Patent US4807285A successfully refreshed from Google Patents.
US4807285A
Expired / Lapsed
US
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Method and apparatus for scrambling a television signal
Assignee: Eagle Comtronics Inc
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Filing: 1982-04-23
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Granted: 1989-02-21
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Expires: 2002-04-23
Abstract
Abstract An in-band television signal scrambling method and apparatus are disclosed which employ a scrambler which receives and scrambles a television signal by suppressing the amplitude of the horizontal synchronizing signals contained therein to a point below the "black" level and which generates whiter-than-white timing pulses in the scrambled television signal for use by a descrambler in reconstructing the suppressed amplitude horizontal synchronizing signals, and one or more descramblers for detecting the whiter-than-white timing pulses in the scrambled television signal and generating therefrom switching signals for a switchable attenuator through which the scrambled television signal passes. The attenuator boosts the amplitude of the suppressed amplitude horizontal synchronizing signals relative to the remainder of the scrambled television signal, thereby restoring the scrambled television signal to an unscrambled condition.
Inventors
- 👤 Dale W. Marland
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 00:09
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/16; H04N7/167; H04N7/171; H04N7/1713
Claims Analysis
Total Claims: 51
Claim 1
Independent Claim
157 words
An apparatus for scrambling a television signal containing horizontal and vertical synchronizing signals and image information signals, said apparatus comprising: means for receiving said television signal; a first detector for deriving horizontal synchronizing signals from said television signal; first signal generating means responsive to the output of said first detector for generating horizontal sync suppression pulses at times corresponding to the occurrence of horizontal synchronizing signals in said television signal; second signal generating means responsive to the output of said first detector for generating timing pulses which are related in time to said horizontal sync suppression pulses; switchable means responsive to the output of said first and second signal generating means for selectively forcing the amplitude of said television signal to a first predetermined level upon the occurrence of said horizontal sync suppression pulses, and for selectively forcing the amplitude of said television signal to a second predetermined whiter-than-white level upon the occurrence of said timing pulses.
Claim 2
Independent Claim
157 words
An apparatus for scrambling a television signal containing horizontal and vertical synchronizing signals and image information signals, said apparatus comprising: means for receiving said television signal; a first detector for deriving horizontal synchronizing signals from said television signal; first signal generating means responsive to the output of said first detector for generating horizontal sync suppression pulses at times corresponding to the occurrence of horizontal synchronizing signals in said television signal; second signal generating means responsive to the output of said first detector for generating timing pulses which are related in time to said horizontal sync suppression pulses; switchable means responsive to the output of said first and second signal generating means for selectively forcing the amplitude of said television signal to a first predetermined level upon the occurrence of said horizontal sync suppression pulses, and for selectively forcing the amplitude of said television signal to a second predetermined whiter-than-white level upon the occurrence of said timing pulses.
Claim 3
Dependent Claim
22 words
An apparatus as in claim 1 wherein said first level is within an amplitude range normally occupied by said image information signals.
Claim 4
Independent Claim
34 words
An apparatus as in claims 1 or 2 wherein said switchable means force the amplitude of said television signal to said first predetermined level for the duration of each said horizontal sync suppression pulse.
Claim 5
Independent Claim
32 words
An apparatus as in claims 1 or 2 wherein said switchable means forces the amplitude of said television signal to said second predetermined level for the duration of each said timing pulse.
Claim 6
Independent Claim
16 words
An apparatus as in claims 1 or 2 wherein said switchable means is a switchable attenuator.
Claim 7
Dependent Claim
28 words
An apparatus as in claim 5 wherein said switchable attenuator attenuates said television signal by approximately 6 db or more in response to said horizontal sync suppression pulses.
Claim 8
Dependent Claim
26 words
An apparatus as in claim 5 wherein said switchable attenuator attenuates said television signal by approximately 20 db or more in response to said timing pulses.
Claim 9
Independent Claim
54 words
An apparatus as in claims 1 or 2 further comprising a second detector for deriving vertical synchronizing signals from said television signal, and means responsive to the output of said second detector for preventing the generation of said horizontal sync suppression pulse during the occurrences of said vertical synchronizing signals in said television signal.
