Lecture
In order to start choosing the satellite you need, or rather, to the fact that it is broadcasting, it is not enough to know the configuration of satellite dishes . You need to learn more, understand the table of satellite transponders. After all, it is this table that displays what a particular satellite transmits, and what configuration of satellite equipment (to put it simply, what set), we can receive a signal from this satellite.
- this table is intended for setting up a satellite receiver, or other receiving device (for example, a DVB card of a computer), to receive a signal from a particular satellite.
Understand the table of transponders, we will on the example of one of the satellites. And also, we will find out what other parameters and terms are encountered when setting up satellite reception.
The complete definition of such a term as a transponder is quite difficult to understand for a newcomer to satellite TV broadcasting, so consider the simplest definition of this parameter.
- includes several values, such as: Frequency, Type of polarization, Symbol speed (SR - Symbol Rate) - or code rate; Error Correction (FEC - Forvard Error Correction), Encoding type (if the signal is encoded).
What is the frequency and type of polarization , I have already explained on the previous pages. So here, I think repeated does not make sense.
Symbol speed
( SR - Symbol Rate), can still occur as "code rate", "flow rate" - this parameter indicates the density of the information flow in the satellite signal. Let us, as always, the meaning of this term, let's look at a simple example.
Imagine a regular school class. There is a lesson. The teacher, in a calm measured voice, leads an object. That is, the flow of information is relatively not large, and all students have time to learn everything. But here, the lesson ended, and after the change, another one began. In this lesson, the subject is already led by another teacher, who “taratorit” like a typewriter (probably you have observed such a situation more than once). So, the flow of information that the teacher conveys to his students is already quite dense, and not every student in this class is able to accept and assimilate this speed of information.
In our case, the satellite, in its transponder, can also transmit information at different speeds, and therefore its number will also be different.
Let's take an example, take some transponders, the satellite Express AM2 80.0 ° E , because at the time of this page creation, this satellite had all the ranges described above, and the types of polarization, as well as different symbolic speeds.
For comparison, we take two transponders, with different symbolic speeds, in the table I marked them in blue and green .
The transponder under №1, where only one TV channel GTRK Buryatia is transmitted, has a symbolic speed of 4275 Kb / s (kilobits per second).
Now, take the transponder under number 5 . Its symbolic speed, already much higher, is 27,500 Kb / s. As a result, not one, but several TV channels are broadcast from this transponder (TV Center, 7TV, TV 21, TV Center Mir, TV Center Siberia, TV Center Ural).
It turns out that the greater the symbol rate, the more information can be transmitted from this transponder.
To receive a high symbolic stream, you also need your satellite receiver to maintain such a speed, otherwise it (as in the example with students) simply cannot process (assimilate) such a large data stream. Although now, almost all modern receivers support such speed, and this question is no longer so urgent.
Error Correction, FEC - Forvard Error Correction (can occur as Viterbi Rate) - Can take values: 1/2, 3/4, 5/6 ... and so on.
The concept of this term will be quite difficult for a beginner. Therefore, in order not to bother you with an already large amount of information, this parameter, we will not consider. We will need it during the setup of the satellite receiver. We just put it from the table to the right place. I will tell about it in the section "Installation and Setup of the Satellite Antenna". By the way, some receivers do not require input of this parameter, and set it automatically.
Encoding type - this parameter applies only to satellite receivers. Coding is usually used to watch paid TV programs.
If you are going to receive a signal from this transponder, then it is necessary that your receiver supports such encoding (could decipher the received data). This becomes possible if there is, in the receiver itself, a conditional access module for the CAM module ( C onditional A process M odule), with a card slot. There is another way. You register your receiver via the Internet, buy a card of the package of paid channels you need, and also register it to this receiver through the Internet, well, as they say, you enjoy watching the paid software package.
Here are some types of encodings - DRE Crypt encoding (DRE Crypt), Irdeto encoding (Irdeto), BISS encoding (ViaSS), Viaccess encoding (Viasess) ...
If in the table of satellite transponders, in the coding type column, there is Free to Air (or FTA ), then this is an open transponder (without a signal coding), i.e., free. Such transponders, as a rule, are opened by any satellite receivers, and it does not matter whether it has a conditional access module or not.
Further, when we figured out the parameters of the table we need, let's learn how to determine , according to the same table, what configuration of satellite dish and which type of receiver we will be able to receive this or that transponder.
Now, let's imagine that we have decided on the choice of satellite. Suppose that this satellite is Express AM2 80.0 ° E. We now need to learn how to determine at a glance the necessary configuration of a satellite dish .
It may happen. You already have a ready-made antenna kit with a receiver (or computer DVB-card), but you need to find out whether the signal can be received from one or another satellite. That is, can you, in the future, tune the satellite dish to your chosen satellite.
