Satellite CXommunications - ISC Presentation · 2019. 10. 5. · Telstar 1, an experimental commsatellite launched in 1962, still orbits in MEO. No Amateur satellites in this orbit

Satellite Communications

John Kernkamp – WB4YJT

Some History• The first artificial satellite was Sputnik-1, launched in

October, 1957. It had a simple transmitter which sent a “beep” signal once per second, on 20.02 MHz.

Some History• The first American satellite was Explorer-1, launched in

January, 1958. It carried a scientific instrumentation package which was able to verify the existence of the Van Allen Radiation Belt, previously only a theory.

Some History• The first amateur radio

satellite was OSCAR-1, launched on December 12, 1961, by Hams in the United States.

• The first OSCARs only had telemetry beacons. But, since 1965, most Ham satellites have had linear transponders for two-way communications.

• Many new satellites have store-and-forward packet communications packages, or digipeatersfor direct packet radio connections.

Some History• The latest Ham satellites are CubeSats. These are low-cost packages,

easy to integrate into existing launch platforms, and, because the package is standardized, able to be included in a launch at short notice.

• Some of the most recent CubeSats have a technical package based on a SmartPhone, to demonstrate the power of these devices.

Satellite Orbits

Satellite Orbits -

Inclination

Four types of Orbits

1) Low Earth Orbit (LEO)

Altitude between 160 km (99 mi) and 2,000 km (1,243 mi)

Period between about 88 minutes and

about 127 minutes

Between the atmosphere and the inner

Van Allen radiation belt

ISS, Iridium, Hubble Space Telescope, and most Ham Radio satellites

Four types of Orbits

2) Medium Earth orbit (MEO)

Above altitude of 2,000 km (1,243 mi) and

below altitude of 35,786 km (22,236 mi)

Most common altitude is approximately 20,200

km (12,552 mi)), which yields an orbital

period of 12 hours, as used by GPS,

Glonass and Galileo

Telstar 1, an experimental comm satellite

launched in 1962, still orbits in MEO.

No Amateur satellites in this orbit level

Four types of Orbits3) Geostationary Earth Orbit (GEO)

A circular orbit 35,786 km (22,236 mi) above the Earth's equator

Satellites in this orbit have a period equal to the Earth's rotational period, and thus appear motionless to ground stations. Antennas used for these satellites do not have to track them. Communications satellites and weather satellites are typically in this orbit.

The idea of a geosynchronous communication satellite was first proposed in 1928 by Herman Potočnik. In 1945, Arthur C. Clarke published the concept more widely, and with operational details.

No Amateur satellites are in this orbit.

Four types of Orbits

4) Highly Elliptical Orbit (HEO)

Elliptic orbit with a perigee (low-altitude point) of about 1,000 km (620 mi), and an apogee (high-altitude point) over 35,786 km (22,236 mi)

Visibility near apogee can exceed twelve hours, and the satellite can appear from the ground to be essentially motionless in the sky when the orbit is at the right inclination

Sirius Satellite Radio is in this orbit and Ham Radio satellites AO-10 and AO-11 are also here.

