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SERVICES
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The services that the data transmission by optical fiber offers until the home are the own ones of a service of telecommunications of subscriber of broadband. In general we can discriminate between three great service groups offered by means of this type of technologies. These are:
The use of networks with technology FTTH offers diverse improvements with respect to other supplied access methods. The most important changes go related, obvious, with the increase of the data transfer rate, which turns to this technology the one of greater quality and interest for the subscriber..
Fig: Scheme of the distribution of the offered services
Fig: Scheme of the distribution of the contents and services
Fig: Comparison of the speeds of access –ADSL and cable– supplied by the companies (dic-2006)
Examples of these technical improvements in the speed of transmission are:
It is in special, without a doubt, television IP the one that wakes up a greater interest, being the one that it requires of a greater amplitude in the communication channel. If we observed the previous graph, we see that with the best one of the offered accesses to Internet and, considering that that speed was effective, guaranteed and constant; even so, we would not arrive at bandwidth required for a single television channel HDTV. The speed required by one of these channels with a format of compression of video MPEG2 - MP@HL (Main Profile AT High Level) that, is the standard used nowadays for the television transmitted by satellite (SATTV), terrenal digital television (TDT) and also used for the disc recording (SVCD, DVD, HD-DVD, Blu-Ray), requires of a minimum rate of bits of 19.2 Mb/s, to which there would be to add the different channels from audio surrounding and subtitles plus other facility. Although it is certain that in some countries (as Chinese) they are used or they been candidates other formats of compression based on standard MPEG4 that allow superior levels of compression, the rate of required bitios is, in the best one of the cases, of about 6 Mb/s only for the video signal; and, it has like counterpart that the equipment processors of this signal (transmitting as as much receiving) is considerably more expensive at the present time that those of the standard MPEG2 that already has been several years in the market.
The speeds that can be reached in FTTH are, by the own capacity of the fiber, almost limitless. But, obvious, there is a electronics behind the optical channel that, has to turn these luminance signals electrical. That is to say, the terminal velocity of transmission does not depend on means, if not of the electronics that accedes to him. There are no devices that work digitally by light; all of them are electronic. Therefore, this conversion, is at the present time the limit that, without a doubt will be growing in the next years. Tests of transmission by Tesa (Telephone of Spain) at a symmetrical speed of 100 have been made Mb/s (equal towards the user that towards the operator). This speed allows the simultaneous transmission of television in quality HDTV (in its different present formats: 1280x720 progressive or 1980x1080 interlaced) and the use of the rest of the bandwidth for other services: unloadings of data of Internet, telephony, video-conference, monitoring…
The home must adapt to take advantage of the improvements offered by this technology. The possibility that opens to the telecontrol of the home also requires of suitable devices that, based on different international standards, is able to be remotely piloted by different means like the telephone one and, the control by networks of computers like Internet. In addition to these devices we have to tell on household-electric that they are susceptible to be controlled by these domóticos apparatuses. Switchboards of security and cameras of monitoring, thermostats and sensors of presence can be other devices that accompany our domótica switchboard and turn our home a true digital home, in addition to the advantage of this technology in their section of leisure and telephony.
Although household-electric the habitual ones not yet come, in their immense majority, adapted to be compatible with the new technological advances in telecontrol; all the international standards of domótica allow – by means of modules – to implement the possibility of being controlled by networks TCP/IP like Internet. The standard more used nowadays in Europe is the KNX - old EIB -, whereas in the U.S.A. it is the X10.
Fig: Domótica power station with control IP of the Jung mark based on standard KNX.
The power station of the previous figure connects a local area network (LAN) with instabús EIB KNX. By means of an Ethernet connection, this equipment can as much be controlled with a PC within the local network, like through a remote connection through Internet. All the functions that are accessible for the control of the domótico home by means of this power station, are it also from the outside of the house.
Some manufacturers of household-electric begin to produce apparatuses able to be remotely operated, developing simultaneously, their particular systems of management, independent of the domótica standards. An example is the domótico system of Siemens that allows without extra wiring to supervise and to control the household-electric ones which they are prepared for it. The control system is called serve@Home and used the mains for the equipment that does not need adapter and a module of communications for which they are not in favor it of not being produced by this manufacturer (heating, blinds, interface with other power stations…).
Fig: Domótico system serve@Home of Siemens with household-electric prepared for the digital home
Fig: Modules adapters of the domótico system property of Siemens for equipment nonprepared.
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