in Figure S without the subtraction of the frame as originally transmitted.
, .~, ;" ~ . -,;, . . . .
4 2.1~.04 Description oî the Preiérred Embodiments Before describing the invention plese note that all Figures of two diminsional Fourier transforms exhibit amplitudes of the transforms verses horizontal and vertical spatial frequencies The present invention is generally indicated in Figures 1 and 2 with the cable transmitting system indicated in Figure 1 at 10 arld the signal quality monitoring system 100 in Figure 2.
The cable system is generally composed of a transmission station or head end 12 which transmits via a signal transmission line 14, television signals for a plurality of different channels to a plurality of different locations, i.e. users homes and the like where the television picture is viewed.
As above indicated impairments creep into the transmitted signal for various reasons and at various positions along the transmission path as defined by the transnussion conductor systems represented by the lines 14.
lS Frame grabber or monitoring stations as indicated 16 are provided at selected locations in the transmission system formed by the lines 14. These monitoring or frame grab stations 16 periodically grab a selected video frame signal being transmitted along the line 14 at that particular location to provide a v;deo frame signal to be subjected to analyses.
The frame grab station 16 may perform various operations on the video frame signal or may recode the video frame signal and return it to the ;head end in for processing or may carry out all of the processing at the station16 and code and transrnit only the end results or findings baclc to the head endfor further processing and display, i.e. the monitoring station 16 mus~ be 2S physically located at particular locations along the transmission path 14 for the signal however, image proeessing of the grabbed image may be performed wherever is jmost suitable, it being important that the information be comm~micated to the required location where it can be used which normally will be at the head end 12. Thus the fraIne grab or monitoring sta~ion 16 transmits information as indicated by the dotted lines 18 back to the head end so that theimpairments and their locations can be displayed as indicated on the display module 20. -Reference to Figure 2 indicating the monitoring system 100 has a 5 2 ~
frame grab 102 that forms part of the frame grab monitoring station 16 there being a separate frame grab 102 in each of the stations. The frame so grabbed is then subject to the formation of a two d;rnensional Fourier transform (FT) asindicated at 104. This Fourier transform FT is analyzed for impairments as 5 indicated a~ 106 and then a suitable signal transmitted to the impairment display 20 which is substantially equivalent to the impairrnent display of Figure 1. If desired the two dimensional Fourier transform may simply be displa~ed together with the location from which it is received.
It was initially believed that it would be necessary to carry on the 10 actions indlcated in the dash lines in Figure 2 namely that a Fourier transform of the corresponding frame to that grabbed by the tesit frame grabber 102 as transrnitted would have to he obtained as indica~ed at 10B, i.e. the Fourier transform of the frame as transmitted (designated as CFT) would have to be determined and then a step of subtraction of FT from CFT to provide the 15 Fourier transform FTl ( i.e. Fr - CFT = FT,) would have to be per~ormed as indicated by the box 110 and this modified Fourier transform FTl would have to be submitted for analyses as indicated at 106 iand displayed via the display ~0.
The development of the present invention is illustrated in the remal~ung figures. ~, Figure 3 illustrates a typical picture being impaired by an intermodulation having a signal to noise ratio of about 40 decibels. This signalin the original concept of the present invention was produced and a two dimensional Fourier transiform of the original signal without the intermodulation, i.e. as transmitted, was obtained as indicated at 108 iand the two transforms were then subtrac~ed to result in modified Fourier tria~sform as indicated at 110 in Fi~re 2. The modified Fourier transform so obtained is indicated in Figure 4, which it will jbe apparent includes a plurality of space irregularities. These irregularities always occur in groups, each group somprising a pair of pulses symetrically positioned around the origin and located on ~he same vertical line. ~`
and the posi~ion of the irregularities provides an indication of the type of irreguliarity, while the size of the irregularity indicates the severity of ~he irregularity or signal imparment.
Figure S shows a television picture that has been impaired by snow 2~
noise having signal to no;se ratio of 33 decibels and Figure 6 is a modified Fourier transform FTl sim~lar to Figure 4 but of the picture of Figure 5, i.e. the Fourier transform for the picture of Figure S was produced and the Fourier transform for the picture of Figure 5 as transmitted was produced and then S subtracted from the other wich results in the modified Fourier transform of Figure 6. It will be noted that the impairment of snow appears as substantially a vertical band of spaced dots.
