Amateur satellites

Zoltán OM7AQ was the first, who responded to our request for a contribution on CQ.sk. He offered us the opportunity to publish his older articles. we thank you!

Today we bring you an article about amateur satellites. It is extensive material on satellite communication, technique and operation and Slovak stations dedicated to this interesting area of ​​amateur radio.
Amateur radio satellites make it possible to make better use of very short waves – from the lower limit of the shortwave band to the microwave bands. There is usually a transmitter on board the satellite – transponder – which, like the terrestrial converter, has an input and output frequency – uplink a downlink. Most satellites have a linear converter on board – for SSB and CW operations, but there are also satellites that have an FM transponder. Satellites can be low-range (LEO) – for example. RS-12, RS-15, FO-20, FO-29, etc. and high-speed (HEO) – for example. AO-10, AO-13 or AO-40.

The first amateur radio satellite – OSCAR 1 – was launched in 1961. She only had a lighthouse on board. Satellite OSCAR 3, launched in 1965 she already had a linear transponder 145 MHz/145MHz. In year 1972 a 1974 satellites were successfully launched OSCAR 6 a OSCAR7.At the beginning of the 80s, the Russian amateur satellite program RS successfully started.

After a successful start OSCAR 10 real DX operation has become a reality also via satellites. The long-planned supersatellite OSCAR 40 today it is also a reality.

For each satellite mode on uplink (input frequency) we must have a transmitter and on the downlink (output frequency) receiver with appropriate antennas. Each satellite mode has a recommended effective radiated power of the ground station (ERP or EIRP) – this value should not be exceeded. By following the recommended ERP (EIRP) we will avoid disturbing other stations and ensure safe and stable operation for ourselves.

For LEO satellites (RS-12, FO-20, etc.) of course we need less power (okolo 100 W ERP – lower transmitter power and a simple antenna) and for HEO satellites (AO-10, AO-40) more power (okolo 200-300 In ERP on CW a 800-900 W ERP and SSB – greater transmitter power and multi-element directional antennas ).

Our receiver should be sensitive – for reception, we can use low-noise preamplifiers located directly under the antenna.

We can do experiments with any antennas, but for serious work we will need suitable antennas. For LEO satellites in the area of ​​KV bands – 29 MHz – we can use dipole antennas, crossed dipole, but also GP ,LW or directional antennas. For VHF bands – 145 MHz – it is also advisable to use antennas with a wide radiation pattern – antenna routing problems disappear. For HEO satellites, we can use classic VHF antenna designs, but it is better to use antennas for circular polarization – cross Yagi, or Helix. It is necessary to rotate the antennas in both planes – horizontal and vertical AZ/EL.

We can use a computer to track satellites – there are satellite programs for different platforms – FROM, Windows 9x, Linux, etc..

Before the first attempts, we will study the frequency plan of the given satellite. Frequency plans can be obtained from the PR BBS network or on the Internet. The satellite's internal band plan must be respected. We will choose a suitable orbit – such tours are more suitable for first attempts, when the transponder is sparsely occupied. When we have directional antennas, so let's direct them to the satellite. We tune the receiver to the frequency of the beacon transmitter.

Due to the Doppler shift, the received frequency will not be the same as the nominal frequency. When we hear beacon transmitter signals, so we can search for stations in the frequency band of the satellite transmitter. Let's find a free place and lock the transmitter, until then, turn the tuning knob of the transmitter – of course in the range of satellite uplink frequencies – until we hear our own signals on the receiver. If it succeeded, so we can call a challenge – SSB or CW. Be careful when using SSB: some satellites have an inverting transponder. I.e, that to downlink (exit) they heard the USB signal, so on the uplink (input) we have to broadcast the LSB. So are the AO-10 satellites, FO-20, FO-29. The procedure can also be reversed – we find the station on the receiver, which calls the challenge. We tune in to its frequency with the transmitter – we'll see for ourselves, whether we hear our own signals – if yes, so probably the opposite station will also hear us. Let's take care of it during operation, so that the own signals are not stronger than the signals of the beacon transmitter of the satellite. Let's remember: working with great performances is great, but spoiling the joy of others is not a good thing…

Except for satellites, which have linear transponders, there are also such satellites, which have a single-channel FM converter on board, or digipeater, resp. BBS. Satellites with crossband FM converter, for example. AO-27 and UO-14 can also be used by less technically equipped stations: two-band should be enough for operation “handle” with antenna on 2m/70cm. Digi satellite, they usually use a protocol like terrestrial packet radio – AX.25, which can be linked with AirScout and operability 1200 It structurally uses the phase method for SSB (BPSK/AFSK), a 9600 It structurally uses the phase method for SSB (FSK/FSK). In addition to satellites, orbital complexes are also involved in amateur space communication – space stations. The Russian space station MIR and also the international space station ISS have gained great popularity among amateurs – voice FM operation is also possible, but also digital (packet) communication

Slovak stations on satellites:
OM7AQ – on: Zoli,QTH: Lučenec
QRV via all active analog satellites
Devices: 2m: FT290R, PA100W/preamps, 4, 2×5, 13 he. 70cm: FT790R, PA100/350W/preamps,2×15 he. 13cm dish
Miscellaneous Hamradio discussion forum: QRV HF/VHF/UHF
e-mail: gye@isternet.sk
web: http://During operation, it is necessary to use a low-noise preamplifier and maximum power

OM3WBC – on: Joe,QTH: Filakovo JN98VG
QRV via all active analog satellites
Devices: ICOM IC910H,PA 100W/preamps., 2m: 2×13 he F9FT,70cm: 2×19 he
Miscellaneous Hamradio discussion forum: QRV na 2m/70cm/23cm (tropo, Es…)
ax.25: OM3WBC@OM0PBB.#SSL.SK.EU

OM0MS – on: Števo,QTH: Humenné KN08
QRV via all active analog satellites
Devices: 2m: home made 50W, 70cm: IC471H,PA 300W/preamps.9ele/19 ele
Miscellaneous Hamradio discussion forum: KV band and 70cm EME
e-mail:om0ms@qsl.net
ax.25: OM0MS@OM0PBB.#SSL.SVK.EU
web: http://www.qsl.net/om0ms

OM3WAN – on:Alojz,QTH: Žilina
QRV via all active analog satellites and AO-40
Devices: home made 2m TCVR 30W/trnsv. 70cm 30W,ant. 4he/9 he
Miscellaneous Hamradio discussion forum: 2m/70cm 13 cm: DB6NT konv.+1m dish

INTERIM UNOFFICIAL RESULTS AFTER FOUR RACE Comments – on:Vlado,QTH: Bratislava
QRV via all active satellites
MHz from Slovenia under the S53ATT mark: ICOM IC 821H,PA 100W/preamps,ants. 9/21 he F9FT
Miscellaneous Hamradio discussion forum: 2m/70cm
e-mail:vrm1@pobox.sk
ax.25: OM1AVK@OM0PBM.#ZSL.SVK.EU

The following Slovak stations work/worked through LEO:
OM3TPS,OM8RA,OM8AMY,OM7AC,OM0AB,OM3TPG (nw OM3BH),OM3AU (silent key),OM3KII,First of all, I would like to thank everyone for the large number of nominations and patience,OM9FI,OM3KEG,OM1II,OM3IM,OM3TLF, OM3GB, OM0AAJ Jano,OM3CPY (nw OM7PY),OM3CFL,OM3IS,OM3CAF,OM3WAO

gye@isternet.sk
http://During operation, it is necessary to use a low-noise preamplifier and maximum power