Appendix E HDTV Output Mode
CX25870/871
E.8 Automatic Insertion of Broad Pulses
Flicker-Free Video Encoder with Ultrascale Technology
E.8 Automatic Insertion of Broad Pulses
In HD televisions, a frame shall begin with five vertical sync lines each
containing a broad pulse. Broad pulses are the HD equivalent to the vertical
synchronizing Serration and Equalization pulses used with present-day analog
TVs. In response to the correct timing provided through the VSYNC* input
which triggers the start of a new frame, the CX25870/871 will automatically
insert broad pulses and trilevel syncs on the first 5 lines of the First Field(#1-#5)
and the first 5 lines in the Second Field (563-568 for 1080i format). These broad
pulses will adhere to the timing and voltage amplitudes found in various SMPTE
specifications.
Figure E-6 illustrates the proper interface timing between the HDTV Source
Device (master) and CX25870/ CX25871(timing slave) during lines that include a
BROAD PULSE in 1080i format. Figure E-8 shows the relationship between the
digital input signals and HDTV output for lines that include a broad pulse in 720p
format.
E-14
Conexant
100381B
CONEXANT [ CONEXANT SYSTEMS, INC ]
