Reception of a signal from the satellite. The frequency of the satellite signal.

The signal coming from the satellite has its own specific frequency. To understand what the signal frequency , let's start with, let's deal with the units of its measurement.

The frequency of the electrical signal, it is customary to measure in Hertz - Hz (Latin - Hz). One hertz is equal to one oscillation of an electrical signal, in 1 second of time.

More precisely, 1 hertz is equal to one electric impulse, in a time period of 1 second . Two hertz will be equal to two electrical impulses that occurred also in the period equal to 1 second , that is:

• " 1 hertz " = 1 pulse / per 1 second.
• " 2 hertz " = 2 pulses / per 1 second.
• " 3 hertz " = 3 pulses / per 1 second.
• " 4 hertz " = 4 impulses / in 1 second.
  
  And so on...

To make it easier for you to understand what a signal frequency is, we temporarily digress from the main topic, and analyze a bit the concept of “frequency” itself, using the example of powering our household appliances, which in turn we use in our daily life.

If we take a technical passport, from which either an electric or electronic device, for example, a refrigerator ... or a TV set (this is not important at all), then in the "power supply" line, we can find the following parameters:

Voltage - 220 volts, network frequency - 50 hertz .

So, what happens here. This device is designed to work in the AC mains, whose frequency is 50 Hertz . That is, in one second in our "power outlet", 50 oscillations (pulses) of electrical voltage occur.

Now, let's move on to a simpler appliance, and as an example, take an ordinary incandescent lamp, which we use to light our apartments.

Inside this lamp, there is a special "tungsten" thread, which, when voltage is applied to it, heats up to very high temperatures, and emits the light we are used to. But since, this lamp is powered by electrical pulses, in fact, it flashes with one particular frequency.

So again, it's easier to understand what an electrical impulse of a certain frequency is, let's see visually what happens to our lamp if the frequency of the home power supply drops to a few hertz.

1 hertz		2 hertz		5 hertz		10 hertz

The more often the light starts to light up, the higher the frequency of the electrical impulse, which lights the lamp.

With a mains frequency of 50 hertz, this lamp flashes 50 times per second. And why, you ask, we do not see her blinking? The thing is, the spiral inside this lamp, at this frequency of the electrical signal, simply does not have time to completely cool down, and our eyes do not have time to notice flashes of the lamp.

Next, let's move on to measuring the frequency of the electrical signal ...

In satellite radio transmission, a very high frequency of electromagnetic waves is used, and as a rule, this frequency is usually specified in Mega- hertz (MHz) or Giga- hertz (GHz). That is, removing in meaning difficult to visually count zeros.

For clarity, we take a rounded integer showing a certain frequency, for example 1 000 000 000 Hz (one billion hertz, in ... ) where:

• Hz = divide by 1
• kHz = divide by 1000
• MHz = divide by 1,000,000
• GHz = divide by 1,000,000,000

Now convert our frequency parameter

• Hz = 1,000,000,000 (Hz)
• In kilohertz = 1,000,000 (kHz)
• In megahertz = 1000 (MHz)
• In gigahertz = 1 (GHz)

Here, it is quite clearly seen that a signal of such a high frequency is much easier to represent in megahertz or gigahertz . Since satellite broadcasting uses precisely high frequency, in the tables of satellite transponders, the frequency parameter is usually specified in MHz (lat. Letters. - Mhz), well, or in GHz (lat. Letters. - Ghz).

In addition to the frequency, the satellite radio signal has a rather complex pulse shape, or rather, pulses. After all, it transmits both the image and the sound, sometimes even several television channels, not to mention the data stream on satellite Internet. All of this explains the very high frequency of the satellite signal itself.