System, method, and apparatus for television signal scrambling and descrambling

A system for providing intelligible video program signals and corresponding video synchronization signals to authorized video displays only comprising transmitting means for transmitting scrambled signals of at least one video program; a receiver for receiving said scrambled video program signals for said at least one video program; and a descrambling unit coupled to said receiver and including an electronic ticket removably coupled to the input of said video receiver for intercepting and descrambling the at least one scrambled video program signal from said receiver and recovering the synchronizing signals, and means coupling the recovered synchronization sweep signals and the unscrambled intelligible video program signals to said video display.

TECHNICAL FIELD 
This invention relates to methods and apparatus for preventing a television 
signal from being acceptably received by an unauthorized television 
receiver while maintaining the television signal recoverable by an 
authorized receiver. 
It particularly relates to a system in which intelligible video signals are 
provided to television receives by using an "electronic ticket to 
descramble received video signals to produce the intelligible video 
signals. If an invalid ticket is attempted to be used, it will be rendered 
unusable. Further, after a selected program has been substantially 
completed, a "valid" ticket will self-destruct so that it cannot be used 
again. 
Subscription television is now in wide and growing use in both cable 
television and over-the-air systems. In over-the-air systems, preventing 
unauthorized receivers from receiving the transmission is a major problem 
for subscription services, but even cable television systems might desire 
to have different classes of customers which can be serviced over the same 
cable. For instance, a special rate might be charged for customers who 
want to view certain sporting events or first run movies. In order to 
solve these problems, many systems have been developed for preventing the 
reception of an acceptable television signal by unauthorized receivers. 
BACKGROUND ART 
Methods of scrambling and descrambling television signals to prevent 
unauthorized viewing of protected material have been proposed almost since 
the inception of television. Everything from moving mirrors shown in U.S. 
Pat. No. 2,531,974, to inserted carriers shown in U.S. Pat. No. 4,074,311 
have been proposed. Some systems in use today seek to modify the 
synchronization pulses in the video signal as shown in U.S. Pat. No. 
3,924,059 or insert interfering video signals which are subsequently 
removed in the descrambling device as shown in U.S. Pat. No. 4,112,464 or 
insert interfering carriers at the transmitter which are subsequently 
removed in the descrambling device with notch filters as shown in U.S. 
Pat. No. 4,074,311. 
Randomized switching between inverted and non-inverted video is expensive 
to perform in the decoder function, requiring demodulation of the received 
coded signal, and in the case of a decoder which normally is placed on the 
top of a video set, the remodulation of the signal after it has been 
restored to viewable condition. While the systems using injection of 
interfering carrier systems do not require demodulation and remodulation, 
they have other disadvantages. For instance, such systems can be easily 
defeated by persons with only modest means and effort. Also, extra 
transmitter power must be devoted to the interfering carrier. This is 
detrimental in cable systems, not so much for the slight penalty in 
consumed energy, but to the care and expense that is involved in 
maintaining linearity in all the amplifiers that must amplify the signals. 
The linearity problem becomes especially severe in over-the-air 
transmission systems because of the high transmitter power involved. 
Further, synchronization pulse modification or suppression systems 
techniques are easy to defeat. On the other hand these techniques lead to 
very effective scrambling and good quality pictures after descrambling. By 
combining this technique with the present invention a 
scrambling-descrambling system is obtained that is both secure and low in 
cost and delivers good quality descrambled video signals. 
DISCLOSURE OF THE INVENTION 
The present invention overcomes the disadvantages of the prior art by 
providing a television scrambling and unscrambling system which utilizes a 
decoder or descrambler in the video signal receiving network which has an 
"electronic ticket" forming a part thereof and which is a removable part 
of the circuit and necessary to descramble the signal. The electronic 
ticket can be purchased for a particular program and inserted in the 
decoder which is coupled to the video set of the user. The ticket includes 
a surface acoustic wave (SAW) device which, in particular, can be used as 
a delay line to descramble the signal being received for viewing. 
A "fusible link" is formed in the video signal path on the surface of the 
SAW device which is destroyed by circuitry in the decoder that is 
activated when a coded signal is transmitted with the scrambled signal. 
All unauthorized tickets which are active at the time a verification 
signal is transmitted are effectively disabled by the decoder which 
destroys the fusible link and renders the ticket unusable. 
The ticket SAW device is packaged in plastic in such a way that the SAW 
device is almost certain to be destroyed by opening the package. This 
means that the device is so constructed that it is extremely difficult to 
copy. 
The electronic ticket can also include a ROM (read only memory) which 
contains a code to identify proper tickets for use with particular 
programs. In the event the code produced by a particular ticket does not 
agree with the verifying code transmitted with the scrambled signal, the 
invalid or unauthorized ticket will be rendered unusable by the fusible 
link being destroyed. 