Satellite Orbits

Satellite Orbits

Ham Radio Satellites

• Mostly in Low Earth Orbits

• Some in Highly Elliptical Orbits

• Linear Repeaters

• FM Repeaters

• Store-and-Forward Packet Repeaters

• Mixed-Mode Satellites

Active Ham Sats - April 14, 2014 - Digital/Mixed Modes

Satellite Name Uplink Downlink Beacon Mode

CO-55 (CUTE-I) . 437.470 436.838 1200bps AFSK

CO-57 (XI-IV) . 437.490 436.848 1200bps AFSK,CW

CO-58 (XI-V) . 437.345 437.465 1200bps AFSK,CW

CO-65 (APDII) . 437.475 437.275 1200bps AFSK,CW

CO-66 (SEEDS-II) . 437.485 437.485 1200bps FM,CW,Talk

COMPASS-1 . 437.405 437.275 1200bps AFSK,CW

DO-64 (DELFI-C3) . 145.870 145.867 1200bps BPSK

E1P-U2 . 437.505 437.502 1200bps AFSK,LSB

FITSAT-1 . 437.445, 5.84GHz 437.250 1200bps/115.2kbps

IO-26 (ITAMSAT) 145.875-950 435.822/867 435.791 1200bps JAS

KKS-1 (KISEKI) . 437.445 437.385 1200bps AFSK,CW

NO-44 (PCsat1) 145.827 145.827 145.827 1200bps AFSK

O/OREOS . 437.305 437.304 1200bps AFSK

STARS (KUKAI mother) . 437.485 437.305 1200bps FM,CW

STARS (KUKAI daught) . 437.465 437.275 1200bps FM,CW

SwissCube-1 . 437.505 437.505 1200bps BFSK,CW

TechEdSat . 437.465 437.465 1200bps FM,CW

Xatcobeo . 437.365/145.940 437.365 1200bps FFSK,SSR,C

ITU-pSat1 . 437.325 437.325 19200bps GFSK,CW

RAIKO . 2.2GHz, 13GHz 13GHz 38.4~500kbps

AAUSat3 . 437.425 437.425 4800bps FSK,CW

MaSat-1 (MO-72) . 437.345 437.345 625/1250bps GFSK,C

Horyu-2 . 437.375 437.378/372 1200bps FSK/CW

BeeSat . 436.000 436.000 9600/4800bps GMSK

CUTE1.7+APDII 267.600 437.475 . 9600bps GMSK

M-Cubed . 437.485 437.485 9600bps GMSK,KISS

NO-44 (PCsat1) 435.250 145.827 145.827 9600bps FSK

RAX-2 . 437.345 437.345 9600bps GMSK

STRaND-1 . 437.568 437.568 9600bps GMSK

Active Ham Sats - April 14, 2014 - Analog Modes

Satellite Name Uplink Downlink Beacon Mode

AO-7 (Phase-2B) 145.850-950 29.400-500 29.502 A

PRISM (HITOMI) . 437.425 437.250 AFSK,GMSK,CW

ISS 145.825 145.825 145.825 APRS

AO-7 (Phase-2B) 432.125-175 145.975-925 145.970 B,C

Jugnu . 437.505 437.276 CW

RS-22 (Mozhayets) . . 435.352 CW

RS-25 . . 435.325 CW

RS-30 (Yubileiniy) . 435.315/215 435.315 CW

SRMSAT 145.900 437.500 437.425 CW

LO-19 (LUSAT) 145.840-900 437.125/150 437.125 CW carrrier

HO-68 (XW-1) 145.825 435.675 435.790 FM_tone 67Hz,CW

SO-50 (SaudiSat-1c) 145.850 436.795 . FM_tone 67Hz,CW

SO-67 (SumbandilaSat) 145.875 435.345 435.300 FM_tone 67Hz,CW

UO-11 (UoSAT-2) . 145.826/435.025 2401.500 (V)FM,(S)PSK

TIsat-1 145.980 437.305 145.980 FM,AFSK,PSK,CW

HO-68 (XW-1) 145.925-975 435.765-715 435.790 SSB inverting,CW

VO-52 (Hamsat) 435.220-280 145.930-870 145.936 SSB,Carrier

FO-29 (JAS-2) 145.900-999 435.900-800 435.796 SSB,CW

RS-15 (Sputnik) 145.858-898 29.354-394 29.352 SSB,CW

VO-52 (Hamsat) 435.225-275 145.925-875 145.860 SSB,CW

Recommended Sats – April 2013• AO-7 – USA

Transponder I: Mode A - Linear, non-inverting

Uplink: 145.850 - 145.950 / Downlink: 29.400 - 29.500

Transponder II: Mode B and Mode C (lp) - Linear, inverting

Uplink: 432.125 - 432.175 MHz / Downlink: 145.975 -145.925

• FO-29 – Japan

Digital Transponder - Mode JD

Uplinks: AFSK (FM) 1200 bps, AX.25, Manchester -145.850,145.870,145.890 145.910 MHz

Downlink: BPSK 1200 bps - 435.910 MHz

Analog Transponder - Mode JA --

Uplink: 145.900 - 146.000 MHz - LSB/CW

Downlink: 435.800 - 435.900 MHz - USB/CW

Recommended Sats – April 2013

• VO-52 – India

Linear Transponder

Uplink: 435.250 MHz / Downlink: 145.900

Bandwidth: 60 kHz . Modes - CW, SSB

• SO-50 – Saudi Arabia

FM Repeater

Uplink: 145.850 MHz (67.0 Hz PL Tone)

Downlink: 436.800 MHz

How to do it –

Digital Modes (FM similar)

How to do it –

Analog Mode – AO-7, RS-15

How to do it –

Linear or mixed-mode Sats

Note – Specific for JAS-2, but typical for linear or mixed-mode sats

Working the ISS

• 145.825 MHz FM (145.800 – Schools)

• Simplex operation

• Vertical antenna OK, Beam is better

• Fixed antenna OK, Tracking is better

• Typical mobile radio is sufficient

• ISS pass lasts about ten minutes

• Intermittently available

• http://www.issfanclub.com/ - Latest info

Simple Antennas

• Base Vertical

• Ground Plane

• Handheld

• Ventenna

Beam Antennas

• Beam antennas come in two types -

Linear Polarization Circular Polarization

Circular PolarizationTwo antennas set 90 degrees apart, on the same boom, fed 90

degrees out of phase, creates a rotating wave front, or circular

polarization.

Tracking

• http://www.parallax.com/tabid/787/default.

aspx - Do-It-Yourself - Uses Basic Stamp

and simple servos for tracking

• VOI System – Yaesu Az/El rotor with Fox-

Delta interface to PC. SATPC32 running

on the computer.

Tracking

The Doppler EffectRelative motion between you and a satellite causes the radio

signals to appear to change frequency. As the satellite moves toward you, the frequency of the signals will increase, and, as the satellite moves away, the frequency will drop. The amount of shift depends on the distance to the satellite, its speed, and the look angle. Typically 1-3 KHz.

You will have to tune your transmitter - not your receiver - to compensate for Doppler shifting and keep your frequency relatively stable on the downlink. That’s why it is helpful to be able to hear your own signal coming through the satellite.

If you and the other station both compensate correctly, your signal will stay at one frequency on the downlink through the pass. If you don’t compensate, your signals will drift through the downlink passband as you attempt to “follow”each other. This is highly annoying to others using the satellite.

PC-SAT-32

• Controls the antenna tracking positioner

• Controls the radio (uplink and downlink)

• Automatically compensates for Doppler

shift

• Tracks multiple satellites

• Alerts operator when a satellite is coming

into view

• Can predict passes at any future time

Resources

• ARRL – Books, Special events

• AMSAT-NA – Latest news, Elements, Sat Status

• AMSAT-UK – Events, How-to, Programs, Satellite

Status, Beginners info, FAQs, Links

• AMSAT-DL – Software, Projects, Photos, Videos

• http://www.dk3wn – SATPC32

• http://www.dxsummit.fi – Current Satellite Status

AMSAT-NA Satellite Status Page

Satellite Communications

John Kernkamp – WB4YJT