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A photo image taken from NOAA series satellites

Learning the operation principle of NOAA series satellites

The NOAA series of satellites represent U.S. National Oceanic and Atmospheric Administration (NOAA) spacecraft units. They are launched into polar sun-synchronous circular orbits at the altitude of about 850 km.

NOAA-15 was launched on May 13, 1998 into the morning orbit

NOAA-18 was launched on May 20, 2005 into the afternoon orbit

NOAA-19 was launched on February 6, 2009 into the afternoon orbit

A sun-synchronous orbit is an orbit in which a satellite passes over any point on the Earth's surface at approximately same local solar time. In order to achieve desired characteristics, necessary orbit parameters are chosen in a way when the orbit precesses eastward by 360 degrees per year (approximately 1 degree per day), compensating for the Earth's rotation around the Sun.

The orbital period is equal to about 101 minutes. The orbital inclination is 98 degrees, in such a way satellites are provided with a good view of the polar regions. NOAA satellites are manufactured by Lockheed Martin Corporation, the applied satellite platform type is TIROS-N.

The following measurement instruments are provided on board: AVHRR/3 6 channel - visible and near infrared bands;

High resolution HIRS/3 Infrared Meter 20 channels - visible and infrared bands

AMSU-A microwave probe 15 channels - IR range;

AMSU-B microwave probe 5 channels - IR range;

All stated instruments operate in different parts of the infrared range and provide the required wealth of information. NOAA satellites collect global data on cloud covering, information on such surface conditions as ice, snow and vegetation, atmospheric temperature, distribution of moisture, aerosols and ozone.

The satellites are also equipped with special instruments facilitating search and rescue of people in distress. They form a part of the COSPAS-SARSAT system, which is designed to detect and locate emergency radar transmitters, emergency locator beacons and personal locator beacons operating at the frequencies of 121.5, 243 and 406.05 MHz.

Photos taken from NOAA series satellites.

The following software is used to acquire photos from NOAA series satellites:

  • SDR# for radio receipt;
  • Orbitron for satellite tracking and Doppler effect accounting;
  • WXtoimg for image decoding.

Launch the SDR# software and select the radio receiver type: RTL-SDR connected via USB.

Set the switch to the WFM mode and set the bandwidth to 34000 in the “Radio” section. Make sure the “Shift” checkbox is unchecked.

Make sure the “Filter Audio” checkbox is unchecked.

Further you need to increase signal amplification parameters. To do this, click on the gear icon.

Move the slider so that the noise level is increased by about 10 dB.

The signal from a NOAA series satellite has the following form.

Information about tracked satellites will appear in the field “Tracking DDE Client”, if Orbitron has been connected properly.

Launch Orbitron and update TLE firstly. Click the button with a tools indication.

Click on the lightning button to update TLE.

Select the file containing information about the weather satellites. Click on the “Load TLE” button.

Download the weather.txt list

Only weather satellites will show up in the side list on the right. Select Meteor-M2, NOAA15, NOAA18, NOAA19.

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

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

The satellites' overflight times will be calculated automatically. Go to the “Rotor/Radio” tab and make sure the tracking button is pressed.

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

  • NOAA 15 - 137.62 MHz;
  • NOAA 18 - 137.91 MHz;
  • NOAA 19 - 137.10 MHz;

Launch WXtoimg and make sure the signal source has been set up correctly.

Select the virtual CABLE Output.

Begin recording.

Turn on the “Auto record” function to receive signals.

From this moment, whenever any NOAA satellite appears to be higher than 10 degrees above the horizon, the software will automatically begin recording of the transmitted image.

Make sure the signal strength, provided in the lower right corner, is green, if not - turn up the audio volume in the SDR# software.

If the signal strength is good, then the resulting image will begin to appear in rows below. The visible range is indicated on the left and the infrared one - on the right.

Wait for the end of the transmission, and stop recording.

Switch to different display modes and analyze the resulting images.

Compare the provided image with the image taken earlier and check in what way the atmospheric situation has changed.

en/lesson05.txt · Last modified: 2021/04/05 11:39 by golikov

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