Inasmuch as the attenuation may vary from ticket to ticket, a variable 
attenuator is provided to balance the system and compensate for insertion 
loss differences of the SAW device from ticket to ticket. 
In addition, a variable phase shifter is provided for matching variations 
in phase shift or delay variations from ticket to ticket. 
SUMMARY OF THE PRESENT INVENTION 
Thus, the present invention relates to a system for providing intelligible 
video program signals and corresponding video synchronization signals to 
authorized video displays only comprising transmitting means for 
transmitting scrambled signals of at least one video program, a receiver 
for receiving said scrambled video program signals for said at least one 
video program, and a descrambling unit coupled to said receiver and 
including a removable electronic ticket for intercepting and descrambling 
said at least one scrambled video program signal from said receiver and 
recovering said synchronization signals, said descrambling unit having an 
output coupled to the input of said video display for coupling said 
recovered synchronization signals and said descrambled, intelligible video 
program signals to said video display.

DETAILED DESCRIPTION OF THE DRAWINGS 
Referring now to the drawings and in particular to FIG. 1 and FIG. 2, a 
system for transmitting and receiving a video signal, according to the 
present invention, includes apparatus for preventing the video signal from 
being acceptably displayed by an unauthorized video receiver while 
maintaining the video signal recoverable by an authorized receiver. While 
the system may be utilized with video systems including radar, sonar, 
games, various information, display systems, and the like, the description 
herein will refer to television systems for ease and simplicity of 
explanation. Further, while the system is discussed in terms of 
"over-the-air" television, the system will function equally well with and 
is directly applicable to cable television systems. 
The apparatus includes the video program signal on line 2 being coupled 
through lines 4 and 8 to a signal scrambling circuit 5 including a surface 
acoustic wave (SAW) delay line 6 and an attenuator 10. SAW device 6 causes 
the video signal applied thereto to be delayed a predetermined amount in 
time. A pulse generator 20 receives the video synchronization signals on 
conductor 22 and produces synchronized, randomly generated, Q and Q 
switching signals on lines 24 and 26 respectively which are coupled to 
switches 12 and 14. The synchronization signals on line 22 are ordinarily 
used to cause the electron beam in the television set to sweep across the 
television screen from one side to the other in the same manner as they 
were transmitted and then the synchronization signal causes a retrace of 
the signal back to the original side but down one line where the sequence 
is repeated a number of times, for instance 525 lines over a time period 
of one second, depending upon the television standard being used. Thus, 
the synchronization signals determine the point in time at which the 
retrace line is generated and the sweep line is begun again from one side 
of the television set to the other. When the synchronization signal 22 
causes pulse generator 20 to produce a Q pulse on line 24, switch 12 gates 
or couples the delayed output of SAW device 6 on line 16 to output line 28 
which is coupled to a summing unit 32. The same program signal on line 2 
is, as stated previously, being coupled through conductor 8 to attenuator 
10 which produces an undelayed output on line 18. However, switch 14 is 
off when the Q pulse on line 24 from pulse generator 20 exists. Thus, only 
the delayed output of the SAW delay line 6 passes through switch 12 to 
line 28 and summing unit 32 during the existence of the Q gating pulse. 
However, when some subsequent synchronization pulse arrives on line 22, 
pulse generator 20 produces a Q signal on line 26 which gates switch 14 on 
but switch 12 is off because the Q pulse does not exist on line 24. Thus, 
the undelayed output of attenuator 10 on line 18 passes through switch 14 
on line 30 to summing unit 32. The output of the summing unit 32 on line 
42 is coupled to transmitter 44 which transmits the recombined scrambled 
signals on antenna 46. The signal is scrambled because the video program 
signal in one sweep line is delayed during the Q pulse with respect to the 
signal on the next sweep line during the Q pulse. Thus, alternate portions 
or sweep lines of the video program signal are delayed with respect to 
each other. 
The delay time through the SAW delay line device 6 differs from the delay 
time through attenuator 10 by a significant fraction of the horizontal 
sweep time. In the United States, for instance, with the NTSC (National 
Television Standardization Committee) broadcast system, the time from the 
start of one horizontal line to the start of the next horizontal line is 
approximately 60 microseconds and the retrace interval is approximately 10 
microseconds. In such a system, a typical preferred range for scrambling 
television signals requires a difference in delay times between that 
caused by SAW delay line 6 and that caused by the attenuator 10 of between 
approximately 3 and 5 microseconds. 
