From: egurney@vcd.hp.com (Ed J. Gurney)
Subject: [FYI] Cable/Scrambling/Satellite Patent List
Summary: (Incomplete) list of patents dealing with CATV/Scrambling/Satellites
Date: Wed, 27 Jan 1993 23:07:01 GMT
Expires: Tue, 27 Apr 1993 23:07:01 GMT
Organization: Hewlett-Packard VCD
X-Newsreader: TIN [version 1.1 PL8.6]
Followup-To: poster
Keywords: Patent CATV Scrambling Video Satellite Descrambler List

________________________________________________________________________

The FAR-FROM-COMPLETE List of CATV/Scrambling/Satellite Patents - Jan'93
________________________________________________________________________

In an attempt to find out more information about the various television
scrambling methods in use today, I have done several U.S.  patent
searches by hand (by looking through the "Official Gazette", the weekly
publication of the U.S.  Patent Office. So far I've done from August '92
through the first week of January '93.)  I plan on doing a computerized 
search sometime in the future, but in the meantime, I figured the
following items might be of interest to rec.video.cable-tv readers. 

Copies of patents may be obtained from the U.S. Patent Office at a
charge of US$3.00 for each patent.  Send requests to Commissioner of
Patents and Trademarks, United States Patents and Trademarks Office,
Washington, D.C.  20231.  Also note that almost every state has at least
one Official Patent and Trademark Depository which has copies of all 
patents on microfilm.  See 'comp.patents' for more information.

Note that the patent numbers on the bottom of my cable converter got me
started on this idea.  You could help update this list by sending me the
patent numbers from your cable box ALONG WITH THE MAKE AND MODEL NUMBER
OF YOUR CONVERTER.  Since the patents don't specify actual models, this
will help classify which patents are in use on which converters. 

I will post this list periodically if I receive sufficient new
information (or enough requests) to do so. 

Mail any info you may have on current cable technology, other applicalbe
patents not listed here, etc. to <egurney@vcd.hp.com>.  (I'm especially
interested in any information on the data stream sent to converters --
the one used to set their clock, map channels, turn the descrambler
on/off, enable the remote control receiver, etc.) 
________________________________________________________________________

                                NOTE:
Dates following "I:" indicate the issue date, "A:" indicates the
application date.  Comments in parenthesis are my interpretation of the
patent (not always easy to determine with all the mumbo-jumbo in the
abstracts!), and things in braces {like this} are my own personal
opinion.  Products that have the patent listed on a label are indicated
within brackets, [like this].  Patents marked with an asterisk (*) I
feel most likely apply to satellite systems, but you never know... 
________________________________________________________________________

5,177,787 - Scientific-Atlanta, Inc. I:01/05/93 A:10/07/91
"Scrambler with Self-Calibration"

5,177,786 - Gold Star Co. I:01/05/93 A:04/30/91
"Method and Apparatus for Scrambling/Descrambling a Video Signal"
(A/D - D/A combo for bit-scrambling video via a pseudo-random number
generator.)

5,177,485 - Laboratoire European de Recherches Electroniques Avancees
I:01/05/93 A:12/08/89
"Method of Scrambling PAL, SECAM, and NTSC Composite Video Signals and
Decoder of Signals Scrambled By This Method"
(Line permutation controlled by synchronized pseudo-random sequences.)

5,173,900 - General Instruments, Inc. I:12/22/92 A:05/17/91 *
"Method and Appartus for Communicating Different Categories of Data in a
Single Data Stream"
(Combining sets of data to form a data group, combining with header data
to form a unit, joining successive units for transmission.) 

5,166,976 - NEC Home Electronics, Ltd. I:11/24/92 A:09/20/91
"System and Method for Detection of a Pulse Within a Video Signal"
("A pedestal detecting system for detecting the duration of a pedestal
pulse...within a received video signal adjacent to active video..." and
various timers for detecting when the pulse crosses various video
levels, etc.) 

5,161,194 - NEC Corporation I:11/03/92 A:07/30/90 *
"Satellite Communications System Operating in Asynchronous Mode for
Central-to-Terminal Station Transmission"
(A central system which generates unique words, a packet assembler, an 
encrypter which encrypts packets without encrypting the unique words; a
terminal with unique word detector to generate a timing signal, a 
decryptor to decrypt packets in response to timing signal, and a packet
deassembler for decomposing deciphered data into blocks of data.)

