QO-100: SSB contacts through the geostationary satellite on 10489.700 MHz

What you hear

Voices in upper sideband, clean and steady in a way shortwave never manages: no fading, no static, no sudden loss of the path, just a quiet background and the signal on top. On 10489.700 MHz a contact sounds like any other, callsigns, reports, names, locations, except that one station is in Germany, the other in Oman or Brazil, and both are heard at the same strength all day. Everyone in the footprint hears everyone, so the segment feels like a single room: regulars greeting each other, newcomers making a first contact through a satellite, special event stations working a queue. Many operators run full duplex and monitor their own signal coming back from the sky, which keeps the frequency discipline tidy.

The SSB segment of the narrowband transponder runs from 10489.650 to 10489.740 MHz, and again above the central beacon from about 10489.760 up to 10489.850 MHz. Between the voices, on other parts of the transponder, there is CW, FT8, SSTV and the beacons at the edges and in the middle.

Who transmits and why

QO-100, Qatar-OSCAR 100, is the amateur payload on the Es'hail-2 communications satellite, launched in November 2018 and opened to amateurs in early 2019. It sits at 25.9 degrees east, over Africa, and because it is geostationary it needs no tracking and has no Doppler shift: the same dish, pointed once, hears it forever. The transponders were built by AMSAT-DL in cooperation with the Qatari satellite operator and the Qatar Amateur Radio Society. Stations transmit up on 2.4 GHz and the satellite sends down on 10.489 GHz, inside the band of ordinary satellite television, which is why an ordinary television LNB on a 60 cm dish receives it; the LNB shifts the signal down to about 739 MHz, where a cheap SDR stick can hear it.

The footprint covers roughly a third of the planet: Europe, Africa, the Middle East, India, western Asia and the eastern edge of South America. The attraction is a shortwave-sized community on a path that is always open, with power levels of a few watts and antennas that fit on a balcony. Next to the narrowband transponder there is a wideband one carrying amateur digital television, which web receivers do not deliver.

When and where to listen

Any hour, since the path never closes; the busiest times are European evenings and weekends, with the Middle East and India in the European morning and Brazil late at night. The receivers that matter are the few public ones with a dish on the satellite, among them a receiver near Paris and a couple of others with a QO-100 profile; the catalogue lists only those. A receiver without a dish cannot hear 10 GHz at all, so there is no point tuning any other.

In ShackDeck

Station catalogue → Amateur radio → QO-100 satellite: SSB contacts 10489.700. The program picks one of the receivers with a dish, tunes it to 10489.700 MHz in USB and takes care of the converter arithmetic: the receiver reports its frequency offset, the program keeps the real frequency on the dial and translates it underneath, so you tune 10489.700 and hear 10489.700. In the logbook the band is 3 cm. No receiver, dish or account of your own is needed; the program only listens.