SAW delay line device 6 causes that portion (i.e. a sweep line) of the 
video program signal 2 passing through the delay line 6 to be considerably 
delayed from that portion (i.e. the next sweep line) passing through the 
attenuator 10 and thus in the summing unit 32 the two signals are not 
aligned with each other but are delayed with respect to each other and 
thus the picture is scrambled. The attenuator 10 attenuates the signal to 
compensate for the attenuation caused by the SAW device 6. It is to be 
noted that while the invention is being described in detail with respect 
to the NTSC system, it is also applicable to other systems, e.g. 
(Phase Alternation Line) and SECAM (derived from French for sequential 
with memory). 
As stated earlier, pulse generator 20 detects the presence of the 
television horizontal sweep pulse or synchronization pulse and randomly 
produces Q and Q signals on lines 24 and 26 which are timed with the 
synchronization pulses on line 22. Pulse generator 20 also drives an 
interfering signal generator 34 by amplitude modulating (AM) the 
interfering signal. The modulated interfering signal generator 34 operates 
on the recombined television signals through summing means 32 in a manner 
well known in the art and described in U.S. Pat. No. 4,074,311. By 
modulating the interfering signal produced by generator 34 with pulse 
generator 20 which detects the horizontal sweep intervals, the information 
for synchronizing the received signal with the transmitted signal (and 
which describes the switch times of the delayed and undelayed segments of 
the signal as it is passed through the SAW delay line 6 and attenuator 10) 
is transmitted along with the television program signal. 
In addition, a system is needed to verify tickets being used at the 
receivers as valid or invalid. Thus, a verification code generator 38 
produces a digital code on line 40 which is summed with the Q switching 
signal on line 24 by summing unit 33 and coupled to interference generator 
34. While the verification code is shown being transmitted on the 
interference signal carrier, it could also be transmitted on the sound 
carrier, the picture carrier (during retrace interval) or any other 
desired carrier. This verification code, as will be explained in detail 
hereinafter, enables the receiver to verify the validity of an electronic 
ticket being used to unscramble a signal that is being received. If the 
ticket is an incorrect or invalid one, the verification code or command 
causes the ticket to be permanently destroyed, disabled, or deactivated so 
that it cannot be used then or in the future. 
FIG. 2 is a schematic representation of the receiving unit for receiving 
the scrambled signal being transmitted by transmitter 44 over antenna 46 
in FIG. 1. The transmitted video information and other signals are 
received by antenna 48 in FIG. 2 and coupled to receiver 50 that 
reproduces the scrambled video signal which is coupled to descrambler 54 
by conductor or connection 52. Descrambler 54 includes an electronic 
ticket 56 which is plugged into the descrambler and forms part of the 
descrambling circuit which will be described in more detail hereinafter. 
The received signal cannot be descrambled without the ticket. The 
descrambled signal is produced on line 58 and coupled to a video display 
60 which may be, for instance, a television set. 
As stated earlier, it should be noted that while FIG. 1 discloses an 
antenna transmitting over-the-air signals, the same principles involved in 
the present invention could be used equally well in a cable system instead 
of a transmitter 44. In that case, the signals on line 42 would be coupled 
to the cable system and then to the display devices such as television 
sets connected thereto. 
Thus, the system incorporating the present invention provides intelligible 
video program signals and corresponding video synchronization signals to 
authorized video receivers or displays only and comprises transmitting 
means 44 for transmitting scrambled signals of at least one video program, 
a receiver 50 for receiving the scrambled video program signals, and a 
descrambling unit 54 coupled to the receiver 50 and including a removable 
electronic ticket 56 for intercepting and at least partially descrambling 
the video program signal from receiver 50 and recovering the 
synchronization signals. The output of the descrambling unit 54 on line 58 
is coupled to the input of video display 60 for coupling the recovered 
synchronization signals and the descrambled, intelligible video program 
signals to the video display 60. 
The descrambling unit 54 will be discussed in relation to FIG. 3 wherein 
the scrambled signal from receiver 50 on line 52 (as shown in FIG. 2) is 
coupled to the descrambler 54 and in particular to an RF amplifier 62. The 
output of the RF amplifier 62 is coupled to an electronic ticket 56 
through connections 64. The output of RF amplifier 62 is also connected 
through line 70 to an attenuator 72 in the descrambling unit 54. The 
electronic ticket 56 has thereon circuitry for at least partially 
descrambling the received signal and is a unitary package which plugs into 
or is insertible into the descrambler 54 at junction or contact points 64, 
82, 86 and 124. The signal passing through junction 64 to electronic 
ticket 54 is coupled through line 66 to a band pass filter 68 and through 
line 74 to a SAW delay device 76. 