It will be apparent that both Figures 4 and Figure 6 show that impairments are distinguishable in the modified Fourier transform which are shown in plan view.
The above technique requires that two corresponding signals be used which for accuracy required that a known signal be be transrnitted without disturbing the viewer and that this known frame be grabbed at the station 16 and used in the process which makes ~his process difficult to car~y out, particularly commercially.
As the invention developed, a Fourier transform was made of a non-impaired signal, particularly a Fourier transform as indicated in Figure 8 was made based on the picture shown in Figure 7 wherein the picture in Figure 7 was relatively clean and had few, if any, impairments.
It will be noted that the two dimensional Fourier transform of Figure 8 shows a low frequency spike 40 substantially in the middle of the ;~Fourier transform. I~ has been found that similar spikes are generally found when most frames are transrnitted and that the positio~ of this spike does not materially affect the disposition of the spikes formed by impairments to the picture, thus the step of subtracting the two dimension Fourier transform of theoriginally transmitted image was determined not to be essential.
~Figure 9 shows a two dimensional Fourier transforrn for the picture illustrated in Figure 3. It will be noted that the central spike remains as indicated at 50 and that two small pealcs indicated at 52 and 54 symmetrically positioned relative to the peak 50 are generated and that horizontal lines of modified frequencies are formed as indicated at 56 and 58.
The two dimensional Fourier transform illustrated in Figure 10 which corresponds to a Fourier trans~orm of the picture or frame illustrated in . ' ' ` "
- `
Figure S has the similar spike 60 which is common to substantially all normal pictures plus a line of frequency disturbances as indicated at 62 along a line of high and low frequencies (s;gnal frequencies) and at a preselected range.
It will thus be apparent that the analysis of the two dimensional S Fourier transfer of the grabbed signal frame may be used to determine impairments and that each impairment results in a different distortion of the two dirnensional Fourier transform which thereby permits classification of the impairment to facilitate the work of the repairman.
It will be apparent that by providing a separate code for each of 10 the monitoring station locations where the impairment is discovered can be pinpointed and by the use of the two dimensional Fourier transform the actual type of impairment and the extent of the impairment may also be defined.
Having described the invention, modifications will be evident to those skilled in the art without departing from the spirit of the in~ention as 15 defined in the ~ppended claims.
'' ' i
SIGNAL QU~LITY MONITORING SYSTEM
Field of the In~vention 1 he present invention relates to a system for signal quali~
monitoring. More particularly the present invention relates to a system for S monitoring a cable television signal using image analyses.
Bacl~ound of the Present Invention The quality of cable t.v. pictures is of great concern to cable companies as well as to their viewers. These cable networks carry dozens of 10 television channel signals a~d programs into millions of homes by transmitting ~he signal along a transmission line, ampli~ying the signal at various locationsalong the system to maintain the strength and quality of the transrnitted signalas close as possible to the signal being transmitted at the head end or transmitting station.
There are many opportunities for extraneous signals to be picked up in line. Such impairment may arise from a variety of different sources. For example, intermodulation problems generally appear on the screen as diagonal bands that may be either narrow or quite broad depending on relationship of the intermodulation frequency with the frequency of the picture carrier. Composite 20 triple beat impalrment has video characteristics of graininess or texture effect over the entire picture. These are generally caused by overdriven cable amplifiers. -Another common problem with television transrnission via cable ~;
networks is snow noise which is generally caused by a weak signal which results 25 in a poor (small~ carrier to noise ratio. Faults in the cable transrnission system itsel~ such as poor cable splices, badly coupled cable connec~ions, or impedancewhish mismatch in the cable system may also result in noise.
Yet another common problem with cable t.v. reception is power line inter~erence which appears as horizontal lines on the television screen.
No automatictelevisionpicture qualitymonitoring systemhas been ava~lable to cable television suppliers and it is believed there is no known adequate system for monitorillg.
The concept of applying a Fourier transform to a signal is not new.
