# US 2013/0156431 A1 · System and method for multiple sub-octave band transmissions

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- Number: US 2013/0156431 A1
- Document ID: US20130156431A1
- Status: Published application
- Kind: A1
- Application number: 13/765,585
- Filed: 2013-02-12
- Published: 2013-06-20
- Earliest claimed: 2010-12-28
- Inventors: Chen-Kuo Sun; Peter H. Wolff
- Web page: https://patentgrep.com/patent/US20130156431A1

## CPC

- H04B 10/2507: for the reduction or elimination of distortion or dispersion
- H04B 10/2543: due to fibre non-linearities, e.g. Kerr effect
- H04B 10/25754: {Star network topology}
- H04J 14/0282: {WDM tree architectures}
- H04J 14/0298: {with sub-carrier multiplexing [SCM]}
- H04B: TRANSMISSION
- 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)

## Abstract

A system and method for enabling multiple sub-octave band transmissions with reduced second order distortions is provided. For this method, first and second sub-octave bands are established. The second sub-octave band is spaced from the first sub-octave band by a non-transmission band. Digital signals are modulated onto RF carrier frequencies in the first and second band to produce first band RF signals and second band RF signals. The first and second band signals are converted into one or more light beams and transmitted over a fiber optic cable. After transmission, an optical receiver reconverts the light beam into an RF signal. Second order distortions outside a selected sub-octave band can be filtered from RF signal and a tuner used to tune in a selected carrier frequency. A receive modem can then be used to demodulate the tuned carrier frequency for receipt of its respective digital signal.

## Claims

### Claim 1

A method for enabling multiple sub-octave band transmissions with reduced second order distortions, the method comprising the steps of:
establishing a first sub-octave band having a plurality of discrete carrier frequencies, including F1 and F2, with F2>F1;
modulating digital signals onto Radio Frequency (RF) carrier frequencies in the first band to produce first band RF signals;
establishing a second sub-octave band having a plurality of discrete carrier frequencies, including F3 and F4, with F4>F3 and wherein the second band is spaced from the first band by a non-transmission band between F2 and F3, with F3>2F2;
modulating digital signals onto RF carrier frequencies in the second band to produce second band RF signals;
converting the first and second band signals into one or more light beams; and
introducing said one or more light beams into a fiber optic cable for transmission through the fiber optic cable.

### Claim 2 (depends on 1)

A method as recited in claim 1 wherein the first band extends from F1 to F2 and the second band extends from F3 to F4.

### Claim 3 (depends on 1)

A method as recited in claim 1 wherein F2<2F1.

### Claim 4 (depends on 1)

A method as recited in claim 1 wherein F4<F1+F3.

### Claim 5 (depends on 1)

A method as recited in claim 1 wherein the first and second band signals are introduced into a same end of the fiber optic cable in the introducing step.

### Claim 6 (depends on 1)

A method as recited in claim 1 wherein the step of modulating digital signals onto Radio Frequency (RF) carrier frequencies in the first band to produce first band RF signals comprises the sub-steps of:
modulating a digital signal onto an initial RF carrier frequency, F0, to produce an initial modulated RF signal; and
up-converting the initial modulated RF signal to up-convert the carrier frequency, F0, to a carrier frequency within the first band.

### Claim 7 (depends on 1)

A method as recited in claim 1 wherein said converting step converts the first and second band signals into a light beam having wavelength (λ1).

### Claim 8 (depends on 7)

A method as recited in claim 7 further comprising the step of multiplexing the light beam having wavelength (λ1) with another light beam having wavelength (λ2) using wavelength division multiplexing prior to said introducing step.

### Claim 9 (depends on 1)

A method as recited in claim 1 further comprising the step of combining the first and second band signals into a combined RF signal prior to said converting step.

### Claim 10 (depends on 1)

A method as recited in claim 1 further comprising the steps of:
establishing a third sub-octave band having a plurality of discrete carrier frequencies, including F5 and F6, with F6>F5 and wherein the third band is spaced from the second band by a non-transmission band between F4 and F5, with F5>2F4;
modulating digital signals onto RF carrier frequencies in the third band to produce third band RF signals; and
wherein the converting step converts the first, second and third band signals into one or more light beams; and
wherein the introducing step introduces the one or more light beams with the first, second and third band signals into a fiber optic cable for transmission through the fiber optic cable.

### Claim 11 (depends on 1)

A method as recited in claim 1 further comprising the steps of:
recovering a first band signal from a light beam retrieved from the fiber optic cable;
filtering second order distortions outside the first sub-octave band from the recovered first band signal; and
demodulating a digital signal from the filtered, first band signal.

### Claim 12 (depends on 11)

A method as recited in claim 11 wherein the filtering step is accomplished using a band pass filter.

### Claim 13 (depends on 1)

A method as recited in claim 1 wherein the frequency, F1, is in a range of frequencies between 750 MHz and 40 GHz.

### Claim 14

A method for multiple sub-octave band transmission of signals, the method comprising the steps of:
modulating digital signals onto RF carrier frequencies in discrete first and second sub-octave bands to produce respective first band signals and second band signals wherein the first band is separated from the second band by more than one octave;
converting the first and second band signals into one or more light beams for transmission through a fiber optic cable;
recovering a first band signal from a light beam retrieved from the fiber optic cable;
filtering second order distortions outside the first sub-octave band from the recovered first band signal; and
demodulating a digital signal from the filtered, first band signal.

### Claim 15 (depends on 14)

A method as recited in claim 14 wherein the first band extends from F1 to F2, the second band extends from F3 to F4 and the second band is spaced from the first band by a non-transmission band between F2 and F3, with F3>2F2.

### Claim 16 (depends on 15)

A method as recited in claim 15 wherein F2<2F1 and F4<F1+F3.

### Claim 17

A system for multiple sub-octave band transmission of signals comprising:
at least one modem modulating digital signals onto RF carrier frequencies in first and second sub-octave bands to produce first band signals and second band signals;
at least one transmitter converting the first and second band signals into one or more light beams for transmission through a fiber optic cable;
a receiver recovering a first band signal from a light beam retrieved from the fiber optic cable;
a band pass filter filtering second order distortions outside the first sub-octave band from the recovered first band signal; and
a modem demodulating a digital signal from the filtered, first band signal.

### Claim 18 (depends on 17)

A system as recited in claim 17 wherein the first band extends from F1 to F2, the second band extends from F3 to F4 and the second band is spaced from the first band by a non-transmission band between F2 and F3, with F3>2F2.

### Claim 19 (depends on 17)

A system as recited in claim 17 wherein the first band extends from F1 to F2, the second band extends from F3 to F4, F2<2F1.

### Claim 20 (depends on 19)

A method as recited in claim 19 wherein F4<F1+F3.