Band pass filter 68 recovers the synchronization signals and the 
interfering signal that is produced by generator 34 in FIG. 1. It also 
assists in recovering the verification code signal produced by generator 
38 in FIG. 1. The output of band pass filter 68 on line 84 is coupled 
through connections 86 of electronic ticket 56 to demodulator 90 in 
descrambling unit 54. Demodulator 90 produces Q and Q signals on output 
lines 104 and 106 respectively. It will be noted that, as compared to the 
switching process in the transmitter of FIG. 1, the Q signal on line 104 
gates or controls RF switch 102 through switch driver 112 for attenuator 
72 while the Q signal is coupled to drive or control RF switch 88 through 
switch driver 108 for SAW device 76. Thus, whereas the delayed signal 
passing through the SAW delay line 6 of the scrambler unit 5 in FIG. 1 is 
gated by the Q signal, in the descrambler unit 54 the delayed output of 
the SAW device 76 on line 78 to RF switch 88 in FIG. 3 is gated by the Q 
signal in FIG. 3. The received signal which was not delayed by attenuator 
10 in the transmitter of FIG. 1 is now delayed through SAW device 76 and 
gated by switch 88 to cause it to be aligned with the formerly delayed 
signal now being gated through attenuator 72 and the signal is 
descrambled. Thus, the outputs of the SAW delay line 76 and attenuator 72 
in FIG. 3 in the descrambler unit 54 are switched and combined in a manner 
complimentary to the switching between the original SAW delay line 6 and 
attenuator 10 in the transmitter of FIG. 1. This means that the total 
delay time of each horizontal sweep through the entire system remains 
substantially constant and the scrambled signal is descrambled. 
Thus, the electronic ticket 56 is used for at least partially descrambling 
transmitted video program signals and providing synchronization signals 
for use in a video receiver 60. The scrambled video signals are received 
on first terminal 64 of ticket 56 and are coupled to delay line 76, a 
portion of the descrambling circuit. Since SAW delay line 76 delays 
successive alternate portions of the scrambled video signal, the signal is 
partially descrambled and that portion of the descrambled signal and the 
recovered synchronization signals from band pass filter 68 are coupled to 
second terminals 82 and 86. These outputs on second terminals 82 and 86 
are coupled to video receiver 60 by notch filter 118. 
The output of SAW delay device 76 is coupled on line 78 directly through 
fuse 80 which will be discussed in more detail hereinafter. However, 
suffice it to say at this point that the fuse 80 is constructed as a part 
of the electronic ticket 56 and is in the video signal path 78 and is used 
to deactivate or destroy the usability of electronic ticket 56 if it is 
not a valid ticket for a particular video program. This will be discussed 
in more detail hereinafter. 
The variable attenuator 72, represented by arrow 92, is used to balance the 
system and allow for variations in insertion loss of the SAW delay line 
76. It is realized with a variable resistor and two fixed resistors in a 
"pi" configuration, the variable resistor being the series leg of the "pi" 
(one of a number of ways in which the desired result could be obtained and 
all of which are also well known in the art). 
The output of attenuator 72 on line 94 is coupled to phase shifter 96 which 
is also adjustable as represented by arrow 98. The variable phase shifter 
96 is used to match variations in phase shift from one electronic ticket 
to the other as may be required. It can also be constructed in a number of 
well known ways but preferably consists of variable coils and/or 
capacitors in a ladder or lattice network in a manner well known in the 
art. Thus, both amplitude and phase can be adjusted by the user of the 
descrambler during a period prior to the occurrence of the event or 
program. A test pattern is transmitted with a one or two color constant 
signal scrambled with a fixed, switch pattern in each frame. The amplitude 
is adjusted with the attenuator adjustment 92 to eliminate any "venetian 
blind" effect on the screen and the phase is adjusted by phase adjustment 
98 to match colors between bars across the screen. Once adjusted, the 
controls are then left alone for the balance of the event. A diagrammatic 
representation of the set top descrambler is shown in FIG. 7 with knobs 
192 and 194 representing the adjustments for attenuator 72 and phase 
shifter 96 respectively. 
As stated earlier, the band pass filter 68 on electronic ticket 56 removes 
the picture carrier, the sound carrier and video frequency modulation 
carrier components from the interfering signal frequency which is also 
used to carry the timing information or synchronizing signals for driving 
switches 88 and 102 to reconstruct the video signal. In addition, the band 
pass filter 68 removes the ticket coding or verification information and 
couples it to demodulator 90 and then to the decoder 126 on line 128. The 
decoder 126 compares the verification code transmitted by generator 38 in 
FIG. 1 on the interfering carrier signal with the code in the ticket lead 
frame or hard wired ROM 122 representing a particular ticket through the 
third set of terminals or ticket output leads 124. The decoder produces an 
output signal on 130 which destroys unauthorized tickets by activating the 
ticket destruct electronics in switch driver and destruct circuitry 108 
which drives RF switch 88 as will be discussed hereinafter. 
