METHOD OF DIFFERENTIAL-PHASE/ABSOLUTE-AMPLITUDE POLAR QAM

• US 20070183536A1
• Filed: 04/13/2007
• Published: 08/09/2007
• Est. Priority Date: 06/04/2003
• Status: Abandoned Application

• Current Assignee: Honeywell Federal Manufacturing & Technologies, LLC (Honeywell International Inc.)
• Original Assignee: Honeywell Federal Manufacturing & Technologies, LLC (Honeywell International Inc.)
• Inventors: DIMSDLE, JEFFREY
• Application Number:
  US11/734,943
• Publication Number:
  US 20070183536A1
• Time in Patent Office: Days
• US Class Current: 375/320
• CPC Class Codes: H04L 27/3405 Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power
• CPC Class Codes: H04L 27/361 Modulation using a single or unspecified number of carriers, e.g. with separate stages of phase and amplitude modulation

Abstract

A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2^N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

Claims

1. A method of amplitude scale tracking to substantially reduce scale variations in a received quadrature amplitude modulated signal, the method comprising the steps of:

(a) determining an amplitude ratio of two or more consecutive sampled amplitude values;

(b) determining whether the amplitude ratio represents a valid transition;

(c) identifying, for a determined valid transition, one or more ideal amplitude levels corresponding to one or more sampled amplitude values of the valid amplitude transition;

(d) determining a scale factor value based upon the ideal amplitude level and the corresponding sampled amplitude level; and

(e) using the scaling factor value to scale and compensate for any changes in strength of the received quadrature amplitude modulated signal.

2. The method as set forth in claim 1, wherein each sampled amplitude value of the two consecutive sampled amplitude values is approximately equal to √

((I value)²+(Q value)²).

3. The method as set forth in claim 1, wherein the valid transition is determined as being within a pre-established tolerance of a nominal amplitude ratio.

4. The method as set forth in claim 3, wherein the nominal amplitude ratio is of one or more higher amplitude values to one or more lower amplitude values.

5. The method as set forth in claim 3, wherein the nominal amplitude ratio is of one or more lower amplitude value to one or more higher amplitude values.

6. The method as set forth in claim 1, wherein the valid transition is determined as being within a pre-established tolerance of either a first nominal amplitude ratio or a second nominal amplitude ratio of any of the multiple possible pairs of amplitude levels, wherein the first nominal amplitude ratio is of a higher amplitude value to a lower amplitude value and the second nominal amplitude ratio is of the lower amplitude value to the higher amplitude value.

7. The method as set forth in claim 1, wherein the scale factor comprises an average of a plurality of scale factors.

8. The method as set forth in claim 7, wherein the average is a windowed/weighted average weighted in favor of the identified amplitude values closer to each received amplitude to be scaled.

9. The method as set forth in claim 1, wherein step (e) includes—

(e₁) determining an I value and a Q value corresponding to each of the two consecutive sampled amplitude values; and

(e₂) multiplying the I value and the Q value by the scaling factor value.

10. A method of amplitude scale tracking to substantially reduce scale variations in a received quadrature amplitude modulated signal, the method comprising the steps of:

(a) determining an amplitude ratio of two consecutive sampled amplitude values, wherein each of the two consecutive sampled amplitude values is approximately equal to √

((I value)²+(Q value)²);

(b) determining whether the amplitude ratio represents a valid transition as being within a pre-established tolerance of a nominal amplitude ratio;

(c) identifying, for a determined valid transition, one or more ideal amplitude levels corresponding to one or more sampled amplitude values of the valid amplitude transition;

(d) determining a scale factor value based upon the ideal amplitude level and the corresponding sampled amplitude level; and

(e) determining an I value and a Q value corresponding to the identified consecutive sampled amplitude values; and

(f) multiplying the I value and the Q value by the scaling factor value to compensate for any changes in strength of the received quadrature amplitude modulated signal.

11. The method as set forth in claim 10, wherein the nominal amplitude ratio is of one or more higher amplitude values to one or more lower amplitude values.

12. The method as set forth in claim 10, wherein the nominal amplitude ratio is of one or more lower amplitude values to one or more higher amplitude values.

13. The method as set forth in claim 10, wherein the nominal amplitude ratio is either a first unique nominal amplitude ratio or a second unique nominal amplitude ratio, wherein the first unique nominal amplitude ratio is of an upper amplitude value to a lower amplitude value and the second unique nominal amplitude ratio is of the lower amplitude value to the higher amplitude value.