[Title 47 CFR 15.119]
[Code of Federal Regulations (annual edition) - October 1, 2004 Edition]
[Title 47 - TELECOMMUNICATION]
[Chapter I - FEDERAL COMMUNICATIONS COMMISSION]
[Subchapter A - GENERAL]
[Part 15 - RADIO FREQUENCY DEVICES]
[Subpart B - Unintentional Radiators]
[Sec. 15.119 - Closed caption decoder requirements for analog television]
[From the U.S. Government Printing Office]


47TELECOMMUNICATION12004-10-012004-10-01false15.119Sec. 15.119TELECOMMUNICATIONFEDERAL COMMUNICATIONS COMMISSIONGENERALRADIO FREQUENCY DEVICESUnintentional Radiators
Sec. 15.119  Closed caption decoder requirements for analog television 
receivers.

    (a) Effective July 1, 1993, all TV broadcast receivers with picture 
screens 33 cm (13 in) or larger in diameter shipped in interstate 
commerce, manufactured, assembled, or imported from any foreign country 
into the United States shall comply with the provisions of this section.

    Note: This paragraph places no restriction on the shipping or sale 
of television receivers that were manufactured before July 1, 1993.

    (b) Transmission format. Closed-caption information is transmitted 
on line 21 of field 1 of the vertical blanking interval of television 
signals, in accordance with Sec. 73.682(a)(22) of this chapter.
    (c) Operating modes. The television receiver will employ customer-
selectable modes of operation for TV and Caption. A third mode of 
operation, Text, may be included on an optional basis. The Caption and 
Text Modes may contain data in either of two operating channels, 
referred to in this document as C1 and C2. The television receiver must 
decode both C1 and C2 captioning, and must display the captioning for 
whichever channel the user selects. The TV Mode of operation allows the 
video to be viewed in its original form. The Caption and Text Modes 
define one or more areas (called ``boxes'') on the screen within which 
caption or text characters are displayed.

    Note: For more information regarding Text mode, see ``Television 
Captioning for the Deaf: Signal and Display Specifications'', 
Engineering Report No. E-7709-C, Public Broadcasting Service, dated May 
1980, and ``TeleCaption II Decoder Module Performance Specification'', 
National Captioning Institute, Inc., dated November 1985. These 
documents are available, respectively, from the Public Broadcasting 
Service, 1320 Braddock Place, Alexandria, VA 22314 and from the National 
Captioning Institute, Inc., 5203 Leesburg Pike, Falls Church, VA 22041.

    (d) Screen format. The display area for captioning and text shall 
fall approximately within the safe caption area as defined in paragraph 
(n)(12) of this section. This display area will be further divided into 
15 character rows of equal height and 32 columns of equal width, to 
provide accurate placement of text on the screen. Vertically, the 
display area begins on line 43 and is 195 lines high, ending on line 237 
on an interlaced display. All captioning and text shall fall within 
these established columns and rows. The characters must be displayed 
clearly separated from the video over which they are placed. In 
addition, the user must have the capability to select a black background 
over which the captioned letters are displaced.
    (1) Caption mode. In the Caption Mode, text can appear on up to 4 
rows simultaneously anywhere on the screen within the defined display 
area. In addition, a solid space equal to one column width may be placed 
before the first character and after the last character of each row to 
enhance legibility. The caption area will be transparent anywhere that 
either:
    (i) No standard space character or other character has been 
addressed and no accompanying solid space is needed; or,
    (ii) An accompanying solid space is used and a ``transparent space'' 
special character has been addressed which does not immediately precede 
or follow a displayed character.
    (2) [Reserved]
    (e) Presentation format. In analyzing the presentation of 
characters, it is convenient to think in terms of a non-visible cursor 
which marks the screen position at which the next event in a given mode 
and data channel will occur. The receiver remembers the cursor position 
for each mode even when data are received for a different address in an 
alternate mode or data channel.
    (1) Screen addressing. Two kinds of control codes are used to move 
the cursor to specific screen locations. In Caption Mode, these 
addressing codes will affect both row and column positioning. In Text 
Mode, the codes affect only column positioning. In both modes, the 
addressing codes are optional. Default positions are defined for each 
mode and style when no addressing code is provided.

