Trimble Navigation Limited

US Government As Represented by the Secretary of the Army

Benjamin W Remondi

Kendall Ferguson

Michael Albright

Michael Timo Allison

Peter Van Wyck Loomis

Herbert Landau

A method of communicating corrections for information related to satellite signals among global navigation satellite system (GNSS) receivers is described. The method includes at a first GNSS device determining a component of position of a satellite. The component is then divided by a first value to thereby obtain an integer value and a remainder value, and the only the remainder value is transmitted from the first GNSS device to the second GNSS device. Knowing the first value, the second GNSS device calculates the component of position.

Ambiguity windowing in communications among global navigation system satellite receivers

A method in a Global Navigation Satellite System (GNSS) receiver for double-nudged broadcast orbit drift correction. A first broadcast orbit message is utilized to nudge a broadcast orbit in use at the GNSS receiver to create a first nudged broadcast orbit for a GNSS satellite, the first nudged broadcast orbit being more precise than the broadcast orbit. A second broadcast orbit message is utilized to nudge the first nudged broadcast orbit in use at the GNSS receiver to create a double-nudged broadcast orbit for a GNSS satellite, the double-nudged broadcast orbit being more precise than the first nudged broadcast orbit. A third broadcast orbit message is utilized to maintain the double-nudged broadcast orbit, the third broadcast orbit message smaller than the second and the first broadcast orbit messages.

Double-nudged broadcast orbit drift correction

In a method of autonomous orbit projection performed within a Global Navigation Satellite System (GNSS) receiver, distinct broadcast orbits are received over time from a GNSS satellite during operation of the GNSS receiver. A plurality of the distinct broadcast orbits are stored within the GNSS receiver. Within the GNSS receiver, a plurality of the stored broadcast orbits are converted into a time series of range data for the GNSS satellite. A projected orbit for the GNSS satellite is determined by utilizing the time series of range data as an input to an orbit projector of the GNSS receiver.

Autonomous projection of global navigation satellite orbits

A method of communicating corrections for information related to satellite signals among global navigation satellite system (GNSS) receivers is described. An ionosphere correction for ionosphere signal path delay is determined for a first satellite. This ionosphere correction is then compared to an ionosphere correction for ionosphere signal path delay for a satellite assumed to be directly over the receiver. The receiver then sends a message which includes only the difference between the ionosphere correction for the actual observation and the ionosphere correction for a satellite assumed to be at the zenith.

Method of compactly communicating ionospheric and tropospheric corrections in a network of global navigation system satellite receivers

A format for providing messages among GNSS apparatus includes providing a message identification block and a message body. The message identification block includes information specifying a message length and a message type block specifying a message type. Rather than sending all data from one apparatus to another, ambiguous observation data is sent to conserve bandwidth. At the sender a deconstruction of GNSS code and carrier observations using knowledge of the signal structure and constellation geometry, together with simplifications of atmospheric models, allows removal from the observation data of that information which can be implicitly understood or recreated by the recipient. This enables only the necessary information to be packed for transmission to the recipient.

Compact transmission of GPS information using compressed measurement record format

In a method of conveying information regarding an orbit used at a Global Navigation Satellite System (GNSS) base station to a GNSS receiver, a satellite position is determined for a particular time from an orbit of a GNSS satellite. An ambiguity value is extracted from the satellite position. The ambiguity value is extracted based upon a satellite position determination margin of error of a GNSS receiver. The ambiguity value is encoded into an encoded ambiguity value which is assembled into a message. The message also includes a time tag representing the particular time. The message is transmitted from the GNSS base station. The encoded ambiguity value and the time tag convey information regarding the orbit to a GNSS receiver in receipt of the message.

Conveying orbit information via ambiguous position information

In method of correcting for drift in a Global Navigation Satellite System (GNSS) receiver, a broadcast orbit in use at the GNSS receiver is nudged based on a first message received from a GNSS base station. The nudging creates a first nudged broadcast orbit for a GNSS satellite, the first nudged broadcast orbit being more precise than the broadcast orbit. A second message is received from the GNSS base station. Information included in the second message is employed to determine a drift rate of the first nudged broadcast orbit relative to a more precise orbit in use at the GNSS base station. Based upon the second message, the broadcast orbit is nudged to create a second nudged broadcast orbit for the GNSS satellite. A component of the drift rate is corrected for, relative to the second nudged broadcast orbit.

Nudged broadcast orbit drift correction

The invention provides a method and apparatus for determining the precise coordinate of a remote roving on-the-fly signal receiver with respect to a reference signal receiver. The reference signal receiver is usually fixed to the Earth's surface but the instant invention's method allows for movement of the reference signal receiver without performance degradation. The reference receiver and remote roving receiver track four or more satellites so that single difference code and carrier ranges between the receivers can be formed. The method can work with just L1 signal alone, the preferred method uses at least one code range (e.g., C/A code) and two carrier ranges (e.g., L1 and L2) with full wavelength L2--squared implementation addition code ranges if available for use. This method allows for initialization of carrier integer ambiguities whether reference or remote receiver are fixed or moving relative to each other and a robust procedure for determining integer ambiguities.

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Dickerson, MD, United States of America

Benjamin W Remondi