Methods and Systems for Optimal PN Phase Detection in DTMB Receivers

• US 20150098529A1
• Filed: 10/04/2013
• Published: 04/09/2015
• Est. Priority Date: 10/04/2013
• Status: Active Grant

• Current Assignee: Amlogic (Shanghai) Co., Ltd. (Amlogic Holdings Ltd.)
• Original Assignee: Amlogic (Shanghai) Co., Ltd. (Amlogic Holdings Ltd.)
• Inventors: Zhang, Jinhong, Li, Guogang
• Granted Patent: US 9,166,776 B2
• Time in Patent Office: Days
• US Class Current: 375/340
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04L 27/2605 Symbol extensions, e.g. Zero Tail, Unique Word [UW]
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 27/2672 Frequency domain
• CPC Class Codes: H04L 7/043 Pseudo-noise [PN] codes variable during transmission synchronisation of spread spectrum receivers H04B1/69

Abstract

A method and system for pseudorandom noise (“PN”) phase detection in digital terrestrial multimedia broadcast (“DTMB”) receivers. This method selects a detection range of symbols from a frame of the received signal; applies FFT to the PN portion of each of the symbols in the detection range to generate H_n(k); applies phase rotation to H_n(k) to obtain phase rotated for the PN portion of the symbols in the detection range; applies differential operations to to generate H_p^d ; sums the H_p^d to generated H_sum; calculates a value Q as a function of H_sum; and determines the PN phase offset as a function of Q and a predefined threshold.

Claims

1. A method for PN phase detection of a received signal for a DTMB receiver, wherein the received signal has a plurality of frames and each frame has a plurality of symbols and each of the symbols having a PN portion, wherein each PN portion having an initial phase offset designated from a plurality of initial phase offsets, comprising the steps of:

selecting a detection range of symbols from a frame of the received signal;

applying FFT to the PN portion of each of the symbols in the detection range to generate H_n(k);

applying phase rotation to H_n(k) to obtain phase rotated for the PN portion of the symbols in the detection range;

applying differential operations to to generate H_p^d;

summing the H_p^d to generated H_sum;

calculating a value Q as a function of H_sum; and

determining the PN phase offset as a function of Q and a predefined threshold.

2. The method of claim 1 wherein in the applying phase rotation step, the phase rotation (m, k) is determined as follows:

3. The method of claim 1 wherein in the applying phase rotation step, the phase rotation of OFF((m+n)% M) is applied to H_n(k) for PN portions of the symbols in the detection range.

4. The method of claim 1 wherein in the applying differential operations step, the differential operations are applied to to generate H_p^d for every symbol.

5. The method of claim 1 wherein in the applying differential operations step, the differential operation H_p^d is calculated as follows:

H_p^d(m,k)=(m,k)*(m,k)*,

where p=0,1, . . . , R−

2;

m=0,1, . . . , M−

1.

6. The method of claim 1 wherein in the summing step, H_sum is summed over the range of the initial phase offsets (m).

7. The method of claim 1 wherein in the summing step, H_sum is calculated as follows:

H_sum(m)=|(Σ

_p=0<sup>R−

2</sup>Σ

_k=0<sup>N−

1</sup>H_p^d(m,k))|,

where m=0,1, . . . , M−

1.

8. The method of claim 1 wherein Q is a function of maximum |H_sum|.

9. The method of claim 1 wherein Q=Max(|H_sum|)/SecondMax(|H_sum|).

10. The method of claim 1 wherein if Q is above the predefined threshold, the index of the initial phase offset is at Max(|H_sum|).

11. A method for PN phase detection of a received signal for a DTMB receiver, wherein the received signal has a plurality of frames and each frame has a plurality of symbols and each of the symbols having a PN portion, wherein each PN portion having an initial phase offset designated from a plurality of initial phase offsets, comprising the steps of:

selecting a detection range of symbols from a frame of the received signal;

applying FFT to the PN portion of each of the symbols in the detection range to generate H_n(k);

applying phase rotation OFF((m+n)% M) to H_n(k) to obtain phase rotated for the PN portion of the symbols in the detection range;

applying differential operations to to generate H_p^d;

summing the H_p^d to generated H_sum over the range of the initial phase offsets (m);

calculating a value Q as a function of H_sum; and

determining the PN phase offset as a function of Q and a predefined threshold.

12. The method of claim 11 wherein in the applying phase rotation step, the phase rotation (m,k) is determined as follows:

13. The method of claim 11 wherein in the applying differential operations step, the differential operation H_p^d is calculated as follows:

H_p^d(m,k)=(m,k)*(m,k)*.

where p =0,1, . . . , R−

2;

m=0,1, . . . , M−

1.

14. The method of claim 11 wherein in the summing step, H_sum is calculated as follows:

H_sum(m)=|(Σ

_p=0<sup>R−

2</sup>Σ

_k=0<sup>N−

1</sup>H_p^d(m,k))|,

where m=0,1, . . . , M−

1.

15. The method of claim 11 wherein Q is a function of maximum |H_sum|.

16. The method of claim 11 wherein Q=Max(|H_sum|)/SecondMax(|H_sum|).

17. The method of claim 11 wherein if Q is above the predefined threshold, the index of the initial phase offset is at Max (|H_sum|).

19. The method of claim 11 wherein Q=Max(|H_sum|)/SecondMax(|H_sum|).

20. The method of claim 11 wherein if Q is above the predefined threshold, the index of the initial phase offset is at Max(|H_sum|).

18. A method for PN phase detection of a received signal for a DTMB receiver, wherein the received signal has a plurality of frames and each frame has a plurality of symbols and each of the symbols having a PN portion, wherein each PN portion having an initial phase offset designated from a plurality of initial phase offsets, comprising the steps of:

selecting a detection range of symbols from a frame of the received signal;

applying FFT to the PN portion of each of the symbols in the detection range to generate H_n(k);

applying phase rotation OFF((m+n)% M) to H_n(k) to obtain phase rotated for the PN portion of the symbols in the detection range, wherein the phase rotation (m, k) is determined as follows;