Claim 10
Independent Claim
33 words
An apparatus as in claims 1 or 2 wherein said horizontal sync suppression pulses have a width equal to or greater than the width of said horizontal synchronizing signals in said television signal.
Claim 11
Dependent Claim
27 words
An apparatus as in claim 4 wherein said timing pulses have a width which is less than that of said horizontal synchronizing signals in said television signal.
Claim 12
Dependent Claim
18 words
An apparatus as in claim 10 wherein said timing pulses have a width of approximately 2 micro seconds.
Claim 13
Dependent Claim
60 words
An apparatus as in claim 8 wherein said preventing means comprises means for generating a blanking signal during the occurrence of said vertical synchronizing signals and a gate means connected to the output of said blanking signal generating means for blocking the passage of said horizontal sync suppression pulses to said switchable means upon the generation of said blanking signal.
Claim 14
Dependent Claim
30 words
An apparatus as in claim 1 wherein said second signal generating means includes a pulse generator which generates a timing pulse upon the occurrence of each horizontal sync suppression pulse.
Claim 15
Independent Claim
37 words
An apparatus as in claims 1 or 2 wherein the amplitude of said television signal is forced to said second predetermined level during an interval corresponding to a front porch which precedes each said horizontal synchronizing signal.
Claim 16
Independent Claim
123 words
An apparatus for descrambling a scrambled television signal containing image information signals, vertical snychronizing signals, suppressed amplitude horizontal synchronizing signals, and horizontal synchronizing reconstruction signals in the form of whiter-than-white pulses in said television signal, said apparatus comprising: means for receiving said television signal; switchable means for selectively boosting the amplitude of said suppressed amplitude horizontal synchronizing signals relative to the remainder of said television signal; means for deriving said whiter-than-white pulses from said television signal; means responsive to said deriving means for generating a pulsed control signal in response to said detected whiter-than-white pulses and for selectively operating said switchable means with said pulsed control signal to boost said suppressed amplitude horizontal synchronizing signals relative to the remainder of said television signal.
Claim 17
Independent Claim
123 words
An apparatus for descrambling a scrambled television signal containing image information signals, vertical snychronizing signals, suppressed amplitude horizontal synchronizing signals, and horizontal synchronizing reconstruction signals in the form of whiter-than-white pulses in said television signal, said apparatus comprising: means for receiving said television signal; switchable means for selectively boosting the amplitude of said suppressed amplitude horizontal synchronizing signals relative to the remainder of said television signal; means for deriving said whiter-than-white pulses from said television signal; means responsive to said deriving means for generating a pulsed control signal in response to said detected whiter-than-white pulses and for selectively operating said switchable means with said pulsed control signal to boost said suppressed amplitude horizontal synchronizing signals relative to the remainder of said television signal.
Claim 18
Dependent Claim
25 words
An apparatus as in claim 15 wherein said whiter-than-white pulses are located in or adjacent an interval occupied by said suppressed amplitude horizontal synchronizing signals.
Claim 19
Dependent Claim
26 words
An apparatus as in claim 16 wherein each said whiter-than-white pulse is located on a front porch which precedes a respective suppressed amplitude horizontal synchronizing signal.
Claim 20
Dependent Claim
15 words
An apparatus as in claim 15 wherein said switchable means is a switched signal attenuator.
Claim 21
Dependent Claim
42 words
An apparatus as in claim 18 wherein said switchable attenuator is operated by said pulsed control signal to attenuate a received said television signal by approximately 6 db or more except at the intervals corresponding to said suppressed amplitude horizontal synchronizing signals.
Claim 22
Dependent Claim
33 words
An apparatus as in claim 16 wherein the pulses of said pulsed control signal has a width corresponding to the width of the interval occupied by the said suppressed amplitude horizontal synchronizing signals.
Claim 23
Dependent Claim
20 words
An apparatus as in claim 15 wherein said generating means includes a monostable multivibrator which generates said pulsed control signal.
Claim 24
Independent Claim
119 words
A method for scrambling a television signal containing horizontal and vertical synchronizing signals and image information signals, said method comprising the steps of: receiving said television signal; deriving vertical synchronizing signals from said television signal; deriving horizontal synchronizing signals from said television signal; generating horizontal sync suppression pulses at times corresponding to the occurrence of horizontal synchronization signals in said television signal; generating timing pulses which are related in time to said horizontal sync suppression pulses; selectively forcing the amplitude of said television signal to a first predetermined level upon the occurrence of said horizontal sync suppression pulses, and forcing the amplitude of said television signal to a second predetermined whiter-than-white level upon the occurrence of said timing pulses.
