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en:lesson02

Tracking satellites with Orbitron

Orbitron allows you to get the flight schedule of spacecraft.

The main elements of the interface are the list of spacecraft (right), the image of the projections of the positions of the vehicles and orbits on Earth map (top), controls (bottom) and the image of devices above the horizon bottom right. The clock and program status signals are also displayed on the right. On the bookmark “Main” in the control unit, you can select the time for which the display is “now”, that is, for the current time, and “simulation” - that is, for any arbitrary time. The latter mode allows you to very conveniently check how the device will move across the sky during the session. You can also choose between display of local time and UTC (single coordinated time). It is very important that the program has fresh data on the parameters of the orbits. It is advisable to update them at least once a week, and also before responsible sessions. For the program to work correctly, it is necessary that the computer is correctly set the time zone and set the exact time. Checking the correct time setting can be done on the site https://time.is

Configure Orbitron

Launch the Orbitron program.

At the first start, the program will offer to update from the Internet information about the location of the satellites - TLE data.

Click on the Yes button.

Press the zipper button.

Wait for the TLE to update and click OK.

Now set the date and time format.

Close the settings window.

When you first start the program starts in full screen mode. Turn it off.

Set your current location.

The exact value of your location can be determined on the map https://www.google.com/maps. Find your location on the map, right-click and select the “What's Here?” Drop-down menu.

An information window opens with the coordinates of this place.

The first number is latitude, and the second is longitude. Now you need to choose the satellites that we will follow. We need weather satellites that transmit open information in the 137 MHz band. Click the Download TLE button.

Download the weather.txt list

In the side list on the right, only weather satellites will appear. Choose Meteor-M2, NOAA15, NOAA18, NOAA19.

The selected satellites will be shown in the main program window.

On the information tab, you can see detailed information on the selected satellite.

On the Display tab, you can configure how the information is displayed.

Terminator is the dividing line of day and night.

The big way is three turns (past current and next).

Zones are the visibility areas of satellites from the surface of the Earth.

Now go to the Calculation tab and click on the corresponding button.

The program will calculate the time of appearance of the satellites when they will rise higher than 10 degrees above the horizon.

The figure shows that the NOAA19 satellite will appear at a height of 10 degrees above the horizon at 15:09, at 15:14 it will reach a height of 40 degrees, and at 15:19 it will leave its visibility range.


Exercise.

Analyze all the communication sessions that Orbitron will show. Find “good” sessions with the satellite rising above 45 degrees above the horizon.


Connect to SDR #

Now the most important thing is that you need to connect Orbitron with the SDR # program so that it automatically sets the desired reception frequency when a satellite appears. Go to the Rotor / Radio tab, select the SDRSharp driver and click on the start tracking button.

Note!

In the window with the receive frequency (Dnlink / MHz) the following correct frequencies should be set.

Meteor M2 - 137.10 MHz

NOAA 15 - 137.62 MHz

NOAA 18 - 137.91 MHz

NOAA 19 - 137.10 MHz

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

When the Meteor-M2 satellite appears, a special Meteor Demodulator plugin is activated.

A special program for processing images from this satellite Meteor-M 2 LRPT Analyzer will also be launched.

Doppler effect

The Doppler effect is a physical phenomenon consisting in a change in the frequency of the waves depending on the movement of the source of these waves relative to the observer. As the source approaches, the frequency of the waves emitted by it increases, and the length decreases. As the wave source moves away from the observer, their frequency decreases, and the wavelength increases. For example, in the case of sound waves, when you remove the source, the pitch will decrease, and when approaching, the tone of the sound will become higher. So, by changing the pitch you can determine whether a train is approaching or moving away, a car with a special sound signal.

The same thing happens with the signal from the satellite. When a traveler appears from beyond the horizon and approaches us, the frequency of the received radio signal will change a little and will be not exactly 137.1 MHz, but 0.003 MHz higher, and when the satellite is removed it will be 0.003 MHz lower. The orbitron automatically takes this into account and sends the frequency of signal reception corrected for the Doppler effect to SDR # to improve the quality of signal reception.

en/lesson02.txt · Last modified: 2019/10/22 12:36 by golikov

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