1. Signature based sensing algorithms
January 2007
Signature based sensing algorithms
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Wen Gao, ThomsonWen Gao, Thomson Inc.

2. Abstract Field-Sync based DTV signal detection and simulation results
January 2007
Abstract
Field-Sync based DTV signal detection and simulation results
Segment-Sync based DTV signal detection and simulation results
Simulations utilize the ATSC A/74 DTV signal captures [1] with following parameters
DTV channels were sampled at Msample/sec and down converted to a low central IF frequency of 5.38 MHz
Wen Gao, ThomsonWen Gao, Thomson Inc.

3. Signature in ATSC DTV signals
January 2007
Signature in ATSC DTV signals
Field Sync and Segment sync are two important time domain signatures of ATSC DTV signals
Wen Gao, ThomsonWen Gao, Thomson Inc.

4. Simulation Procedure for Field Sync Detector
January 2007
Simulation Procedure for Field Sync Detector
Lowpass filter bandwidth: 6MHz
AWGN is filtered using the same lowpass filter
Correlation detector use a matched filter that matches the field sync pattern: [ ] + PN511+PN63+zeros(1,63)+PN63
Decision statistics: the maximum magnitude value of the field sync correlator output within a field (24.2ms)
Wen Gao, ThomsonWen Gao, Thomson Inc.

5. January 2007
Simulation results of the field sync detector (Average over 50 data capture ensembles)
Wen Gao, ThomsonWen Gao, Thomson Inc.

6. Simulation Procedure for Segment Sync Detector
January 2007
Simulation Procedure for Segment Sync Detector
Lowpass filter bandwidth: 6MHz
AWGN is filtered using the same lowpass filter
Wen Gao, ThomsonWen Gao, Thomson Inc.

7. Segment Sync Detector structure
January 2007
Segment Sync Detector structure
Test Statistics is
Where L=1664, ND is number of collected sgements, K=8, M=1 or K=4, M=2
Wen Gao, ThomsonWen Gao, Thomson Inc.

8. Simulation results of the Segment sync detector
January 2007
Simulation results of the Segment sync detector
The curves are obtained by average results over 12 data captures [2].
PFA = 10 percent, observation time = 31 ms ( ND = 400)
-110
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-102 10 -2 -1
Received Signal Power (dBm) P MD
4 every other sample autocorrelation
8 consecutive sample autocorrelation
Wen Gao, ThomsonWen Gao, Thomson Inc.

9. Sliced segment sync detector
January 2007
Sliced segment sync detector
when the observation time is long, timing drift effect will restrict the improvement of the performance comes from longer observation time.
In order to alleviate the timing drift effect, we can slice total observation time into multiple slices , and then apply segment sync detector to each slices
The total observation time can be discontinuous while each slice contains continuous observation time.
Finally we use the average (or summation) of the test statistics of each slice as our overall test statistics. We will call this detector as Sliced Segment Sync Detector (SSSD)
Wen Gao, ThomsonWen Gao, Thomson Inc.

10. Simulation results of Sliced Segment-sync detector (1)
January 2007
Simulation results of Sliced Segment-sync detector (1)
Use data capture ensemble: WAS_3_27_ _REF
PFA = 10 percent
One slice for 2.156ms, 3.123ms, 4.06ms; two slices for 9.25ms
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-98 10 -2 -1
Received Signal Power (dBm) P MD
2.156 ms
3.123 ms
4.06 ms
9.25 ms
Wen Gao, ThomsonWen Gao, Thomson Inc.

11. Simulation results of Sliced Segment sync detector (2)
January 2007
Simulation results of Sliced Segment sync detector (2)
The curves are obtained by average results over 12 data captures [2]
PFA = 10 percent
Observe 4.06ms or 9.25ms per 10ms frame. Two slices for 9.25ms
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-107 10 -2 -1
Received Signal Power (dBm) P MD
4.06 ms x 10 frames
9.25 ms x 10 frames
Wen Gao, ThomsonWen Gao, Thomson Inc.

12. January 2007
Conclusions
Segment sync detector has low computation complexity with good performance.
Segment sync detector can be used for discontinuous observation interval, just like power detector.
Both the results of Segment sync detector and field sync detector provide high confidence about the presence of ATSC DTV signals.
Field sync and segment sync detector are complementary to energy or eigenvalue-based detector. A combination of both types of detector will provide a good solution for
Wen Gao, ThomsonWen Gao, Thomson Inc.

13. January 2007
References
Victor Tawil, “DTV Signal Capture Database”, IEEE /0081r0, May, 2006.
Steve Shellhammer, Victor Tawil, Gerald Chouinard, Max Muterspaugh, and Monisha Ghosh, “Spectrum Sensing Simulation Model”, IEEE /0028r10, September, 2006.
Wen Gao, ThomsonWen Gao, Thomson Inc.