Claim 25
Independent Claim
119 words
A method for scrambling a television signal containing horizontal and vertical synchronizing signals and image information signals, said method comprising the steps of: receiving said television signal; deriving vertical synchronizing signals from said television signal; deriving horizontal synchronizing signals from said television signal; generating horizontal sync suppression pulses at times corresponding to the occurrence of horizontal synchronization signals in said television signal; generating timing pulses which are related in time to said horizontal sync suppression pulses; selectively forcing the amplitude of said television signal to a first predetermined level upon the occurrence of said horizontal sync suppression pulses, and forcing the amplitude of said television signal to a second predetermined whiter-than-white level upon the occurrence of said timing pulses.
Claim 26
Dependent Claim
22 words
A method as in claim 22 wherein said first level is within an amplitude range normally occupied by said image information signals.
Claim 27
Dependent Claim
29 words
A method as in claim 23 wherein the amplitude of said television signal is forced to said first predetermined level for the duration of said horizontal sync suppression pulses.
Claim 28
Independent Claim
29 words
A method as in claims 23 or 24 wherein the amplitude of said television signal is forced to said second predetermined level for the duration of said timing pulses.
Claim 29
Independent Claim
27 words
A method as in claims 22 or 23 wherein said television signal is attenuated upon the occurrence of said horizontal sync suppression pulses and said timing pulses.
Claim 30
Dependent Claim
26 words
A method as in claim 26 wherein said television signal is attenuated by approximately 6 db or more in response to said horizontal sync suppression pulses.
Claim 31
Dependent Claim
24 words
A method as in claim 26 wherein said television signal is attenuated by approximately 20 db or more in response to said timing pulses.
Claim 32
Dependent Claim
29 words
A method as in claim 22 wherein the generation of said horizontal sync suppression pulses is prevented during the occurrence of said vertical synchronizing signals in said television signal.
Claim 33
Dependent Claim
31 words
A method as in claim 26 wherein said horizontal sync suppression pulses have a width equal to or greater than the width of said horizontal synchronizing signals in said television signal.
Claim 34
Dependent Claim
27 words
A method as in claim 25 wherein said timing pulses have a width which is less than that of said horizontal synchronizing signals in said television signal.
Claim 35
Dependent Claim
18 words
A method as in claim 31 wherein said timing pulses have a width of approximately 2 micro seconds.
Claim 36
Independent Claim
37 words
A method as in claims 22 or 23 wherein the amplitude of said television signal is forced to said second predetermined level during an interval corresponding to a front porch which precedes each said horizontal synchronizing signal.
Claim 37
Independent Claim
96 words
A method for descrambling a scrambled television signal containing image information signals, vertical synchronizing signals, suppressed amplitude horizontal synchronizing signals, and horizontal synchronizing reconstruction signals in the form of whiter-than-white pulses in said television signal, said method comprising the steps of: receiving said television signal; deriving said whiter-than-white pulses from said television signal; generating a pulsed control signal in response to said detected whiter-than-white pulses and using said pulsed control signal to selectively operate a switchable means to boost the amplitude of said suppressed amplitude horizontal synchronizing signals relative to the remainder of said television signal.
Claim 38
Independent Claim
96 words
A method for descrambling a scrambled television signal containing image information signals, vertical synchronizing signals, suppressed amplitude horizontal synchronizing signals, and horizontal synchronizing reconstruction signals in the form of whiter-than-white pulses in said television signal, said method comprising the steps of: receiving said television signal; deriving said whiter-than-white pulses from said television signal; generating a pulsed control signal in response to said detected whiter-than-white pulses and using said pulsed control signal to selectively operate a switchable means to boost the amplitude of said suppressed amplitude horizontal synchronizing signals relative to the remainder of said television signal.
Claim 39
Dependent Claim
25 words
A method as in claim 34 wherein said whiter-than-white pulses are located in or adjacent an interval occupied by said suppressed amplitude horizontal synchronizing signals.
