Circuit Board of the Set Top
D-View is a Set
Top Box that enables viewers to access a wide range
of services like Analog TV, Digital TV, Internet, Video
on Demand, VoIP provided by Broadcasters. Broadcasters
use Satellite, Terrestrial and Cable networks to transmit
the TV signals and are increasingly demanding that viewers
pay for their services and hence transmit scrambled
For the decoding and
viewing of free to air and scrambled signals therefore
a Set Top Box is required at the TV user site. To address
this requirement, C-DAC, Noida has designed a multi-purpose
Set Top Box enabling decoding and decrypting of signals
from all the three modes of transmission.
Digital Set Top Box
has been categorized as:
- D-View 1 - for Digital Terrestrial
- D-View 2 - for Digital to
Home through Satellite
D-View 0 version
is free to air, and would cost the viewers about Rs.
3000/-. The cost of other three versions of D-View range
from Rs. 3000/- to Rs. 6000/-. The CAS is going to be
implemented in four Metros w.e.f. september 1, 2003.
DIGITAL SET TOP BOX
Set-top boxes (STB)
act as a gateway between the user's television and telephone,
satellite, terrestrial or cable feed (incoming signal).
The STB receives encoded and/or compressed digital signals
from the signal source (satellite, TV station, cable
network and so on) and decodes (and/or decompresses)
those signals, converting them into analog signals displayable
on the television. Set-top boxes are usually embedded
computers that process digital information. These typically
have on-screen user interfaces that can be seen on the
TV screen and interacted with, through the use of a
Hand-held Interactive Keypad, which is little more than
an advanced remote control. STBs also have facilities
for upgrading software such as browsers and Electronic
Program Guides (EPGs) hard-drives and smart card slots
for purchases and eCommerce applications.
Common Interface describes
hardware and software architecture for Conditional Access
Systems whereby the generic "host" set-top
box is not dedicated to one particular encryption system.
Consumers can use detachable hardware, which allows
them to receive encrypted services they pay subscription
fee(s) for. The interface between host set-top box and
the CI hardware is standardized (PCMCIA-Interface) so
that the same set-top box can be used to handle a variety
of encryption systems.
With a set-top box
and a standard (analog) TV set, viewers with this service
can access more channels, than what their standard tv
allows. Also the STB enhances resolution.
A Conditional Access
(CA) system comprises a combination of scrambling and
encryption to prevent unauthorized reception. Encryption
is the process of protecting the secret keys that are
transmitted with a scrambled signal to enable the descrambler
to work. The scrambler key, called the control word
must, of course, be sent to the receiver in encrypted
form as an entitlement control message (ECM). The CA
subsystem in the receiver will decrypt the control word
only when authorized to do so, that authority is sent
to the receiver in the form of an Entitlement Management
Message (EMM). This layered approach is fundamental
to all proprietary CA systems in use today. This technique
is primarily used in a Digital Set Top Box.
C-DAC (Noida) developed
the Digital STB, capable of receiving signals through
DTT, DTH and Cable medium. The costs of these STB are
1. DTT Rs. 3500/-
2. DTH Rs. 4000/-
3. Cable Rs. 6000/-
The Cable Set Top
Box is available with Conditional Access System and
Smart Card Compatibility.