The outputs of RF switch 88 and RF switch 102 are combined on line 116 and 
represent the descrambled video signal which is to be used by the video 
receiver such as a television set. The combined signal is coupled to notch 
filter 118 which removes the interfering signal as described in U.S. Pat. 
No. 4,074,311. 
Thus, the apparatus for descrambling the transmitted, scrambled video 
program and providing synchronization signals for use in a video display 
comprises the descrambler 54 with a receptacle 186 for receiving an 
electronic ticket 56. The descrambler 54 has first terminals 52 for 
receiving the transmitted scrambled video signal and second terminals 58 
for coupling the unscrambled signal to display 60 for viewing. The 
electronic ticket 56 is inserted in receptacle 186 and has circuitry 68, 
76 for connection to descrambler 54 for receiving the scrambled signals. 
The circuitry 68, 76 in electronic ticket 56 is necessary for descrambler 
54 to descramble the received video signal. The output from SAW delay line 
circuitry 76 is a partially descrambled signal which is coupled to second 
terminals 58 through notch filter 118 and RF switch 88 for coupling to 
video display 60. Descrambler 54 also includes means such as decoder 126 
which is coupled to electronic ticket 56 for verifying an authorized 
electronic ticket 56 inserted in receptacle 186. Further, a circuit 
including fuse 80, RF switch 88 and switch driver and fuse destruct 
circuitry 108 is coupled to the decoder 126, the ticket verifying means, 
and the ticket 56 for deactivating any unauthorized ticket 56 inserted in 
receptacle 186. 
The band pass filter 68 in electronic ticket 56 receives and recovers the 
interfering carrier and its modulation components which contains the 
ticket verification digital code. The electrical connections 124 on ticket 
56 are formed in a predetermined digitally coded connection pattern on 
said ticket 56 in conformance with the verification code so that an 
authorized ticket can be determined. The decoder 126 is coupled to 
connections 124 and also receives and decodes the transmitted verification 
code from demodulator 90 on line 128 and compares the digitally coded 
connection pattern of connections 124 to said transmitted verification 
code and produces an output signal on line 130 if the ticket 56 is 
unauthorized. Means, such as fuse 80, in ticket 56 responds to the output 
signal on line 130 and deactivates the unauthorized ticket 56 by melting. 
The detailed construction of the RF switch, switch driver and fuse destruct 
circuitry is shown in FIG. 4. The Q output from demodulator 90 on line 104 
is coupled to transistor 105 in the switch drive portion of circuit 108 
which in turn drives the RF switch 88 with direct current passing through 
diodes 140 and 142 and RF choke 144. Thus, RF switch 88 is gated "on" when 
the Q signal from demodulator 90 is present on line 104 and the delayed 
signal from the SAW device 76 is allowed to pass to notch filter 118. When 
the Q signal is not present, diodes 140 and 142 are reverse biased and are 
gated "off" and no delayed signal from the SAW device 76 is allowed to 
pass to notch filter 118 on line 116. RF choke 117 and its associated 
resistor and capacitor provide a return path for the d.c. current which 
biases diode 142. 
The current through diode 140, which is connected directly to electronic 
ticket 56 through RF switch 88, also passes through the SAW device 76 to 
ground potential to complete the circuit. This will be seen more clearly 
with respect to FIG. 5. The dimensions of the fuse 80 on the SAW device 76 
as shown in FIGS. 5 and 6 are carefully controlled so that the switch 88 
drive current does not normally damage the fuse. However, when the decoder 
chip 126 commands the destruction of a ticket by declamping its output on 
line 130 from ground, resistor R3 in the fuse destruct portion of circuit 
108 drives current into the base of associated transistor 131 which in 
turn drives excessive additional current through diode 140 and fuse 80 
resulting in the destruction of the fuse. Since the fuse 80 is in the 
video signal path or circuit, once it is destroyed or fused, the 
electronic ticket 56 is no longer usable. 
Also, if the destruct command (verification signal from the transmitter) is 
comprised of an invalid code and transmitted at the end of the broadcast, 
all valid tickets for that broadcast would be destroyed as rendered 
unusable for future use. Thus, invalid tickets are rendered unusable at 
the start of a program and all the tickets in use at the and of the 
program are rendered permanently unusable. 
