Solar interference. Attention! Autumn solar interference begins Solar interference dear skynet users

Solar interference- distortion of the signal received as a result of radiation, when the latter approaches the ground station-satellite axis.

On a global scale, solar interference occurs twice a year during the 3.5 week period surrounding spring and autumn (March 20-21 and September 21-22, respectively).

In the spring, interference first affects ground stations in the northern hemisphere, moves to equatorial stations (where the peak of interference occurs exactly on the day of the equinox), and then moves to stations in the southern hemisphere. In autumn, everything repeats in the opposite direction.

From the point of view of a ground station, interference continues for 5-12 days, during which, as it passes through the sky, the sun crosses the antenna-satellite axis for 1-10 minutes, in the morning for stations in the eastern hemisphere, for the western hemisphere - in the evening. At the beginning of the period, interference is manifested by a decrease in the signal level and an increase in the number of errors; by the middle of the period, reception breaks down completely.

For a specific ground station, the start and end times of interference can be calculated to the nearest second. The initial data for the calculation are:

• satellite location
• ground station coordinates
• antenna diameter
• range (C or K u)

On a duplex communication channel (between two ground stations), interference affects twice - first on the reception of one ground station, then on the reception of another.

Damage caused by solar interference

First of all, interference deteriorates the quality of communication and leads to breakdowns, which affects the quality of services provided using it. The only way to avoid this is to switch in advance to another satellite (with a different interference period) or an alternative communication channel.

Some positioning systems for satellites with inclined orbits may begin to track the sun instead of the satellite during interference. It is recommended that positioners subject to this effect be turned off or switched to geostationary mode for the duration of the interference.

Large-diameter antennas painted in light colors focus light on the converter (or feed) in sunny weather, which can lead to heating, melting of plastic parts and damage to its electronic components. To avoid damage, in such antennas it is recommended to shield the converter with a sheet of radio-transparent material (cardboard, plastic, etc.) during interference.

Owners of satellite dishes sooner or later are faced with the concept of “solar interference”. This usually happens in the first year of operation of the antenna, when the provider himself warns users about the possibility of signal loss for precisely this reason. Let's figure out what it is and why the radio signal transmission deteriorates or disappears altogether.

What is solar interference

Any star, including our Sun, emits not only visible light energy, but also radio waves in the centimeter range. When the sun is in direct line with the satellite and satellite TV antennas, signal reception is impossible. This is all due to the fact that the Sun creates interference, and the transponder signals are simply blocked by noise from the Sun.

When does this happen

This phenomenon occurs 2 times a year - in autumn and spring. It is during these seasons that solar interference can be observed. Most often, this phenomenon occurs within 3.5 weeks from the days of the spring and autumn equinox. During this time it makes an annual journey, crossing the plane of the equator.

In February and March, interference first affects earth stations located in northern latitudes, then affects more southern receiving stations. At the equator, the most significant event falls on September 21 (equinox). The zone then moves to the southern hemisphere. It is the southern receiving stations that are the last to experience the influence of solar interference, which ends 3.5 weeks after the spring equinox.

In August, September, and October the picture is reversed, because the Sun begins to move in the opposite direction - to the Southern Hemisphere from the Northern. During this period, the interference period for each station lasts for one week. Every day during this time interference occurs. Moreover, in the morning, eastern communication satellites are influenced, and in the evening - western ones.

How does it manifest itself?

At first, with a weak influence, weak noises may appear on the TV screen, which become strong during the day. At the very peak of solar interference, there is absolutely no signal from the satellite. Therefore, you should not worry about this and think that something is broken or the antenna has moved to the side. Everything is fine with you, and this phenomenon is completely normal.

What to do

At the very peak of the signal, in the middle of a sunny day, it is advisable to move the antenna away from the satellite line altogether. This is done to prevent the plastic parts of the irradiators from melting. This may result in complete breakdown of the converter electronics. Because of this, aluminum reflectors are very “successful” in concentrating the sun’s rays at a focal point.

So if you notice severe interference or complete loss of signal from the satellite, check with your provider to determine whether solar interference has occurred or whether the signal is being lost for another reason. If this is an interference effect, then go up to the roof (or wherever you have an antenna installed) and move it to the side. And then it will have to be aimed at the satellite again. This is better than spending money on new converter electronics. Although there are simpler ways. For example, you can simply cover the antenna with something opaque that does not let the sun's rays through.

Harm from solar interference

First of all, radio stations and television companies that relay the signal from the satellite onto the air suffer from solar interference. As a result of this phenomenon, they lose the signal, which is fraught with defects on air and loss of ratings. Therefore, all self-respecting companies prepare alternative signal sources and switch to them before solar interference takes full effect.