~ 2~ ~2~
ThfiS has been practised ~or many years in a variety of different industries.
Similarly two dimensional Fourier transforms have been used. For example, as taught in U.S. patent 4,f843,631 where it is used for pattern recognition in a pattern recognition process which, in order to locate an image content or a S portion of an original image which is identical with a reEerence pattern, the received reference pattern or a two diminsional Fourier transform thereof is compared to the image content or portion in respect of size and orientation by inverse rotary extension with the ascertained twist angle of enlargement factor to find the position or positions at which the reference pattern when converted in that way has maximum identity with a section of the image.
Brief Descr~fption of the Present Invention It is an object of the present invention to provide a cable television picture monitoring system to detect signal impairment affecting the picture quality receiYed by subscribers.
It is a further object of the present invention to provide an image processing system for analyzing a selected video frame or portion thereof to deterrnine the quality of the signal used to generate the frame at or near the location where the frfame is to be sff-~en.
Broadly the present invention relates to a signal quality monitoring system comprising grabbing at least a portion of a selected transrnitted frame of video informatioll transmitted from a head end at a mornfitoring station away from said head~end to provide a video frame signal performfing a two dimensional Fourier trallsform of at least a selected area of said video frame signal to obtain a two dimensional Fourier trans~orm of video frequencies versusfrequency of occurrence, analyzing said two dimensional Fourier transforrn to determinfe areas ha~ing above average occurrence of specific frefsluencies to provide an indication of signal impairments included in said selected area of said video fraIne signal.
Preferably said steps will be repeated periodically on a routine basis to provide continuing detailed information of the siffgnal at said monitoring station. ~
Preferably said transform is provided at said head end and used f' r ~ 2 1 ~
to alert repairmen as to the signal at the monitoring station.
It is also possible to subtract from the video frame signal, the corresponding video frame signal as transrnitted from the head end to form an impairment signal and then yerform a two dimensional Fourier transform on the S impairment signal to provide indications of impairmen~s and types of impairments.
Brief De~cription of the Dr~wings Further features, objec~s and advantages will be evident from the following detailed description of the preferred embodiments of the present 10 invent;on taken in conjunction with the accompanying drawings in which.
Figure 1 is a schematic illustration of a transm~ssion system for cable television incorporating the present invention.
Figure 2 is a schematic illustration of the monitoring system of the present invention.
Figure 3 is an illustration of a picture or frame impaired by intermodulation with a signal to noise ratio of 40 decibels, and Figure 4 is a two dimensional Fourier transform of impairmen~s of the picture in Figure 3 obtained by subtracting the original image from the impaired image.
Figure S shows the signal with snow noise having a signal to noise -ratio of 33 decibels and Figure 6 is two diminsional Fourier spectra of the impairment obtained by subtracting the original image from the impaired image.
Figure 7 illustra~es a substantially normal image alld Figure 8 is a two dirninsional Fourier transform of the grabbed picture of Figure 7.
Figure 9 is a two diminsional Fourier transform of the actual picture or frame of Figure 3 without the subtraction of the frame as originally transrnitted. '~ -Figure 10 is a two diminsional Fourier transform of the actual picture or frame as shown in Figure S without the subtraction of the frame as originally transmitted.
, .~, ;" ~ . -,;, . . . .
4 2.1~.04 Description oî the Preiérred Embodiments Before describing the invention plese note that all Figures of two diminsional Fourier transforms exhibit amplitudes of the transforms verses horizontal and vertical spatial frequencies The present invention is generally indicated in Figures 1 and 2 with the cable transmitting system indicated in Figure 1 at 10 arld the signal quality monitoring system 100 in Figure 2.
The cable system is generally composed of a transmission station or head end 12 which transmits via a signal transmission line 14, television signals for a plurality of different channels to a plurality of different locations, i.e. users homes and the like where the television picture is viewed.
As above indicated impairments creep into the transmitted signal for various reasons and at various positions along the transmission path as defined by the transnussion conductor systems represented by the lines 14.
lS Frame grabber or monitoring stations as indicated 16 are provided at selected locations in the transmission system formed by the lines 14. These monitoring or frame grab stations 16 periodically grab a selected video frame signal being transmitted along the line 14 at that particular location to provide a v;deo frame signal to be subjected to analyses.
