第四台 (台灣CABLE TV 有線電視的俗稱) 的鎖碼頻道, 不小心掃到, 看來還是 ANALOG 的 99 頻道, 但是有干擾. 好奇他們用的方法.
這是鎖碼的畫面, 普通電視機不一定看到. 用電視卡看數位電視時無意中看到的. 為何要干擾, 原因是第四台要向你收月費才讓你看到所謂的 A片.
A 片這個名稱應該都有來由, 需要多向台灣同胞了解, 但現在是不得而知. 大陸的叫法有幾種, 例如黃色電影, 小電影, 毛片. 港燦稱為 3仔, 4仔 或是 AV, 通常日本拍的叫日系AV, 至於由來...還是不清楚.
reading for followings,
http://www.ronaldsnoeck.com/cabledecoder.htm#20
http://www.bombshock.com/electronics/cable-descrambling/cable_tv_scrambling_techniques.html
http://www.hackerscatalog.com/Services/TECH_Notes/eleven.html
這是鎖碼的畫面, 普通電視機不一定看到. 用電視卡看數位電視時無意中看到的. 為何要干擾, 原因是第四台要向你收月費才讓你看到所謂的 A片.
A 片這個名稱應該都有來由, 需要多向台灣同胞了解, 但現在是不得而知. 大陸的叫法有幾種, 例如黃色電影, 小電影, 毛片. 港燦稱為 3仔, 4仔 或是 AV, 通常日本拍的叫日系AV, 至於由來...還是不清楚.
reading for followings,
http://www.ronaldsnoeck.com/cabledecoder.htm#20
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Old design shotsHere you can find old designs that I used in the past for RTL and Filmnet on satellite and cable. I will probably use the drawings again. The Tuner and IF part will also be easy to build. VCXOThe first part is the VCXO. The VCXO is build around the CMOS IC 4007. The VCXO generates a 4MHz reference frequency for the sync generator. Sync GeneratorThe sync generator is responsible for generating all line related synchronization. For now only the line sync. Burst gateThe Burst gate will gate the burst out of the CVBS signal. The burstgate signal can be generated by the sync generator. The Burst pulse is active during the burst. The problem with using the burst as synchronization is the phase problem. When the video signal changes in amplitude the phase of the detected burst changes, for the burst envelop is very slow. Voltage GeneratorThe Old Tuning voltage generator.
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http://www.bombshock.com/electronics/cable-descrambling/cable_tv_scrambling_techniques.html
Cable TV Scrambling Methods
There are 4 major methods of pay-channel security and each has
different consequences for cable ready receivers. The 4 Cable TV
Scrambling Methods are jamming, trapping out-of-band scrambling and
in-band scrambling.
Jamming:
A jamming signal is placed between the picture carrier and and the
aural carrier of the secured channels. The cable operator supplies a
filter for each customer for each paid channel. This type of security is
easily defeated by homemade notch filters.
Trapping:
In these systems frequency filters are installed in line with the
cable drops on telephone poles. The traps are removed for customers
paying for the premium channels. Cable-ready TV’s work fine in these
systems.
Scrambling:
The gated Sync Methods:
Scrambling in the cable TV business still generaly means pulsed sync
suppression. In its simplist form, amplitude of the picture carrier is
reduced by 6 db during the horizontal blanking intervals and sometimes
during the vertical blanking intervals. The resulting video signal has
sync tips between the black and white levels. Sync seperators in the set
cannot operate properly with this signal, nor can AGC and color
circuts, so the picture is scrambled.
The decoder compensates by antennuating the signal during the time in
which the transmited signal was not antennuated. In order to accomplish
this, the logic controlled gain switch must get timing information.
In-band systems transmit pulses as amplitude modulation of aural carrier
or a seperate carrier in out of band systems.
Out of band scrambling:
The usual setup is that the decoder is connected directly to the
cable ahead of the channel converter. Decoding is done at the pay
channel frequency. The decoder is likely to be in a seperate box, added
to an old system to provide pay channels. The box consists of a simple
receiver (90-120mhz) for the out-of-band data carrier and a broad band
6db gain switch.
There is provision for several scrambled channels, each which has a
different data carrier. This system is directly compatable with cable
ready receivers. Without the cable converter, the decoder is connected
to the TV. Tuning and remote features of the TV are preserved with the
only inconvience being the need to operate the switch on the decoder
when changing to and from any scrambled channel. Out-of- band systems
tend to last until the operators using them rebuild to provide for a
large increase in the number of channels.
In Band Scrambling:
In this system any number of the available channels can be scrambled.
Because the data carrier for each scrambled channel is its own aural
carrier, only one data receiver, at the aural carrier frequency (eg. ch
3) is required. The decoder detects the presence or absense of data
automaticly switching itself in or out. The converter-decoder box can be
hardwired to decode just the channels ordered, using a prom like
device.
Alternatively, the transmitted channels can be “tagged” by time
division multiplexing binary tag (program identification) data with the
sync data on the aural carrier. The decoder boxes can be wired for
“tiers” (groups of programs the cable operator sells togeather) rather
than fixed channels, giving the operator more flexibility. The decoder
boxes can be “addressable”. These boxes have a seperate out of band data
channel for data from the head end. Each box has a serial number burned
into its logic or otherwise available to its logic circutry, and its
channel or tier authorization stored in volatile ram.
A computer at the headend periodicaly addresses all decoders in the
system individualy and loads each with the channel or tier capacity
ordered by the customer. The need for house calls is reduced, PPV (Pay
per view) is possible, and missing boxes cam be turned off, rendering
them useless for premium channel viewing. Some but not all of these
features can be programmed into out-of-band systems.
Aside form their ability to generate sync pulses, thus foiling the
scrambling system, cable ready TV’s have presented another dificult
problem for in-band systems. Because the decoder operates at the
converted channel, a channel converter is required ahead of it. Wheather
the TV receiver is cable-ready or not, it operates only at the
converted channel, wasting the tuning and remote control features.
http://www.hackerscatalog.com/Services/TECH_Notes/eleven.html
- echnical
Notes: - CABLE FAQ
#2 ( Updated ) - GENERAL
INFORMATION ON ALL DESCRAMBLERS - CABLE HACK
FAQ DISCLAIMER - The
ownership of a signal descrambler does NOT
give the owner the automatic right to decode
or view any scrambled signals without
authorization from the corresponding company
or individual. Use of such a device without
permission may be in violation of state
and/or federal laws. The information
contained herein is intended to serve as a
technical aid to those person seeking
information on various scrambling
technologies. No liability is assumed for the
use or misuse of this information.
