1. Basic Amateur Satellite Communications
Presented by:
John Shearer
N3ASE,
LHVHFS Club President
9/19/2018
N3ASE

2. Purpose of the presentation
Discuss what amateur satellites are available and how they differ in both orbit and operation.
What modes of operation are available.
Provide limited details about some of the satellites in the Amateur Satellite Service.
Brief primer on ‘how to’ get on the air with a basic system that you may already have.
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3. Some Basic Terminology
LEO: Low Earth Orbit. Circular in shape.
Molniya: High Earth orbit. Elliptical in shape.
Apogee: Point of orbit farthest earth.
Perigee: Point of orbit nearest earth.
AZ / EL: Azimuth and Elevation. Used to describe the present location of a bird in space.
Inclination: The angle of an orbit with respect to the equator.
Keplerian Elements: A set of numerical data the describes a satellites orbit.
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4. Satellite Classifications
LEO Digitals
LEO Analogs
High Earth Orbit (elliptical)
Manned Space Craft
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5. LEO Digitals (6) UO-16 AO-22 IO-26 NO-44 (PCSAT) MO-46 AO-49 9/19/2018
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6. LEO Analogs (6) UO-14 (UoSat 14) FO-20 (Fuji OSCAR 20) AO-27 (AMRAD)
SO-41 (Saudisat-1A)
SO-50 (Saudisat-1C)
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7. High Earth Orbit AO-10 (OSCAR 10)
Very difficult to work. Satellite is not functioning properly.
AO (AMSAT OSCAR 40)
Requires above average interest in satellites. Not for the beginner.
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8. Manned Spacecraft International Space Station (ISS)
Offer very rare voice contacts. Mostly pre-arranged with schools world wide. Have packet station onboard.
Space Shuttle (SAREX)
Same as ISS but less opportunities. Astronauts have extremely busy work schedule and shuttle is currently grounded due to Columbia accident.
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9. Modes of Operation Mode A 2m uplink 10m downlink
Mode B 70cm up, 2m down
Mode J 2m up, 70cm down
Mode L 23cm up, 70cm down
Mode S 70cm up, 23cm down
1. JA is the Analog mode of Mode J
2. JD is the Digital mode of Mode J
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10. Analog Satellites
There are two classifications of Analog Satellites transponders.
FM Repeaters
Single pair of input and output frequencies. Used in FM mode only.
Linear Transponders.
Offer a large passband of input frequencies that are linearly translated to a passband of outputs. Some are inverted. Support CW and SSB where USB becomes LSB on an inverted system.
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11. For simplicity, this presentation will focus only on Mode JA (LEO Analog FM satellites currently functioning in orbit. These ‘birds’ are the easiest to work and require the least amount of investment in equipment and can be worked by simple antennas with reasonable performance. They are:
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12. LEO Analog FM Birds (Mode JA)
The ‘Flying Repeaters’
UO-14 (UoSat 14)
AO-27 (AMRAD)
SO-41 (Saudisat-1A)
SO-50 (Saudisat-1C)
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13. The Analog LEOs Properties:
Orbital plane is approximately 300 to 600 miles above the Earth
Period of view can be upto 15 minutes depending in the pass.
Have broadband inputs to accommodate Doppler Shift of uplink signal.
Have enough downlink signal strong enough to be heard on a mobile radio.
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N3ASE

14. UO-14 Uplink: 145.975 MHz Downlink: 435.070 MHz
Launched: January 22, 1990
Originally used as a digital store and forward BBS. It carried digital traffic for medical staff working in communication challenged third world countries.
Excellent ‘Easy Sat’ to work. Available full time.
Transmitter is a more powerful than AO-27, so antenna gain and orientation are not as critical.
Status: Non-Operational, Possible bad battery cell.
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N3ASE

