# US 12,007,486 B2 · Systems and methods for synchronizing satellite-based clock devices

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,007,486 B2
- Document ID: US12007486B2
- Status: Granted
- Kind: B2
- Application number: 17/455,632
- Filed: 2021-11-18
- Published: 2022-05-19
- Granted: 2024-06-11
- Earliest claimed: 2020-11-18
- Assignees: Vit Tall LLC
- Applicants: Vit Tall LLC
- Inventors: Steve Chan
- Web page: https://patentgrep.com/patent/US12007486B2

## CPC

- G01S 19/256: {relating to timing, e.g. time of week, code phase, timing offset}
- H04J 3/0644: {External master-clock}
- H04W 56/0015: {one node acting as a reference for the others}
- H04W 56/0035: {detecting errors in frequency or phase}
- G01S 19/02: Details of the space or ground control segments
- H04B 7/1851: {Systems using a satellite or space-based relay (H04B7/18508, H04B7/18521 take precedence; providing specific services H04B7/18523 - H04B7/18576)}
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04B: TRANSMISSION

## Abstract

The present disclosure provides methods and systems for improving the time synchronization of global positioning system (GPS) satellite systems and related methods of using such systems. In some aspects, the GPS satellite systems comprise a swarm of CubeSat or other small form factor satellites.

## Claims

### Claim 1

A method for managing a plurality of satellites, comprising:
providing the plurality of satellites, wherein each satellite comprises a clock device, and a communications system configured to allow communications with one or more other satellites selected from the plurality of satellites;
assigning each of the plurality of clock devices to a clock group, wherein there are at least three clock groups;
receiving clock data from a subset of the plurality of clock devices located on the plurality of satellites;
selecting a group election logic for each clock group;
for each clock group, applying the group election logic to the received clock data corresponding to that clock group to select a group best clock and storing each selected group best clock in a set of group best clocks;
selecting a master election logic; and
applying the master election logic to the set of group best clocks to select a grand master clock device.

### Claim 2 (depends on 1)

The method of claim 1, wherein the communications system of one or more of the plurality of satellites is configured to transmit and/or receive signals using a Ka band frequency within the range of 26.5-40 gigahertz.

### Claim 3 (depends on 1)

The method of claim 1, wherein the receiving step is performed using a Ka band frequency within the range of 26.5-40 gigahertz.

### Claim 4 (depends on 1)

The method of claim 1, wherein one or more of the plurality of satellites further comprises at least one magnetorquer configured to provide attitude control, detumbling, and/or stabilization of the respective satellite.

### Claim 5 (depends on 1)

The method of claim 1, further comprising:
broadcasting a GPS signal, by a satellite selected from the plurality of satellites which comprises the selected grand master clock device.

### Claim 6 (depends on 1)

The method of claim 1, further comprising synchronizing the plurality of clock devices to the grand master clock device.

### Claim 7 (depends on 1)

The method of claim 1, wherein the group election logic comprises a Q-input harmonization algorithm.

### Claim 8 (depends on 1)

The method of claim 1, wherein applying the master election logic to the set of group best clocks to select a grand master clock device comprises selecting the clock device with the median time value from the set of group best clocks.

### Claim 9 (depends on 1)

The method of claim 1, wherein electing the grand master clock comprises calculating an average time value from the clock data in the master clock group and selecting the clock device with the value closest to the average.

### Claim 10 (depends on 1)

The method of claim 1, further comprising verifying the integrity of a message from the grand master clock.

### Claim 11 (depends on 1)

The method of claim 1, wherein the group election logic is selected based on available processing time.

### Claim 12 (depends on 1)

The method of claim 1, wherein at least some of the satellites in the plurality of satellites are CubeSats.

### Claim 13 (depends on 1)

The method of claim 1, wherein all of the satellites in the plurality of satellites are CubeSats.

### Claim 14

A method for synchronizing a plurality of clock devices, comprising:
providing a plurality of satellites, wherein each satellite comprises a clock device, and a communications system configured to allow communications with one or more other satellites selected from the plurality of satellites;
receiving clock data from a subset of the plurality of clock devices located on the plurality of satellites;
grouping the clock devices into clock groups;
selecting a group best clock for each group using a first selection process and providing a set of group best clocks;
selecting a master clock group based on the set of group best clocks using a second selection process;
selecting a grand master clock from the master clock group using a third selection process; and
synchronizing the plurality of clock devices to the grand master clock;
wherein the first selection process and second selection process use different selection algorithms.

### Claim 15 (depends on 14)

The method of claim 14, wherein the first selection process is an Q-input harmonization algorithm and the second selection process is a fault-tolerant average algorithm.

### Claim 16 (depends on 14)

The method of claim 14, wherein the third selection process is the Enhanced Best Master Algorithm.

### Claim 17 (depends on 14)

The method of claim 14, further comprising verifying the integrity of a message from the grand master clock.

### Claim 18 (depends on 14)

The method of claim 14, wherein:
the first selection process comprises: setting an accuracy threshold; selecting a candidate group best clock by applying the Enhanced Best Master Algorithm to the clock data corresponding to the clock devices in a given group; electing a reference value using an Q-input harmonization algorithm; comparing the candidate group best clock to the reference value; and returning the candidate group best clock if the comparison between the candidate group best clock and the reference value is less than the accuracy threshold;
the second selection process comprises selecting the clock group corresponding to the clock device with the median time value from the set of group best clocks; and
the third selection process comprises applying the Enhanced Best Master Algorithm to the master clock group.

### Claim 19 (depends on 18)

The method of claim 18, wherein the accuracy threshold is a preset value.

### Claim 20

A time-synchronizing GPS satellite network, comprising:
a plurality of satellites, wherein each satellite comprises a clock device, and a communications system configured to allow communications with one or more other satellites selected from the plurality of satellites;
wherein one satellite selected from the plurality of satellites is a time controller configured to
assign each of the plurality of clock devices to a clock group, wherein there are at least three clock groups;
receive clock data from a subset of the plurality of clock devices located on the plurality of satellites;
select a group election logic for each clock group;
for each clock group, apply the group election logic to the received clock data corresponding to that clock group to select a group best clock and storing each selected group best clock in a set of group best clocks;
select a master election logic; and
apply the master election logic to the set of group best clocks to select a grand master clock device, wherein the groups are assigned to correspond to the plurality of satellites.

### Claim 21 (depends on 20)

The system of claim 20, wherein the time controller is configured to:
apply a group election logic comprising an Q-input harmonization algorithm; and
select a grand master clock device by selecting the clock device with the median time value from the set of group best clocks.