Valaki nem tudja veletlenul, hogy hogy van angolul az, hogy visszirany?

"Receive and send signals".

Ez lenne a legkozelebbi. Na, de persze azt tudod, hogy ez nem megy egy idoben. Kuldeni es kapni szignalt se TV se mobil egyszerre a per pillantban nem tudod.

Hu, a szaknyelvhez mitsem ertek. Nem tudtm, hogy ezert kerdezed.

Ha az alabbiakra gondoltal, olvasd el, es itt van a link tobb infoval.

[link]

Idezet a linkbol:

TRANSPORT OVER HFC NETWORK

By using frequency division multiplexing, an HFC network may carry a variety of services, including analogue TV, digital TV (SDTV or HDTV), Video on demand, telephony, and high-speed data. Services on these systems are carried on Radio Frequency (RF) signals in the 5 MHz to 1000 MHz frequency band.

The HFC network can be operated BI-DIRECTIONALLY, meaning that signals are carried in both directions on the same network from the headend/hub office to the home, and from the home to the headend/hub office. The FORWARD-PATH or downstream signals carry information from the headend/hub office to the home, such as video content, voice and internet data. The return-path or upstream signals carry information from the home to the headend/hub office, such as control signals to order a movie or internet data to send an email. The forward-path and the return-path are actually carried over the same coaxial cable in both directions between the optical node and the home. In order to prevent interference of signals, the frequency band is divided into two sections. In countries that have traditionally used NTSC System M, the sections are 52 MHz to 1000 MHz for forward-path signals, and 5 MHz to 42 MHz for return-path signals. Other countries use different band sizes, but are similar in that there is much more bandwidth for downstream communication instead of upstream communication.

As detailed above, much more of the frequency band is dedicated to the forward-path than the return-path. Traditionally much more information is sent in the forward-path due to video content only needing to be sent to the home, so the HFC network is structured to be non-symmetrical, meaning that one direction has much more data-carrying capacity than the other direction. Years ago, the return-path was only used for some control signals to order movies, etc., which required very little bandwidth. As additional services have been added to the HFC network, such as internet data and telephony, the return-path is being utilised more.

Multiple System Operators (MSOs) developed methods of sending the various services over RF signals on the fiber optic and coaxial copper cables. The original method to transport video over the HFC network and, still the most widely used method, is by modulation of standard analogue TV channels which is similar to the method used for transmission of over-the-air broadcast. See broadcast television system for more information. One analogue TV channel occupies a 6 MHz-wide frequency band in NTSC-based systems, or an 8 MHz-wide frequency band in PAL or SECAM-based systems. Each channel is centred on a specific frequency carrier so that there is no interference with adjacent or harmonic channels. Digital TV channels offer a more-efficient way to transport video by using MPEG-2 or MPEG-4 coding over Quadrature amplitude modulation (QAM) channels. To be able to view a digitally modulated channel, home, or customer-premises equipment (CPE), e.g. digital televisions, computers, or set-top boxes, are required to convert the RF signals to signals that are compatible with display devices such as analogue televisions or computer monitors. The Federal Communication Commission (FCC) has ruled that consumers can obtain a cable card from their local MSO to authorise viewing digital channels. By using digital compression techniques, multiple standard and high-definition TV channels can be carried on one 6 or 8 MHz frequency carrier thus increasing the channel carrying-capacity of the HFC network by 10 times or more versus an all analogue network. Note that a digital tuner (i.e. TV set-top box) is not required for standard analogue TV channels since most televisions have integrated analogue tuners that can decode the signal, unless some type of scrambling is used.