Claim 40
Dependent Claim
24 words
A method as in claim 35 wherein said whiter-than-white pulses are located on a front porch preceding each said suppressed amplitude horizontal synchronizing signal.
Claim 41
Dependent Claim
18 words
A method as in claim 35 wherein each said whiter-than-white pulse is approximately 2 micro seconds in width.
Claim 42
Dependent Claim
42 words
A method as in claim 34 wherein said switchable means is operated by said pulsed control signal to attenuate a received said television signal by aproximately 6 db or more except at the intervals corresponding to said suppressed amplitude horizontal synchronizing signals.
Claim 43
Dependent Claim
33 words
A method as in claim 34 wherein the pulses of said pulsed control signal have a width corresponding to the width of the interval occupied by the said suppressed amplitude horizontal synchronizing signals.
Claim 44
Independent Claim
180 words
An apparatus for scrambling an RF television signal wherein said television signal contains horizontal and vertical synchronizing signals and image information signals, said apparatus comprising: means for receiving an RF television signal containing horizontal and vertical synchronizing signals and image information signals; a first detector for deriving horizontal synchronizing signals from said television signal; first signal generating means responsive to the output of said first detector for generating horizontal sync suppression pulses at times corresponding to the occurrence of horizontal synchronizing signals in said television signal; second signal generating means responsive to the output of said first detector for generating timing pulses which are related in time to said horizontal sync suppression pulses; and switchable means coupled to receive said RF television signal and responsive to the output of said first and second signal generating means for selectively attenuating the amplitude of said RF television signal so that it is forced to a first predetermined level upon the occurrence of said horizontal sync suppression pulses and forced to a second predetermined whiter-than-white level upon the occurrence of said timing pulses.
Claim 45
Independent Claim
180 words
An apparatus for scrambling an RF television signal wherein said television signal contains horizontal and vertical synchronizing signals and image information signals, said apparatus comprising: means for receiving an RF television signal containing horizontal and vertical synchronizing signals and image information signals; a first detector for deriving horizontal synchronizing signals from said television signal; first signal generating means responsive to the output of said first detector for generating horizontal sync suppression pulses at times corresponding to the occurrence of horizontal synchronizing signals in said television signal; second signal generating means responsive to the output of said first detector for generating timing pulses which are related in time to said horizontal sync suppression pulses; and switchable means coupled to receive said RF television signal and responsive to the output of said first and second signal generating means for selectively attenuating the amplitude of said RF television signal so that it is forced to a first predetermined level upon the occurrence of said horizontal sync suppression pulses and forced to a second predetermined whiter-than-white level upon the occurrence of said timing pulses.
Claim 46
Independent Claim
210 words
An apparatus for descrambling a scrambled RF television signal containing image information signals, vertical synchronizing signals, suppressed amplitude horizontal synchronizing signals, and horizontal synchronizing reconstruction signals in the form of whiter-than-white levels in said RF television signal amplitude, said apparatus comprising: means for receiving a scrambled RF television signal containing image information signals, vertical synchronizing signals, suppressed amplitude horizontal synchronizing signals, and horizontal synchronizing reconstruction signals in the form of whiter-than-white levels formed in said received RF television signal by attenuating the amplitude of an RF television signal; switchable means for selectively attenuating selected portions of said received scrambled RF television signal relative to other portions of said received scrambled RF television signal to boost the amplitude of said suppressed amplitude horizontal synchronizing signals relative to the remainder of said received scrambled RF television signal; means for detecting said whiter-than-white levels from said scrambled RF television signal; and means responsive to said deriving means for generating a pulsed control signal in response to said detected whiter-than-white levels and for selectively operating said switchable means with said pulsed control signal to boost said suppressed amplitude horizontal synchronizing signals in said scrambled television signal relative to the remainder of said received scrambled RF television signal to provide a descrambled RF television signal.
