A supplement for GPS
Locata has published the interface spec for a new local constellation to supplement or replace GPS in difficult conditions.
The Australian Locata Corporation claims to have solved the problem of badly degraded or unavailable GPS signals in environments such as cities, urban canyons and indoors.
LocataTech explains that the system is not designed necessarily to replace GPS - it should be considered as an extension and expansion of GPS that can either work with GPS, or operate independently when GPS is not working well.
Locata transmits GPS-like signals that can be synchronised with GPS - but on a different frequency around 2.4 GHz. So the system does not interfere with GPS L1 (~1.5 GHz) transmissions.
The transmitters - LocataLites, like GPS pseudolites - are fixed, so the complications of ephemerides associated with moving satellites are not needed; they just declare where they are fixed. Otherwise, they simply transmit as if they were GPS satellites - but on a different frequency.
Because the Locata signals are much stronger than those of GPS over an area of typically tens of sq kms, the system can be used in areas where GPS traditionally struggles - either supplementing GPS or acting alone.
And, as the GPS and Locata signals are almost identical, receivers covering both need be very little more compicated than a 'simple' GPS one.
The Locata signal Interface Control Document (ICD) has just been published. It can be downloaded from the Locata site below.