Radio positioning systems

A method of generating in a virtual location measurement unit a list of offsets relative to a common reference, said list of offsets being in time, phase, frequency, or derivatives thereof, or their equivalents expressed as offsets in distance or derivatives thereof, of a plurality of transmission source signals, which would be received at a given location, the method comprising;

• (a) acquiring, in the virtual location measurement unit, data from plural receivers, the plural receivers not necessarily fixed or at known positions, the data from each of the plural receivers being representative of the received signals;
• (b) determining from the acquired data, in the virtual location measurement unit, the offsets in time, phase, frequency, or derivatives thereof, respectively of signals received from the transmission sources relative to a reference source in each receiver or to each other;
• and
• (c) combining the determined offsets and calculating the list of offsets relative to the common reference in the virtual location measurement unit.

Apparatus for generating, in a virtual location measurement unit, a list of offsets relative to a common reference, said list of offsets being in time, phase, frequency, or derivatives thereof, or their equivalents expressed as offsets in distance or derivatives thereof, of a plurality of transmission source signals, which would be received at a given location, the method comprising;

• (a) means for acquiring, in the virtual location measurement unit, data from plural receivers, the plural receivers not necessarily fixed or at known positions, the data from each of the plural receiver being representative of the received signals;
• (b) means for determining from the acquired data, in the virtual location measurement unit, the offsets in time, phase, frequency, or derivatives thereof, respectively of signals received from the transmission sources relative to a reference source in each receiver or to each other;
• and
• (c) means for combining the determined offsets and calculating the list of offsets relative to the common reference in the virtual location measurement unit.