- SCRAMBLING
TECHNOLOGIES - Traps(Traps/Addressable
Taps) - A cable
system may not be scrambled at all. Some
older systems (and many apartment complexes)
use traps or filters which actually remove
the signals you aren't paying for from your
cable. (These are negative traps because they
remove the WHOLE signal.) These systems are
relatively secure because the traps are often
located in locked boxes, and once a service
technician finds out they're missing or have
been tampered with (by pushing a pin through
a coax trap it to change its frequency, for
example), it's a pretty solid piece of
evidence for prosecution. - Another
method is where the head-end ADDS an
extraneous signal about 2.5 MHz above the
normal visual carrier which causes a tuner to
think its receiving a very strong signal--the
tuner then adjust the automatic gain control
and buries the real signal. If you pay for
the service, the cable company adds a
positive trap which then REMOVES the
extraneous injected signal so it becomes
viewable. (This system is very easy to
circumvent by building your own notch filter,
so it is not very commonly used.) - Advantages
to a cable system with this technology is
that you don't need a cable box--all your
cable-ready TVs, VCRs, etc. will all work
beautifully. The disadvantage is that
pay-per-view events are not possible, and
that every time someone requests a change in
service, a technician has to be dispatched to
add/remove the traps. - An article
for building a tunable notch filter to block
data streams sent just above the FM band was
in the April 1992 issue of Radio-Electronics
(pp. 37-39). Notch filters (as well as kits
for them) for other frequencies are
frequently advertised in Nuts & Volts
magazines as beep filters and the like.
- Becoming
more and more popular, not only because of
the Cable Act of 1992 but also in an effort
to stop pirates are addressable taps. Many
cable companies will be moving to this
technology in the near future, (which they
call interdiction). These are devices located
at the pole, where your individual cable feed
is tapped from the head-end. Similar to
addressable converters, they each have a
unique ID number and can be turned on/off by
a computer at the head-end. - Any stations
which you are not paying for are filtered out
by electronically switchable traps in the
units. (Including the whole signal if you
haven't paid your bill or had the service
disconnected.) {Several patents have already
been issued for various methods of making
SURE you don't see a channel you don't pay
for.} Again, these almost guarantee an end to
piracy and don't have any of the
disadvantages of the manual traps.
- Plus, they
provide a superior signal to those customers
paying for service because they no longer
need complicated cable boxes or A/B switches
-- and they can finally use all of the
cable-ready capabilities of the VCR, TV, etc.
About the only known attack on this type of
system is to splice into a neighbors cable,
which again provides plenty of physical
evidence for prosecution. - SINE-WAVE
- Early Oak
(and some very early Pioneer boxes) employed
a sine-wave sync suppression system. In this
system, the picture would remain vertically
stable, but wiggling black bars with white on
either side would run down the center of the
screen. The lines were caused by a 15,750 Hz
sine-wave being injected with the original
signal, causing the sync separator in the TV
to be unable to detect and separate the sync
pulses. - Later, Oak
came out with a Vari-Sync model, which also
removed a 31,500 Hz sine-wave added to the
signal. Oak was one of the first to use extra
signals (tags) as a counter-measure for
pirate boxes -- in the normal mode, a short
burst of a 100 kHz sine-wave (the tag signal)
would be sent during the VBI, along with the
AM sine-wave reference on the audio carrier
and scrambled video. They would then put the
AM sine-wave reference signal onto the audio
carrier, leave the video alone, and NOT send
the tag. - Any box
which simply looked for the AM sine-wave
reference would effectively scramble the
video by adding a sine-wave to the
unscrambled video! Real decoders looked for
the tag signal and still worked correctly.
Other combinations of tag/no tag,
scrambled/unscrambled video were also
possible. - 6 DB IN-BAND
SYNC SUPPRESSION Early Jerrold boxes used
in-band gated sync suppression. The
horizontal blanking interval was suppressed
by 6 dB. A 15.734, 31.468 or 94.404 kHz
reference signal (conveniently all even
multiples of the horizontal sync frequency)
was modulated on the sound carrier of the
signal, and used to reconstruct the sync
pulse. - An article
in February 1984 issue of Radio-Electronics
explains this somewhat-old technique.
Converters which have been known to use this
system include the Scientific-Atlanta
8500-321/421, a number of Jerrold systems
[see numbering chart], Jerrold SB-#,
SB-#-200, SB-#A, RCA KSR53DA, Sylvania 4040
and Magnavox Magna 6400. - TRI-MODE
IN-BAND SYNC SUPPRESSION - A
modification to the 6dB sync suppression
system, dubbed Tri-mode, allows for 0, 6 and
10 dB suppression of the horizontal sync
pulse. The three sync levels can be varied at
random ,as fast as once per field, and the
data necessary to decode the signal is
contained in unused lines during the VBI
along with other information in the cable
data stream. - See the
February 1987 issue of Radio-Electronics for
a good article including both theory and
schematics, on the Tri-mode system.
Converters which have been known to use this
system include a number of Jerrold systems
[see numbering chart], Jerrold
SBD-#A, SBD-#DIC, Jerrold Starcom VI (DP5/DPV
models), Regency, Scientific- Atlanta
8550-321 and early Pioneer systems.
- Out-Band
Sync Suppression - Out-band
gated sync systems also exist, such as in
early Hamlin converters. In this system, the
reference signal is located on an unused
channel, usually towards the higher end
(channels in the 40's and 50's are common,
but never in the low 30's due to potential
false signaling.) The signal is comprised of
only sync pulse information without any
video. Tuning in such a channel will show
nothing but a white screen and will usually
have no audio. - SSAVI /
ZTAC - SSAVI is an
acronym for Synchronization Suppression and
Active Video Inversion and is most commonly
found on Zenith converters. ZTAC is an
acronym for Zenith Tiered Addressable
Converter. Besides suppressing sync pulses in
gated-sync fashion, video inversion is used
to yield four scrambling modes (suppressed
sync, normal video; suppressed sync, inverted
video; normal sync, inverted video; and
normal sync, normal video). - The
horizontal sync pulses of an SSAVI signal can
be absent completely, at the wrong level, or
even present, and can be varied on a
field-by-field basis. Any decoder for an
SSAVI or similar system has to be able to
separate a video line into its two basic
components-- the control and picture signals.
In SSAVI, the horizontal sync is never
inverted, even if the picture is.
- So a method
of inverting the picture without inverting
the control section is necessary. This is
complicated by the fact that almost every
line in an SSAVI signal has no horizontal
sync information, making it difficult to
perform the separation since the usual
reference point, the horizontal sync pulse,
is gone. - In the older
suppressed-sync system, the sync pulse could
be recovered from the gating signal buried in
the audio subcarrier, but SSAVI is pilotless.
