There are no special requirements as far as licensing goes for talking to a satellite; it's a station like any other, it just happens to be in a very remote location. As long as you are allowed to transmit on the uplink frequency (the frequency the satellite listens on) you can communicate through it.

Just remember that if you're allowed to transmit then you're allowed to use it!

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This is a good rule of thumb in any case; never use more power than you actually need, and particularly not when communicating over a long distance. The reason is that the more power you use the more likely you are to cause inadvertant but harmful interference to other stations.

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Satellite tracking programs tell you where a satellite is at a given time, including its altitude and where it will be at the start and end of a pass, relative to your location.

The tracking programs even tell you how much to change your transmitter's and receiver's frequency to compensate for the Doppler shift you get when the satellite is coming toward you or moving away from you.

So all of these answers are correct.

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There are no special requirements as far as licensing goes for talking to a satellite or space station; it's a station like any other, it just happens to be in a very remote location. As long as you are allowed to transmit on the uplink frequency (the frequency the satellite listens on) you can communicate through it.

Since any amateur radio operator with a Technician or higher class license can operate on the 2 meter and 70 cm bands, that means that those operators can also make contact with a station in space.

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A beacon provides us with a gauge to determine how much power we should use. If you transmit your signal and compare it to the beacon strength, you can then adjust your power up or down to match the beacon. That would be the optimum transmitting power for your station. The next thing that the beacons provide us with is a schedule of the satellite's activity. It might tell you that it is on during a particular time period and off during others.

The beacon can also help us tune our radio to compensate for doppler shift. Since we know the beacon is supposed to be on a certain frequency, we can calculate where our signal will be based on the current reception of the beacon (http://www.amsat.org/articles/houston-net/beacons.html)

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Tags: satellite operation definitions arrl chapter 6 arrl module 14

Keplerian elements, named after Johannes Kepler (1571-1630) and his laws of planetary motion, are the parameters that define the orbit of a satellite. From these elements, a computer program can calculate the time and bearing of a satellite pass, relative to your position on the earth.

The weight of the satellite is not one of the Keplerian elements. The last observed time of zero Doppler shift would be the time that the satellite was moving neither toward you nor away from you (like when it was overhead, for example). While this might be interesting data, it isn't enough to predict where it will be coming from or going to on its next pass, or at what altitudes.

According to AMSAT's "Keplerian Elements Tutorial" the "basic orbital elements are":

1. Epoch
2. Orbital Inclination
3. Right Ascension of Ascending Node (R.A.A.N.)
4. Argument of Perigee
5. Eccentricity
6. Mean Motion
7. Mean Anomaly
8. Drag (optional)

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The most common references to the doppler effect (or doppler shift) refer to sound; one of the most common examples used in highschool science classes involves a fire engine (or other vehicle with a siren) whose siren seems to drop in pitch drastically when the vehicle passes you. The producer of the sound does not actually change frequency, but the relative speed of the vehicle producing the sound to the object (you) receiving the sound makes it seem to you that it does.

The same principle applies to a radio frequency signal; the relative motion between a satellite and the earth station can cause a shift in the frequency at which you can receive the signal depending on what its position and momentum are relative to the receiving station.

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"mode U/V" is short for "mode UHF/VHF" -- meaning that the uplink is UHF, meaning 70 cm, and the downlink is VHF, meaning 2 meters. There are of course other UHF and VHF amateur bands, but those below 1 GHz are not available for amateur satellite operation.

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Memory aid: 'spin' = 'rotation'

Satellites are not stationary in space; they are constantly moving, and generally they are rotating as well. As they turn, the antennas on the satellite change position relative to your location. The signal may fade if the antennas are directional, or even if omnidirectional, if they are obscured by the rest of the satellite.

This is referred to as "spin fading" because the fading is caused by the satellite spinning around.

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Just remember that we are talking about a satellite; this question could be a bit tricky if you haven't seen it before, but LEO refers to the position, not to any operation. It is, as the answer indicates, Low Earth Orbit.

Although a Low Earth Orbit is highly elliptical to escape the Earth's gravity at the low point (perigee), the question is asking what is the satellite, not what type of orbit is the satellite following.

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Most amateur satellite communication takes place on 2 meters or 70 cm, though 15 meters is also used at times. With both 2m and 70cm, FM is the most common mode, and so FM packet is the most logical mode to use.

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