Application of DVBS/S2 in digital TV system VIII (now popular dual tuner application)

Source: Internet
Author: User

Application of DVBS/S2 in digital TV system VIII (now popular dual tuner application)

Lao Xie in the field of digital television has been mixed for some years, "dvbs/s2 in the application of digital television system" series of articles, a brief introduction of a number of satellite receiving relevant knowledge points. Today Lao Xie continues to play waste heat, and wants to chat with friends about the most popular dual tuner applications in the high-end TV species.

First, Google Android New Feature–pip

Before introducing dual tuner related knowledge, Lao Xie first share a picture, this picture is this year Google I/O on the Android n share, the picture refers to the "pictures in" application.
This picture in the picture, short Pip, in the end and old Xie to talk about the dual tuner have Mao relationship? With this question patiently, let's look down.

Second, what is dual tuner?

What is dual tuner? Good question. As the name implies, dual tuner is double tuner. Two of tuner? Not also. Strictly speaking, is two sets of independent Tuner&demod reception system integrates in a television, we call dual tuner. In the case of European digital television, the general single tuner, which supports DVBT/C/S and ATV TV, usually sees two tuner connector. A threaded receive head is used separately for dvbs, and the other non-threaded is for DVBT/C/ATV reception. So, dual tuner can basically be considered as two sets of single tuner, but not simply splicing.

Say so much, it is better to look first, that is, dual tuner basic block diagram, I believe that our understanding dual tuner have certain help:

For reference, look from left to right:
On the far left, we can see three tuner connector, two threaded, one non-threaded. The two threads are the receiving heads of the Dvbs main tuner and Dvbs Sub tuner respectively. And the other non-spiral connector is DVBT/C/ATV main&sub Tuner co-receiver head. Careful friend, will ask why Dvbs main and sub connector to separate, and DVBT/C/ATV is shared? In the previous article, Lao Xie introduced the satellite to receive the signal, it is necessary to send the DiSEqC or singlecable command through the coaxial line, and these commands are modulated by 13v/18v,0/22k and other signals. In the simplest case, if main tuner wants to output 13V, and the sub tuner wants to output 18V voltage, how can this conflict be resolved? There is no way, main dvbs and sub dvbs can only use their own separate receive headers. And dvbt/c is different, there is no such restriction, through the same receiving head to the signal into the tuner interior, only need to put the incoming signal in split.

Terrestrial/cable connector, which is a non-helical receiver, DVBT/C/ATV signal is input to the digital TV via the same coaxial line, passing an amp. Zoom in (or amp., as in, this is where the LNA is on/off), And then through the Div. The module transmits the RF signal in two to two tuner, that is, main tuner and sub tuner, to do the spectrum removal (decrease frequency, from RF to IF), and the output of both tuner is the IF signal input to main demod and sub demod to do demodulation, In order to obtain two TS signal, supply back-end DMX to do the work of re-use (because space is limited, only talk about DMX, please understand).

As the leftmost satellite 1, which is main dvbs. The satellite signal passes through an amp. Zoom in, through Div. In two, straight to main tuner/demod, and the other all the way to a switch SW, we would first think that the road is not through, that is, SW off, so the second signal will not pass.

Satellite 2, or sub dvbs. The RF signal also passes through an amp. Zoom in, this time without a div., but even to just the SPDT switch, if just satellite 1 we assume that SW off, then for Satellite 2 is SW on, so satellite The 2 RF signal will be able to reach sub tuner/demod successfully.

You notice, at the top, there are two things, main LNBC and sub LNBC. We know that satellite reception process, it is necessary to control the LNB, then LNBC is the device that produces control signals, so LNBC is the abbreviation of the LNB controller. In general, main LNBC and sub LNBC work independently to meet the application requirements of satellite 1 and satellite 2 respectively. So, the switch between the two (not just the SPDT switch, which we call the LNB SW, to differentiate just that SW) is the off state.

The discussion above is based on SW off and LNBC SW off. Since there is such a design, it must have its own unique application, yes. This is a discussion that has to involve the Dvbs application scenario. Dvbs not only has DISEQC applications, but also a single cable application. The previous discussion (SW off + LNBC SW off) is in fact the basic application of DiSEqC under dual tuner case. If it is a single cable application under the dual tuner case, what is different? Single Cable, as the name implies, only a coaxial input to the TV, then in order to be compatible with such application needs, only then appeared the SW, set SW on, then, satellite 1 of the RF signal can go through the Div. Two to the main tuner/ Demod and Sub Tuner/demod, this scenario is very similar to DVBT/C/ATV. The difference is that not only the SW on, but also the LNBC SW on, so that the sub Demod can also control the main tuner coaxial (to the main tuner coaxial Transmission control signal).

Originally this article can end, but old Xie thought, it is necessary to put forward another application scenario, that is, under the dual tuner architecture of the single tuner mode. What do you mean? If the user has only one satellite signal to enter the room, but the external device is not a single Cable, but DiSEqC device, then users do not want to waste the benefits of dual tuner (the article will add the benefits of dual tuner), we need to do? Also follow the single cable application scenario, the SW on + LNBC SW on, so main/sub Tuner&demod can control the coaxial signal. This is the single tuner mode. However, please note that this application is limited. Because in this scenario, the user is not free to switch the LNB state (for example, 13/18v, etc.). Don't understand? Think again, hehe.

Iii. applications based on the Dual Tuner architecture (benefits)

Why is high-end digital TV using dual tuner architecture design? Because more and more applications are now being used, for example, users want to picture, that is, to display two TV shows on the same screen, and if they want to burn a TV show, they can watch other TV programs and so on. The popularization of these application requirements is bound to need to adopt dual tuner architecture design.

Speaking of which, I believe you already understand the relationship between "PIP" and dual tuner architecture.

Sharing is the traditional virtue of the Chinese nation, if you feel old Xie's share of help you, pay attention to Itxiebo bar.


Application of DVBS/S2 in digital TV system VIII (now popular dual tuner application)

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