# US 12,119,879 B2 · Signal processing device

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- Number: US 12,119,879 B2
- Document ID: US12119879B2
- Status: Granted
- Kind: B2
- Application number: 17/995,667
- Filed: 2021-04-05
- Published: 2023-05-18
- Granted: 2024-10-15
- Earliest claimed: 2020-04-08
- Assignees: Tamagawa University and Tamagawa Academy
- Applicants: Tamagawa University and Tamagawa Academy
- Inventors: Ken Tanizawa; Fumio Futami
- Web page: https://patentgrep.com/patent/US12119879B2

## CPC

- H04B 10/516: Details of coding or modulation
- H04B 10/506: {Multiwavelength transmitters}
- H04B 10/556: Digital modulation, e.g. differential phase shift keying [DPSK] or frequency shift keying [FSK]
- H04B 10/85: Protection from unauthorised access, e.g. eavesdrop protection
- H04K 1/02: by adding a second signal to make the desired signal unintelligible
- H04B: TRANSMISSION
- H04K: SECRET COMMUNICATION; JAMMING OF COMMUNICATION

## Abstract

The present invention addresses the problem of improving data transmission/reception equipment and transmission efficiency per hour. A light output unit 111 of a light transmitting/receiving device outputs n optical signals (where n is an integer value of 2 or more), each with a different wavelength, based on n respective pieces of data to be transmitted. From the n optical signals, a multiplexer 112 produces an optical signal multiplexed with respect to wavelength. From the multiplexed optical signal, an encryption unit 113 produces an encrypted signal by performing multi-level modulation on the basis of a Y-00 protocol. The problem is solved thereby.

## Claims

### Claim 1

A signal processing device, comprising:
an optical output unit that outputs each of n first type optical signals having different wavelengths based on each of n pieces of data to be transmitted, wherein n is an integer value of 2 or more;
a multiplexing unit that multiplexes each of the n first type optical signals to generate one second type optical signal wavelength-multiplexed; and
a multi-level modulation unit that performs multi-level modulation on the second type optical signal wavelength-multiplexed based on a predetermined algorithm to generate a third type optical signal, wherein performing the multi-level modulation on the second type optical signal includes performing at least a first stage modulation and a second stage modulation subsequently.

### Claim 2 (depends on 1)

The signal processing device according to claim 1, further comprising a delay unit that delays a timing at which each of the n first type optical signals is input to the multiplexing unit based on a timing at which modulation is performed by the multi-level modulation unit in at least one of a front stage and a rear stage of the optical output unit.

### Claim 3 (depends on 1)

The signal processing device according to claim 1, wherein the first stage modulation is a coarse modulation and the second stage modulation is a fine modulation.

### Claim 4 (depends on 1)

The signal processing device according to claim 1, wherein the multi-level modulation unit includes j stages of multi-level modulations that are performed subsequently, wherein j is an integer value of 2 or more.

### Claim 5 (depends on 1)

The signal processing device according to claim 1, wherein the first stage modulation and the second stage modulation are phase modulations.

### Claim 6

A signal processing device, comprising:
a modulation unit that converts a first type optical signal subjected to first multi-level modulation based on a predetermined algorithm after being multiplexed with respect to n wavelengths into a second type optical signal wavelength-multiplexed, using second modulation based on an algorithm corresponding to a predetermined algorithm, wherein n is an integer value of 2 or more; and
a separation unit that separates the second type optical signal into respective n third type optical signals.

### Claim 7 (depends on 6)

The signal processing device according to claim 6, further comprising a compensation unit that compensates a delay until each of components of the n wavelengths contained in the first type optical signal reaches the signal processing device to generate a fourth type optical signal,
wherein the modulation unit is configured to convert the fourth type optical signal into the second type optical signal using the second modulation.