Amateur radio geostationary satellite to support disaster relief communication

August 22nd, 2019, Published in Articles: EngineerIT, Featured: EngineerIT

While radio amateurs have been building and operating satellites since 1961, most were in low earth orbits until earlier this year when radio amateurs acquired access to a geostationary satellite. The Qatar Amateur Radio Society (QARS) secured the privilege to have an amateur radio payload as part of Es’hailSat-2. Discussions regarding the payload were held with experts from AMSAT-DL (Germany), AMSAT-OH (Finland) and AMSAT-UK (United Kingdom). The flight model of the transponder was built by AMSAT-DL. The transponder is managed from ground stations in Qatar and Germany.

Fig. 1: Artist illustration of Es’hailSat-2.

In November 2018, a Space-X Falcon-9 rocket launched the Qatar Satellite Company’s second satellite. It carried an amateur radio linear transponder as a secondary payload, giving radio amateurs access to satellite communication capabilities over a vast area. Es’hail-2 is “parked” at 35 786 km above the equator at 25,8° East, nearly due North from Pretoria and Johannesburg covering from the East Coast of Brazil, the whole of Europe, Africa and the middle East.

One of the facets of amateur radio is to provide a community service in the form of radio communication during disasters. In South Africa, that service is provided by HAMNET, the disaster communication arm of the South African Radio League. In addition, to be ready to respond to any declared disaster, HAMNET members also provide communications support for sporting events such as cycle rallies and marathons (such as the Comrades and Two Oceans).

For many decades, most of the communication support was on high frequency (HF) and VHF frequencies. The only documented use of an amateur radio satellite in a disaster communication scenario was a store and forward CubeSat during the Indian Ocean tsunami of 2004. The main reason for not using satellites is because amateur radio satellites are mainly in low earth orbits having small footprints and are visible only for a few short periods each day. Es’hailSat-2 has changed all that and now offers opportunities for radio amateurs to increase their community support with a much wider reach.

In some quarters, it is argued that there is no need for amateur radio support as commercial mobile and satellite services can cope adequately. This has been proven wrong so many times as mobile phone towers are often damaged and rendered inoperable or suffer traffic overload and crash during a disaster and its follow-up relief operation. The same is true of commercial satellite phone systems which often cannot handle the high volumes of traffic when disaster relief operations get into full swing.

Fig. 2: Footprint of QA-100.

Speaking at a recent Gauteng Disaster Management workshop, Leon Lessing, who heads up the Gauteng South HAMNET organisation, said this became quite clear during disaster relief operations after two hurricanes hit Mozambique last year. The work of first responders was seriously hampered by erratic satellite phone communication and no operational mobile networks. The workshop was chaired by Dr Elias Sithole, the head of the Provincial Disaster Management Centre, and arranged to receive presentations from NGOs about their disaster relief activities. Lessing said that radio amateurs in South Africa are now well poised to add satellites to their communication armoury. However, there are challenges to overcome, of which a major one is to equip radio amateurs around the country with portable satellite stations. “There are a number of initiatives ongoing both here and overseas to develop a cost effective and very mobile solution. The main hardware is in the sky and as part of the International Amateur Radio Union and with the agreement of the Qatar Amateur Radio Society, all licensed radio amateurs have access”, he said.

With the commissioning of the amateur radio transponder on Es’hailSat-2, the satellite became officially known as Qatar Oscar-100, QA-100 for short. The uplink frequency is 2 400.050 – 2 400.300 MHz with the centre of the band being 2 400.175 MHz. Total bandwidth is 250 kHz and, from the earth, a transmission with right hand circular polarisation is required.

The downlink frequency is 10 489.550 – 10 489.800 MHz with the centre of the band being 10 489.675 MHz. Vertical polarisation is used. The preferred modes of operation are single side band (SSB) and CW (Morse Code). Uplink power of 5 W to a 60 – 75 cm offset dish is more than sufficient for the uplink which makes it relatively simple to deploy anywhere. The transponder is also fitted with a “LEILA” (LEIstungs Limit Anzeige) input power limiter to ensure fair play and that the automatic gain control (AGC) of the transponder is not hogged by a single, high power transmission, thus reducing the sensitivity of the satellite. Running higher uplink power than necessary is counterproductive.

At the Gauteng Disaster Management workshop, several of the NGOs expressed interest to work with HAMNET but for that privilege their members will have to write the amateur radio examination (RAE) to obtain a license.

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