The key to this system relies on the strict
timings imposed by the NTSC standard--if you
can locate one part of the signal accurately,
you can determine where everything else
should be mathematically. - Since the
cable company is sending a digital data
stream---the security and
access-rights--during the VBI of the signal,
the VBI makes a great place to find a known
point in the signal. Obviously if the
electronics in the cable box can locate this
information, so can electronics outside the
cable box! - The only
constant in the SSAVI system are the
horizontal sync pulses during the VBI (the
first 26 lines of video), which are sent "in
the clear". The pulses from the VBI can be
used as a reference for a phase-locked loop
(PLL) and used to supply the missing pulses
for the rest of the video frame. With 20 or
so reliable pulses at the beginning of each
frame, you can accurately generate the
missing 240 or so pulses. - Of the 26
lines in the VBI, lines zero through nine are
left alone by request of the FCC, lines 10 to
13 are commonly used to transmit a digital
data stream, line 21 contains closed-caption
information, while other lines are used for a
variety of stuff depending on the cable
system and the channel you're watching. When
you tune to a scrambled channel with a cable
box, logic circuits in the unit count the
video lines, read the transmitted data
stream, and compare the transmitted data with
the information stored in the box.
- If the box
is authorized to receive the signal with that
particular data stream, the decoder is
enabled and the scrambled signal becomes
viewable. If not, the signal is passed
through without being decoded, or more
commonly, a barker channel (whose channel
number is sent via the data stream) is
automatically tuned instead. This prevents
people from using the unit as a tuner for
add-on descramblers often advertised in the
back of electronics magazines. - In the SSAVI
system, the video can be sent with either
normal or inverted picture information. The
descrambler needs a way to determine whether
to invert the video or not. Originally this
information could be found on line 20, but
has since moved around a lot as the
popularity and knowledge of the system
increased. In any event, the last half of the
line would tell the decoder whether to invert
the picture or not. If the rest of the field
was not inverted, the last half of the line
would be black. If the video in the rest of
the frame was inverted, the last half of the
line would be white. - The Drawing
Board column of Radio-Electronics starting in
August '92 and going through May '93
described the system and provided several
circuits for use on an SSAVI system. Note
that audio in the system can be scrambled -
usually by burying it on a subcarrier that's
related mathematically to the IF component of
the signal. Addressable data for Zenith
systems is sent in the VBI, lines 10-13, with
26 bits of data per line. - TOCOM
SYSTEMS The Tocom system is similar to the
Zenith system since it provides three levels
of addressable baseband scrambling: partial
video inversion, random dynamic sync
suppression and random dynamic video
inversion. Data necessary to recover the
signal is encrypted and sent during lines 17
and 18 of the VBI (along with head-end
supplied Teletext data for on-screen
display). - The control
signal contains 92 bits, and is a 53 ms burst
sent just after the color burst. Up to 32
tiers of scrambling can be controlled from
the head-end. Audio is not scrambled.
- NEW PIONEER
SYSTEMS - The newer
6000-series converters from Pioneer
supposedly offer one of the most secure CATV
scrambling technologies from a major CATV
equipment supplier. From the very limited
information available on the system, it
appears that false keys, pseudo-keys and both
in-band and out-band signals are used in
various combinations for a secure system.
- From U.S.
patent abstract #5,113,441 which was issued
to Pioneer in May '92 (and may or may not be
used in the 6000-series converters, but could
be), "An audio signal is used on which a key
signal containing compression information and
information concerning the position of a
vertical blanking interval is superimposed on
a portion of the audio signal corresponding
to a horizontal blanking interval. In
addition, a pseudo-key signal is
superimposed...so that the vertical blanking
interval cannot be detected through the
detection of the audio
signal… - Descrambling
can be performed by detecting the vertical
blanking interval based on the
information...in the key signal, and decoding
the information for the position which is
transmitted in the form of out-band data.
Compression information can then be extracted
from the key signal based on the detected
vertical blanking interval, and an expansion
signal for expanding the signal in the
horizontal and vertical blanking periods can
be generated." - Note that
Pioneer boxes are booby-trapped and opening
the unit will release a spring-mechanism
which positively indicates access was gained
to the interior (and sends a signal to the
head-end on a two-way system, and may disable
the box completely.) {See U.S. patent
#4,149,158 for details.} The unit cannot be
reset without a special device. - Pioneer
systems transmit their addressing data on
110.0 MHz, and there are several programmable
cubes that can activate these systems. The
data is a manchester I encoded FSK signal at
~6kHz data rate. - NEW
SCIENTIFIC-ATLANTA SYSTEMS - Some of the
early S-A boxes used 6 dB only sync
suppression (some of the 8500 models), and
some of the 8550 boxes are Tri-mode systems.
The three digit number after the model (such
as 321) is a code which indicates the make of
the descrambler in the unit. Apparently some
of the newer S-A boxes use a technique called
dropfield, and some of the newer 8600 and
8570 models use baseband methods.
- Scientific-Atlanta
systems transmit their FSK addressing data on
106.2 or 108.2 MHz. There are several
programmable cubes that can activate these
systems. On the newest 8600 systems the
address data is hidden elsewhere, possibly
the video blanking region. - OAK SIGMA
SYSTEMS - This a
secure system which replaces the horizontal
sync of each line of video with a three-byte
digital word. Video is switched from inverted
to non-inverted between scene changes, and
the colorburst frequency is shifted up. This
is a standard suppressed sync video
scrambling method and is relatively simple to
defeat with the appropriate
circuitry. - However, the
three-byte digital word in the area where the
sync normally is contains audio and sync
information. The first two bytes contain a
digitized versions of the audio, the third
byte contains sync information and perhaps
addressing data. The two bytes of digitized
audio are encrypted; a separate carrier
signal contains the decryption keys for the
digital audio datastream. - JERROLD
BASEBAND (DPBB AND CFT MODEL
UNITS) - Jerrold has
gone one step further in scrambling the
signal at the baseband level. Other less
complicated methods like Tri-mode scramble
the signal at the RF level where the channel
73 signal is scrambled when the signal is
already modulated on channel 73. With
baseband scrambling the signal is scrambled,
then modulated on the desired channel. Using
this method the scrambling device has more
control and more complicated methods can be
used. - The most
popular way to defeat these systems is to use
a test chip or a cube device to activate the
original Jerrold equipment. Add-on
descramblers are more difficult to build
since you have to convert the signal to
baseband levels, descramble, then remodulate
the signal. - Cable
Companies have been experimenting with
several new methods of defeating test chips
and cubes, most notably is the use of Multi
Mode and adding an extra checksum byte in the
FSK data packet format. Pirates are starting
to clone cable companies test boxes to get
around the most problem areas of multi mode
and newer test chips and cubes are getting
smarter to combat both multimode and the
extra checksum bytes. - CHAMELEON
- The research
and development division of Fundy Cable Ltd.,
NCA Microelectronics, has a system dubbed
Chameleon. They claim it is a cost-effective
solution that prevents pay TV theft by
digitally encrypting the video timing
information of sync suppression systems.