[[Page 783]]

    (i) The first type of addressing code is the Preamble Address Code 
(PAC). It assigns a row number and one of eight ``indent'' figures. Each 
successive indent moves the cursor four columns to the right (starting 
from the left margin). Thus, an indent of 0 places the cursor at Column 
1, an indent of 4 sets it at Column 5, etc. The PAC indent is non-
destructive to displayable characters. It will not affect the display to 
the left of the new cursor position on the indicated row. Note that 
Preamble Address Codes also set initial attributes for the displayable 
characters which follow. See paragraph (h) of this section and the 
Preamble Address Code table.
    (ii) The second type of addressing code is the Tab Offset, which is 
one of three Miscellaneous Control Codes. Tab Offset will move the 
cursor one, two, or three columns to the right. The character cells 
skipped over will be unaffected; displayable characters in these cells, 
if any, will remain intact while empty cells will remain empty, in the 
same manner that a PAC indent is non-destructive.
    (2) [Reserved]
    (f) Caption Mode. There are three styles of presenting text in 
Caption Mode: roll-up, pop-on, and paint-on. Character display varies 
significantly with the style used, but certain rules of character 
erasure are common to all styles. A character can be erased by 
addressing another character to the same screen location or by 
backspacing over the character from a subsequent location on the same 
row. The entire displayed memory will be erased instantly by receipt of 
an Erase Displayed Memory command. Both displayed memory and non-
displayed memory will be entirely erased simultaneously by either: The 
user switching receiver channels or data channels (C1/C2) or fields (F1/
F2) in decoders so equipped; the loss of valid data (see paragraph (j) 
of this section); or selecting non-captioning receiver functions which 
use the display memory of the decoder. Receipt of an End of Caption 
command will cause a displayed caption to become non-displayed (and vice 
versa) without being erased from memory. Changing the receiver to a non-
captioning mode which does not require use of the decoder's display 
memory will leave that memory intact, and the decoder will continue to 
process data as if the caption display were selected.
    (1) Roll-up. Roll-up style captioning is initiated by receipt of one 
of three Miscellaneous Control Codes that determine the maximum number 
of rows displayed simultaneously, either 2, 3 or 4 contiguous rows. 
These are the three Roll-Up Caption commands.
    (i) The bottom row of the display is known as the ``base row''. The 
cursor always remains on the base row. Rows of text roll upwards into 
the contiguous rows immediately above the base row to create a 
``window'' 2 to 4 rows high.
    (ii) The Roll-Up command, in normal practice, will be followed (not 
necessarily immediately) by a Preamble Address Code indicating the base 
row and the horizontal indent position. If no Preamble Address Code is 
received, the base row will default to Row 15 or, if a roll-up caption 
is currently displayed, to the same base row last received, and the 
cursor will be placed at Column 1. If the Preamble Address Code received 
contains a different base row than that of a currently displayed 
caption, the entire window will move intact (and without erasing) to the 
new base row immediately.
    (iii) Each time a Carriage Return is received, the text in the top 
row of the window is erased from memory and from the display or scrolled 
off the top of the window. The remaining rows of text are each rolled up 
into the next highest row in the window, leaving the base row blank and 
ready to accept new text. This roll-up must appear smooth to the user, 
and must take no more than 0.433 second to complete. The cursor is 
automatically placed at Column 1 (pending receipt of a Preamble Address 
Code).
    (iv) Increasing or decreasing the number of roll-up rows instantly 
changes the size of the active display window, appropriately turning on 
or off the display of the top one or two rows. A row which is turned off 
should also be erased from memory.
    (v) Characters are always displayed immediately when received by the 
receiver. Once the cursor reaches the 32nd column position on any row, 
all