5,161,188 - H. George Pires I:11/03/92 A:07/19/91
"Scrambling Video By Horizontal and Vertical Time Shifting"
(Method of scrambling video by removing pre-equalizing pulses to render
unidentifiable the beginning of the video signal and regenerating after
transmission a pulse train which is incorporated into the video signal.) 

5,161,187 - Matsushita Electric Co., Ltd. I:11/03/92 A:03/07/91
"Cable Televsion System"
(A means for suppressing vertical and horizontal sync information in
amplitude to execute selective scrambling; means for superimposing a
sync width signal and key data with vertical blanking period, the sync
width info being modulated at a video band frequency and having a burst
form and a predetermined width, the sync width info representing whether
the sync pulses are missing or present, the key data having bits
representing the contents of the scrambling.  The receiver generates a
reference signal based on the edge of the sync width information pulse;
means for extracting the key data from the scrambled video in response
to the reference signal; ability to generate pseduo horizontal and
vertical sync signals; means for increasing the vertical and horizontal
sync information of the scrambled video in amplitude in response to the
extracted key data at timings determined by the pseudo horizontal and
vertical sync signals.) 

5,159,631 - Macrovision Corporation I:10/27/92 A:04/26/90
"Audio Scrambling System Using In-Band Carrier"
(Generates a modulation carrier at 1.5KHz and single side band
modulating the original audio information with the 1.5KHz carrier to
translate the signals to a higher frequency.  {Big deal!})

5,155,590 - Scientific-Atlanta, Co. I:10/13/92 A:03/20/90
"System for Data Channel Level Control"
(Allows "automatically calibrating a particular optimum transmit level
for transmitting data from the television terminals to the system
manager".  {The one diagram given in the abstracts shows a label of
"104.2 MHz" going to a box labelled "SA 8580".  Boxes labelled "SA 8570"
and "SA 8590" are also shown, connected to an "In-band Scrambler" at the
head-end.})

5,146,496 - General Instruments Corporation I:09/08/92 A:06/13/91
"Method and Apparatus for Enhancing the Security of a Scrambled
Television Signal"
(The colorburst component of the video signal is caused to drift over
time without corrupting color content while rendering it unacceptable
for use as a timing reference.  {This particular method would most
definitely defeat the Universal Descrambler, since the U.D.  relies on
the colorburst for generating sync pulses at the proper time.})

5,144,664 - General Instruments Corporation I:10/01/92 A:11/16/90 *
"Apparatus and Method for Upgrading Terminals to Maintain a Secure
Communications Network"
(Allows selective termination of encryption algorithms, and a secure 
means of providing a replacement algorithm to the associated subset of
terminals to use instead of terminated algorithm.) 

5,142,576 - Market Data Corporatoin I:08/25/92 A:05/06/91
"System for Securely Providing Restricted Video Information"

5,142,575 - Scientific-Atlanta, Inc. I:08/25/92 A:11/02/89
"Method and Apparatus for Improving Video Scrambling and Employing Split
Sync Pulses"

5,142,574 - Scientific-Atlanta, Inc. I:08/25/92 A:12/06/89
"Optimum Amplitude and Frequency of Jamming Carrier in Interdiction
Program Denial System"
("Cable television premium channel interdiction apparatus for
selectively jamming unauthorized premium programming transmitted to a
subscriber...")

5,140,633 - North American Philips Corporation I:08/18/92 A:03/22/91
"Cable Subscriber Control Device Using Shared Jamming Modules"

5,138,659 - General Instruments Corporation I:08/11/92 A:05/02/91
"Conversion of TV Signal Formats With Retention of Common Control Data
Stream"
(Allows conversion between NTSC/PAL/SECAM video formats while retaining
the control data stream sent during the vertical blanking interval.) 

5,014,310 - General Instrument Corporation I:05/07/91 A:12/18/89
"Video Scrambling and Descrambling by Varying Sequence of Segments In
Adjacent Video Information Lines"
(Store frame of video in memory; scramble video by retrieving from
memory a segment of one of the odd video lines followed by a segment of
one of even video lines to form a scrambled video line.  Shift the phase
of one of the retrieved segments in relation to the other retrieved
segment by an odd-multiple of one-half the even number of video
samples.) 