Referring now to FIG. 5 which is a diagrammatic representation of the SAW 
delay device chip 76, it will be seen that the input signal is applied to 
input transducer 148 on lead 66, 74 which is coupled to an input bonding 
pad 152. The output of input transducer 148 on bonding pad 150 coupled to 
ground potential through conductor 170. Each of the pads 150 and 152 have 
fingers 154 and 156 which are placed in an interdigitated manner to form 
input transducer 148 in a manner well known in the art. 
The band pass filter transducer 158 in FIG. 5 is the same unit designated 
band pass filter 68 in FIG. 3 and may be formed on the same SAW device 76 
as the input transducer 148 as shown. Band pass filter transducer 158 has 
an output developed between output line 84 connected to bonding pad 161 
and ground connectio 168 which is connected to bonding pad 159. The 
bonding connection pads 159 and 161 on band pass filter transducer 158 
also have interdigitated fingers which form the band pass filter in a 
manner well known in the art. 
In addition, the delayed signal output is produced by transducer 160 which 
has a bonding connection pad 163 having interdigitated fingers with 
bonding pad 159 to form the delay line as is well known in the prior art. 
The output of transducer 160 is coupled through a fuse link 80 to an 
output bonding connection pad 162 which produces the delayed output on 
connection 82. Thus, the band pass filter output transducer 158 and the 
delayed signal output transducer 160 are formed on the same SAW device or 
chip 76. 
It will also be noted in FIG. 5 that an electrical connection, including 
meandering line 166, exists between bonding pad 163 of delayed output 
transducer 160 and ground connection 168. This meandering line 166 acts as 
a high impedance at RF frequencies and is the equivalent of an inductance 
and resistance in series. However, it has a low resistance to d.c. current 
flow. Thus, it effectively isolates bonding pads 159 and 163 at RF 
frequencies but directly couples them for direct current flow. 
As stated earlier with respect to FIG. 4, when the demodulator 90 produces 
a Q output indicating that RF switch 88 is to be gated "on", it drives the 
RF switch 88 through transistor 105 in switch driver 108 to cause the 
direct current to pass through diodes 140 and 142 in RF switch 88 and thus 
turn the gate "on". The direct current from diode 140 which is connected 
directly to the ticket on line 82 passes through bonding pad 162 in FIG. 5 
and fuse 80 through meandering line 166 to ground 168. The physical 
dimensions of fuse 80 are carefully controlled so that the switch drive 
current through transmitter 105 does not normally damage the fuse 80. 
However, when the decoder chip 126 commands the destruction of a ticket by 
declamping its output from ground, resistor R3 in switch drive and fuse 
destruction unit 108 shown in FIG. 4 drives current into the base of the 
transistor 131 which in turn drives substantially more current through 
diode 140, line 82, fuse 80 and meandering line 166 to ground 168 (FIG. 5) 
resulting in the destruction of the fuse. Since the fuse 80 is a part of 
the electronic ticket and is directly in the RF path from the output 163 
of the delay line transducer 160 to junction point or bonding pad 162, the 
ticket 56 is rendered inoperative permanently. 
The details of the construction of the electronic ticket 56 including the 
SAW delay line 76 and the band pass filter 68 formed on a crystal 
substrate 57 coterminous with the periphery of ticket 56 and the formation 
of read only memory (ROM) 122 for ticket verification are disclosed in 
FIG. 6. Thus, the construction of the electronic ticket 56 utilizes a lead 
frame construction that is well known in the art. The electronic ticket is 
shown in FIG. 6 by dotted lines 56 and includes thereon the combined SAW 
delay line 76 and band pass filter 68 as well as the ROM 122. The SAW 
device including band pass filter 68 and delay line 76 include leads 66, 
74 and ground lead 170 for receiving the scrambled video input from RF 
amplifier 62 in FIG. 3. Also on the SAW device is band pass filter output 
connection 84, ground connection 168 and SAW delay line device output 
connection 82. The fuse 80 is shown located between bonding pads 162 and 
163 and meandering line 166 is located between bonding pads 159 and 163. 
These connections are all coupled to the leads from frames 176 and 178. 
In addition, the ROM 122 consists of four leads designated as bit 1, bit 2, 
bit 3, and bit 4 extending from the lead frames 176, 178 to the electronic 
ticket 56. It will be noted that only bit 3 is actually attached to the 
ground line connection 168. Thus, the code that would be detected by 
decoder 126 in FIG. 3 is 0100 in which bit 4 is the first 0, bit 3 is the 
1, bit 2 is a 0 and bit 1 is a 0. It will be noted that this construction 
provides sixteen different digital combinations which can be formed by 
connecting various ones of the four bits to the ground plane or connection 
168. Thus, those leads attached to the ground buss 168 are interpreted by 
the decoder circuitry 126 as a 1 while those not so connected are 
interpreted as a 0. The decoder chip 126 is of the same type as used in 
today's security and garage door opener receivers and is well known in the 
art. Thus, the physical configuration or arrangement of the leads or 
connections must be physically configured in conformance with the 
verification code to represent a valid ticket. A particular ticket can 
then be required in order to view a particular event. Invalid tickets will 
be destroyed. 
