our mind has a very special power. The power of making anything happen. if we actually want some thing our mind will definitely works hard to achieve that goal. This is Wyatt id's called the part of mind or rather the power of subconscious mind. You give anything to subconscious mind, it will try to achieve. Usually during prayer we will focus our mind and may ask something to God. If it is a real desire it will be taken by the subconscious mind. You may notice that people will pay in a silent atmosphere. It is for this reason we should stay and mediate for say 20 min minimum a day. The best time is morning. After this mediation one can calmly plan that days activitiesone by one. This will help our mind to formulate a timetable for that day. If everything it's scheduled in our mind things will be easy.
Friday, August 4, 2017
Thursday, July 9, 2009
Isdn
Labels:
communication,
informations,
isdn
Continuing ISDN------
For enabling digital communication the singal should come in bits..10001 like that..this is decoded in 2b1q format..ie 2bits and one qua: .for this bits are grouped into 2 .Each two bits are represented by a particular voltage level.So there are 4 voltage levels available for representing the bits.they are +3,-3,+1,-1. If the bits are 00-->-3 v 01-->-1v 10-->+1,11-->+3 v.Thus only single voltage level is required to represent the signal.
The Components in ISDN architecture.
TE-2 category of instruments are ordinary phone,ordinary fax ,pc etc
Exchange line is first connected to a network terminal interface .To this TE-1 Equipments can be connected.But TE-2 equipments cannot be connected directly to this.For connecting them an adapter should be there.that is called TA(Terminal Adapter).
So TA+TE-2=TE-1
Functions of Terminal adapter is to make the analog devices ready for connecting to Terminal Equipt-1.
Usually the NT will be provided by the operated itself.
There are Two channels involved in the isdn communication
They are Bearer Channels(B Channels) and Data Channels(D Channels).The bearer channels carry the voice,data,image,video...information and D channels carry the controls required for enabling the communication.
The bit rate of B channel is 64kbps and that of D channel varies from 16 kbps to 64 kbps.
depends upon the type of isdn connection provided.
Then comes the types of isdn connections
For enabling digital communication the singal should come in bits..10001 like that..this is decoded in 2b1q format..ie 2bits and one qua: .for this bits are grouped into 2 .Each two bits are represented by a particular voltage level.So there are 4 voltage levels available for representing the bits.they are +3,-3,+1,-1. If the bits are 00-->-3 v 01-->-1v 10-->+1,11-->+3 v.Thus only single voltage level is required to represent the signal.
The Components in ISDN architecture.
- Network Terminal Interface
- TE-1
- TE-2
- TA
TE-2 category of instruments are ordinary phone,ordinary fax ,pc etc
Exchange line is first connected to a network terminal interface .To this TE-1 Equipments can be connected.But TE-2 equipments cannot be connected directly to this.For connecting them an adapter should be there.that is called TA(Terminal Adapter).
So TA+TE-2=TE-1
Functions of Terminal adapter is to make the analog devices ready for connecting to Terminal Equipt-1.
Usually the NT will be provided by the operated itself.
There are Two channels involved in the isdn communication
They are Bearer Channels(B Channels) and Data Channels(D Channels).The bearer channels carry the voice,data,image,video...information and D channels carry the controls required for enabling the communication.
The bit rate of B channel is 64kbps and that of D channel varies from 16 kbps to 64 kbps.
depends upon the type of isdn connection provided.
Then comes the types of isdn connections
- BRI
- PRI
Basic Rate Interface and Primary Rate Interface.BRI supports 2 ISDN B channels and 1D Channel.so(2*64+16)=144kbps... and for PRI supports 30 B Channels and 1 D channels .So for a PRI connection the D channel has to carry the control and signal information of 30 B Channels.So there will be more than 1 NT for this.
For further reference pls go to
Isdn contined
There are two classifications of isdn.. Narrow band ISDN and Broadband ISDN.For broadband ISDN packet switching should be used.In our country that is not implemented.In narrow band Isdn itself there are two groups - PRI and BRI.usually PRI connections are taken by customers who require more bandwidth.so let us analize the term isdn...IS--means Integrated services....For a single telephone connection extending from the exchange to customer premises,the subscriber can enjoy only one service at a time...(either voice,or data or fax like that).But In isdn these services can be integrated..ie voice,fax,data ...can be made available simultaneously.Then DN---Digital Network means...right from the exchange to customer end in the digital format.since it is in the digital format...some coding techniques should be employed.
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