5,014,309 - Scientific-Atlanta, Inc I:05/07/91 A:12/05/88
"Off-Premises Cable Television Channel Interdiction Method and 
Apparatus"
(Gain control apparatus for use in premium channel interdiction for
selectively jamming unauthorized premium programs on a broadband signal
transmitted to a subscriber.) 

5,003,592 - H. George Pires I:03/26/91 A:05/05/90
"Scrambling Video by Time Shifting"
(Removing horizontal sync to render unidentifiable a point in time of
the beginning of the line; time shifting sync info by a predetermined
period of time with respect to location in time where sync pulses were;
unscrambling by restoring line synchronization through the time
relationship of removed sync signals.) 

5,003,591 - General Insturments Corporation I:03/26/91 A:05/25/89
"Functionally Modifiable Cable Television Converter System"
(Allows receiving of firmware upgrades from a headend; storing of the
upgrade; verifying integrity of the upgrade; ability to access stored
upgrade.  Also nonvolatile "default" operation mode in case of loss of
firmware upgrade.) 

4,995,080 - Zenith Electronics Corporation I:02/19/91 A:07/16/90
"Television Signal Scrambling System and Method"
(Alternately transmit a scrambled signal with a data packet encrypted
with first key and with the data packet encrypted with second key, allow
operation of descrambler to terminals having said first key or second
key.  Transmit said second key to authorized terminals only. 
Alternately transmit a scrambled signal with a data packet encrypted
with second key and with the data packet encrypted with a third key. 
Terminals with first key and without second key or third key cannot
descramble signal.) 

4,716,410 - Pioneer Electronics Corporation, I:12/29/87 A:05/27/87
"CATV Data Transmission Method"
[Pioneer BA-6110, BA-6310]
(Each unit has a unique address and a "plurality of group addresses"
stored in memory.  When addressed by the central facility, the terminal
unit compares the data with its own address and the group addresses
successively.  "When coincidence is obtained in the comparison, data is
received".  If some part of the group address pattern does not match,
another signal is generated.  {My guess is that part of the group
address is used to determine if a cable box from a different head-end is
being used on the system (or was bought from the back of a magazine :-),
and to disable it...  after-market Pioneer boxess often end up
displaying error codes like 'E4' or 'E5' on their display...})

4,710,971 - Pioneer Electronics Corporation, I:12/01/87 A:08/20/85
"Channel Selecting Device for CATV Terminal Unit"
[Pionner BA-6110, BA-6310]
(In the channel selection device, the channel codes table is stored in
ROM, and only a code arrangement in the channel code table is written in
RAM in compressed form, so the writing time and RAM size are reduced. 
The "compression" of the channel code table consists of writing the
first and last channels of a continuous channel range.) 

4,550,341 - Pioneer Electronics Corporation, I:10/29/85 A:08/03/82
"Unauthorized Observation Preventing Device for CATV System"
[Pioneer BA-6110, BA-6310]
(Converter unit listens for certain signal from central facility, if the
signal is not received satisfactorily, then a timer provides a signal to
the tuner which after a pre-determined amount of time after the absence
of the signal, enables reception of only a single preselected channel.) 

4,322,745 - Pioneer Electronics Corporation, I:03/30/82 A:03/21/80
"Television Signal Scrambling Method for CATV System"
[Pionner BA-6110]
("The scrambling mode employed is changed from time to time so that one
cannot illegally receive the transmitted signals over a long period of
time if only one of the scrambling techniques employed is decoded...An
identifying signal is transmitted which indicates which of the
scrambling circuits is active...")

4,149,158 - Pioneer Electronics Corporation, I:04/10/79 A:05/10/77
"Security System for CATV Terminal"
[Pioneer BA-6110, BA-6310]
("...removal of at least one of the cover screws causes shifting of a
spring loaded movable member that normally...is retained by the screw. 
The shifting movement operates a switch, causing transmission of a
signal to the head end {only in two-way systems!} that indicates that an
entry has been made to the terminal...the mechanism can be arranged such
that the screw cannot be reinserted to provide a positive indication of
tampering.")

--
Ed J. Gurney  N8FPW   Hewlett-Packard Company   Vancouver (USA!) Division
egurney@vcd.hp.com                       #include <standard-disclaimer.h>
"Failures are divided into two classes-- those who thought and never did,
      and those who did and never thought."     John Charles Salak
Newsgroups: rec.video.cable-tv