As stated earlier, the lead frame construction shown in FIG. 6 is also well 
known in the art. However, in packaging a SAW device such as SAW device 76 
in a lead frame, care must be taken to protect the surface of the crystal 
57 (on which the connection pads are bonded) from contact by the plastic 
encapsulating the device. A two piece plastic case indicated by dashed 
lines 56 representing the electronic ticket encapsulates the descrambling 
circuit (delay line 76 and band pass filter 68) the ROM and at least a 
portion of the electrically conductive terminals 179 on the lead frame 
176, 178. The two piece plastic case is welded along coterminous edges and 
once the welding is complete, the lead frames are broken or sheared off 
along lines 180 and 182 designated as shear planes in FIG. 6. The welding 
of the plastic case can be done in several ways, possibly in one instance 
with ultrasound. After the lead frames 176, 178 are sheared off, the 
remaining portion of the leads 179 extending outwardly from the 
encapsulated electronic ticket 56 are bent over at right angles and the 
electronic ticket is an enclosed unitary package which may be used as a 
removable plug-in unit. FIG. 8 and FIG. 9 disclose this concept. For this 
electronic ticket 56, it also may be preferable to bring all of the leads 
out on one side to facilitate easy plug in operation as shown in FIG. 10. 
This is represented in FIG. 5 by dotted lines 172 and 174 which suggest 
that the input leads to the SAW device on 66, 74 could extend out on the 
other side of the SAW chip 76 along line 172 while the output lead 84 from 
the band pass filter circuit 158 could also be extended along line 174 to 
exit the SAW chip 76 on the same side as the other leads. Thus, all 
connections would be on the same side in that case. As indicated earlier, 
this concept is also illustrated in FIG. 10. 
This technique for packaging the SAW device 76 uniquely provides security 
against tampering. Once the lead frames 176 and 178 as shown in FIG. 6 
have been removed, removing the plastic housing or encapsulation covering 
the ticket 56 leaves the active or nongrounded leads (66, 74, 82, 84) 
supported only by the bond wires going to the SAW pads. These wires are 
typically 0.0005 to 0.001 of an inch in diameter and cannot support the 
weight of the lead, much less the torque or tension likely to be applied 
to remove the plastic. Thus, these connections to the external terminals 
would be destroyed. Even if a person could successfully open the plastic 
package and determine how the unit is constructed, the unit could not be 
easily duplicated because the thin metal on the surface of the crystal 
cannot be easily wired. A semiconductor like wire bonding machine is 
required and is not commonly available to the public. Thus, the 
descrambling circuit formed in the unitary package as indicated above will 
be physically destroyed if the unitary package is attempted to be opened 
or tampered with. 
Further, a 9 volt d.c. battery power supply 136 as shown in FIG. 3 is 
required in the descrambler unit 54 to power the descrambler unit and 
activate the fuse destruct circuit as seen in the switch drive and fuse 
destruct circuit 108 in FIG. 4. That 9 volt battery 136 may be coupled 
from the descrambler 54 on lead 132 through a contact into the ticket 56 
as shown in FIG. 3, thus conserving battery power when no ticket is 
inserted. However, alternatively, a 9 volt d.c. power supply which is 
obtained from an external source 134 may be plugged in to the descrambling 
unit 54 and thus the battery eliminated. Either source, of course, can be 
used. 
FIG. 7 is a diagrammatic representation of a descrambler unit 54. The 
incoming scrambled video signals on cable 52 are coupled internally to the 
circuits shown in FIG. 3 as shown schematically by lead or connection 200. 
The output from the circuit shown in FIG. 3 is coupled through connection 
202 in FIG. 7 to conductor 58 for transmission to the video receiver 60 in 
FIG. 2. The descrambler 54 includes a receptacle 186 having connections 
188 therein for the insertion of a ticket. Such a ticket is shown in FIG. 
10 which has all of the connections extending from one side of the ticket 
only. In the event that a ticket having leads extending from both sides 
such as that shown in FIG. 8 or FIG. 9 is used, an additional receptacle 
190 (shown in dashed lines) having connections 187 therein is formed in 
the descrambler 54 thus allowing the dual inline package type electronic 
ticket to be utilized. Also, on descrambler unit 54 are located the 
attenuator control knob 192 and the phase shift control knob 194. These 
controls, as explained earlier, allow the owner of the descrambling unit 
to adjust his unit for both attenuation and phase shift prior to the 
beginning of any program. 
