# US 2022/0286209 A1 · Method and system for performing signal analysis using a correlative receiver

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- Number: US 2022/0286209 A1
- Document ID: US20220286209A1
- Status: Published application
- Kind: A1
- Application number: 17/681,629
- Filed: 2022-02-25
- Published: 2022-09-08
- Earliest claimed: 2021-02-26
- Assignees: RAM Photonics, LLC
- Applicants: RAM Photonics, LLC
- Inventors: Vahid Ataie
- Web page: https://patentgrep.com/patent/US20220286209A1

## CPC

- H04B 10/61: Coherent receivers
- H04B 10/6161: {Compensation of chromatic dispersion}
- H04B 10/2575: Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
- H04B 10/505: {using external modulation}
- H04B 2210/006: Devices for generating or processing an RF signal by optical means
- H04B 2210/25: Distortion or dispersion compensation
- H04B: TRANSMISSION

## Abstract

An apparatus includes a first antenna, a tunable optical carrier source, a second antenna, and a delay generation module coupled to the first antenna and the tunable optical carrier source. The apparatus also includes a fixed wavelength optical carrier source, an optical carrier generation module coupled to the fixed wavelength optical carrier source, and a local oscillator generation module. The apparatus further includes a correlative kernel generation and integration module coupled to the delay generation module and the local oscillator generation module and an optoelectronic conversion module coupled to the correlative kernel generation and integration module.

## Claims

### Claim 1

An apparatus comprising:
a first antenna;
a tunable optical carrier source;
a second antenna;
a delay generation module coupled to the first antenna and the tunable optical carrier source;
a fixed wavelength optical carrier source;
an optical carrier generation module coupled to the fixed wavelength optical carrier source;
a local oscillator generation module;
a correlative kernel generation and integration module coupled to the delay generation module and the local oscillator generation module; and
an optoelectronic conversion module coupled to the correlative kernel generation and integration module.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the delay generation module is also coupled to second antenna.

### Claim 3 (depends on 1)

The apparatus of claim 1, wherein the delay generation module includes:
a first single-sideband optical modulator coupled to the tunable optical carrier source; and
a second single-sideband optical modulator coupled to the fixed wavelength optical carrier source.

### Claim 4 (depends on 1)

The apparatus of claim 1, wherein the delay generation module includes a dispersion compensating fiber.

### Claim 5 (depends on 1)

The apparatus of claim 1, wherein the correlative kernel generation and integration module comprises:
a first optical detector configured to receive signals modulated onto a tunable optical carrier provided by the tunable optical carrier source;
a second optical detector configured to receive signals modulated onto a fixed optical carrier provided by the fixed wavelength optical carrier source;
a third, null-biased optical modulator coupled to the first optical detector; and
a fourth, null-biased optical modulator coupled to the second optical detector.

### Claim 6 (depends on 1)

The apparatus of claim 1, wherein the optoelectronic conversion module comprises:
an optical 90-degree hybrid element; and
a plurality of optical detectors, each of the plurality of optical detectors being optically coupled to the optical 90-degree hybrid element.

### Claim 7 (depends on 1)

The apparatus of claim 1, wherein the fixed wavelength optical carrier source comprises an optical frequency comb providing a plurality of fixed optical carriers.

### Claim 8

An apparatus for generating a cross ambiguity function from two input signals, the apparatus comprising:
a tunable optical laser providing a tunable optical carrier;
a first single sideband optical modulator configured to modulate the tunable optical carrier with one of the two input signals;
a fixed wavelength laser comb source providing an optical comb including a plurality of fixed wavelength optical carriers;
a second optical modulator configured to modulate the fixed wavelength optical carrier with the other of the two input signals;
a dispersive element configured to provide a delay between the modulated tunable optical carrier and the modulated fixed wavelength optical carrier;
a first optical detector coupled to the dispersive element;
a second optical detector coupled to the dispersive element;
a third optical modulator coupled to the first optical detector;
a fourth optical modulator coupled to the second optical detector;
a wavelength division demultiplexer optically coupled to the third optical modulator and the fourth optical modulator and configured to transmit demultiplexed signals;
a plurality of optical 90-degree hybrid elements optically coupled to the wavelength division demultiplexer; and
a plurality of optical detectors, each of the plurality of optical detectors being optically coupled to a corresponding optical 90-degree hybrid element of the plurality of optical 90-degree hybrid elements.

### Claim 9 (depends on 8)

The apparatus of claim 8, wherein the two input signals are independent signals.

### Claim 10 (depends on 8)

The apparatus of claim 8, wherein the plurality of fixed wavelength optical carriers is split into two paths and one path is frequency shifted with respect to the other path.

### Claim 11 (depends on 8)

The apparatus of claim 8, wherein the third optical modulator comprises a null-biased optical modulator configured to modulate the plurality of fixed wavelength optical carriers using an output of the first optical detector.

### Claim 12 (depends on 8)

The apparatus of claim 8, wherein the fourth optical modulator comprises a null-biased optical modulator configured to modulate the plurality of fixed wavelength optical carriers using an output of the second optical detector.

### Claim 13 (depends on 8)

The apparatus of claim 8, wherein the plurality of optical 90-degree hybrid elements are configured to separate quadratures of an output of the third optical modulator.

### Claim 14 (depends on 8)

The apparatus of claim 8, wherein each of the plurality of optical 90-degree hybrid elements produces four output quadratures.

### Claim 15 (depends on 14)

The apparatus of claim 14, wherein each of the plurality of optical detectors is configured to convert two of the four output quadratures to electrical signals.