15. AO-27 (AMRAD) Uplink: 145.850 MHz Downlink: 436.795 MHz
Launched: September 26, 1993
Not dedicated to the Amateur Satellite Service
AO-27 is actually an amateur payload aboard a commercial satellite known as Eyesat-1, which runs experiments for Interferometrics.
Harder to work because of lower power. (500mW)
Status: Operational but only in non-eclipsed portion of orbit. Day operation ONLY. AO-27 turns itself on every day over the northern hemisphere between roughly 8 am and 1 pm, local time.
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N3ASE

16. SO-41 (SAUDISAT-1A) Uplink: 145.850 MHz Downlink: 436.775 MHz
Launched: September 26, 2000
Designed and built by the Space  Research Institute in Riyadh, Saudi Arabia. Launched along with SO-42, however SO-42 status UNKNOWN
Satellite is designed to provide store-and-forward communications and carry several space experiments.
1W of RF power so it can be heard well with a basic setup.
Fully available to the Amateur Satellite Service as power permits.
Status: Operational and VERY active.
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N3ASE

17. SO-50 (SAUDISAT-1C) Uplink: 145.850 MHz Downlink: 436.800 MHz
Launched: December 20, 2002
Requires a PL tone of 67Hz for on demand activation of the transponder.
Fully available to the Amateur Satellite Serive as power permints.
250mW of RF power into a ¼ antenna. Not very strong.
Status: Operational and VERY active.
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18. Basic Satellite Station
‘So what is the basic system I need to make a contact’
Dual Band Radio
UHF and VHF Antenna(s)
A PC and a tracking program
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19. The Radio
The radio must be capable of operating Mode JA which is 2 meter FM transmit and 70cm FM receive.
A dual band mobile with 45W on 2m and 25w on 70cm will work well.
The minimum frequency step must be 5kHz. (10kHz is to high)
The radio must be capable of full duplex operation or crossband operation.
Must be able to operate outside of UHF FM spectrum. (i.e 430MHz to 440MHz)
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20. Antenna
Dual band UHF/VHF antenna or two separate antennas with a duplexer.
Both antennas should be ¼ λ as opposed to 5/8 λ. This is because of the radiation angle.
A preamp for 70cm would help substantially.
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21. Tracking Programs and a PC
Nova (commercial)
Instantrack (shareware)
WinOrbit (shareware)
STSPlus (freeware)
LogSat (commercial)
J-Track (commercial)
Heaven’s Above (Internet Web-site)
Many others
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22. Keplarian Elements
All tracking programs need some form of Keplarian elements to stay updated. There are basically two different formats.
NORAD 2 Line Elements or TLE
AMSAT Format.
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23. Sources for KEPs Internet websites Packet BBS www.amsat.org
Packet BBS
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24. Operating Making the first contact
Use the tracking program. Verify the PC system clock is accurate to within a second.
Make sure your Keplarian elements are current.
Tune the radio about 15kHz above the satellites input frequency. And tune downward as the satellite approaches and passes.
If your antennas are directional, pre-position them to the AZ and AL generated by the tracking program.
Be patient. There will be a lot of operators trying to access the machine. Remember, operating the FM satellites are like trying to access one repeater.
Don’t get disappointed if you do not make a contact on the first or second pass. Keep trying.
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25. Above and Beyond Next you will want to try FO-20 and FO-29
Some requirements
Directional antennas for both 70cm and 2m.
Recommend circular polarization. RHCP
A good low NF high gain pre-amp.
Low loss transmission line. LMR400, 9913, etc.
A multimode dual band radio that has dual independent VFOs that can track in either a normal or inverted mode.
Rotors that support Azimuth and Elevation tracking.
A lot of $$$.
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26. A Directional Earth Station Antenna System
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27. Omnidirectional Earth Station Antenna System
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28. In Conclusion Remember
You can get ‘on’ the amateur satellites with equipment you might already have.
Be patient. Once you get the hang of it, it is really fun.
The Internet has a tremendous wealth of information and Web sites devoted to Hamsats.
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31. Thankyou and 73
9/19/2018
N3ASE