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Tracking of satellites with the help of Orbitron

Orbitron allows users to get a schedule of satellite overflights.

The main elements of the interface are represented by the list of spacecraft units (right), image of satellite location projections and orbits on the Earth map (top), controls (bottom) and images of units over the horizon at the bottom right. The clock and program status signals are also displayed in the right part. The “Main” tab contains the control box, where a user can select time for which the display shows “currently” for the current time and “simulation” for any arbitrary time value. The latter mode makes it very convenient to check how a satellite will move across the sky during a certain session. A user can also choose between displaying local time and UTC (Coordinated Universal Time). It is very important that the software applies up-to-date data about orbit parameters. It is desirable to update such data at least once a week and before important sessions. In order to implement correct operation of the software it is necessary, that the time zone and exact time are set correctly in the computer. A user can check if the time is set correctly at

Orbitron configuration

Carry out Orbitron launching. During the first launch, the software prompts a user to update the satellite position from the Internet, i.e. using the TLE data. Click the “Yes” button.

Click the button with a lightning bolt.

Wait for TLE update performance and click OK.

Set the date and time format.

Close the settings window.

The first time the software is started, it is launched in the full screen mode. Deactivate this mode.

Select your current location.

You can find exact coordinates of your location on the map at Determine your location on the map, right-click and select “What's Here?” from the menu.

An information window will be opened showing the coordinates of the location.

The first number is the latitude and the second number is the longitude. Now you need to select satellites we are going to monitor. We need meteorological satellites which transmit open information in the 137 MHz band. Click the “Download TLE” button.

Download the weather.txt list.

Only meteorological satellites will be displayed in the list on the right. Select Meteor-M2, NOAA15, NOAA18, NOAA19.

All selected satellites will be shown in the main software window.

You can see the detailed information about the selected satellite on the information tab.

You can adjust the way the information is displayed on the “Display” tab.

A terminator is a line separating day and night.

The trajectory of the satellite overflight contains three turns (past, current and next).

The oval areas are zones of satellite visibility from the Earth surface.

Proceed to the “Calculation” tab and click on the appropriate button.

The software will calculate the time of appearance of corresponding satellites, when they rise above 10 degrees above the horizon.

The figure shows that the satellite coded NOAA 19 will appear at 10 degrees above the horizon at 15:09; it will reach an altitude of 40 degrees at 15:14 and at 15:19 it will leave the visibility zone.


Analyze all communication sessions shown by Orbitron. Determine the “good” sessions when the satellite is above 45 degrees above the horizon.

Connection to SDR#

Now, let's consider the most important thing - you need to connect Orbitron to the SDR# software so that it automatically sets the desired reception frequency when a satellite appears. Transfer to the “Rotor / Radio” tab, select the SDRSharp driver, and click “Start tracking”.

The recording procedure will begin!

The following correct frequencies must be set in the window with the reception frequency (Dnlink / MHz).

Meteor M2 - 137.10 MHz

Meteor M2-2 - 137.10 MHz

NOAA 15 - 137.62 MHz

NOAA 18 - 137.91 MHz

NOAA 19 - 137.10 MHz

Now, when a satellite appears in the SDR# software, all information about it will appear and the receipt frequency will be set by Orbitron taking into account the Doppler effect.

When the Meteor-M2 satellite is registered, a special plugin called “Meteor Demodulator” will be activated.

The special software for processing of images received from the satellite, named “Meteor-M 2 LRPT Analyzer”, will also be launched.

Doppler effect

The Doppler effect is a physical phenomenon consisting of a change in the frequency of waves depending on motion of the source of these waves relative to the observer. As the source gets closer, the frequency of waves emitted by it is increased and the length is decreased. As the source of the waves moves away from the observer, their frequency decreases and their wavelength increases.

For example, in case of sound waves receipt, the pitch of the sound decreases as a person moves away from the source and becomes higher as he/she gets closer. Thus, by changing the pitch, a user can determine whether a train, a car providing a special sound signal alarm is approaching or moving away.

The same happens with a satellite signal. When a satellite appears from behind the horizon and approaches a person, the frequency of the received radio signal is changed slightly and will not be exactly equal to 137.1 MHz rather being 0.003 MHz higher and when the satellite is moving away - it will be 0.003 MHz lower. Orbitron takes this peculiarity into account and sends the signal receipt frequency in a form corrected for reaching of the Doppler effect to the SDR# software in order to improve the quality of signal receipt.

en/lesson02.txt · Last modified: 2021/04/02 13:23 by golikov

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