Features; Hardware System Features; Figure 1-1: Typical Line 21 Closed Caption Signal - evertz 8084 Instruction Manual

IRE H Sync Color Burst
50
25
0
-40
1.2

FEATURES

OVERVIEW
Models 8084/8084AD/8085 Closed Caption Encoder Manual
Clock Run-In Start Bits
S1 S2 S3 b0

Figure 1-1: Typical Line 21 Closed Caption Signal

Figure 1-1 shows the typical waveform of the signal. The line 21 data
signal consists of a 7 cycle sine wave clock burst, a start bit, and two data
characters. Each character consists of seven data bits with odd parity.
The clock rate is 32 times the horizontal line frequency or 503.4 KHz. The
signal amplitude is 50 IRE units peak to peak. There is no setup on the
line when the caption signal is present. When caption data is encoded into
field 2, there must at least be null characters encoded into field 1. The full
specification for the caption data waveform and data content is given in the
EIA-608-B standard.
1.2.1

Hardware System Features:

•
3 RS-232 serial ports can be configured for direct connection to
captioning computer.
•
One built-in modem and an optional second modem for connection to
remote captioning computers via the telephone network.
•
Rack mountable chassis.
•
16 digit alphanumeric display, with 8 push buttons.
•
Parallel remote port for GPI control of six important 8084 functions.
•
Real-time clock and calendar with battery backup.
•
Flash ROM program memory for easy in-system-programmable
firmware upgrades.
•
Optional redundant power supply.
Revision 1.6.6
Character One
b1 b2 b3 b4 b5 b6 P1 b0
Character Two
b1 b2 b3 b4 b5 b6 P2
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