# US 12,761,374 B2 · Method and apparatus to retrofit legacy global positioning satellite (GPS) and other global navigation satellite system (GNSS) receivers

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

- Number: US 12,761,374 B2
- Document ID: US12761374B2
- Status: Granted
- Kind: B2
- Application number: 18/635,435
- Filed: 2024-04-15
- Published: 2025-09-18
- Granted: 2026-10-13
- Earliest claimed: 2017-02-09
- Assignees: Viavi Solutions Inc.
- Applicants: Viavi Solutions, Inc.
- Inventors: Gregor Said Jackson; Giovanni D'Andrea
- Web page: https://patentgrep.com/patent/US12761374B2

## CPC

- G01S 19/36: relating to the receiver frond end
- G01S 19/23: Testing, monitoring, correcting or calibrating of receiver elements
- G01S 19/32: Multimode operation in a single same satellite system, e.g. GPS L1/L2
- G01S 19/426: {by combining or switching between position solutions or signals derived from different modes of operation in a single system}
- 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

## Abstract

There is provided n interface apparatus for retrofitting a GNSS apparatus. The interface apparatus includes an antenna configured to receive a first GPS transmission, and an amplifier coupled to the antenna to receive and amplify a first GPS signal.

## Claims

### Claim 1

A Global Positioning System (GPS) simulator coupled to a GPS receiver and an oscillator, the GPS simulator configured to:
when a first timing signal and a position signal are received from the GPS receiver:
generate a first simulated GPS signal based on the first timing signal and the position signal received from the GPS receiver; and
when the first timing signal and the position signal are not received from the GPS receiver:
receive a second timing signal from the oscillator; and
generate a second simulated GPS signal based on the second timing signal received from the oscillator.

### Claim 2 (depends on 1)

The GPS simulator of claim 1, further configured to:
when the first timing signal and the position signal are received from the GPS receiver:
output the first simulated GPS signal to a Global Navigation Satellite System (GNSS) receiver; and
when the first timing signal and the position signal are not received from the GPS receiver:
output the second simulated GPS signal to the GNSS receiver.

### Claim 3 (depends on 2)

The GPS simulator of claim 2, wherein the GNSS is one of GPS, Glonass, BeiDou, QZSS, or Galileo.

### Claim 4 (depends on 1)

The GPS simulator of claim 1, wherein the GPS simulator is coupled to a power manager configured to generate a simulated antenna load.

### Claim 5 (depends on 4)

The GPS simulator of claim 4, wherein the simulated antenna load is a predetermined load compatible with legacy GNSS antenna systems.

### Claim 6 (depends on 4)

The GPS simulator of claim 4, wherein the simulated antenna load makes a combination of the GPS simulator, the GPS receiver and the oscillator to appear as a legacy GNSS antenna system.

### Claim 7 (depends on 1)

The GPS simulator of claim 1, wherein the GPS simulator is coupled to at least one of a high-stability oscillator using chip-scale-atomic-clocks (CSACs) or a high-stability ovensized oscillators (OCXOs).

### Claim 8 (depends on 7)

The GPS simulator of claim 7, wherein the GPS simulator is further configured to:
use the CSACs or the OCXOs when the first timing signal and the position signal are not received from the GPS receiver.

### Claim 9 (depends on 8)

The GPS simulator of claim 8, wherein the CSACs or the OCXOs is combined with an Inertial Navigation system and/or a peer-to-peer navigation using one of a visual decoding of camera images or a geo-location using time-difference-of-arrival (TDOA) or frequency-difference-of-arrival (FDOA).

### Claim 10 (depends on 1)

The GPS simulator of claim 1, wherein the GPS simulator is coupled to a Selective Availability Anti-Spoofing Module (SAASM) GPS receiver with a military M-Code decoding.

### Claim 11

A method for use by a Global Positioning System (GPS) simulator coupled to a GPS receiver and an oscillator, the method comprising:
when a first timing signal and a position signal are received from the GPS receiver:
generating a first simulated GPS signal based on the first timing signal and the position signal received from the GPS receiver; and
when the first timing signal and the position signal are not received from the GPS receiver:
receiving a second timing signal from the oscillator; and
generating a second simulated GPS signal based on the second timing signal received from the oscillator.

### Claim 12 (depends on 11)

The method of claim 11, further comprising:
when the first timing signal and the position signal are received from the GPS receiver:
outputting the first simulated GPS signal to a Global Navigation Satellite System (GNSS) receiver; and
when the first timing signal and the position signal are not received from the GPS receiver:
outputting the second simulated GPS signal to the GNSS receiver.

### Claim 13 (depends on 12)

The method of claim 12, wherein the GNSS is one of GPS, Glonass, BeiDou, QZSS, or Galileo.

### Claim 14 (depends on 11)

The method of claim 11, further comprising:
generating, using a power manager, a simulated antenna load.

### Claim 15 (depends on 14)

The method of claim 14, wherein the simulated antenna load is a predetermined load compatible with legacy GNSS antenna systems.

### Claim 16 (depends on 14)

The method of claim 14, wherein the simulated antenna load makes a combination of the GPS simulator, the GPS receiver and the oscillator to appear as a legacy GNSS antenna system.

### Claim 17 (depends on 11)

The method of claim 11, wherein the GPS simulator is coupled to at least one of a high-stability oscillator using chip-scale-atomic-clocks (CSACs) or a high-stability ovensized oscillators (OCXOs).

### Claim 18 (depends on 17)

The method of claim 17, further comprising:
using the CSACs or the OCXOs when the first timing signal and the position signal are not received from the GPS receiver.

### Claim 19 (depends on 18)

The method of claim 18, wherein the CSACs or the OCXOs is combined with an Inertial Navigation system and/or a peer-to-peer navigation using one of a visual decoding of camera images or a geo-location using time-difference-of-arrival (TDOA) or frequency-difference-of-arrival (FDOA).

### Claim 20 (depends on 11)

The method of claim 11, wherein the GPS simulator is coupled to a Selective Availability Anti-Spoofing Module (SAASM) GPS receiver with a military M-Code decoding.