[[Page 784]]

subsequent characters received prior to a Carriage Return, Preamble 
Address Code, or Backspace will be displayed in that column replacing 
any previous character occupying that address.
    (vi) The cursor moves automatically one column to the right after 
each character or Mid-Row Code received. A Backspace will move the 
cursor one column to the left, erasing the character or Mid-Row Code 
occupying that location. (A Backspace received when the cursor is in 
Column 1 will be ignored.)
    (vii) The Delete to End of Row command will erase from memory any 
characters or control codes starting at the current cursor location and 
in all columns to its right on the same row. If no displayable 
characters remain on the row after the Delete to End of Row is acted 
upon, the solid space (if any) for that row should also be erased to 
conform with the following provisions.
    (viii) If a solid space is used for legibility, it should appear 
when the first displayable character (not a transparent space) or Mid-
Row Code is received on a row, not when the Preamble Address Code, if 
any, is given. A row on which there are no displayable characters or 
Mid-Row Codes will not display a solid space, even when rolled up 
between two rows which do display a solid space.
    (ix) If the reception of data for a row is interrupted by data for 
the alternate data channel or for Text Mode, the display of caption text 
will resume from the same cursor position if a Roll-Up Caption command 
is received and no Preamble Address Code is given which would move the 
cursor.
    (x) A roll-up caption remains displayed until one of the standard 
caption erasure techniques is applied. Receipt of a Resume Caption 
Loading command (for pop-on style) or a Resume Direct Captioning command 
(for paint-on style) will not affect a roll-up display. Receipt of a 
Roll-Up Caption command will cause any pop-on or paint-on caption to be 
erased from displayed memory and non-displayed memory.
    (2) Pop-on. Pop-on style captioning is initiated by receipt of a 
Resume Caption Loading command. Subsequent data are loaded into a non-
displayed memory and held there until an End of Caption command is 
received, at which point the non-displayed memory becomes the displayed 
memory and vice versa. (This process is often referred to as ``flipping 
memories'' and does not automatically erase memory.) An End of Caption 
command forces the receiver into pop-on style if no Resume Caption 
Loading command has been received which would do so. The display will be 
capable of 4 full rows, not necessarily contiguous, simultaneous 
anywhere on the screen.
    (i) Preamble Address Codes can be used to move the cursor around the 
screen in random order to place captions on Rows 1 to 15. Carriage 
Returns have no effect on cursor location during caption loading.
    (ii) The cursor moves automatically one column to the right after 
each character or Mid-Row Code received. Receipt of a Backspace will 
move the cursor one column to the left, erasing the character or Mid-Row 
Code occupying that location. (A Backspace received when the cursor is 
in Column 1 will be ignored.) Once the cursor reaches the 32nd column 
position on any row, all subsequent characters received prior to a 
Backspace, an End of Caption, or a Preamble Address Code, will replace 
any previous character at that location.
    (iii) The Delete to End of Row command will erase from memory any 
characters or control codes starting at the current cursor location and 
in all columns to its right on the same row. If no displayable 
characters remain on a row after the Delete to End of Row is acted upon, 
the solid space (if any) for that element should also be erased.
    (iv) If data reception is interrupted during caption loading by data 
for the alternate caption channel or for Text Mode, caption loading will 
resume at the same cursor position if a Resume Caption Loading command 
is received and no Preamble Address Code is given that would move the 
cursor.
    (v) Characters remain in non-displayed memory until an End of 
Caption command flips memories. The caption will be erased without being 
displayed upon receipt of an Erase Non-Displayed Memory command, a Roll-
Up Caption

[[Page 785]]

