Combined c and ku converter. Satellite converter LNB, for receiving a satellite signal, breakdown

types of satellite converters.

Converters (“LNB” or “LNA”), as well as a radio signal, are divided into receiving a specific frequency spectrum, that is, again, a range.

Satellite converter

You may come across the following designations for converters, LNB or LNBF - in principle, correct name both. But if you consider that converters going to offset satellite dishes, have an integral housing with an irradiator (Photo 1), then it would be more correct to use the name - LNBF (LNB - converter, + Feeder - feeder, i.e. receiving antenna, or feed = LNBF).

There are types of converters where the irradiator is attached to the converter body, and they are usually assembled before mounting on satellite dish. In this case, the correct name would be LNB + F (LNB - converter, + Feeder - feeder).

Satellite converter ranges

Satellite converters, which are usually used for viewing home satellite broadcasting, by the way and not only, are also designed to receive: C-band, Ku, or combined C and Ku-band.

Ku-band satellite converters are more common since the diameter satellite dish , when using such a converter, is usually from 0.5 to 1.2 meters. When receiving the C-band, the antenna dimensions are required to be slightly larger.

For example, to receive a Ku band signal from the Yamal 201 90.0°E satellite, you can use satellite dish with a diameter of 0.9 - 1.2 meters, and for receiving C-band from the same satellite, it is advisable to use an antenna of at least 1.5, and preferably 1.8 or 2.0 meters.

Note: Dimensions satellite antennas are given only approximately; we will consider how to calculate its more accurate parameter a little later.

There are many models of satellite converters, different both in type and appearance. Below are photos of some of them.

Polarization of converters

In addition to the frequency spectrum (range), converters, again, like a radio signal, differ in the type of signal polarization. Moreover, two types of polarization can be present in one converter at once.

Here are the two main types of converters you may encounter:

Linear universal satellite converter

Linear horizontal(H - Horizontal).

Linear vertical(V - Vertical).

Circular satellite converter

Circular right (R - Right).

Circular left (L - Leftl).

The name of the circular satellite converter may also contain the word “universal”, since it contains two types of polarization “right” and “left”, but... do not confuse it with a linear converter.

Converters can also be single- or dual-band. Dual-band converters capture a slightly larger portion of the frequency spectrum. Controls range switching itself satellite receiver(it sends a special tone signal to the converter).

Selecting the type of satellite converter is, so to speak, an individual approach, and each user chooses it in accordance with their requirements. That is, according to the type of signal that it is going to receive from the satellite. Also, you should pay attention to the number of receiving devices (for example, a converter with two outputs to two receivers located in different rooms, or a receiver and a computer DVB card, etc...).

I will also dwell on some of the use of satellite converters, as well as some aspects of the principle of its operation, in the section - installation and configuration of a satellite dish, that is, during the installation itself and satellite dish settings.

To begin choosing the satellite you need, or rather, what it broadcasts, it’s not enough to know the configuration satellite antennas. You also need to learn to understand the table of satellite transponders. After all, it is this table that displays what this or that satellite transmits, and what configuration satellite equipment(to put it simply, which set), we can receive a signal from this satellite.

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Satellite converter(eng. low-noise block converter - literally low-noise monoblock converter) - a receiving device that combines an LNA (Low-Noise Amplifier) ​​signal preamplifier received from a satellite and a downconverter (Downconverter), also known as a local oscillator (stabilized source of high frequency, producing a sinusoidal signal), which serves for frequency conversion electromagnetic wave Ku (10700-12750 MHz) or C-band (3400-4200 MHz) into an intermediate frequency (950 to 2150 MHz), called L-band, in order to transmit with the least loss over coaxial cable to the consumer. The converter is installed in the focal center of the satellite dish (on a remote bracket).

Operating principle

Electromagnetic frequency oscillations satellite signal experience very strong attenuation in cable lines. That is why in the converter not only amplification of oscillations occurs, but also frequency conversion. The input frequency is converted by subtracting (or adding) the local oscillator frequency. For each range, the converter uses its own local oscillator.

For C-band(3400-4200 MHz) one local oscillator with a frequency of 5150 MHz or 5750 MHz is used. Since the width of the Ku-band (12750 - 10700 = 2050 MHz) does not allow it to be simultaneously converted to intermediate frequency, since the width L-band significantly less (2150-950 = 1200 MHz), the Ku-band was conditionally divided into sub-bands:

• Ku-FSS (Fixed Satellite Services, 10.7-11.7 GHz) is usually called “low” - “Low”;
• Ku-DBS (Direct Broadcast Services, 11.7-12.5 GHz) received the designation “upper” - “High”;
• Ku-BSS (Broadcast Satellite Services, 12.5-12.75 GHz) - Telecom subband.

Modern, so-called “universal” converters, which allow receiving the entire Ku-band, have two local oscillators 9750 MHz and 10600 MHz. Single-heterodyne converters are also widely used. circular polarization. the local oscillator frequency is 10750. They are used to receive signals from NTV+ and Tricolor TV operators. Switching between local oscillators is carried out using a 22 kHz tone signal coming from the control device (satellite television receiver - receiver) depending on the received subband.