Stations that receive radio signals from the Express and Horizon satellites are also affected. A special feature of these satellites is their movement in an inclined orbit. Pansat XR4600D, Drake ESR-700 and ESR2000XT-plus receivers are used to receive the signal. As a result of interference, these receivers can “lose” satellites and begin tracking the sun. Therefore, it is necessary to program the receivers in advance for the specified satellites as stationary and turn off tracking when such a phenomenon occurs. Once the interference wears off, the receivers must be reprogrammed to these satellites as inclined orbit satellites. All these actions need to be performed 2 times a year, and this is an extra effort. However, if not used, you can simply switch it to Stanby mode for the duration of solar interference.

Last but not least, stations receiving signals from the Express and Horizon satellites with inclined orbits suffer. Occasionally, tracking table data may be checked during interference. If at this time the controller is pointed at the Sun, it will spoil the entire table row. As a result, repeated disruption of signal reception cannot be avoided even if the interference ends on the second day. Therefore, the controller is disconnected from the network in advance and, after normal reception conditions are restored, it is turned on again. The main thing is not to miss this moment.

Regular users who use large diameter antennas may also suffer. In clear weather, the sun's rays are focused on the converter using this very antenna. The converter becomes hot and may melt. This will cause it to fail, and the user will have to replace it with a new one. Therefore, watch out for solar interference and when it occurs, either move the antenna to the side or cover it with cardboard or opaque film. Otherwise, the sun's radiation from the antenna will melt the receivers.

Determination of interference time

There are special programs for the onset of solar interference. One of them is called Look, and it is distributed free of charge on the Internet. The program is simple and even primitive, it simply shows the exact date when the interference will be maximum. You can also use it to find out the first and last days of the interference “session”. To do this, you need to count the number of days back and forth from the specified date. The number of these days is also determined by the program depending on the specified diameter and range of the antenna. But it is worth noting that this program only works with receiving stations in the Northern Hemisphere.

Interference Determination Calculator

If you haven’t found or don’t want to download the above program, you can use an online calculator. It is presented on the PanAmSat website. However, to work with it you need to have some data.

For example, you need to know the orbital position of the satellite (you can select from the search or enter manually), the coordinates of the receiving station (you can select your city listed in the list), frequency range, antenna diameter, season. If you have all this data, you need to enter it into the online calculator and click “Calculate”. The program will show the start and end times of the interference. All data will be provided in HTML format, so you can print it out and hang it on your wall to always remember it.

Features of working with the calculator

Note that although this program is focused more on the USA, it works for all receiving stations. However, there are some features of working with this program:

1. When entering antenna diameter, you must enter values ​​with decimal places, using a period rather than a comma. Otherwise, the program will freeze and will not be able to calculate anything.
2. Satellite positions are indicated in degrees west longitude from 0 to 360 W (west of Therefore, for satellites in the Eastern Hemisphere, you must enter values ​​​​with a minus sign.
3. Also, don't get confused about dates. In the USA they write the date like this: “month-day-year”. We are used to indicating the date like this: “day-month-year”.

Usually this calculator is quite enough to accurately calculate the onset of interference and its end. But if you can’t figure it out, then visit thematic forums on satellite television. There are usually topics for determining interference for different cities. Moreover, some providers warn users about the onset of this period and even give advice on how to “survive” it correctly.

Yes, in satellite technologies the sun is a source of interference. But how do you ask?

It's very simple: thermal energy coming from the sun is a very strong source of interference. When the sun is in line with the transmitting satellite and the receiving antenna, it seems to drown out the useful signal from the satellite.

For a better understanding, you can compare it to a conversation at a bus stop, when the noise from a passing car drowns out your conversation and the interlocutor is inaudible.

In such cases, the receiving antenna cannot distinguish the desired signal due to the abundance of interference from the sun. There will be no signal until the sun moves away a little.

This phenomenon occurs rarely but mainly in autumn and spring. This is because it is at this time that all these factors coincide. Such periods are called solar interference or solar illumination. This is when there is no signal on your satellite equipment.

The duration of the influence of solar interference depends on the geographical location of the receiving antenna, its diameter, the orbital position of the satellite, as well as on the transmitting frequency. It all starts with short-term signal losses lasting a few minutes. Which indicates that the sun is approaching close to illumination, that is, building in one line.

The heat from the sun is so powerful that it becomes an obstacle to high-quality recognition of the useful signal from the satellite even when approaching the point of solar illumination. The closer it gets to a direct line with the transmitting and receiving antennas, the longer the periods of solar interference become. But after passing through the most dangerous zone, the sun begins to move away and will no longer pose a danger to radio signal reception.

Depending on the position of the satellite and the satellite antenna tuned to it at one geographical point, the influence of solar interference will change at certain times throughout the day. First, the more eastern satellites will be affected, and later the illumination will move from one antenna to another in a westerly direction relative to the satellites in orbit. This is because the earth rotates on its axis along with geostationary satellites, so the sun changes its position relative to us and our receiving antenna.

The duration of solar interference periods is inversely proportional to the size of the satellite antenna and the carrier frequency. In other words, the larger the diameter of the satellite antenna, the shorter the interference periods and the lower the level of interference. Well, and vice versa, the smaller your antenna, the longer the periods of exposure.