- The company
claims the technology has been proven to be
effective against pirate and tampered boxes.
Supposedly, existing decoders can be upgraded
to Chameleon technology with a low-cost
add-in circuit, and that the card's sealed
custom IC, developed by NCA, is copy-proof.
- VIDEOCIPHER
- The
VideoCipher system is now owned by General
Instrument and is used primarily for
satellite signals at this time. VideoCipher
II is the "commercial" version which uses
slightly watered-down version of the DES
(Data Encryption Standard) for encrypted
audio. - Video is
"scrambled" by deleting the horizontal sync
signal. A VC-I descrambler uses line dicing
for the video portion and the same audio
scrambling scheme as the VCII, but is not
available for "home" owners. VideoCipher II
is the now-obsolete system which used a
relatively simple video encryption method
with DES-encrypted audio. - Specifically,
the audio is 15 bit PCM, sampled at ~44.1
kHz. It is mu-law companded to 10 bits before
transmission. This has recently been replaced
by the VideoCipher II+, which has been
incorporated as the 'default' encryption
method used by VideoCipher IIRS (a smart-card
based, upgradeable system). - Coded data
relating to the digitized, encrypted audio is
sent in the area normally occupied by the
horizontal sync pulse in the VCII system.
(The Oak Sigma CATV system uses a similar
technology.) The Plus format put the
datastream data in the HBI. - DIGICABLE/DIGICIPHER
- DigiCipher
is an upcoming technology being developed by
General Instrument for use in both NTSC and
HDTV environments. The DigiCipher format is
for use on satellites, and the DigiCable
variation will address CATV needs. It
provides compression algorithms with forward
error correction modulation techniques to
allow up to 10 "entertainment quality" NTSC
channels in the space normally occupied by
one channel. - It provides
true video encryption (as opposed to the
VCII-series which only DES encrypts the
audio). In a Multiple Channel Per Carrier
(MCPC) application, the data rate is ~27
MB/second via offset QPSK modulation. Audio
is CD-quality through Dolby AC-2 technology,
allowing up to four audio channels per video
channel. - The system
uses renewable security cards (like the
VCIIRS), has 256 bits of tier information,
copy protection capability to prevent events
from being recorded, commercial insertion
capability for CATV companies, and more. The
multichannel NTSC satellite version of
DigiCipher started testing in July of 1992,
and went into production several months
later. - B-MAC
- MAC is an
acronym for Mixed Analog Components. It
refers to placing TV sound into the
horizontal-blanking interval, and then
separating the color and luminance portions
of the picture signal for periods of 20 to 40
microseconds each. In the process, luminance
and chrominance are compressed during
transmission and expanded during reception,
enlarging their bandwidths
considerably. - Transmitted
as FM, this system, when used in satellite
transmission, provides considerably better TV
definition and resolution. Its present
parameters are within the existing NTSC
format, but is mostly used in Europe at this
time. - MISCELLANEOUS
INFORMATION - Two-Piece
vs. One-Piece - There are
both advantages and disadvantages to the
one-piece and two-piece descramblers often
advertised in the back of electronics
magazines. Most one-piece units are real
cable converters, just like you'd get if you
rented one from the cable company. It has the
advantages of real descrambling circuitry and
the ability to fit-in well when neighbors
come over (avoids those my box doesn't look
like that...or get all these channels!
conversations. - A
disadvantage is that if you move or the cable
company installs new hardware, you may now
have a worthless box -- most one-piece units
only work on the specific system they were
designed for. Another disadvantage is that if
the box has not been modified, it can be very
easy for the head-end to disable the unit
completely. - A two-piece
unit (combo) usually consists of an any-brand
cable TV tuner with a third-party descrambler
(often referred to as a pan) which is
designed to work with a specific scrambling
technology. The descrambler typically
connects to the channel 3 output of the
tuner, and has a channel 3 output which
connects to your TV. Although some tuners
have a decoder loop for such
devices. - They have
the advantage that if you move or your system
is upgraded, you can try to purchase a new
descrambler -- which is much cheaper than a
whole new set-up. You also can select the
cable TV tuner with the features you want ,
i.e., remote, volume control, parental
lockout, baseband video output, etc.
Two-piece units typically cannot be disabled
by the data stream on your cable.
- Note however
that there ARE add-on pans manufactured by
the same companies who make the one-piece
units that DO pay attention to the data
stream and can be disabled
similarly! - The main
disadvantage is that a third-party
descrambler MAY not provide as high of
quality descrambling as the real thing, and
it may arouse suspicion if someone notices
your cable thing is different from theirs.
