Systems and methods for communication in a global positioning system (GPS) device

A method of timing the transmission of symbols of a local direct-sequence spread spectrum (DSSS) signal, wherein the local DSSS signal is sent from a first transceiver to a second transceiver, the method comprising:

• providing the first transceiver, wherein the first transceiver is capable of adjustably offsetting symbols of the local DSSS signal relative to satellite system time when transmitted by the first transceiver;
• providing the second transceiver, wherein the second transceiver is separate from the first transceiver;
• receiving at least sporadically, one or more satellite navigation signals in the first transceiver such that the first transceiver is synchronized with satellite system time;
• receiving, at least sporadically, one or more satellite navigation signals in the second transceiver such that the second transceiver is synchronized with satellite system time;
• and
• under control of a processor of the first transceiver, modulating or pulsing symbols of the local DSSS signal such that the symbols are transmitted by a transmitter and antenna of the first transceiver with actively corrected timing so that when the symbols of the local DSSS signal are received in the second transceiver, the symbols are received with substantially zero offset relative to boundaries of a clock signal based on satellite system time even when the first transceiver and the second transceiver are moving relative to each other.

A method of timing a local direct-sequence spread spectrum (DSSS) signal, wherein the local DSSS signal is sent from a first device to a second device, the method comprising:

• receiving one or more satellite navigation signals in the first device;
• receiving one or more satellite navigation signals in the second device;
• sending symbols of the local DSSS signal from the first device to the second device such that the symbols of the local DSSS signal are substantially time-aligned with a predetermined offset from satellite system time, wherein the local DSSS signal includes a pseudorandom noise (PN) ranging code;
• acquiring the local DSSS signal in the second device with a correlator circuit;
• computing a first offset in the local DSSS signal relative to the satellite system time;
• and
• sending a second local DSSS signal from the second device to the first device, wherein the second local DSSS signal is deliberately offset by the second device from the satellite system time such that a second offset in timing in the second local DSSS signal relative to the satellite navigation signal as received in the first device is less than the first offset.

A method in a first node of determining range to a second node, the method comprising:

• at least sporadically receiving satellite ranging codes in the first node so that the first node is synchronized to satellite system time;
• receiving ultra wideband (UWB) pulses transmitted from the second node, wherein the second node is also synchronized to satellite system time, wherein the UWB pulses encode a pseudorandom noise (PN) ranging code that is synchronized with satellite system time when transmitted by the second node;
• determining an offset in the first node based on the PN ranging code originally sent by and received from the second node and satellite system time;
• using the offset to determine range from the first node to the second node;
• and
• retrieving an absolute position of the second node encoded on the PN ranging code, and using the range to the second node and the absolute position of the second node to supplement positioning of the first node obtained via Global Positioning System (GPS).

A method in a data processing unit of indirectly calculating an absolute position of a first node, the method comprising:

• determining ranges among at least a subset of a plurality of nodes including between the first node and a second node, wherein each node of the plurality of nodes is synchronized to GPS system time, wherein each node:
• transmits UWB pulses encoding a particular pseudorandom noise (PN) ranging code, wherein the PN ranging code is synchronized with GPS system time when transmitted;
• determines an offset between a received PN ranging code originating from another node of the plurality of nodes and GPS system time to determine range from the node that sent the PN ranging code;
• using the ranges to resolve relative positioning at least with respect to the second node, wherein the second node is aware of an absolute position via GPS;
• receiving an indication of the absolute position of the second node;
• and
• combining the indication of the absolute position of the second node and the relative positioning to the second node to compute the indirectly-calculated absolute position of the first node.

A method in a data processing unit of indirectly calculating an absolute position of a first node, the method comprising:

• determining ranges among at least a subset of a plurality of nodes including between the first node and a second node, wherein ranging is performed using UWB pulses encoding a pseudorandom noise (PN) ranging code, wherein the range between the first node and the second node is cooperatively determined by communication in both directions to and from the first node and the second node, wherein the second node is aware of an absolute position;
• using the ranges to resolve relative positioning at least with respect to the second node;
• receiving an indication of the absolute position of the second node;
• combining the indication of the absolute position of the second node and the relative positioning to the second node to compute the indirectly-calculated absolute position of the first node;
• determining relative positioning to one or more additional nodes;
• receiving indications of the absolute positions of the one or more additional nodes;
• and
• combining the relative positioning and the absolute positions of the one or more additional nodes to compute one or more additional indirectly-calculated absolute positions.

A method in a data processing unit of indirectly calculating an absolute position of a first node, the method comprising:

• determining ranges among at least a subset of a plurality of nodes including between the first node and a second node, wherein the range between the first node and the second node is cooperatively determined by communication in both directions to and from the first node and the second node, wherein the second node is aware of an absolute position;
• using the ranges to resolve relative positioning at least with respect to the second node;
• receiving an indication of the absolute position of the second node;
• combining the indication of the absolute position of the second node and the relative positioning to the second node to compute the indirectly-calculated absolute position of the first node;
• computing a second absolute position for the first node via satellite navigation;
• and
• combining the second absolute position with the indirectly-calculated absolute position of the first node using an unequal weighting to generate an aggregate absolute position, wherein weights are at least partially based on an estimated clock error.

A method in a data processing unit of indirectly calculating an absolute position of a first node, the method comprising:

• determining ranges among at least a subset of a plurality of nodes including between the first node and a second node, wherein ranging is performed using UWB pulses encoding a pseudorandom noise (PN) ranging code, wherein the range between the first node and the second node is cooperatively determined by communication in both directions to and from the first node and the second node, wherein the second node is aware of an absolute position;
• using the ranges to resolve relative positioning at least with respect to the second node;
• receiving an indication of the absolute position of the second node;
• combining the indication of the absolute position of the second node and the relative positioning to the second node to compute the indirectly-calculated absolute position of the first node;
• computing a second absolute position for the first node via satellite navigation;
• and
• combining the second absolute position with the indirectly-calculated absolute position of the first node to generate an aggregate absolute position.