Claim 47
Independent Claim
210 words
An apparatus for descrambling a scrambled RF television signal containing image information signals, vertical synchronizing signals, suppressed amplitude horizontal synchronizing signals, and horizontal synchronizing reconstruction signals in the form of whiter-than-white levels in said RF television signal amplitude, said apparatus comprising: means for receiving a scrambled RF television signal containing image information signals, vertical synchronizing signals, suppressed amplitude horizontal synchronizing signals, and horizontal synchronizing reconstruction signals in the form of whiter-than-white levels formed in said received RF television signal by attenuating the amplitude of an RF television signal; switchable means for selectively attenuating selected portions of said received scrambled RF television signal relative to other portions of said received scrambled RF television signal to boost the amplitude of said suppressed amplitude horizontal synchronizing signals relative to the remainder of said received scrambled RF television signal; means for detecting said whiter-than-white levels from said scrambled RF television signal; and means responsive to said deriving means for generating a pulsed control signal in response to said detected whiter-than-white levels and for selectively operating said switchable means with said pulsed control signal to boost said suppressed amplitude horizontal synchronizing signals in said scrambled television signal relative to the remainder of said received scrambled RF television signal to provide a descrambled RF television signal.
Claim 48
Independent Claim
127 words
A method for scrambling an RF television signal wherein said television signal contains horizontal and vertical synchronizing signals and image information signals, said method comprising: receiving an RF television signal containing horizontal and vertical synchronizing signals and image information signals; deriving horizontal synchronizing signals from said television signal; generating horizontal sync suppression pulses at times corresponding to the occurrences of said derived horizontal synchronizing signals in said television signal; generating timing pulses which are related in time to said horizontal sync suppression pulses; and selectively attenuating the amplitude of said RF television signal so that it is forced to a first predetermined level upon the occurrence of said horizontal sync suppression pulses and forced to a second predetermined whiter-than-white level upon the occurrence of said timing pulses.
Claim 49
Independent Claim
127 words
A method for scrambling an RF television signal wherein said television signal contains horizontal and vertical synchronizing signals and image information signals, said method comprising: receiving an RF television signal containing horizontal and vertical synchronizing signals and image information signals; deriving horizontal synchronizing signals from said television signal; generating horizontal sync suppression pulses at times corresponding to the occurrences of said derived horizontal synchronizing signals in said television signal; generating timing pulses which are related in time to said horizontal sync suppression pulses; and selectively attenuating the amplitude of said RF television signal so that it is forced to a first predetermined level upon the occurrence of said horizontal sync suppression pulses and forced to a second predetermined whiter-than-white level upon the occurrence of said timing pulses.
Claim 50
Independent Claim
168 words
A method for descrambling a scrambled RF television signal containing image information signals, vertical synchronizing signals, suppressed amplitude horizontal synchronizing signals, and horizontal synchronizing reconstruction signals in the form of whiter-than-white levels in said RF television signal amplitude, said method comprising: receiving a scrambled RF television signal containing image information signals, vertical synchronizing signals, suppressed amplitude horizontal synchronizing signals, and horizontal synchronizing reconstruction signals in the form of whiter-than-white levels formed in said received RF television signal by attenuating the amplitude of an RF television signal; detecting said whiter-than-white levels from said scrambled RF television signal; and generating a pulsed control signal in response to said detected whiter-than-white levels for selectively attenuating selected portions of said received scrambled RF television signal relative to other portions of said received scrambled RF television signal to boost the amplitude of said suppressed amplitude horizontal synchronizing signals relative to the remainder of said received scrambled RF television signal in response to said pulsed control signal to provide a descrambled RF television signal.
Claim 51
Independent Claim
168 words
A method for descrambling a scrambled RF television signal containing image information signals, vertical synchronizing signals, suppressed amplitude horizontal synchronizing signals, and horizontal synchronizing reconstruction signals in the form of whiter-than-white levels in said RF television signal amplitude, said method comprising: receiving a scrambled RF television signal containing image information signals, vertical synchronizing signals, suppressed amplitude horizontal synchronizing signals, and horizontal synchronizing reconstruction signals in the form of whiter-than-white levels formed in said received RF television signal by attenuating the amplitude of an RF television signal; detecting said whiter-than-white levels from said scrambled RF television signal; and generating a pulsed control signal in response to said detected whiter-than-white levels for selectively attenuating selected portions of said received scrambled RF television signal relative to other portions of said received scrambled RF television signal to boost the amplitude of said suppressed amplitude horizontal synchronizing signals relative to the remainder of said received scrambled RF television signal in response to said pulsed control signal to provide a descrambled RF television signal.
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