PaCoRa is a non-invasive ranging method which can be used for multiple downlink signal types. Due to its passive nature there is no need to transmit a tracking signal to the satellite, minimising the potential impact on spacecraft and ground operations. Additionally, the ground stations do not require large antennae, which helps to keep down the cost of the system.
The system measures the time of arrival of the downlink signal for the satellite of interest at various small ground terminals deployed along the satellite’s footprint. The Time Difference of Arrival (TDOA) between the different station pairs is calculated from these measurements and processed in order to determine the satellite’s orbit.
In its first implementation, PaCoRa used 5 front-end receiving stations, 4 main and 1 back up. The initial implementation system has been designed, built and tested for Ku band signals, but it can easily be upgraded to other frequency bands by means of a simple adaptation of the RF components on the antenna front end.
Automated functions enable the operator to configure a schedule from which the system can run autonomously. Centralised monitoring and control software enable a new satellite to be added to an existing schedule by the ground operator.
Javier DeVicente, from ESA's Ground Station Systems Division, described the new system as “an accurate and great low cost alternative to conventional ranging systems.’ PaCoRa has been developed for a wide international market, including small operators with single satellites and also large organisations looking to track multiple satellites.
The PaCoRa system will be available for commercialization as a complete turn-key system. SES Techcom Services are also considering offering PaCoRa as a service to customers who do not want to purchase the complete system but wish to access its data.
