The present disclosure relates to a technical field for airborne navigation and discloses a data acquisition system and method for airborne navigation devices based on unmanned aerial vehicle. The system includes an unmanned aerial vehicle flight control system, a navigation devices test antenna array, a multi-channel signal processing module, a signal acquisition module, an ADS-B transmitting module, a GNSS receiver, a UHF data link receiver, a power module and a ground station. The unmanned aerial vehicle is equipped with corresponding modules to receive signals from ground navigation devices, perform corresponding processing and storage, and transmit data to the ground, at the same time, receive control instructions sent by the ground to complete corresponding monitoring, analysis and inspection.

The present disclosure relates to a technical field for airborne navigation and discloses a data acquisition system and method for airborne navigation devices based on unmanned aerial vehicle. The system includes an unmanned aerial vehicle flight control system, a navigation devices test antenna array, a multi-channel signal processing module, a signal acquisition module, an ADS-B transmitting module, a GNSS receiver, a UHF data link receiver, a power module and a ground station. The unmanned aerial vehicle is equipped with corresponding modules to receive signals from ground navigation devices, perform corresponding processing and storage, and transmit data to the ground, at the same time, receive control instructions sent by the ground to complete corresponding monitoring, analysis and inspection.

Time-synchronization of a space-system having a plurality of satellites. During a first period, a first satellite of the plurality of satellites is designated as a master satellite. A clock of the master satellite is configured to provide time and frequency to remaining satellites of the plurality of satellites and the remaining satellites are designated as slave satellites. During a second period, a second satellite of the slave satellites is designated as the master satellite based on a performance indicator and the first satellite is designated as a slave satellite. During the first period and the second period, clocks of the slave satellites are crosslinked with a clock of the master satellite using time transfer. At least one satellite during the first period and the second period, delivers time data having the time and the frequency generated by a clock of the at least one satellite.

Time-synchronization of a space-system having a plurality of satellites. During a first period, a first satellite of the plurality of satellites is designated as a master satellite. A clock of the master satellite is configured to provide time and frequency to remaining satellites of the plurality of satellites and the remaining satellites are designated as slave satellites. During a second period, a second satellite of the slave satellites is designated as the master satellite based on a performance indicator and the first satellite is designated as a slave satellite. During the first period and the second period, clocks of the slave satellites are crosslinked with a clock of the master satellite using time transfer. At least one satellite during the first period and the second period, delivers time data having the time and the frequency generated by a clock of the at least one satellite.

A navigation satellite time system and its autonomous recovery method are provided, including a load time system, the load time system is configured to generate and maintain the load time, and the load time system comprises an space borne atomic clock, a time-frequency processing unit and a plurality of load time backups module, the time information of the load time is obtained from the ground station time; the pulse-per-second signals of the load time are generated and maintained by the space borne atomic clock and the time-frequency processing unit; when the time-frequency processing unit fails, the first-level recovery state is triggered: the time-frequency processing unit compares the time information and the pulse-per-second signals reversely output by the multiple load time backup modules to perform load time recovery.

Aspects of the subject disclosure may include, for example, a device that has a processing system including a processor; and a memory that stores executable instructions that, when executed by the processing system, facilitate performance of operations, including receiving a request for an observation of an overhead viewing area from an observer location; discovering an interference of a satellite with the observation of the overhead viewing area; determining possible solutions to the interference; selecting a solution of the possible solutions; receiving the observation from one or more satellites responding to the solution selected; and providing a response to the request including the observation received. Other embodiments are disclosed.

Aspects of the subject disclosure may include, for example, a device that has a processing system including a processor; and a memory that stores executable instructions that, when executed by the processing system, facilitate performance of operations, including receiving a request for an observation of an overhead viewing area from an observer location; discovering an interference of a satellite with the observation of the overhead viewing area; determining possible solutions to the interference; selecting a solution of the possible solutions; receiving the observation from one or more satellites responding to the solution selected; and providing a response to the request including the observation received. Other embodiments are disclosed.

A node of a satellite constellation system includes a global positioning receiver configured to receive first signaling from a first plurality of non-LEO navigation satellites of a constellation of non-LEO navigation satellites in non-LEO around the earth. A transceiver is configured to send and receive inter-node communications with other nodes of the satellite constellation system. At least one processor is configured to execute operational instructions that cause the at least one processor to perform operations that include: determining a state of the node of the satellite constellation system based on applying precise point positioning (PPP) correction data to the first signaling, wherein the PPP correction data is received separately from the first signaling; and generating a navigation message based on the state of the node. A navigation signal transmitter is configured to broadcast the navigation message to at least one client device, wherein the client device is space-based, the navigation message facilitating the at least one client device to determine an enhanced position of the at least one client device based on the navigation message.

A direct digital synthesis transmitter that uses a programmable digital circuit to generate a digital signal representing at least one radio frequency signal, the generated signal is filtered, amplified by an amplifier, and provided to a transmission antenna without upconversion. The transmitter generating the digital signal at a desired output frequency range such that a frequency upconverter is not needed to produce signals in the desired radio frequency range.

A global navigation satellite system (“GNSS”) positioning method is provided, based upon a GNSS radio signal that comprises a navigation message transmitted as a succession of data packets. Each data packet is present in the GNSS radio signal as a sequence of symbols obtained by application of a code preceded by a synchronization symbol header. The data packets are organized internally into data fields. At least certain data packets of the succession of data packets contain a synchronization bit field translated by application of the code into a synchronization symbol pattern.