Method for determining the position of a transmitting beacon using only one antenna
|463 - Abstract of the offer:|
|The European Space Agency (ESA) is offering a new innovative algorithm able to determine the position of a beacon transmitting a signal to certain satellites in a constellation. This allows for relevant simplification of the ground installation facilities because the huge directive antennas, which are more difficult and expensive to manage, can be replaced by simply one omidirectional small antenna slightly bigger than a mobile phone that collects information from all directions.|
Description of the offer:
The classical method for determining the position of a beacon transmitting a signal to certain satellites which, in turn, being supplied with transparent transponders, retransmit ‘mirror’ signals, is based on the calculation of the position with the least square method. This is possible because the positions of the satellites sending the retransmitted signals are known. The retransmitted signals sent by the satellites are detected by ground stations. Therefore when the terrestrial detection stations have directional receiver antennas pointed at the various satellites situated in the zone of visibility then each retransmitted signal is automatically associated to a specific satellite. This allows calculating the beacon position just by using the least squares method. The main drawback of such method is that each ground station needs to be fitted with the same number of antennas as there are satellites whose signals are to be detected. In addition, each antenna must also be provided with control apparatus suitable for ensuring that it tracks the satellite with which it is associated.
The innovation proposed by ESA simplifies the above described method by limiting the number and dimension of antennas, more specifically using only an ominidirectional antenna. As a matter of fact the basic idea is that for each ground station preferably only one antenna (as small as that of a mobile phone) is implemented, being suitable for receiving signals from a plurality of satellites situated in the visibility zone of that station. Under such conditions the retransmitted signals as received are no longer identified as coming from any particular satellite. The real innovation herein proposed is to achieve such identification by computation.
This new method of calculation of the position implements the main folllowing steps:
- computing the position for all combinations associating retransmitted signals received by the antenna with the satellites of the constellation whose retransmitted signals are capable of being detected by the antenna;
- computing the position of the beacon for at least some of the satellite combinations using the least squares method;
- determining the position of the transmitting beacon that corresponds to the combination which presents the smallest computation residue by the least squares method.
ESA proposes this algorithm solution for various types of applications especially in telecommunication and navigation fields (e.g. telecom systems, GPS, etc).
Innovations and advantages:
The main innovation of this method comes from the relevant simplification of the ground installation facilities: big directive antennas, which are more difficult and expensive to install, control and maintain, can be replaced by one omidirectional small antenna (slightly bigger than a mobile phone) that collects information from all directions. The new identified algorithm is able to differentiate which part of the retransmitted signal comes from a specific satellite using an iterative method in which the correct combination can be determined by computing the computation residue for each case. For all combinations that do not correspond to the real situation, the value of this residue is considerably higher (even by several order of magnitude) than when the signals are correctly associated with the satellites that have retransmitted them.
Domain of Application:
Method currently applied to determine the position of a transmitting beacon. It may be applied to telecom systems, more specifically for positioning and navigation.
- Computer Software
- Software services
Last update: 16 March 2011