- JERROLD
NUMBERING SYSTEM - To decode
older Jerrold converters, the following chart
may be helpful. - __ __ __ __
- __ __ __ - | | | | | |
| - | | | | | |
|____________ T = two-way capability, C =
PROM programmable - | | | | |
| - | | | | |
|____________ DI = Inband decoder, DO =
Outband decoder, - | | | | | PC
= Single pay channel, A =
Addressable - | | | |
| - | | | |
|______________ Output channel number (3 very
common) - | | | |
- | | |
|________________ D or I = Tri-mode system, N
= parental lockout - | | |
feature (6 dB-only systems are "blank"
here) - | |
| - | |
|_________________ M = mid-band only, X =
thru 400 MHz, - | | Z = thru
450 MHz, BB = baseband - | |
- |
|___________________ S = Set-top, R =
Remote - |
- |____________________
D = Digital tuning, J = Analog
tuning - Also note
that some Jerrold converters (particularly
the DP5 series and some CFTs) have a
tamper-switch, and that opening the box will
clear the contents of a RAM chip in the
converter. This may or may not be corrected
by letting the unit get refreshed by the
head-end FSK data stream. - Most Jerrold
systems in the United States and Canada
transmit their addressing data on 97.5, 106.5
or 108.5 MHz. Some DPV7 and DPBB7 models have
S7, S8, or S9 as the last numbers on there
model numbers, these correlate to 97.5, 106.5
and 108.5 MHz directly. - CFT model
numbers almost always use 108.5Mhz. DPV5 and
older units mostly use 106.5Mhz. In Europe
122.75 Mhz seems to be the addressing
frequency used, at least in several parts of
England. The datastream is Manchester II
encoded FSK, with approximately a 14kHz
clock. - SCIENTIFIC-ATLANTA
SUPPRESSED SYNC BOX NUMBERING - Model 8600 -
_ _ _ _ - | | |
| - | | | |___
Impulse PPV Return: N=none, T=telephone,
R=RF - | | |_____
Dual cable option: N=none, D=dual
cable - | |_______
Descrambler type: S=SA standard,
K=oak - |_________
Channel: S=selectable channel 3/4 - The 8600 has
240 character on-screen display, multimode
scrambling, - 8 event 14
day timer, and is "expandable". - Model 859_ -
7 _ 7 _ - | |
| - | | |__ Dual
cable option: D=dual cable - | |______
Descrambler: 5=SA scrambling+video
inversion, - |
7=5+Oak - |____________
0=No Impulse PPV, 5=Telephone IPPV, 7=RF
IPPV - The 8590s
feature volume control, multimode scrambling,
8 event - 14 day
timer... - Model 858_ -
_ 3 _ - _ - | | | |__
Dual cable option: D=dual cable - | | |______
Data carrier: 6=106.2 MHz, 8=108.2
MHz - |
|__________ Channel: 3=channel 3, 4=channel
4 - |______________
0=No Impulse PPV, 5=Telephone IPPV, 7=RF
IPPV - The 8580s
use dynamic sync suppression, 8 event 14 day
timer, and - built-in
pre-amp. - The 8570 is
similar to the 8580. - Model 8550 -
_ _ _ - | | |__
1=108.2 MHz data stream - | |____
Jerrold, dropfield, SA
descrambling - |______
Channel: 3=channel 3 - The 8550 is
not a current model; it can be replaced with
an 8580-321. - Non-addressable
products include the 8511, 8536, 8540 and
8490. - The SA
models below 8600 transmit there FSK
addressing data on one of two frequencies.
- MARKET CODES
Note that almost every addressable decoder in
use today has a unique serial number
programmed into the unit -- either in a PROM,
non-volatile RAM, EAROM, etc. This allows the
head-end to send commands specifically to a
certain unit to authorize a pay-per-view
events, for example. - Part of this
serial number is what is commonly called a
market code, which can be used to uniquely
identify a certain cable company. This
prevents an addressable decoder destined for
use in Chicago from being used in Houston. In
most cases, when a box receives a signal with
a different market code, it will enter an
error mode and become unusable. - This is just
a friendly little note to anyone who might
consider purchasing a unit from the back of a
magazine -- if the unit has not been modified
in any way to prevent such behavior, you
could end up with an expensive paper
weight. - TEST
CHIPS - Test chips
are used to place single-piece converters
that is, units with both a tuner and a
descrambler into full service. There are a
number of ways to accomplish this, but in
some cases, the serial number/market code for
the unit is set to a known universal case or,
better yet, the comparison checks to
determine which channels to enable/disable
are bypassed by replacing an IC in the unit.
- Hence, the
descrambler will always be active, no matter
what. This latter type of chip is superior
because it cannot be disabled and is said to
be bullet proof, even if the cable company
finds out about a universal serial number.
When the cable company finds out about a
universal serial number, it is easy for them
to disable the converter with a variation on
the bullet described below. - CUBES
- Another type
of test device has been advertised in
magazines such as Electronics and Nuts &
Volts. It's called a cube and it simulates
the addressing data signal test signal for a
cable box, most commonly for those from
Pioneer and Jerrold. The Zenith data stream
is sent in the VBI, making this approach more
difficult. - You plug the
cable into one side, where it filters out the
real data signal, and out the other side
comes a normal signal, but with a new data
stream. There are also wireless cubes which
you just periodically set near your box with
the cable disconnected to refresh
it. - This new
data signal tells whatever boxes the cube
addresses to go into full-service mode,
including any cable company-provided boxes.
Sometimes it is a non-destructive signal, and
if the cube is removed from the line, the
real data signal gets to the electronics
inside and the converter goes back to normal
non-test mode. - Note that
sometimes it is destructive. There are some
cubes that re-program the electronic serial
number in a converter to a new value. This
type has the advantage that it will work with
any converter the cube was designed to test
but changes the serial number to some preset
value. - The
non-destructive versions of a cube usually
require that you provide the serial number
from the converter you're interested in
testing. That way a custom IC can be
programmed to address that converter with the
necessary data. Otherwise the converter would
ignore the information, since the serial
number the cube was sending and the one in
converter wouldn't match. - BULLETS
- First and
foremost, the "Bullet" is nothing more than
the normal cable FSK data stream with the
appropriate code to disable a converter which
has not been acknowledged by the cable
company. For instance, the head end could
send a code to all converters which says
unless you've been told otherwise in the last
12 hours, shut down. - All
legitimate boxes were individually sent a
code to ignore this shut down code, but the
pirate decoders didn't get such a code
because the cable company doesn't have their
serial number. So they shut down when the see
the bullet code. - The bullet
is not a harmful high-voltage signal or
something as the cable companies might like
you to believe. If it was, it would damage
anyone with a cable-ready TV or VCR connected
to the cable and certainly not something the
cable company wants to deal with!
