# US 12,181,571 B2 · Altimeter testing device and methods

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

- Number: US 12,181,571 B2
- Document ID: US12181571B2
- Status: Granted
- Kind: B2
- Application number: 17/818,088
- Filed: 2022-08-08
- Published: 2023-04-13
- Granted: 2024-12-31
- Earliest claimed: 2020-02-12
- Assignees: Viavi Solutions Inc.
- Applicants: Viavi Solutions Inc.
- Inventors: Rock Crawford
- Web page: https://patentgrep.com/patent/US12181571B2

## CPC

- G01S 13/882: {for altimeters (measuring height using barometric means G01C5/06)}
- G01S 7/4052: {by simulation of echoes}
- G01S 7/4065: {involving a delay line}
- H04W 24/06: Testing, {supervising or monitoring} using simulated traffic
- 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
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

Devices and methods for testing altimeters are provided. A radio-frequency (RF) signal may be received from an altimeter and passed through an RF delay module to delay the RF signal. The delayed RF signal may be converted to an optical signal, which may be passed through an optical delay module to delay the optical signal. The system tests the accuracy of the altimeter based on the combined RF signal delay and optical signal delay.

## Claims

### Claim 1

A method of testing an altimeter, the method comprising:
receiving a radio-frequency (RF) signal from the altimeter;
passing the received RF signal through at least one delay module to delay the RF signal by a delay corresponding to a test altitude comprising a first altitude and a second altitude larger than the first altitude, wherein the delay comprises an RF delay that corresponds to the first altitude and an optical delay that corresponds to the second altitude; and
transmitting the delayed RF signal to the altimeter.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
passing the received RF signal through an RF delay module to delay the RF signal by the RF delay;
converting the RF signal delayed by the RF delay to an optical signal;
passing the optical signal through an optical delay module to delay the optical signal by the optical delay; and
converting the optical signal delayed by the optical delay to a return RF signal to generate the delayed RF signal sent to the altimeter.

### Claim 3 (depends on 2)

The method of claim 2, wherein passing the received RF signal through the RF delay module comprises passing the received RF signal through one or more of a plurality of coaxial cable coils of the RF delay module.

### Claim 4 (depends on 3)

The method of claim 3, wherein a length of each of the plurality of coaxial cable coils correlates to a respective predetermined RF delay for the RF signal.

### Claim 5 (depends on 2)

The method of claim 2, wherein passing the optical signal through the optical delay module comprises passing the optical signal through one or more of a plurality of fiber optic cable coils.

### Claim 6 (depends on 5)

The method of claim 5, wherein each of the plurality of fiber optic cable coils includes a different length of fiber optic cable and a length of each of the plurality of fiber optic cable coils correlates to a respective predetermined optical delay for the optical signal.

### Claim 7 (depends on 2)

The method of claim 2, wherein passing the RF signal through the RF delay module comprises attenuating the RF signal.

### Claim 8 (depends on 1)

The method of claim 1, further comprising passing the received RF signal through at least one component that correlates to path loss of the received RF signal at the test altitude.

### Claim 9 (depends on 1)

The method of claim 1, being performed by an altimeter testing device.

### Claim 10 (depends on 9)

The method of claim 9, further comprising receiving the test altitude at an interface of the altimeter testing device.

### Claim 11

A device for testing an altimeter, comprising:
an input to receive a radio-frequency (RF) signal from the altimeter;
at least one delay module to delay the RF signal by a delay corresponding to a test altitude comprising a first altitude and a second altitude larger than the first altitude, wherein the delay comprises an RF delay that corresponds to the first altitude and an optical delay that corresponds to the second altitude; and
an output for transmitting the delayed RF signal to the altimeter.

### Claim 12 (depends on 11)

The device of claim 11, wherein the at least one delay module comprises:
an RF delay module to delay the received RF signal by the RF delay;
a first signal converter to convert the RF signal delayed by the RF delay to an optical signal;
an optical delay module to delay the optical signal by the optical delay; and
a second signal converter to convert the optical signal delayed by the optical delay to a return RF signal to generate the delayed RF signal sent to the altimeter.

### Claim 13 (depends on 12)

The device of claim 12, wherein the RF delay module comprises:
a plurality of coaxial cable coils, each including a different length of coaxial cable; and
a plurality of RF switches coupled across the coaxial cables and each being operable to selectively couple a corresponding one of the plurality of coaxial cable coils to a signal path of the received RF signal through the RF delay module.

### Claim 14 (depends on 13)

The device of claim 13, wherein the length of each of the plurality of coaxial cable coils correlates to a respective predetermined RF delay in the RF signal.

### Claim 15 (depends on 13)

The device of claim 13, wherein:
a first coaxial cable of the plurality of coaxial cable coils has a length that correlates to an altitude of 10 feet,
a second coaxial cable of the plurality of coaxial cable coils has a length that correlates to an altitude of 20 feet, and
a third coaxial cable of the plurality of coaxial cable coils has a length that correlates to an altitude of 40 feet.

### Claim 16 (depends on 12)

The device of claim 12, wherein the optical delay module comprises:
a plurality of fiber optic cable coils, each including a different length of optical fiber; and
a plurality of optical switches coupled across the fiber optic cable coils and each being operable to selectively couple a corresponding one of the plurality of fiber optic cable coils to a signal path of the optical signal through the optical delay module.

### Claim 17 (depends on 16)

The device of claim 16, wherein the length of each of the plurality of fiber optic cable coils correlates to a respective optical delay in the optical signal.

### Claim 18 (depends on 16)

The device of claim 16, wherein:
a first fiber optic cable of the plurality of fiber optic cable coils has a length that correlates to an altitude of 80 feet,
a second fiber optic cable of the plurality of fiber optic cable coils has a length that correlates to an altitude of 160 feet,
a third fiber optic cable of the plurality of fiber optic cable coils has a length that correlates to an altitude of 320 feet,
a fourth fiber optic cable of the plurality of fiber optic cable coils has a length that correlates to an altitude of 640 feet,
a fifth fiber optic cable of the plurality of fiber optic cable coils has a length that correlates to an altitude of 1280 feet,
a sixth fiber optic cable of the plurality of fiber optic cable coils has a length that correlates to an altitude of 2560 feet, and
a seventh fiber optic cable of the plurality of fiber optic cable coils has a length that correlates to an altitude of 5120 feet.

### Claim 19 (depends on 11)

The device of claim 11, wherein the delay module includes a digital attenuator to attenuate the RF signal.

### Claim 20 (depends on 11)

The device of claim 11, further comprising at least one component that correlates to path loss of the received RF signal at the test altitude.