2/24/2008 9T6WP
BCM7405
Preliminary Hardware Data Module
Functional Description
06/29/07
Bro a d c o m C o rp o r a ti o n
Page 1-56
RF Modulator
Document
7405-1HDM00-R
RF M
ODULATOR
O
VERVIEW
The RF Modulator core (RFM) converts a NTSC/PAL-compliant digital composite video source and a Pulse Code Modulated
(PCM) audio source into an analog RF-modulated television signal that is suitable for demodulation by a television
demodulator.
illustrates the various operations to be performed in the RFM as well as the primary data path
inputs and output signals.
Figure 1-14: RF Modulator Block Diagram
F
EATURES
The Broadcom RFM is highly programmable and supports a variety of features:
•
Digital Audio Processor
-
Flexibility allows support for FM-audio-based television standards B/G, D/K, H, I, K1, M, and N.
-
Supports monaural audio formats used worldwide including NTSC and most PAL variants.
-
Supports stereo encoding and transmission for BTSC and NICAM standards. For BTSC, this includes generation of
a pilot signal that is locked to the input start-of-line.
-
Supports secondary audio program (SAP) encoding and transmission in BTSC mode and dual-mono encoding and
transmission in NICAM mode. In BTSC mode, the secondary audio program may be transmitted simultaneously with
a monaural channel.
-
Supports NICAM stereo and dual-mono encoding and transmission for standards B/G, H, and I.
-
Programmable main channel preemphasis filters.
-
J.17 preemphasis filtering of audio used in NICAM mode.
-
Programmable audio carrier frequency and level.
PCM Audio Data
(2 channels)
Video
Start-of-line
BTSC &
A2
Encoders
Rate
Converters
+ FM
Modulators
NICAM
Encoder
DQPSK
modulator
Audio Processor
Baseband
Composite
Video
Signal
Off chip
Digital
Video
Processor
Rate
Con
Mix to RF
Digital-to-
Analog
Converter