Satellite signal passing

No matter how desirable, but it will have to happen again. Even if we know the frequency range of the television program package we liked and the coverage area of ​​the selected satellite, then all the same, we will only know the diameter of our satellite dish . Why? The fact is that the satellite signal coming to us is repeatedly transformed, starting with the satellite itself, and ending with your receiver (receiver). Let's follow all the simplest chain of receiving a signal from the satellite.

Electromagnetic signal from the satellite, meeting a satellite dish , and being reflected from its mirror, falls on the converter feed. After that, the signal transformed into electrical pulses in the converter via a coaxial cable enters our satellite receiver.

It turns out that the satellite signal, before getting into the receiver, is not once transformed.

To all this, the signal from the satellite, before entering the receiver, overcomes a huge outer space, passes through the dense layers of the atmosphere, at the same time meeting with those or other weather conditions. Imagine a small, drizzling rain, and how many water droplets it has to go through. Or, for example, if there is a winter, then how many snowflakes will meet on his way.

Now, let's follow the satellite signal from the satellite dish to the receiver, in more detail ...

And so, the satellite signal, having already undergone significant attenuation, is encountered with a satellite dish mirror.

Reflecting from the satellite dish mirror, and changing its direction, the signal focuses on the converter feed.

In a converter, the electromagnetic signal is converted to electrical.

Further, the signal enters a special cable, shielded from external interference.

From the cable, the signal enters the end device, a satellite receiver (receiver).

From the receiver, the image and sound signal (video-audio) is fed to the TV.

(since the TV is not involved in the processing of a satellite signal, this device will not be taken into account)

Proceeding from this chain, let's define more precisely what parameters will be used for, the final power level of the satellite signal:

These parameters depend on the satellite and weather conditions (we can not change them).

1 . The power and direction of a signal emitted by a satellite.

2 The frequency range of the satellite signal.

3 Distance from satellite to satellite dish .

4 Good or bad weather.

These parameters depend on the configuration of our receiving equipment (we can change these parameters for the better, while acquiring equipment with good technical characteristics).

5 The diameter of the satellite antenna we are looking for and its gain. The gain depends on the reflective properties of the metal from which the satellite antenna mirror itself is made.

6 Converter parameters, its sensitivity and noise figure.

7 The length of the connecting cable (the shorter the length, the better), and the quality of the material from which it is made.

8 The sensitivity of the input of the receiver (in different models, it is different).

And now, let's find out ... Why? Even knowing the exact parameters of the satellite coverage map, we will only know the approximate dimensions of our satellite dish . Weather conditions, as this phenomenon is temporary, we still exclude.

The point here is that the satellite itself transmits a signal for receiving equipment of a certain standard . For example, a converter should have certain parameters (but not less), in terms of sensitivity, and in terms of noise figure. The receiver must also have certain minimum requirements. And so on, and so on ... According to the same characteristics, the satellite provider, and calculates the coverage of a satellite, sufficient for reliable reception of the satellite signal.

Let's imagine this example. On the roof of the building is already a satellite dish . It is tuned to any satellite from which a certain package of TV channels is broadcast. Suppose the user was bored with these channels, and he decided to switch to another satellite. Looking at the coverage map of this satellite, as it turned out, the diameter of the satellite dish should be larger than that of the antenna it already has. But here, this user still decides to try. And what happens? And here it is being tuned to this satellite, and ... Oh, a miracle ... The signal is being received, and with a fairly good level. And what is it? Really a miracle ...? No, in reality there is no miracle. Simply, technical progress does not stand still, and the receiving equipment itself is constantly being improved. Converters, for example, are already produced with a lower noise figure, receivers, with improved reception characteristics, etc.

And now, let's imagine another, completely opposite example. The user, having studied the satellite coverage map, bought a satellite dish of the desired diameter. Tune in to your favorite satellite. And ... silence ... from the signal of no response, no greeting. Or, the picture will appear, then disappear. Why...? Has the satellite provider, on the coverage map, indicated an incorrect antenna diameter? Well ... Let's accuse him of all mortal sins ... But, the very reason for the uncertain reception may be hiding in a completely different way.

Perhaps the converter is mounted on a satellite dish , with an unnecessarily high noise figure. Or the user decided to save money and bought a cheap cable with low bandwidths. Maybe on top of everything else, the satellite receiver itself has a weak input sensitivity (the parameters of the "input level" are underestimated), for example, for me, the first receiver was caught like that.

Now, based on the above, it is possible to summarize such a result - as you now understand, it is theoretically, simply not realistic to choose the required diameter of the satellite dish accurately enough. One hundred percent confidence, you will have only when you check everything in practice . Therefore, we will proceed from the parameters provided by the satellite provider.

Unfortunately, we cannot change the signal power coming from the satellite, but ... we can learn how to choose the configuration of satellite equipment correctly . In other words, we need to be able to understand some of the parameters of individual elements of satellite equipment, and that they are not worse than certain standards. And as practice has shown, in most cases, this will be more than enough.