The system therefore also relates to a method of descrambling video program 
and synchronization signals for use in a video display comprising the 
steps of providing partial descrambling circuitry having first terminals 
52, 200 for receiving the scrambled video signal and second terminals 58, 
202 coupled to the video display 60, coupling an electronic ticket 56 
containing the balance of said descrambling circuitry 68 and 76 to said 
partial descrambling circuity for forming a complete descrambling unit 
which descrambles the received video signal and couples the descrambled 
video signal to second terminals 58, 202 for transfer to the video 
display. 
FIG. 8 discloses a diagrammatic representation of a dual inline pin 
electronic ticket 56 having the SAW devices thereon and having external 
leads 196 and 198 extending outwardly and downwardly therefrom to form the 
dual inline pin plug-in module. 
An end view of the dual inline electronic ticket shown in FIG. 8 is also 
shown in FIG. 9. Electronic ticket 56 is encapsulated by two plastic 
halves 212 and 214 which are bonded together as by ultrasound or other 
well known means along their adjoining edges 213. The leads 196 and 198 
extend from both sides of the electronic ticket 56 and are bent downwardly 
at right angles at point 220. The ends 218 and 222 of the leads 198 and 
196 are the points where the lead frames were broken off as described 
earlier in reference to FIG. 6. 
In like manner, in FIG. 10, the electronic ticket 56 is shown with the 
leads 216 extending from one side thereof only. Again, the ticket is 
formed of plastic halves 212 and 214 which are bonded together at their 
common edges 213. Also, the ends of the leads 216 and 218 are the points 
where the lead frames are broken off as described previously in relation 
to FIG. 6. 
Thus, the system also relates to a method of constructing a low cost, mass 
producible electronic ticket 56 for descrambling transmitted video program 
and synchronization signals for use in a video receiver 60 comprising the 
steps of forming at least a portion 68, 76 of a descrambling circuit on a 
substrate 57, forming a lead frame 176, 178 having electrically conductive 
terminals 179 thereon, electrically attaching said descrambling circuit 
68, 76 to predetermined ones of said conductive terminals 179 on lead 
frame 176, 178 and encapsulating 56 said descrambling circuit 68, 76 and 
at least a portion of the electrically conductive termianls 179 on lead 
frame 176, 178 to form a unitary package. 
FIG. 11 is a diagrammatic representation of an alternative form of 
electronic ticket 56 using a charge coupled device (CCD). CCD's operate at 
a lower frequency than SAW devices and will require the use of 
demodulators to translate the received frequency into the frequency range 
of the CCD as is well known by those who are skilled in the art. In this 
case, the SAW device 76 shown in FIG. 3 is replaced with a charge coupled 
delay line 184 which produces an output on line 78 to connection 82. As is 
well known in the art, the delay time of a charge coupled device can be 
changed simply by changing the clock frequency applied to the charge 
coupled device. In this case, the clock frequency on line 204 from 
connection 208 differs from the clock signal on line 206 from connection 
210. These clock signals can be switched by the output signals developed 
from band pass filter 68 on line 84 to demodulator 90 as explained earlier 
in relation to FIG. 3. Thus, as shown in FIG. 3 demodulator 90 produces 
the Q and Q on lines 104 and 106 respectfully which would be used to 
switch the clock from one frequency to the other and apply them 
alternately to the charge coupled device 184 on lines 204 and 206. In all 
other respects, the electronic ticket 56 as shown in FIG. 11 would operate 
as disclosed earlier. No attenuator or phase shifter will be required. It 
is apparent that the hard wired ROM 122 as shown in FIGS. 6 and 11 could 
be constructed in any manner well known in the art instead of by the lead 
frames as shown in FIG. 6. In addition, the band pass filter 68 would not 
have to be a SAW device but could be constructed in any other well known 
manner. It is also understood by those skilled in the art that the 
function of the CCD can be provided by means of an A-D converter, digital 
shift registers and D-A converters connected in tandem. 
Thus, the present invention has disclosed a novel system with method and 
apparatus for using a lost cost, mass producible electronic ticket which 
is designed to adapt a particular ticket for a particular show to prevent 
a television signal from being acceptably received by an unauthorized 
television receiver while maintaining the television signal recoverable by 
an authorized receiver utilizing one of the electronic tickets. Such 
tickets can easily be sold in supermarkets, drug stores, convenience 
stores and the like. 
It is understood that suitable modifications may be made in the structure 
as disclosed provided such modifications come within the spirit and scope 
of the appended claims.