For example, we again take the same table of transponders, the satellite Express AM2 80.0 ° E , and go through each column separately.
Where:
0. № - ordinal number of the transponder. This column applies only to this table. Since this value is not necessary in other tables of transponders, it may not be.
1. Channel name - the name of the satellite service, which is transmitted from this transponder. For example, the name of a TV, radio channel, or the name of an Internet service (@Raduga Internet, @HeliosNet, @PlanetSky ..., etc.).
2. Frequency - By this parameter, we can immediately find out the type of the desired converter . First you need to determine what range this frequency is in, then what the C converter itself will be - or Ku band, or combined C and Ku .
Also, by the value of the range, we can determine the approximate dimensions of the satellite dish . If Ku is a range, then the size of her mirror will be up to 1.2 meters. Well, if C , then at least 1.5 ... 1.8 meters.
3. Type of polarization - This parameter clearly indicates which type of converter will be used. That is, what kind of polarization your converter should support. Linear ( H orisontal, V ertical), or Circular (Right, L eftl). Since all modern receivers support almost all polarizations, this parameter can be attributed only to the choice of the converter.
4 SR (symbol rate) - this value indicates which symbol rate your receiver should support. But again, since all modern satellite receivers support high speeds, this parameter can be skipped.
5 FEC (Error Correction) - This parameter is required to set up the receiver. Since all modern satellite tuners support the necessary values, this parameter can also be skipped.
6 Type of encoding - this parameter directly determines which satellite receiver you will use. That is, if there is any coding in the transponder, it means that this service is paid. And of course in the receiver, there must be an appropriate access module (or emulator program) that support this encoding.
To select satellite equipment, or, more precisely, selection, it is usually enough to know three values, these are Frequency, Type of polarization, Type of coding .
Now, let's follow the example of two transponders from the table above, we define the desired configuration of satellite equipment .
Transponder serial number " 1 ":
Satellite equipment configuration:
Now, consider the transponder under the sequence number " 6 ":
Satellite equipment configuration:
To further tune the satellite receiver to the selected transponder, as a rule, you need to know four values (or three, in case the FEC value is automatically determined by the receiver), these are “Frequency”, “Polarization type”, “Symbol rate”, “FEC value” ".
Since the transponder tables may have to be taken from different sources, you will need to learn to screen out unnecessary data, and select the ones I mentioned above.
Now we will talk, where to us to take these tables of transponders ...
Where do we get the transponder tables? There are two options here, either from typographical paper editions of the respective topics, for example from the magazine TeleSputnik , or from Internet sites. The latter option is preferable, since if you are reading these pages, you already have access to the Internet. You must first subscribe to the magazine and wait until the new issue arrives, or, at the very least, contact the nearest newsstand. I would like to recommend here, if you prefer the latter option, be sure to check that the magazine is as late as possible, since satellite channels change to other transponders from time to time, and these changes may not be in the last month or last month.
If you want to use the Internet service, you can go to any search engine (Google, etc.), and enter there approximately such a query " table of satellite transponders ", or " table of frequencies of satellite channels ", well, in general, that something like that. And in any case, you will find the necessary information.
Below I gave a couple of fairly popular links, where you can find almost all the tables of transponders, well-known satellites.
The official website of the magazine TeleSputnik
Frequency Table Page - http://www.telesputnik.ru/ft/freqtab.php
Actions :
Professional website on the parameters of satellite transponders LyngSat
Actions :
The site is English-speaking, but as a rule, Russian channels are written in Russian, only in English letters.
Reading above, you have come across two words that may not be familiar to you - an analogue , and a digital signal. There will have to digress a bit from the topic.
In order not to unnecessarily fill your head with too abstruse information, we will not go into details of the parameters of these signals, but analyze only the main point.
Until some time, both satellite and terrestrial broadcasting was transmitted by an analog signal, but due to the fact that the number of channels is constantly growing, it became problematic to fit the entire flow of information into the ranges we need. As for example in our case, in the satellite bands "C" and "Ku". Therefore, the developers decided to convert the analog signal to a digital one (as they say, “drive to digital”). In such a compressed digital format, in one transponder, it is possible to transmit more than one channel, as it was with an analog signal, but several at once. In this type of information and transmitted to the end user. At the final stage, your satellite receiver from the compressed digital stream selects the desired TV channel and converts it back into an analog signal convenient for us, which goes to your TV via a cable with a separate Audio and a separate Video signal (for example, for options for connecting the receiver and TV via cable, with connectors such as "tulip").
To receive an analog or digital signal, your receiver must support these formats. Since the analog transmission of satellite signal, has ceased to meet modern needs, the majority of receivers released today support the reception of a digital signal. For example, "MPEG-2" or more modern, "MPEG-4".
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The television. Theory. Satellite
Terms: The television. Theory. Satellite