- The only way
to get caught by such a signal is to contact
the cable company and tell them your illegal
descrambler just quit working for some
reason. Not a smart thing to do, but you'd be
surprised, especially if it's someone else in
the house who calls, like a spouse, child,
babysitter, etc. While we're on the subject,
it's also not a good idea to have cable
service personnel come into your residence
and find an unauthorized decoder. Don't hack
on cable company decoders. - TIME DOMAIN
REFLECTOMETRY / LEAK DETECTION - The cable
company can use a technique called Time
Domain Reflectometry (TDR) to try and
determine how many devices are connected to
your cable. In simple terms, a tiny, short
test signal is sent into your residence and
the time domain reflectometer determines the
number of connections by the various echoes
returned down the cable. Since each device is
at a different point along the cable, they
can be counted. - Each
splitter, filter, etc. will affect this
count. A simple way to avoid being probed is
to install an CATV amplifier just inside your
premises before any connections. This
isolates the other side of the cable from the
outside, and a TDR will only show one
connection to the amplifier. Radio-Shack sell
these as "Splitter Amplifiers" for about
$15.00. - The cable
company also has various ways of detecting
signal leaks in their cable. The FCC requires
them to allow only so much signal to be
radiated from their cables. You may see a
suspicious looking van driving around your
neighborhood with odd-looking antennas on the
roof. These are connected inside to field
strength meters which help locate where the
leaks are coming from so they can be fixed
thus preventing fines from the
FCC! - If you've
tampered with a connection at the pole , say
to hook up a cable that had been disconnected
and didn't do a good job, chances are the
connection will "leak" and be easily found by
such a device. This can also happen inside
your residence if you use cheap
splitters/amplifiers or have poorly-shielded
connections. - The cable
company will ask to come inside, and bring
with them a portable field strength meter to
help them locate the problem. Often they will
totally remove anything causing the leak, and
may go further, e.g., legal action, if they
feel you're in violation of your contract
with them with which you have already agreed
to by paying your bill. - Obviously
it's a bad idea to let cable service
personnel into your house if you are doing
something you shouldn't ,but if you don't let
them in, as is your right, it will definitely
arouse suspicion. Eventually you will have to
let them in to fix the "leak", or they will
disconnect your cable to stop the leak
altogether. - SOME COMMON
WAYS PIRATES GET CAUGHT - There are
many ways for a pirate to get caught. Since
stealing cable is illegal in the U.S., you
can be fined and sent to jail for theft of
service. Cable companies claim to lose
millions of dollars in revenue every year
because of pirates, so they are serious in
their pursuit of ridding them from their
system. - A pirate
will often show-off the fact they can get
every channel to their friends. Pretty soon
lots of people know about it, and then the
cable company offers a "Turn In A Pirate And
Get $50" program. A "friend" needs the money
and turns the Pirate in. - A pirate or
more likely, unsuspecting housemate of a
pirate who knows nothing about what's going
on calls the cable company to report a
problem with the equipment or signal. The
cable company makes a service call and finds
gray-market equipment connected to the cable.
- During a
pay-per-view event such as a fight, the cable
company offers a free T-shirt to all viewers.
Little does the "Pirates" know that just
before that message appeared on the screen,
legitimate viewer's boxes were told to switch
to another channel while still displaying the
original channel number. - So now the
legitimate subscriber continues to see the
"original" signal, without the T-shirt offer,
while the pirate gets an 800 number plastered
on the screen. The pirate calls, and the
cable company gets a list of all potential
pirates... - The cable
company temporarily broadcasts some soft-core
pornography onto what is supposed to be The
Disney Channel (and vice-versa). They
simultaneously reprogram subscriber
converters to re-map the channels correctly,
so the change is transparent to all but
non-company converters. Those who call to
complain about the "non-Disney" entertainment
(or cartoons on the Playboy channel are more
than likely to have gray-market decoders.
- A big cable
descrambler business gets busted. The
authorities confiscate their UPS shipping
records and now have a list of "customers"
who most likely ordered descramblers for
illegitimate use. Unconfirmed reports of the
cable company driving around with special
equipment allowing them to determine what
you're watching on your TV have also been
mentioned. But this is unlikely. - Of course,
the best thing to do is simply pay for what
you watch! Then you don't have to worry about
the possibility of a prison term, criminal
record, hefty fine, etc. - THE
UNIVERSAL DESCRAMBLER - In May of
1990, Radio-Electronics magazine published an
article on building a universal descrambler
for decoding scrambled TV signals. There has
been much talk on the net about the device,
and many have found it to be lacking in a
number of respects. Several modifications,
hoping to fix some of the problems have also
been posted, with limited success.
- The
Universal Descrambler relies on the presence
of the colorburst for its reference signal.
In a normal line of NTSC video, the
colorburst is 8 to 11 cycles of a 3.579545
MHz clock (that comes out to 2.31
microseconds) which follows the 4.71
microseconds of horizontal sync during the
horizontal blanking interval. - Since a
large number of scrambling systems depend on
messing with the horizontal sync pulse to
scramble the picture, the Universal
Descrambler attempts to use the colorburst
signal to help it replace the tainted sync
pulse. Unfortunately, random video inversion
is still a problem, as are color shifts which
occur from distorted or clamped colorburst
signals, etc. Most people have not had very
good results from the system, even after
incorporating some modifications.
- GLOSSARY OF
RELATED TERMS - CATV:
Acronym for Community Antenna television.
Originally cable TV came about as a way to
avoid having everyone in a community have to
spend a lot of money on a fancy antenna just
to get good TV reception. Really all you need
is one very good antenna and then just feed
the output to everyone. It was called
Community Antenna Television (CATV). Of
course, it has grown quite a bit since then
and everyone now just calls it cable TV. The
old acronym still sort-of works. - Converter: A
device, sometimes issued by the cable
company, to "convert" many TV channels to one
specific channel, usually channel 3. Used
early-on when VHF & UHF channels were on
different dials (and before remote controls)
to provide "convenience" to cable customers.
Now mostly considered a nuisance, thanks to
the advent of cable-ready video equipment,
they are mainly used as
descramblers. - An
"addressable" converter is one that has a
unique serial number and can be told
individually by FSK or other signal, by the
head-end to act in a certain manner such as
enabling channel x, but not channel y.
Addressable converters nearly always contain
descramblers for decoding premium services
subscribed to by the customer. - Colorburst:
Approximately 8 to 10 cycles of a 3.579545
MHz clock sent during the HBI. This signal is
used as a reference to determine both hue and
saturation of the colors. A separate
colorburst signal is sent for each line of
video, and are all exactly in phase to
prevent color shifts. - Control
Signal: The first 11.1 microseconds of a line
of NTSC video. The signal area from 0 to 0.3
volts (-40 to 0 IRE units) is reserved for
control signals, the rest for picture
information. If the signal is at 0.3 volts
(or 0 IRE) the picture will be black. See IRE
Units; Set-up Level. - Cube: A test
device that generates an FSK signal to the
cable box to activate itself into full
service mode also called FSK device or FSK
unit. The first Cubes were named because of
the cube shaped box that they were sold in.
- Field: One
half of a full video frame. The first field
contains the odd numbered lines, the second
field contains the even numbered lines. Each
field takes 1/60th of a second to transmit.
Note that both fields contain a complete
vertical-blanking interval and they both
should have the same information during that
interval. Since the NTSC standard is 525
lines, each field contains 262.5
lines--therefore it's the half-line that
allows the two fields of a frame to be
distinguished from one another. See Frame;
Line. - Frame: An
NTSC video signal which contains both fields.
A frame lasts 1/30th of a second. See Field;
Line. - FSK: Acronym
for Frequency Shift Keying. A common data
modulation method. Addressable cable systems
usually send there control information using
this method. - FSK Device:
See Cube. - Head-end:
The main cable distribution facility where
your CATV signal originates from. Easily
identified by several large satellite dishes,
some smaller ones, and usually an antenna
tower. - HBI: Acronym
for Horizontal Blanking Interval. The first
11.1 microseconds of a line of video. It
contains the front porch, the 4.71
microsecond horizontal sync pulse, the 2.31
microseconds of colorburst, and the back
porch. The horizontal sync pulse directs the
beam back to left side of the screen. Almost
every scrambling method in use today mutates
this part of the signal in some way to
prevent unauthorized viewing. See Colorburst.