command, or if the user switches receiver channels, data channels or 
fields, or upon the loss of valid data (see paragraph (j) of this 
section).
    (vi) A pop-on caption, once displayed, remains displayed until one 
of the standard caption erasure techniques is applied or until a Roll-Up 
Caption command is received. Characters within a displayed pop-on 
caption will be replaced by receipt of the Resume Direct Captioning 
command and paint-on style techniques (see below).
    (3) Paint-on. Paint-on style captioning is initiated by receipt of a 
Resume Direct Captioning command. Subsequent data are addressed 
immediately to displayed memory without need for an End of Caption 
command.
    (i) Preamble Address Codes can be used to move the cursor around the 
screen in random order to display captions on Rows 1 to 15. Carriage 
Returns have no affect on cursor location during direct captioning. The 
cursor moves automatically one column to the right after each character 
or Mid-Row Code is received. Receipt of a Backspace will move the cursor 
one column to the left, erasing the character or Mid-Row Code occupying 
that location. (A Backspace received when the cursor is in Column 1 will 
be ignored.) Once the cursor reaches the 32nd column position on any 
row, all subsequent characters received prior to a Preamble Address Code 
or Backspace will be displayed in that column replacing any previous 
character occupying that location.
    (ii) The Delete to End of Row command will erase from memory any 
characters or control codes starting at the current cursor location and 
in all columns to its right on the same row. If no displayable 
characters remain on the row after the Delete to End of Row is acted 
upon, the solid space (if any) for that element should also be erased.
    (iii) If the reception of data is interrupted during the direct 
captioning by data for the alternate caption channel or for Text Mode, 
the display of caption text will resume at the same cursor position if a 
Resume Direct Captioning command is received and no Preamble Address 
Code is given which would move the cursor.
    (iv) Characters remain displayed until one of the standard caption 
erasure techniques is applied or until a Roll-Up Caption command is 
received. An End of Caption command leaves a paint-on caption fully 
intact in non-displayed memory. In other words, a paint-on style caption 
behaves precisely like a pop-on style caption which has been displayed.
    (g) Character format. Characters are to be displayed on the screen 
within a character ``cell'' which is the height and width of a single 
row and column. The following codes define the displayable character 
set. Television receivers manufactured prior to January 1, 1996 and 
having a character resolution of 5 x 7 dots, or less, may display the 
allowable alternate characters in the character table. A statement must 
be in a prominent location on the box or other package in which the 
receiver is to be marketed, and information must be in the owner's 
manual, indicating the receiver displays closed captioning in upper case 
only.

                           Character Set Table

                           Special Characters

    These require two bytes for each symbol. Each hex code as shown will 
be preceded by a 11h for data channel 1 or by a 19h for data channel 2. 
For example: 19h 37h will place a musical note in data channel 2.

------------------------------------------------------------------------
HEX   Example     Alternate                   Description
------------------------------------------------------------------------
 30     [reg]   See note\1\   Registered mark symbol
 31     [deg]   ............  Degree sign
 32     \1/2\   ............  \1/2\
 33             ............  Inverse query
 34        TM   See note\1\   Trademark symbol
 35    [cent]   ............  Cents sign
 36   [pound]   ............  Pounds Sterling sign
 37         X   ............  Music note
 38         a             A   Lower-case a with grave accent
 39             ............  Transparent space
 3A         e             E   Lower-case e with grave accent
 3B         a             A   Lower-case a with circumflex
 3C         e             E   Lower-case e with circumflex
 3D         i             I   Lower-case i with circumflex
 3E         o             O   Lower-case o with circumflex
 3F         u             U   Lower-case u with circumflex
------------------------------------------------------------------------
\1\ Note: The registered and trademark symbols are used to satisfy
  certain legal requirements. There are various legal ways in which
  these symbols may be drawn or displayed. For example, the trademark
  symbol may be drawn with the ``T'' next to the ``M'' or over the
  ``M''. It is preferred that the trademark symbol be superscripted,
  i.e., XYZTM. It is left to each individual manufacturer to interpret
  these symbols in any way that meets the legal needs of the user.


[[Page 786]]

                           Standard characters

------------------------------------------------------------------------
HEX   Example    Alternate                   Description
------------------------------------------------------------------------
 20             ..........  Standard space
 21         !   ..........  Exclamation mark
 22        ``   ..........  Quotation mark
 23    ..........  Pounds (number) sign
 24         $   ..........  Dollar sign
 25         %   ..........  Percentage sign
 26         &   ..........  Ampersand
 27         '   ..........  Apostrophe
 28         (   ..........  Open parentheses
 29         )   ..........  Close parentheses
 2A         a           A   Lower-case a with acute accent
 2B         +   ..........  Plus sign
 2C         ,   ..........  Comma
 2D         -   ..........  Minus (hyphen) sign
 2E         .   ..........  Period
 2F         /   ..........  Slash
 30         0   ..........  Zero
 31         1   ..........  One
 32         2   ..........  Two
 33         3   ..........  Three
 34         4   ..........  Four
 35         5   ..........  Five
 36         6   ..........  Six
 37         7   ..........  Seven
 38         8   ..........  Eight
 39         9   ..........  Nine
 3A         :   ..........  Colon
 3B         ;   ..........  Semi-colon
 3C         <   ..........  Less than sign
 3D         =   ..........  Equal sign
 3E