About ISDN - Revision history

Monica: /* About the E1/T1 carrier systems */

2013-08-21T15:03:36Z

‎About the E1/T1 carrier systems

Monica: /* About the E1/T1 carrier systems */

2013-08-21T14:59:17Z

‎About the E1/T1 carrier systems

Monica: /* About the E1/T1 carrier systems */

2013-08-21T14:59:09Z

‎About the E1/T1 carrier systems

Monica: /* About the E1/T1 carrier systems */

2013-08-21T14:58:29Z

‎About the E1/T1 carrier systems

Monica: /* About the E1/T1 carrier systems */

2013-08-21T14:56:19Z

‎About the E1/T1 carrier systems

Monica: /* About the E1/T1 carrier systems */

2013-08-21T14:56:08Z

‎About the E1/T1 carrier systems

Monica: /* ISDN and the future */

2013-08-21T14:55:12Z

‎ISDN and the future

Monica: /* Advantages */

2013-08-21T14:54:27Z

‎Advantages

Monica: /* What does it take to connect to ISDN? */

2013-08-21T14:53:13Z

‎What does it take to connect to ISDN?

Monica: /* Why ISDN? */

2013-08-21T14:44:28Z

‎Why ISDN?

← Older revision		Revision as of 15:03, 21 August 2013
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	* [[About VoIP]]		* [[About VoIP]]
	* [[About PSTN]]		* [[About PSTN]]
		+	* [[Signaling module]]

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 The T-carrier is the American version of the E-carrier. These two types are incompatible. The DS0 (the basic unit) is a channel of 64kbit/s, normally used for voice circuit. The transfer rate is 1544Mbit/s, obtained like this: the highest frequency for human voice is 4000Hz. When converting analog to digital, there is a need to at least double that frequency for the sample rate. Each T1 frame contains 1 byte for each one of the 24 channels and a control bit. S, the result is ( (8*24+1)*2*4000=1544000bit/s.
 '''See also'''
 * [[About VoIP]]
 * [[About PSTN]]

← Older revision		Revision as of 14:59, 21 August 2013
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	The T-carrier is the American version of the E-carrier. These two types are incompatible. The DS0 (the basic unit) is a channel of 64kbit/s, normally used for voice circuit. The transfer rate is 1544Mbit/s, obtained like this: the highest frequency for human voice is 4000Hz. When converting analog to digital, there is a need to at least double that frequency for the sample rate. Each T1 frame contains 1 byte for each one of the 24 channels and a control bit. S, the result is ( (824+1)2*4000=1544000bit/s.		The T-carrier is the American version of the E-carrier. These two types are incompatible. The DS0 (the basic unit) is a channel of 64kbit/s, normally used for voice circuit. The transfer rate is 1544Mbit/s, obtained like this: the highest frequency for human voice is 4000Hz. When converting analog to digital, there is a need to at least double that frequency for the sample rate. Each T1 frame contains 1 byte for each one of the 24 channels and a control bit. S, the result is ( (824+1)2*4000=1544000bit/s.
		+
		+	'''See also'''
		+	* [[About VoIP]]
		+	* [[About PSTN]]

@@ Line 39: / Line 39: @@
 ===About the E1/T1 carrier systems===
-The E-carrier system is the standarziation of digital communications, where a single wire can be used to carry more than one simultaneous voice conversations.
+The E-carrier system is the standardization of digital communications, where a single wire can be used to carry more than one simultaneous voice conversations.
 It was first designed in America. There it has the name T-carrier, but the CEPT (European Conference of Postal and Telecommunications Administrations) revised and improved it becoming today the standard for the majority of countries, minus USA, Canada and Japan.
-The whole idea is to group more circuits to form a high bandwitdth network. For now, only the E1 (30 circuits) and E3 (512 circuits) are used. E1 is transmited as 32 time slots and E3 as 512 timeslots. This way, private end-to-end E1 circuits can be provided to the users in different countries that want to share a single high speed link.
+The whole idea is to group more circuits to form a high bandwidth network. For now, only the E1 (30 circuits) and E3 (512 circuits) are used. E1 is transmited as 32 time slots and E3 as 512 timeslots. This way, private end-to-end E1 circuits can be provided to the users in different countries that want to share a single high speed link.
-Here are some technical data about E1. The 2048Mbit/s speed is achieved using E1 carriers. This is possible by splitting this number into 32 time slots. Each time slot sends and receives a 8-bit sample 8000 times per second. This leads to 8*8000*32=2048Mbit/s. There are two timeslots that are specialized on other things than data trasnport. These are TS0 (time slot 0), used for framing purposes and TS16, used for singalling and control.
+Here are some technical data about E1. The 2048Mbit/s speed is achieved using E1 carriers. This is possible by splitting this number into 32 time slots. Each time slot sends and receives a 8-bit sample 8000 times per second. This leads to 8*8000*32=2048Mbit/s. There are two timeslots that are specialized on other things than data transport. These are TS0 (time slot 0), used for framing purposes and TS16, used for singalling and control.
-The T-carrier is the American version of the E-carrier. These two types are incompatible. The DS0 (the basic unit) is a channel of 64kbit/s, normally used for voice circuit. The transfer rate is 1544Mbit/s, obtained like this: the highest frequency for human voice is 4000Hz. When converting analog to digital, there is a need to at least double that frequency for the sample rate. Each T1 frame contains 1 byte for each one of the 24 channels and a control bit. S, theresult is ( (8*24+1)*2*4000=1544000bit/s.