- Interlace:
Term used to describe the dual-field approach
used in the NTSC standard. By drawing every
other line, screen flicker is increased--but
if all the lines were painted sequentially,
the top would begin to fade before the screen
was completely "painted". Computer monitors,
which do "paint" from top to bottom, do not
have the problem due to higher refresh rates.
- IPPV:
Impulse Pay-Per-View. A method whereby a
viewer can order a pay-per-view event "on
impulse" by just pushing an "Order" (or
similar) button on a remote control or cable
converter keypad. A customer's purchases are
sent back to the head-end via a standard
telephone connection (the converter dials
into the cable co. computer and uploads the
data) or via radio frequency (RF) if the
cable supports two-way communication (most
don't). A pre-set maximum number of events
can be ordered before the box requires the
data to be sent to the head-end for billing
purposes. - IRE Units:
IRE is an acronym for Institute of Radio
Engineers. The NTSC standard calls for a
peak-to-peak signal voltage of 1 volt.
Instead of referring to the video level in
volts, IRE units are used instead. The IRE
scale divides the 1- volt range into 140
parts, with zero-IRE corresponding to about
0.3V. The full scale goes from -40 IRE to
+100 IRE. This is convenient scale to make a
distinction between control signals (< 0
IRE) and picture signals (> 0 IRE). See
Control Signal. - Line: A
video signal is a series of repeated
horizontal lines, consisting of control and
picture information. The color NTSC standard
allows a total time of 63.56 microseconds for
each line, and each frame is composed of 525
lines of video information. The first 11.1
microseconds make up the horizontal blanking
interval, or control signal, the following
52.46 microseconds make up the picture
signal. See HBI; VBI. - NTSC:
Acronym for National Television Standards
Committee (or Never The Same Color, if you
prefer. - Picture
Signal: The 52.46 microseconds of signal
following the control signal. Information in
this area is between 0 and 100 IRE units. See
IRE Units. - PPV: Acronym
for Pay-Per-View. A revenue-enhancing system
where customer's pay to watch a movie or
event on a "per view" basis. Customers
usually place a phone call to a special
number and order the event of their choice;
some systems provide Impulse PPV. The
presence of a PPV movie channel or your
system guarantees you have addressable
converters. See IPPV. - Set-up
Level: Picture information technically has
slightly less than 100 IRE units available.
That's because picture information starts at
7.5 IRE units rather than at 0 IRE units. The
area from 0 to 7.5 IRE units are reserved for
what is commonly called the "set-up level".
Having a small buffer area between the
control signal information and the picture
information is a "fudge factor" to compensate
for the fact that real-life things that don't
always work as nicely as they do on paper.
:-) See IRE Units. - VBI: Acronym
for Vertical-Blanking Interval. The first 26
lines of an NTSC video signal. This signal is
used to direct the beam back to the
upper-left corner of the screen to start the
next frame. In order for the horizontal sync
to continue operating, the vertical pulse is
serrated into small segments which keep the
horizontal circuits active. Both actions can
then take place simultaneously. The VBI is
the most common place for "extra" information
to be sent, such as various test signals, and
in some cable systems, a data stream.
- TELEVISION
FREQUENCY CHART The following chart lists
frequency information for the "standard"
carrier sets. In an HRC (Harmonically Related
Carrier) system, all picture carrier
frequencies are derived from a 6 MHz
oscillator, so all channels except 5 and 6
will be 1.25 MHz lower than usual. Channels 5
and 6 will be 0.75 MHz HIGHER than usual. An
IRC (Incrementally Related Carrier) system,
all channels are at their normal frequency
except for channels 5 and 6, which will be 2
MHz higher than usual. - Some older
TV sets can't receive any channels except 5
and 6 on an HRC system, and can't receive
channels 5 and 6 on an IRC system. This is
also true of some cable converters. A few
converters are set up to allow HRC or IRC
operation but with channels 5 and 6 on
different numbers -- 55 and 56, or 55 and
66. - VHF-Low
Band - Center Video
Color Sound Osc. - Channel Band
Freq. Carrier Carrier Carrier
Freq. - TVIF 40-46
43 41.25 44.83 47.75 --- - 2 54-60 57
55.25 58.83 59.75 101 - 3 60-66 63
61.25 64.83 65.75 107 - 4 66-72 69
67.25 70.83 71.75 113 - 5 76-82 79
77.25 80.83 81.75 123 - 6 82-88 85
83.25 86.83 87.75 129 - FM
(Pseudo) - FM-1 88-94
91 89.25 92.83 93.75 --- - FM-2 94-100
97 95.25 98.83 99.75 --- - FM-3 100-106
103 101.25 104.83 105.75 --- - VHF-Mid Band
(CATV) - A2-(00)
108-114 111 109.25 112.83 113.75
155 - A1-(01)
114-120 117 115.25 118.83 119.75
161 - A-(14)
120-126 123 121.25 124.83 125.75
167 - B-(15)
126-132 129 127.25 130.83 131.75
173 - C-(16)
132-138 135 133.25 136.83 137.75
179 - D-(17)
138-144 141 139.25 142.83 143.75
185 - E-(18)
144-150 147 145.25 148.83 149.75
191 - F-(19)
150-156 153 151.25 154.83 155.75
197 - G-(20)
156-162 159 157.25 160.83 161.75
203 - H-(21)
162-168 165 163.25 166.83 167.75
209 - I-(22)
168-174 171 169.25 172.83 173.75
215 - VHF-High
Band - 7 174-180
177 175.25 178.83 179.75 221 - 8 180-186
