Following a competitive process where a number of proposals were considered, the Hub space team elected Errol Aerodrome, a former WWII RAF airfield between Dundee and Perth, for the Hub’s state-of-the-art new optical ground station. The proposal for use of this site was prepared jointly by the Heriot-Watt University Hub team (who retain responsibility for the installation and continued operation of HOGS) and the Dundee Satellite Station (DSS). Although a commercial entity, the latter is a radio-frequency satellite ground station comprising of four ground mount antennas operated by a team of scientists/engineers with interests in research and innovation activities.
The Errol site is in a very low flood risk rural agricultural area with good access to the satellite (147 days of low cloud cover), low light pollution at the site and surrounding area, and offers a wide and obscuration-free field-of-view for satellite communications. The high latitude location also allows for longer contact time with polar orbit satellites.
The DSS site already has critical infrastructure needs in place including X and S-band RF transceiver terminals with Ofcom approval for transmission. The site also had use of lasers approved by the CAA for testing activities. It can be easily accessed from Perth and Dundee (20-minute drive) as well as Edinburgh Airport and Heriot-Watt University (1-hour drive).
The HOGS consists of a robotic observatory dome (Allsky 4.5m dome with base and support systems procured by BAADER) and 70cm-wide observatory reflective telescope (RC700 design with metallic coatings, procured by Planewave), used to both track the low-Earth orbit satellite path with high precision and receive the quantum signals. Adaptive optics, supported with additional EPSRC funding, will be used to further enhance the telescope capability. Both HOGS and the satellite will employ laser beacons to accurately point towards each other. Once they are precisely aligned, the quantum communications will commence. The HOGS will utilise one of two quantum receivers, dependent upon which quantum source on SPOQC is active. DV quantum signals will be measured and analysed using photon detectors. CV quantum signals will be detected and analysed, against the reference beam also sent from the satellite, using a homodyne detector. In both cases, after combination with the supporting RF communications, quantum keys can be generated.
