Modes of operations in QAM modems using hysteresis sub-states

1. A method of automated acquisition of a QAM signal said method employing a State machine progressing from an initial State to a final State; said State machine comprising: a symbol timing recovery loop; a carrier loop; a coarse frequency loop; and an equalizer; said method comprising:

(A1) causing said State machine to enter a State AGC;

(A2) performing a loop test for a AGC minimum Sub-State;

(A3) performing a loop test for a AGC Lock Sub-State;

(B) Performing a symbol timing recovery of said input QAM signal by adjusting a sampling clock of said symbol timing recovery loop;

(C) Performing a Blind Equalization of said QAM signal without carrier lock to minimize a dispersion error of said received QAM signal constellation as compared with an error-free QAM signal constellation by adjusting a set of coefficients of said equalizer;

(D) Performing a carrier recovery of said QAM signal to eliminate a residual carrier frequency error and to eliminate a phase error from said acquired QAM signal;

and

(E) Performing a decision directed equalization (DDE) of said QAM signal by updating a set of coefficients of said equalizer by using a decision based algorithm.

2. The method of claim 1 , wherein said step (A2) of performing said loop test for said AGC minimum Sub-State further comprises:

(A2, 1) performing a loop test for a AGC Coarse Estimation Sub-State.

3. The method of claim 1 , wherein said step (A3) of performing said loop test for said AGC Lock Sub-State further comprises:

(A3, 1) performing a loop test for a AGC Maximum Sub-State.

4. A method of automated acquisition of a QAM signal said method employing a State machine progressing from an initial State to a final State; said State machine comprising: a symbol timing recovery loop; a carrier loop; a coarse frequency loop; and an equalizer; said method comprising:

(A) Performing an automatic gain control (AGC) operation on said incoming QAM signal to maintain a steady amplitude of said QAM signal;

(B1) causing said State machine to enter a Clock 1 State;

(B2) performing a loop test for a Clock 1 Minimum Sub-State;

(B3) performing a loop test for a Clock 1 Maximum Sub-State;

(C) Performing a Blind Equalization of said QAM signal without carrier lock to minimize a dispersion error of said received QAM signal constellation as compared with an error-free QAM signal constellation by adjusting a set of coefficients of said equalizer;

(D) Performing a carrier recovery of said QAM signal to eliminate a residual carrier frequency error and to eliminate a phase error from said acquired QAM signal;

and

(E) Performing a decision directed equalization (DDE) of said QAM signal by updating a set of coefficients of said equalizer by using a decision based algorithm.

5. The method of claim 4 , wherein the method further comprises the steps of:

(B4) causing said State machine to enter a Clock 2 State;

(B5) performing a loop test for a Clock 2 Minimum Sub-State;

and

(B6) performing a loop test for a Clock 2 Maximum Sub-State.

6. A method of automated acquisition of a QAM signal said method employing a State machine progressing from an initial State to a final State; said State machine comprising: a symbol timing recovery loop; a carrier loop; a coarse frequency loop; and an equalizer; said method comprising:

(A) Performing an automatic gain control (AGC) operation on said incoming QAM signal to maintain a steady amplitude of said QAM signal;

(B) Performing a symbol timing recovery of said input QAM signal by adjusting a sampling clock of said symbol timing recovery loop;

(C1) causing said State machine to enter a Blind State;

(C2) performing a loop test for a Blind Minimum Sub-State;

(C3) performing a loop test for a Blind Threshold Sub-State;

(C4) performing a loop test for a Blind Maximum Sub-State;

(C5) performing a loop test for a Blind Hysteresis Sub-State;

(D) Performing a carrier recovery of said QAM signal to eliminate a residual carrier frequency error and to eliminate a phase error from said acquired QAM signal;

and

(E) Performing a decision directed equalization (DDE) of said QAM signal by updating a set of coefficients of said equalizer by using a decision based algorithm.

7. A method of automated acquisition of a QAM signal said method employing a State machine progressing from an initial State to a final State; said State machine comprising: a symbol timing recovery loop; a carrier loop; a coarse frequency loop; and an equalizer; said method comprising:

(A) Performing an automatic gain control (AGC) operation on said incoming QAM signal to maintain a steady amplitude of said QAM signal;

(B) Performing a symbol timing recovery of said input QAM signal by adjusting a sampling clock of said symbol timing recovery loop;

(C) Performing a Blind Equalization of said QAM signal without carrier lock to minimize a dispersion error of said received QAM signal constellation as compared with an error-free QAM signal constellation by adjusting a set of coefficients of said equalizer;

D1) causing said State machine to enter a Carrier 1 State;

(D2) performing a loop test for a Carrier 1 Minimum Sub-State;

(D3) performing a loop test for a Carrier 1 Threshold Sub-State;

(D4) performing a loop test for a Carrier 1 Maximum Sub-State;

(D5) performing a loop test for a Carrier 1 Hysteresis Sub-State;

and

(E) Performing a decision directed equalization (DDE) of said QAM signal by updating a set of coefficients of said equalizer by using a decision based algorithm.

8. The method of claim 7 , wherein said step (D4) of performing said loop test for said Carrier 1 Maximum Sub-State further comprises:

(D4, 1) performing a loop test for a Sweep Sub-State.

9. The method of claim 7 , wherein the method further comprises the steps of

(D6) causing said State machine to enter a Carrier 2 State;

(D7) performing a loop test for a Carrier 2 Minimum Sub-State;

(D8) performing a loop test for a Carrier 2 Threshold Sub-State;

(D9) performing a loop test for a Carrier 2 Maximum Sub-State;

and

(D10) performing a loop test for a Carrier 2 Hysteresis Sub-State.

10. A method of automated acquisition of a QAM signal said method employing a State machine progressing from an initial State to a final State; said State machine comprising: a symbol timing recovery loop; a carrier loop; a coarse frequency loop; and an equalizer; said method comprising:

(A) Performing an automatic gain control (AGC) operation on said incoming QAM signal to maintain a steady amplitude of said QAM signal;

(B) Performing a symbol timing recovery of said input QAM signal by adjusting a sampling clock of said symbol timing recovery loop;

(C) Performing a Blind Equalization of said QAM signal without carrier lock to minimize a dispersion error of said received QAM signal constellation as compared with an error-free QAM signal constellation by adjusting a set of coefficients of said equalizer;

(D) Performing a carrier recovery of said QAM signal to eliminate a residual carrier frequency error and to eliminate a phase error from said acquired QAM signal;

(E1) causing said State machine to enter DDE 1 State;

(E2) performing a loop test for a DDE 1 Minimum Sub-State;

(E3) performing a loop test for a DDE 1 Threshold Sub-State;

(E4) performing a loop test for a DDE 1 Maximum Sub-State;

and

(E5) performing a loop test for a DDE 1 Hysteresis Sub-State.

11. The method of claim 10 , wherein the method further comprises the steps of

(E6) causing said State machine to enter State DDE 2 State;

(E7) performing a loop test for a DDE 2 Minimum Sub-State;

(E8) performing a loop test for a DDE 2 Threshold Sub-State;

(E9) performing a loop test for a DDE 2 Maximum Sub-State;

and

(E10) performing a loop test for a DDE 2 Hysteresis Sub-State.

12. The method of claim 11 , wherein the method further comprises the steps of

(E11) causing said State machine to enter a Tracking State;

(E12) performing a loop test for a Tracking State Minimum Sub-State;

(E13) performing a loop test for a Tracking State Threshold Sub-State;

and

(E14) performing a loop test for a Tracking State Maximum Sub-State.