Amateur satellites

Zoltán OM7AQ was the first to respond to our request for a post on CQ .sk. He offered us the opportunity to publish his older articles. Thank you!

Today we bring you an article about amateur satellites. It is extensive material on satellite communication, technology and operation, and Slovak stations dedicated to this fascinating 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. On board the satellite there is usually a converter - a transponder - which, like a terrestrial converter, has an input and output frequency - uplink a downlink . Väčšina družíc má na palube lineárny prevádzač – na prevádzky SSB a CW , ale sú aj také satelity ktoré majú FM transpondér.Družice môžu byť nízkodráhové (LEO ) – such as RS-12, RS-15, FO-20, FO-29, etc. and high-speed (HEO) - such as AO-10, AO-13 or AO-40.

The first amateur radio satellite – OSCAR 1 – bola vypustená v roku 1961. Na palube mala len maják . Družica OSCAR 3, vypustená v roku 1965 už mala lineárny transpondér 145 MHz/145MHz. V roku 1972 a 1974 boli úspešne vypustené družice OSCAR 6 a OSCAR7.Na začiatku 80-tich rokoch úspešne odštartoval ruský amatérsky družicový program RS.

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.

Pre každý družicový mód na uplink (vstupná frekvencia) musíme mať vysielač a na downlink (výstupná frekvencia) receiver s príslušnými anténami. Každý mód družice má doporučený efektívny vyžiarený výkon pozemnej stanice (ERP alebo EIRP ) – túto hodnotu by sme nemali prekročiť. Dodržiavaním doporučeného ERP (EIRP) sa vyhneme rušeniu ostatných staníc a pre seba zabezpečíme bezpečnú a stabilnú prevádzku.

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

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

Pokusy môžeme robiť so ľubovoľnými anténami, ale pre serióznu prácu budeme potrebovať vhodné antény. Pre družice LEO v oblasti sq pásiem – 29 MHz – môžeme použiť antény Dipól , krížený dipól, ale aj GP ,LW alebo smerové antény. Pre VHF bands - 145 MHz - it is also advisable to use antennas with a wide radiation pattern - there are no problems with antenna routing. 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 - DOS, 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. Internal bandplan satellites must be observed. We will choose a suitable round trip - for the first attempts, such rounds are more suitable when the transponder is not very busy. If we have directional antennas, let's point them at 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 the signals of the beacon transmitter, we can search for stations in the frequency band of the satellite transmitter. Let's find a free place and lock the transmitter, while turning the tuning knob of the transmitter - of course in the uplink frequency range of the satellite - until we hear our own signals on the receiver. If it was successful, then we can call the challenge - SSB or CW. Be careful with SSB operation: some satellites have an inverting transponder. This means that in order to hear a USB signal on the downlink (output), we must transmit on the uplink (input) LSB . So are the AO-10, FO-20, FO-29 satellites. The procedure can also be reversed - on the receiver we find the station that calls out the call. We tune the transmitter to its frequency - we make sure that we can hear our own signals - if so, the opposing station will probably hear us as well. During operation, make sure that your own signals are not stronger than the signals of the satellite's beacon transmitter. Let's remember: working with great achievements is great, but spoiling the joy of others is not good...

Okrem družíc, ktoré majú lineárne transpondéry, sú aj také satelity, ktoré majú na palube jednokanálový FM prevádzač, alebo Digipeater , resp. BBS. Družice s Crossband FM prevádzačom, ako napr. AO-27 a UO-14 sú využiteľné aj technicky menej vybaveným staniciam: na prevádzku by mala stačiť dvojpásmová „rúčka“ s anténou na 2m/70cm. Digi družice, obvykle používajú protokol ako pozemné packetrádio – AX.25, rýchlosť 1200 Bd (BPSK/AFSK ), a 9600 Bd (FSK /FSK). Okrem družíc sú zapojení do amatérskej kozmickej komunikácie aj orbitálne komplexy – kozmické stanice. Veľkú popularitu získala medzi amatérmi ruská vesmírna stanica MIR a tiež medzinárodná kozmická stanica ISS – je možná aj hlasová FM prevádzka, ale aj digitálna (packetová) komunikácia

Slovak stations on satellites

OM7AQ – op: Zoli,QTH : Lučenec
QRV via all active analog satellites
Equipment: 2m: FT290R, PA100W/preamps, 4, 2×5, 13 ele. 70cm: FT790R, PA100/350W/preamps, 2×15 ele. 13 cm dish
Other: QRV HF/VHF/UHF
e-mail: gye@isternet.sk
website: http://OM7AQ.host.sk

OM3WBC – op: Joe, QTH: Fiľakovo JN98VG
QRV via all active analog satellites
Devices: Icom IC910H, PA 100W/preamps., 2m: 2×13 ele F9FT, 70cm: 2×19 ele
Other: QRV on 2m/70cm/23cm (tropo, Es...)
ax.25: OM3WBC@OM0PBB.#SSL.SK.EU

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

OM3WAN – op: Alojz, QTH: Žilina
QRV via all active analog satellites and AO-40
Equipment: home made 2m TCVR 30W/trnsv. 70cm 30W, ant. 4 ele/9 ele
Other: 2m/70cm 13 cm: DB6NT conv.+1m dish

OM1AVK – op: Vlado, QTH: Bratislava
QRV via all active satellites
Equipment: Icom IC 821H, PA 100W/preamps, ants. 9/21 ele F9FT
Other: 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, OM3MM, OM9FI, OM3KEG, OM1II, OM3IM, OM3TLF, OM3GB, OM3LU, OM3CPY (nw OM7PY), OM3CFL, OM3IS, OM3CAF,OM3WAO

gye@isternet.sk
http://OM7AQ.host.sk