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Circuit Descriptions, Abbreviation List, and IC Data Sheets

EN 147

BJ3.0E PA

9.3

Front-End

Main goal of the front-end module is to connect the host (core
with source processing) with the outside world via an RF
connector.
For a DVB-T application the connection to the outside world is
through DVB broadcasts via terrestrial connection. It delivers a
number of digital broadcasts services, grouped into a
frequency spectrum. The front-end module processes one
channel and forwards the digital channel to the core as MPEG
data packets at the demodulator’s output. To maintain common
naming with an ATSC application this path is also referred to as
the ‘in-band’ signal path.

Figure 9-6 Block diagram DVB-T front-end

9.4

Common Interface (CI)

9.4.1

Introduction

This chassis is provided with a special slot (Common Interface
- CI). Together with a Conditional Access Module (CAM) and a
smart card it is possible to receive scrambled TV programs.
This means that it is not necessary to have a separate Set Top
Box to receive digital cable SDTV and HDTV programs
(however this is still possible).
The removable smart card, distributed by cable companies,
allows you to tune digital and high definition scrambled or
encrypted cable channels through the cable antenna. The
smart card is also required to receive premium digital TV
channels and services (where available) through the cable. A
smart card functionality includes conditional access and copy
protection.

9.4.2

Implementation

The receiver receives the digital data stream.

The data flows into the Conditional Access Module, which
contains the content provider's unscrambling algorithms.

This module verifies the existence of a smart card that
contains the subscriber's authorization code.

If the authorization code is accepted, the CAM
unscrambles the data and returns the data to the receiver
(if the code is not accepted, the data remains scrambled,
restricting access).

The receiver then decodes the data and outputs it for
viewing.

Figure 9-7 In Band channel reception (without CAM inserted)

Figure 9-8 In Band channel reception (with smart card inserted)

Conditional Access Working Principle

The Conditional Access Module (CAM), also called POD (Point
Of Deployment), is a removable CAM, implementing the
Conditional Access (CA) system for a Host (i.e. the TV set).
The CAM is inserted into a standard PCMCIA slot in the Host.
When the CAM is inserted into the Host, it goes through an
initialization procedure, which is called the "CAM personality
change". This initialization procedure consists of:
•

CAM and Host verify each other’s identity by means of
certificate and/or key exchange.

•

Reporting CAM-ID and Host-ID to the Cable Head end, in
order to entitle the CAM for descrambling services. In case
of uni-directional operation (as for this chassis), this
reporting requires user-interaction.

•

Key generation for secure communication between CAM
and Host.

After initialization, the CAM is used to unscramble any
particular scrambled service in the In Band (IB) transport
stream. The host must provide the selection choice (which
program to descramble). The host can only do so if it gets
specific data like PSIP (Program and System Information
Protocol) data from the CAM.
The CAM implements a copy protection system, so the
unscrambled Transport Stream signal from CAM to Host can
be re-scrambled.

G_15960_1

Channel Decoder

TDA10046AHT

Channel Decoder

TDA10046AHT

RF in

1-858 MHz

Main tuner

TD1316AF -3

Main MPIF
analog demodulation

I2C local

(addr 0xC0)