The frame grab station 16 may perform various operations on the video frame signal or may recode the video frame signal and return it to the ;head end in for processing or may carry out all of the processing at the station16 and code and transrnit only the end results or findings baclc to the head endfor further processing and display, i.e. the monitoring station 16 mus~ be 2S physically located at particular locations along the transmission path 14 for the signal however, image proeessing of the grabbed image may be performed wherever is jmost suitable, it being important that the information be comm~micated to the required location where it can be used which normally will be at the head end 12. Thus the fraIne grab or monitoring sta~ion 16 transmits information as indicated by the dotted lines 18 back to the head end so that theimpairments and their locations can be displayed as indicated on the display module 20. -Reference to Figure 2 indicating the monitoring system 100 has a 5 2 ~
frame grab 102 that forms part of the frame grab monitoring station 16 there being a separate frame grab 102 in each of the stations. The frame so grabbed is then subject to the formation of a two d;rnensional Fourier transform (FT) asindicated at 104. This Fourier transform FT is analyzed for impairments as 5 indicated a~ 106 and then a suitable signal transmitted to the impairment display 20 which is substantially equivalent to the impairrnent display of Figure 1. If desired the two dimensional Fourier transform may simply be displa~ed together with the location from which it is received.
It was initially believed that it would be necessary to carry on the 10 actions indlcated in the dash lines in Figure 2 namely that a Fourier transform of the corresponding frame to that grabbed by the tesit frame grabber 102 as transrnitted would have to he obtained as indica~ed at 10B, i.e. the Fourier transform of the frame as transmitted (designated as CFT) would have to be determined and then a step of subtraction of FT from CFT to provide the 15 Fourier transform FTl ( i.e. Fr - CFT = FT,) would have to be per~ormed as indicated by the box 110 and this modified Fourier transform FTl would have to be submitted for analyses as indicated at 106 iand displayed via the display ~0.
The development of the present invention is illustrated in the remal~ung figures. ~, Figure 3 illustrates a typical picture being impaired by an intermodulation having a signal to noise ratio of about 40 decibels. This signalin the original concept of the present invention was produced and a two dimensional Fourier transiform of the original signal without the intermodulation, i.e. as transmitted, was obtained as indicated at 108 iand the two transforms were then subtrac~ed to result in modified Fourier tria~sform as indicated at 110 in Fi~re 2. The modified Fourier transform so obtained is indicated in Figure 4, which it will jbe apparent includes a plurality of space irregularities. These irregularities always occur in groups, each group somprising a pair of pulses symetrically positioned around the origin and located on ~he same vertical line. ~`
and the posi~ion of the irregularities provides an indication of the type of irreguliarity, while the size of the irregularity indicates the severity of ~he irregularity or signal imparment.
Figure S shows a television picture that has been impaired by snow 2~
noise having signal to no;se ratio of 33 decibels and Figure 6 is a modified Fourier transform FTl sim~lar to Figure 4 but of the picture of Figure 5, i.e. the Fourier transform for the picture of Figure S was produced and the Fourier transform for the picture of Figure 5 as transmitted was produced and then S subtracted from the other wich results in the modified Fourier transform of Figure 6. It will be noted that the impairment of snow appears as substantially a vertical band of spaced dots.
It will be apparent that both Figures 4 and Figure 6 show that impairments are distinguishable in the modified Fourier transform which are shown in plan view.
The above technique requires that two corresponding signals be used which for accuracy required that a known signal be be transrnitted without disturbing the viewer and that this known frame be grabbed at the station 16 and used in the process which makes ~his process difficult to car~y out, particularly commercially.
As the invention developed, a Fourier transform was made of a non-impaired signal, particularly a Fourier transform as indicated in Figure 8 was made based on the picture shown in Figure 7 wherein the picture in Figure 7 was relatively clean and had few, if any, impairments.
It will be noted that the two dimensional Fourier transform of Figure 8 shows a low frequency spike 40 substantially in the middle of the ;~Fourier transform. I~ has been found that similar spikes are generally found when most frames are transrnitted and that the positio~ of this spike does not materially affect the disposition of the spikes formed by impairments to the picture, thus the step of subtracting the two dimension Fourier transform of theoriginally transmitted image was determined not to be essential.