@@ Line 40: / Line 40: @@
 ===About the E1/T1 carrier systems===
 The E-carrier system is the standarziation of digital communications, where a single wire can be used to carry more than one simultaneous voice conversations.
 It was first designed in America. There it has the name T-carrier, but the CEPT (European Conference of Postal and Telecommunications Administrations) revised and improved it becoming today the standard for the majority of countries, minus USA, Canada and Japan.
 The whole idea is to group more circuits to form a high bandwitdth network. For now, only the E1 (30 circuits) and E3 (512 circuits) are used. E1 is transmited as 32 time slots and E3 as 512 timeslots. This way, private end-to-end E1 circuits can be provided to the users in different countries that want to share a single high speed link.

@@ Line 37: / Line 37: @@
 Regardind broadband ISDN, there are still many things to be done. One example is the finalization of ATM.
 Curently, few people are replacing their whole telephone network with ISDN. For the moment the solution appears to be an entire ISDN network put inside one box which gathers all the ISDN needed devices (NT1, TA and TE1).
 ===About the E1/T1 carrier systems===

← Older revision		Revision as of 14:54, 21 August 2013
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	One disadvantage of using ISDN is the power source. While normal telephones provide their own power (this means that they are powered up from the telephone company and if the power goes down, the telephone will still work), to ISDN devices this rule does not apply. They need more power to run than a normal telephone, so the only place to get it is from inside the house.		One disadvantage of using ISDN is the power source. While normal telephones provide their own power (this means that they are powered up from the telephone company and if the power goes down, the telephone will still work), to ISDN devices this rule does not apply. They need more power to run than a normal telephone, so the only place to get it is from inside the house.
−
−

	===ISDN and the future===		===ISDN and the future===

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 ===What does it take to connect to ISDN?===
-All you have to do is to subscribe to a ISDN phone line. But there are some limitations. You cannot be at a distance greater than 5.5km from the telephone company central office, because of the need of expensive repeaters. ISDN Terminal Adapters (TA) are required, which are special hardwar equipments for communicating with other ISDN devices and with the telephone company.
+All you have to do is to subscribe to a ISDN phone line. But there are some limitations. You cannot be at a distance greater than 5.5km from the telephone company central office, because of the need of expensive repeaters. ISDN Terminal Adapters (TA) are required, which are special hardware equipments for communicating with other ISDN devices and with the telephone company.
 ===Advantages===

@@ Line 4: / Line 4: @@
 A couple of years ago, when all the telephone communication was entirely analog there was a problem. Going from switch to switch, farther and farther, the signal lost its intensity and noise appeared. This resulted in poor quality services over long distances.
-By turning the analog signal into a digital one the voice does not loose any of its quality. It is encrypted at one end and is transmited using special error correcting and syncronization algorithms and then it is decoded at the other end.
+By turning the analog signal into a digital one the voice does not loose any of its quality. It is encrypted at one end and is transmited using special error correction and syncronization algorithms and then it is decoded at the other end.
 This makes digital communication very attractive. Computer users benefit of increased speed, telephone companies remove all the possible noise that could intervene in the audio data. Also, this brings a lot of new services to the public, that were not available with analog systems.