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About Satellites

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This page will be about Satellite Communications, and what to use for a successful contact.

Getting Started link

AMATER SATELLITE
     Currently all Obiting Satellites Carrying Amateur Radio or O.S.C.A.R. are in some type of a non-goestationary orbit.  Some are called L.E.O. for Low Earth Orbit, and some have a long elliptical orbit that goes far into space before returning.  In any case You will have to deal with doppler shift.  That being said, it is common to still make a contact using a hand held antenna, portable high gain antenna, and 5 channel pairs of frequencies on the radio.  Some have even made contacts with the International Space Station.
    

Tracking link

TRACKING
     Since these satellites do not stay in one place, you will have to track them.  There is some software available to do this, and several will even move antenna rotors that have computer control.  There are 3 major pieces of information that is needed .  One, is time.  You have to know when you can start to talk, and have to stop.  Two, is the Azimuth.  This is the compass heading around you.  And third is the Elevation.  I will give you an example.  Let's Say you see a satellite will come over your horizon at 12noon, and leave a differnt part of the horizon at 12:10pm.  This is a 10 minute window. (common)  The Satellite aproaches at 0 dregrees azimuth (North) and leaves at 90 degrees (East).  And lastly, it starts at 0 degrees (horizon), at it peak it is 45 degrees (1/2 way from horizon and directy above), and back down to the horizon at 0 degrees.   So in this example imagine an invisible arch that at noon, is pointed north at the horizon.   Slowly arching so that at 12:05pm you are pointed North East at 45 dergees.  Then by 12:10pm, you are pointing East at the horizon again.  This was just an example, and they can vary a lot in real life.  But Hopefully this gave you an idea about tracking. 

Satscape Tracking Program

NOVA Tracking Program

DOPPLER SHIFT
 
     Doppler Shift is the drifting of the frequency of a moving object.  You can hear this effect when standing at the side of the road, and a vehicle passes you.  As it approaches you, it slowly decreases in frequency as it aproaches.  The frequency change is faster as the object gets closer.  Then when it passes there is a sudden decrease in frequency, and continues to slowly decrease.  The Satellites do the same thing.  Also most Satellites have one frequency for the uplink (TX), and a separate one for the downlink (RX).
 
RADIOS
 
     Many  Radios can do a resonable job.  What  is needed is a tranciever that works on two bands, and can receive on one, then transmit on the other.  Also have several memories, usually about 5 memory channels per satellite.  Most modern dual band HT's will do fine.  Also the Yaesu FT-847 is a very popular Full Duplexing Radio for satellite use.  Full Duplexing allows you to hear yourself on the recieve of the satellite and to make corrections on the fly.  You can use a high gain antenna with low power or a omni-directional on higher power ( omni-directional has more problems with faraday rotaion).  Faraday rotation sounds like the volume is going up, and down as the satellites is rotating and it's antenna goes in and out of phase with yours.  It can be extemely annoying.  For the best performance most hams use circular polarized high gain antennas with a antenna rotor and elevator.

circularpolarizedantenna.jpg

satellitedishantennaj.jpg

arrowantenna.jpg

sattrakpic.jpg

OSCAR status, and band page

All OSCARS

Future OSCARS

OSCAR Frequencies

OSCAR Chronology

Satellite AO-51 / Echo
(FM) PL 67.0hz
1 acquisition of signal
2
 
 

3
 peak of signal

4

5
loss of signal

Receive Frequency (downlink) open squelch
435.310 Mhz
435.305 Mhz

435.300 Mhz

435.295 Mhz

435.290 Mhz

Transmit Frequency (uplink)
145.925 Mhz
145.925 Mhz

145.920 Mhz

145.920 Mhz

145.915 Mhz

UO-14 (FM) Dead?
1
AOS (acquisition of signal)
2
3
Mid Pass
4
5 LOS (loss of signal)
Receive (downlink) open squelch
435.080 Mhz
435.075 Mhz
435.070 Mhz
435.065 Mhz
435.060 Mhz
Transmit (uplink)
145.970 Mhz
145.975 Mhz
145.975 Mhz
145.975 Mhz
145.980 Mhz

Satellite AO-27 (FM)
1 AOS
2
3 Mid Pass
4
5 LOS
Receive (downlink)
436.805 Mhz
436.800 Mhz
436.795 Mhz
436.790 Mhz
436.785 Mhz
Transmit (uplink)
145.845 Mhz
145.850 Mhz
145.850 Mhz
145.850 Mhz
145.855 Mhz

SO-50 (FM) PL 67.0 hz
1 AOS
2
3 Mid Pass
4
5 LOS
RX (downlink)
436.805 Mhz
436.800 Mhz
436.795 Mhz
436.790 Mhz
436.785 Mhz
TX (uplink)
145.845 Mhz
145.850 Mhz
145.850 Mhz
145.850 Mhz
145.855 Mhz

AO-7 info

FO-29 info

International Space Station info