Introduction Of General Terms Used In Digital Headend Industry


Introduction – Digital Headend Industry

In this article we will discuss about terms which are generally used in Digital Headend industry. So this is the overview of different useful terms.

Pay Per View / PPV

As its name indicates subscriber pay only for service what he use. He need not to purchase whole subscription. In this system a smart card is credited by subscriber for some value. When subscriber wants to purchase a single service then he can purchase it by debiting his smart card. Thus subscriber use Electronic cash to get access of a single service.

Impulse Pay Per View / IPPV

Impulse pay per view does not require pre booking. IPVV supports both payment options electronic banking via telephone line and smart card debit.


It is known as unauthorized access of programs. It is also known as use of counterfeit smart cards and decoders which bypass the Conditional Access System.

Period Subscription

It is a payment system in which subscriber subscribe for a service for specific period of time. So it is known as Period Subscription.


Event is group of elementary broadcast data streams with defines start and end time.


A program can be a television channel and radio channel which is used to deliver at subscriber end.  It is also called one or more than one group of events.


It is sequence of event , program or data which is used to deliver subscriber end by the service provider.


Group of services is know as bouquet. There are many categories of tv channels. So we can make different bouquet of channels for each category.


In multiplexing we assemble all the digital data information which contain one or more service and then send it via one physical channel. Thus this process is known as Multiplexing.

headend info book download

Conditional Access System / Access Control System

CAS is the system used for the protection of digital data from unauthorized user. It enable to access digital information for the subscriber who is entitled for this. Scrambling , Encryption and SMS plays an important role to do so.


Encryption is the method which continuously changes the electronic key. This electronic key is used to descramble the data at subscriber end. This method is used in both Over The Air and Smart cards.

Entitlement Control Message / ECM

It is known as the cryptogram of access conditions and control word. It is used for to control the descrambler. ECMs are transmitted over the air in encrypted form.

Entitlement Management Massage / EMM

EMM  is used to descramble the service for authorized subscriber only. EMM can on or off the STB or group of STBs, It is also tranmitted over air in encrypted form.

headend info store buy

Control Word

This is the key used in the descrambler. The control word changes in specific period of time which  is in seconds. This period of time is called the crypto period. Crypto period can be 2 sec or 10 seconds.


When we are using more than one CAS in a system then it is called simulcrypt. Because we need to send more than one ECMs and EMMs to subscriber end. If you are using two cas in your system then you need to send two different ECMs and EMMs to the STBs. So the STB would select its CAS and decode the data.


It allows the users to easily switch between two different service providers. In this system one service provider,  provides encrypted stream 100% with one CA system only. Likewise other service provider provides his encrypted stream 100% in one CA system only. Thus it enable users to switch between these two service providers. It is mandatory in spain.


scrambling is used to change the form of broadcast signal which can only be accessible by authorized STB and for others it is not easy to understand. This is why scrambling is used.


Descrambling is opposite of scrambling which enable STB to access the information.

Electronic Key

Electronic Key is used to control the descrambling process at the STB. There are several factors which needs to be satisfied to access the information by the decoder. These factors are identify the network , available services in the network for subscriber and control information to operate the descramber.


Algorithm is mathematical process which is used to scramble and descramble the data. This mathematical process can be DES or RSA.

Smart Card

SC is a electronic card used to descramble the broadcasted data. Some of them are physical electronic cards which we can change in STB, While Smart Cards are in built. These cards are issued by the SMS. One smart card is used for one stb.

Subscriber Authorization System / SAS

Subscriber Authorization System is a center which delivers ECMs and EMMs data streams according to direction of Subscriber Management System.

Subscriber Management System / SMS

A SMS system save all the information about the subscribers like IRD number , CA number and package. It also stores the personal information of subscribers. It is also responsible for generation of bills for subscribers as well as for LCOs too. It contains the sensitive information of the network.

Know More About    What Is DVBS and DVBS2

headend info logo forum

Subscribe Headend INFO By Email

If Headend INFO really helped you then you can Donate Headend INFO

Donate Headend INFO (PAYPAL)

headend info android app

banner standard

headend info youtube channel subscribe

join headend info whatsapp group

Free Download To Make Money With Brave

error: Want To Download These Articles ? Go To Books Tab !!!