AMPLITUDE ENHANCED FREQUENCY MODULATION

• US 20130259148A1
• Filed: 03/29/2012
• Published: 10/03/2013
• Est. Priority Date: 03/29/2012
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: General Electric Company
• Inventors: Place, Richard Alan
• Granted Patent: US 8,965,290 B2
• Time in Patent Office: Days
• US Class Current: 375/261
• CPC Class Codes: H03C 5/00 Amplitude modulation and angle modulation produced simultaneously or at will by the same modulating signal H03C7/00 takes precedence
• CPC Class Codes: H04L 27/12 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/2003 for continuous phase modulation frequency shift keying H04L27/10
• CPC Class Codes: H04L 27/34 Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems

Abstract

Methods and systems for transmitting a spectrally efficient signal. The method includes frequency modulating an input signal in a transmitter to generate a first frequency modulated (FM) signal and generating in the transmitter an amplitude modulated (AM) component based at least on the input signal. The method may then include generating a second FM signal based at least on the AM component and the first FM signal and sending the second FM signal to a receiver.

Claims

1. A communication system comprising:

a transmitter, comprising;

a frequency modulator configured to generate a first frequency modulated (FM) signal based at least on an input signal;

a component configured to generate an amplitude modulated (AM) component based at least on the input signal; and

an amplitude modulator configured to add the AM component to the first FM signal thereby generating a second FM signal;

wherein the transmitter is configured to send the second FM signal to a receiver.

2. The communication system of claim 1, wherein the component comprises a digital signal processor (DSP), a circuit, a look up table, or any combinations thereof.

3. The communication system of claim 2, wherein the DSP comprises an integrator configured to integrate the input signal and generate an integrated signal.

4. The communication system of claim 3, wherein the DSP comprises a high pass filter configured to filter the integrated signal and generate a filtered signal

5. The communication system of claim 1, wherein the AM component is configured to cancel a second sideband energy in the first FM signal.

6. The communication system of claim 1, wherein the amplitude modulator is configured to amplify the AM component.

7. A communication system comprising:

a transmitter, comprising;

a digital signal processor (DSP) configured to;

generate an inphase (I) signal and quadrature phase (Q) signal using a frequency modulation, wherein the I signal and the Q signal comprise at least a first sideband component and a second sideband component; and

remove the second sideband component from the I signal and the Q signal, thereby generating a filtered I signal and a filtered Q signal; and

a complex modulator configured to generate a frequency modulated (FM) signal based at least on the filtered I signal and the filtered Q signal, wherein the transmitter sends the FM signal to a receiver.

8. The communication system of claim 7, wherein the DSP comprises an integrator, a sine module, a cosine module, and at least two filters.

9. The communication system of claim 8, wherein the at least two filters correspond to low pass filters.

10. The communication system of claim 8, wherein the at least two filters comprise:

a first filter configured to remove the second sideband component from the Q signal, thereby generating an amplitude modulated (AM) component on the FM signal; and

a second filter configured to time shift the I signal to match a delay in the Q signal introduced by the first filter.

11. A method for transmitting a spectrally efficient signal, comprising:

frequency modulating an input signal in a transmitter to generate a first frequency modulated (FM) signal;

generating in the transmitter an amplitude modulated (AM) component based at least on the input signal;

generating a second FM signal based at least on the AM component and the first FM signal; and

sending the second FM signal to a receiver.

12. The method of claim 11, wherein generating the AM component comprises:

integrating the input signal to generate an integrated signal;

filtering the integrated signal to generate a filtered signal;

doubling a frequency of the filtered signal, thereby generating the AM component.

13. The method of claim 12, wherein integrating the input signal comprises:

scaling the input signal; and

phase shifting the scaled input signal.

14. The method of claim 13, wherein the input signal is scaled by 1/f, wherein f is a frequency of a carrier wave for the first FM signal.

15. The method of claim 13, wherein the input signal is phase shifted by 90 degrees.

16. The method of claim 12, wherein filtering the integrated signal comprises removing a lower half of a baseband modulation bandwidth in the integrated signal.

17. The method of claim 12, wherein the AM component is configured to cancel the second sideband energy in the first FM signal.

18. The method of claim 11, wherein generating the second FM signal comprises adding the AM component to the first FM signal.

19. The method of claim 11, wherein the AM component comprises about 3 to about 5 percent amplitude modulation of the input signal.

20. The method of claim 11, wherein frequency modulating the input signal in the transmitter is performed by a digital signal processor (DSP) configured to generate an inphase signal having the first FM signal, wherein generating the second FM signal is performed by a complex modulator.