~Figure 9 shows a two dimensional Fourier transforrn for the picture illustrated in Figure 3. It will be noted that the central spike remains as indicated at 50 and that two small pealcs indicated at 52 and 54 symmetrically positioned relative to the peak 50 are generated and that horizontal lines of modified frequencies are formed as indicated at 56 and 58.
The two dimensional Fourier transform illustrated in Figure 10 which corresponds to a Fourier trans~orm of the picture or frame illustrated in . ' ' ` "
- `
Figure S has the similar spike 60 which is common to substantially all normal pictures plus a line of frequency disturbances as indicated at 62 along a line of high and low frequencies (s;gnal frequencies) and at a preselected range.
It will thus be apparent that the analysis of the two dimensional S Fourier transfer of the grabbed signal frame may be used to determine impairments and that each impairment results in a different distortion of the two dirnensional Fourier transform which thereby permits classification of the impairment to facilitate the work of the repairman.
It will be apparent that by providing a separate code for each of 10 the monitoring station locations where the impairment is discovered can be pinpointed and by the use of the two dimensional Fourier transform the actual type of impairment and the extent of the impairment may also be defined.
Having described the invention, modifications will be evident to those skilled in the art without departing from the spirit of the in~ention as 15 defined in the ~ppended claims.
'' ' i
Claims (5)
1. A signal quality monitoring method comprising grabbing at least a portion of a selected transmitted frame of video information transmitted from a head-end at a monitoring station away from said head end to provide a video frame signal, performing a two dimensional Fourier transform of at least a selected area of said video frame signal to obtain a two dimensional Fourier transform of amplitudes versus horizontal and vertical spatial frequencies, analyzing said two dimensional Fourier transform to determine areas having above average occurrence of specific frequencies to provide an indication of signal impairments included in said selected area of said video frame signal.
2. A method as defined in claim 1 wherein said steps of grabbing, performing a two diminsional Fourier transform and analyzing are repeated periodically on a routine basis to provide continuing detailed information of the video information at said monitoring station.
3. A method as defined in claim 1 wherein said transform is provided at said head-end and used to alert repairmen as to the signal at the monitoring station.
4. A method as defined in claim 2 wherein said transform is provided at said head-end and used to alert repairmen as to the signal at the monitoring station.
5. A method as defined in claim 1 further comprising forming a two diminsional Fourier transform of the video signal signal as transmitted by said head-end corresponding to said video frame signal, subtracting the Fournier transform of the video signal as transmitted from the Fourier transform of the video frame signal to form modified two dimensional Fourier transform to provide indications of impairments and types of impairments.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/696,945 US5221967A (en) | 1991-05-08 | 1991-05-08 | Signal quality monitoring system |
| US696,945 | 1991-05-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2102404A1 true CA2102404A1 (en) | 1992-11-09 |
Family
ID=24799150
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002102404A Abandoned CA2102404A1 (en) | 1991-05-08 | 1992-05-05 | Signal quality monitoring system |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US5221967A (en) |
| EP (1) | EP0583275A1 (en) |
| JP (1) | JP3103594B2 (en) |
| CA (1) | CA2102404A1 (en) |
| WO (1) | WO1992020194A1 (en) |
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| WO1994003872A1 (en) * | 1992-07-31 | 1994-02-17 | Pressco Technology, Inc. | Inspection system using compressed image data |
| FR2694813B1 (en) * | 1992-08-12 | 1994-11-04 | Pierre Itibar | Network remote control and maintenance system. |
