in non cooperative environment
Novagrid develops software products for signal analysis in non cooperative environments. The targeted applications are communications satellites payload monitoring, spectrum surveillance, analysis and identification of radio signals HyperMon.
As it is also interesting to estimate the position of the received signals, Hyperloc is the companion software dedicated to this task, with a particular emphasis on geolocation of satellite carriers. HyperTask allows automatic complex tasks like monitoring of a transponder with automatic geolocation of unknown carriers (interferrers).
Simulatenous Multi-Target Geolocation Without Reference
Actually, the geolocation process using TDOA and FDOA measures needs to use a known location carrier (which is usually called the "Reference carrier") in order to compensate the satellites on board OL drift and accuracy.
In some situations, the user of a geolocation system works with a couple of satellite where no reference carrier is known. What are the solutions provided by modern geolocation systems in this case ? Usually, the suggested solution is to make two measures (several hours is needed between each measure) and to cross the two TDOA line of points (one line for each measure). While it is a good idea when one of the two satellites has an inclined orbit, when the two satellites have stabilized orbits this method gives a very poor geolocation accuracy (several 100 km) for the following reasons:
- the TDOA lines offers very small angular variations during the day (typically 0.1 degres )
- the limited accuracy of both TDOA measure and satellites orbits will move the estimated TDOA line (typically in the longitude direction)
In order to answer this kind situation, NovaGrid has developped an original method called "Simultaneous Multi-target Geolocation Without Reference" which is relevant when accurate orbits are available for both main and mirror satellites. The procedure is the folowing:
- Selection of the satellites (and orbits) used and the transponder of interest
- Selection of 5 to 15 targets to locate
The following video shows HyperTask in real life running a "Simultaneous Multi-target Geolocation Without Reference" task.