Broadcom BCM7405 - RF Modulator; Features; Figure 1-14: RF Modulator Block Diagram; Overview

2/24/2008 9T6WP
BCM7405 Preliminary Hardware Data Module
Functional Description 06/29/07
Broadcom Corporation
Page 1-56 RF Modulator Document 7405-1HDM00-R
RF MODULATOR
OVERVIEW
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. Figure 1-14 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
FEATURES
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
Converter +
Mix to RF
Digital-to-
Analog
Converter