Also, modern converters can work with different signal polarizations. Typically this is: linear (horizontal, vertical) or circular (left, right) polarization. Switching is carried out by changing the converter supply voltage - 13 or 18 Volts.

An important characteristic of the converter is noise factor (measured in dB), since when amplifying the useful signal, the converter introduces its own noise. Noise figure (NR) shows how much the signal-to-noise ratio will deteriorate after amplification and frequency transfer. CN determines the sensitivity of the converter - threshold value minimum level useful signal, below which the converter will no longer be able to register this signal due to its own noise. How less value Ksh, so much the better. Good performance CN for cheap converters is 0.1-0.5 dB. In fact, noise factors indicated by manufacturers are always underestimated, due to marketing tricks. “Honest” noise reduction values ​​are indicated on expensive (from $500) synthesizer (PLL) converters and cannot be better than 3-5 dB.

Without of this device V satellite system, of course, there is no way around it. Converter important part to watch satellite television. Since it is a parabolic mirror, thanks to this shape the signal is focused at one point, specified by the geometric parameters of the antenna.

From Fig. 1 it is clear that, due to its spherical shape, the signal falling on the mirror of the satellite “dish” is reflected strictly in one direction and focused at one point. The converter is attached to this point. It “collects” the signal coming to it. The received signal is then amplified and converted into low frequency. After this, the signal is transmitted to the cable.

Converter(more precisely, this device is called LNB, from “Low Noise Block” low-noise block) is designed to convert the frequency of the electromagnetic wave “Ku” (10...13 GHz) or “C” range (3.5...4.5 GHz) into a lower intermediate frequency 0.95...2.5 GHz so that the signal can be transmitted with minimal losses along the cable up to satellite receiver(receiver). Thanks less high frequency signal and its increased power, you can use an inexpensive signal and increase its length up to one hundred meters without significant loss of the signal.

All converters are characterized by their own noise factor. The lower the self-noise, the better the converter. The typical value of this parameter, which is indicated by converter manufacturers, is 0.3 - 0.5 dB. On at the moment There are no converters with an intrinsic noise of less than 0.3 dB on the general market. All manufacturers' claims that their converters have a noise figure of 0.1 dB are a marketing ploy.

The variety of converters is very large. We will highlight three main types that are most often used in our everyday life.

• “C” band converter.
• “Ku” band converter with circular polarization.
• Universal “Ku” band converter (vertical and horizontal polarization).

"C" band converter	Universal “Ku” band converter	Ku-band converter with circular polarization. (outwardly no different from the universal one)

Tell me which converter I should choose. Let's figure out how to choose the right one converter(LNB). I can safely reassure you that when choosing a converter you will not have any particular difficulties or problems. Since the characteristics of most converters used in household satellite television very similar.

The first thing you need to decide is the type of converter (LNB), i.e. in what range it will be used in “Ku” or “C”. Fundamental difference between the types of converters is that they operate in different frequency ranges.

The C-band local oscillator frequency is 5150 MHz. In addition, the C-band LNB has larger size compared to Ku-band LNB. First of all, this is due to the different wavelengths.

Universal “Ku” band converters have a dual-frequency local oscillator. The use of such a local oscillator is determined by the fact that the Ku-band is quite wide, according to this Ku-band is divided into two sub-bands: the lower 10700 - 11800 MHz and the upper 11800 - 12750 MHz. Switching between bands is carried out by a signal transmitted via cable from a satellite receiver (receiver). In modern universal converters, bands are switched using a 22 kHz signal. And to switch the polarization, a 13/18 V signal is used.

If you have chosen a Ku-band converter, you must consider the LNB type: linear or circular. Without going into details of the technical differences between them, we can say that when purchasing universal converter, You can easily make a circular one out of it, but the universal converter is linear from the very beginning. For the most part, all satellites have a predominant list of channels in the Ku-band, mainly with linear polarization. An exception is the NTV+ and Tricolor TV packages, which broadcast in circular polarization and require a converter with circular polarization.

Characteristics that you need to pay attention to when choosing a converter. This is the noise figure described above and which is important technical parameter. Noise figure is measured in dB (decibels) and indicates the threshold value of the signal level c below which the signal will be lost. Accordingly, it would be reasonable to assume that the more low coefficient noise, we’ll install a converter, especially weak signal we can accept.

For C-band converters, a value equivalent to the noise figure is used, it is called noise temperature. This is an effective quantity that serves as a measure of the noise power in radio receiving devices; it is equal to the temperature of an absolutely black body or matched resistance, at which the power of its thermal noise is equal to the noise power of this device. Accordingly, the lower the value noise temperature, the lower the noise threshold value, the better. The typical noise temperature for currently produced C-band converters is 15K.

There are also a number of converters that differ from conventional ones - these are converters with several independent outputs.

In fact, everything is simple here. If you decide to add a couple more TVs for independent viewing, then you need to focus on a certain amount outputs at the converter. Independent outputs give us the opportunity to view satellite channels different polarizations, regardless of the number of receivers connected to the converter. Suppose you have a receiver with a TV in each room, and there are four of them, then you need to purchase a converter for four outputs, i.e. Quadro.