183 181.25 184.83 185.75 227 - 9 186-192
189 187.25 190.83 191.75 233 - 10 192-198
195 193.25 196.83 197.75 239 - 11 198-204
201 199.25 202.83 203.75 245 - 12 204-210
207 205.25 208.83 209.75 251 - 13 210-216
213 211.25 214.83 215.75 257 - VHF-Super
Band (CATV) - J-(23)
216-222 219 217.25 220.83 221.75
263 - K-(24)
222-228 225 223.25 226.83 227.75
269 - L-(25)
228-234 231 229.25 232.83 233.75
275 - M-(26)
234-240 237 235.25 238.83 239.75
281 - N-(27)
240-246 243 241.25 244.83 245.75
287 - O-(28)
246-252 249 247.25 250.83 251.75
293 - P-(29)
252-258 255 253.25 256.83 257.75
299 - Q-(30)
258-264 261 259.25 262.83 263.75
305 - R-(31)
264-270 267 265.25 268.83 269.75
311 - S-(32)
270-276 273 271.25 274.83 275.75
317 - T-(33)
276-282 279 277.25 280.83 281.75
323 - U-(34)
282-288 285 283.25 286.83 287.75
329 - V-(35)
288-294 291 289.25 292.83 293.75
335 - W-(36)
294-300 297 295.25 298.83 299.75
341 - VHF-Hyper
Band (CATV) - AA-(37)
300-306 303 301.25 304.83 305.75
347 - BB-(38)
306-312 309 307.25 310.83 311.75
353 - CC-(39)
312-318 315 313.25 316.83 317.75
359 - DD-(40)
318-324 321 319.25 322.83 323.75
365 - EE-(41)
324-330 327 325.25 328.83 329.75
371 - FF-(42)
330-336 333 331.25 334.83 335.75
377 - GG-(43)
336-342 339 337.25 340.83 341.75
383 - HH-(44)
342-348 345 343.25 346.83 347.75
389 - II-(45)
348-354 351 349.25 352.83 353.75
395 - JJ-(46)
354-360 357 355.25 358.83 359.75
401 - KK-(47)
360-366 363 361.25 364.83 365.75
407 - LL-(48)
366-372 369 367.25 370.83 371.75
413 - MM-(49)
372-378 375 373.25 376.83 377.75
419 - NN-(50)
378-384 381 379.25 382.83 383.75
425 - OO-(51)
384-390 387 385.25 388.83 389.75
431 - PP-(52)
390-396 393 391.25 394.83 395.75
437 - QQ-(53)
396-402 399 397.25 400.83 401.75
443 - RR-(54)
402-408 405 403.25 406.83 407.75
449 - UHF
Broadcast Band (Broadcast) - 14 470-476
473 471.25 474.83 475.75 517 - 15 476-482
479 477.25 480.83 481.75 523 - 16 482-488
485 483.25 486.83 487.75 529 - 17 488-494
491 489.25 492.83 493.75 535 - 18 494-500
497 495.25 498.83 499.75 541 - 19 500-506
503 501.25 504.83 505.75 547 - 20 506-512
509 507.25 510.83 511.75 553 - 21 512-518
515 513.25 516.83 517.75 559 - 22 518-524
521 519.25 522.83 523.75 565 - 23 524-530
527 525.25 528.83 529.75 571 - 24 530-536
533 531.25 534.83 535.75 577 - 25 536-542
539 537.25 540.83 541.75 583 - 26 542-548
545 543.25 546.83 547.75 589 - 27 548-554
551 549.25 552.83 553.75 595 - 28 554-560
557 555.25 558.83 559.75 601 - 29 560-566
563 561.25 564.83 565.75 607 - 30 566-572
569 567.25 570.83 571.75 613 - 31 572-578
575 573.25 576.83 577.75 619 - 32 578-584
581 579.25 582.83 583.75 625 - 33 584-590
587 585.25 588.83 589.75 631 - 34 590-596
593 591.25 594.83 595.75 637 - 35 596-602
599 597.25 600.83 601.75 643 - 36 602-608
605 603.25 606.83 607.75 649 - 37 608-614
611 609.25 612.83 613.75 655 - 38 614-620
617 615.25 618.83 619.75 661 - 39 620-626
623 621.25 624.83 625.75 667 - 40 626-632
629 627.25 630.83 631.75 673 - 41 632-638
635 633.25 636.83 637.75 679 - 42 638-644
641 639.25 642.83 643.75 685 - 43 644-650
647 645.25 648.83 649.75 691 - 44 650-656
653 651.25 654.83 655.75 697 - 45 656-662
659 657.25 660.83 661.75 703 - 46 662-668
665 663.25 666.83 667.75 709 - 47 668-674
671 669.25 672.83 673.75 715 - 48 674-680
677 675.25 678.83 679.75 721 - 49 680-686
683 681.25 684.83 685.75 727 - 50 686-692
689 687.25 690.83 691.75 733 - 51 692-698
695 693.25 696.83 697.75 739 - 52 698-704
701 699.25 702.83 703.75 745 - 53 704-710
707 705.25 708.83 709.75 751 - 54 710-716
713 711.25 714.83 715.75 757 - 55 716-722
719 717.25 720.83 721.75 763 - 56 722-728
725 723.25 726.83 727.75 769 - 57 728-734
731 729.25 732.83 733.75 775 - 58 734-740
737 735.25 738.83 739.75 781 - 59 740-746
743 741.25 744.83 745.75 787 - 60 746-752
749 747.25 750.83 751.75 793 - 61 752-758
755 753.25 756.83 757.75 799 - 62 758-764
761 759.25 762.83 763.75 805 - 63 764-770
767 765.25 768.83 769.75 811 - 64 770-776
773 771.25 774.83 775.75 817 - 65 776-782
779 777.25 780.83 781.75 823 - 66 782-788
785 783.25 786.83 787.75 829 - 67 788-794
791 789.25 792.83 793.75 835 - 68 794-800
797 795.25 798.83 799.75 841 - 69 800-806
803 801.25 804.83 805.75 847 - 70* 806-812
809 807.25 810.83 811.75 853 - 71* 812-818
815 813.25 816.83 817.75 859 - 72* 818-824
821 819.25 822.83 823.75 865 - 73* 824-830
827 825.25 828.83 829.75 871 - 74* 830-836
833 831.25 834.83 835.75 877 - 75* 836-842
839 837.25 840.83 841.75 883 - 76* 842-848
845 843.25 846.83 847.75 889 - 77* 848-854
851 849.25 852.83 853.75 895 - 78* 854-860
857 855.25 858.83 859.75 901 - 79* 860-866
863 861.25 864.83 865.75 907 - 80* 866-872
869 867.25 870.83 871.75 913 - 81* 872-878
875 873.25 876.83 877.75 919 - 82* 878-884
881 879.25 882.83 883.75 925 - 83* 884-890
887 885.25 888.83 889.75 931 - Channels
70-83 have been allocated to land mobile
communication services. Operation, on a
secondary basis, of some television
translators may continue on these
frequencies. - OTHER
REFERENCES Video Scrambling and Descrambling
for Satellite and Cable TV by Rudolf F. Graf
and William Sheets (ISBN 0-672-22499-2) US
$20.00. Published in 1987, it is somewhat
dated but is useful for understanding what is
happening when a video signal is scrambled.
Covered topics include SSAVI, gated sync,
sine wave, subcarrier recovery, outband,
VideoCipher II, B-MAC, etc. 246 pages.
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