| US5446492A (en) * | 1993-01-19 | 1995-08-29 | Wolf; Stephen | Perception-based video quality measurement system |
| US5325198A (en) * | 1993-03-31 | 1994-06-28 | General Electric Company | Unitary transform methods of identifying defects in imaging devices |
| US5329311A (en) * | 1993-05-11 | 1994-07-12 | The University Of British Columbia | System for determining noise content of a video signal in the disclosure |
| US5654751A (en) * | 1995-05-31 | 1997-08-05 | Bell Atlantic Network Services, Inc. | Testing jig and method of testing video using testing jig |
| US5661529A (en) * | 1995-06-07 | 1997-08-26 | The University Of British Columbia | Measurement of noise impairments of TV signals |
| US5790199A (en) * | 1997-03-06 | 1998-08-04 | International Business Machines Corporation | Method and apparatus to accommodate partial picture input to an MPEG-compliant encoder |
| GB9713790D0 (en) * | 1997-07-01 | 1997-09-03 | Raychem Sa Nv | Noise monitoring unit |
| GB2329294B (en) * | 1997-09-11 | 2002-01-16 | Hamlet Video Internat Ltd | Signal monitoring apparatus |
| US6219095B1 (en) | 1998-02-10 | 2001-04-17 | Wavetek Corporation | Noise measurement system |
| JP3566546B2 (en) * | 1998-04-01 | 2004-09-15 | Ｋｄｄｉ株式会社 | Image quality abnormality detection method and apparatus |
| US6285797B1 (en) * | 1999-04-13 | 2001-09-04 | Sarnoff Corporation | Method and apparatus for estimating digital video quality without using a reference video |
| US6943827B2 (en) * | 2001-04-16 | 2005-09-13 | Kddi Corporation | Apparatus for monitoring quality of picture in transmission |
| CA2344930C (en) * | 2001-04-23 | 2007-04-17 | Leitch Technology International Inc. | Data monitoring system |
| TWI268813B (en) * | 2002-04-24 | 2006-12-21 | Sipix Imaging Inc | Process for forming a patterned thin film conductive structure on a substrate |
| US7925206B2 (en) | 2003-12-10 | 2011-04-12 | The Boeing Company | Systems and methods for providing adaptive wireless connectivity |
| US8294772B2 (en) * | 2009-01-29 | 2012-10-23 | Pelco, Inc. | System and method for monitoring connections within an analog video system |
| US8923135B2 (en) | 2010-06-24 | 2014-12-30 | At&T Intellectual Property I, L.P. | System and method to detect a fault in transmission of a stream of media data corresponding to a media channel |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS609384B2 (en) * | 1980-01-29 | 1985-03-09 | 郵政省電波研究所長 | Code error noise suppression method |
| JPS57196678A (en) * | 1981-05-27 | 1982-12-02 | Pioneer Electronic Corp | Table network managing mechanism in catv system |
| US4630228A (en) * | 1982-06-28 | 1986-12-16 | Systron-Donner Corporation | Transmission line analyzer for automatically identifying the severities and locations of multiple mismatches |
| US4633411A (en) * | 1982-12-27 | 1986-12-30 | Rockwell International Corporation | Link quality analyzer |
| AU587103B2 (en) * | 1985-12-20 | 1989-08-03 | Gerhard Wolfgang Osterreicher | Pattern recognition process |
| US4901147A (en) * | 1987-03-30 | 1990-02-13 | Kabushiki Kaisha Toshiba | Video system with self-diagnose function |
| US5047724A (en) * | 1989-12-19 | 1991-09-10 | Bell Communications Research, Inc. | Power cable arcing fault detection system |
| US5073822A (en) * | 1990-11-19 | 1991-12-17 | Tektronix, Inc. | In-service cable television measurements |
-
1991
- 1991-05-08 US US07/696,945 patent/US5221967A/en not_active Expired - Lifetime
-
1992
- 1992-05-05 EP EP92908960A patent/EP0583275A1/en not_active Ceased
- 1992-05-05 CA CA002102404A patent/CA2102404A1/en not_active Abandoned
- 1992-05-05 JP JP04508411A patent/JP3103594B2/en not_active Expired - Fee Related
- 1992-05-05 WO PCT/CA1992/000187 patent/WO1992020194A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| JP3103594B2 (en) | 2000-10-30 |
| JPH06507280A (en) | 1994-08-11 |
| WO1992020194A1 (en) | 1992-11-12 |
| US5221967A (en) | 1993-06-22 |
| EP0583275A1 (en) | 1994-02-23 |
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| Date | Code | Title | Description |
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| FZDE | Dead |