Synchronizing ranging signals in an asynchronous ranging or position system
First Claim
1. A system for transmitting to determine a range or position from a transmitter relative to a first receiver, the system comprising:
- a first transmitter operable to transmit a ranging signal with a modulation rate of a code being at least about 30 MHz; and
a first oscillator connected with the first transmitter, the first oscillator being free-running, the ranging signal responsive to the first oscillator.
9 Assignments
0 Petitions
Accused Products
Abstract
In a local positioning system, the land-based transmitters include free running oscillators or oscillators free of clock synchronization with any remote oscillator. A reference receiver receives the ranging signals from different transmitters and generates timing offset information, such as code phase measurements. The timing offset information is then communicated back to transmitters. The temporal offset information indicates relative timing or phasing of the different transmitted ranging signals to the reference receiver. The transmitters then transmit the temporal offset information with the ranging signals, such as modulating the transmitted code by the timing offset information. A mobile receiver is operable to receive the ranging signals and timing offset information in a same communications path, such as on a same carrier. Position is determined with the temporal offset information and the ranging signals. The temporal offset information for the various transmitters allows the mobile receiver to more accurately determine position than in an unsynchronized system.
-
Citations
37 Claims
-
1. A system for transmitting to determine a range or position from a transmitter relative to a first receiver, the system comprising:
-
a first transmitter operable to transmit a ranging signal with a modulation rate of a code being at least about 30 MHz; and
a first oscillator connected with the first transmitter, the first oscillator being free-running, the ranging signal responsive to the first oscillator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
-
-
20. A method for transmitting to determine a range or position from a transmitter relative to a first receiver, the method comprising:
-
(a) generating a ranging signal in response to a first oscillator, a phase of the oscillator being unsynchronized with any remote oscillator; and
(b) transmitting the ranging signal with a modulation rate of a code being at least about 30 MHz. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28)
-
-
29. A system for determining a position of a first receiver, the system comprising:
-
a first land-based transmitter having a first oscillator, the first land-based transmitter operable to transmit a first ranging signal with a first modulation rate of a first code being at least about 30 MHz, and the first ranging signal responsive to the first oscillator;
a second land-based transmitter having a second oscillator, the second land-based transmitter operable to transmit a second ranging signal with a second modulation rate of a second code being at least about 30 MHz, and the second ranging signal responsive to the second oscillator;
a third land-based transmitter having a third oscillator, the third land-based transmitter operable to transmit a third ranging signal with a third modulation rate of a third code being at least about 30 MHz, and the third ranging signal responsive to the third oscillator;
a fourth land-based transmitter having a fourth oscillator, the fourth land-based transmitter operable to transmit a fourth ranging signal with a fourth modulation rate of a fourth code being at least about 30 MHz, and the fourth ranging signal responsive to the fourth oscillator;
a second receiver spaced from the first receiver, both the first and second receivers operable to receive the first, second and third ranging signals;
wherein the first, second and third oscillators are free of phase synchronization with each other;
wherein the first receiver is mobile; and
a processor operable to determine the position as a function of a differential measurement of the first, second, third, and fourth ranging signals between the first and second receivers, the differential measurement having a code based accuracy of better than ten centimeters. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36)
-
-
37. A system for transmitting to determine a range or position from a transmitter relative to a first receiver, the system comprising:
-
a first transmitter connected operable to transmit a ranging signal with at least about 60 MHz of available bandwidth;
a first oscillator connected with the first transmitter, the first oscillator being free-running, the ranging signal responsive to the first oscillator.
-
Specification