VSB a), a) An Alternative Carrier Phase Independent Symbol Timing Offset Estimation Methods for VSB Receivers Sung Soo Shin a) and Joon Tae Kim a) VSB. VSB.,,., VSB,. Abstract In this paper, we propose an alternative carrier phase independent timing recovery method for VSB receivers. The Gardner algorithm may not estimate a timing offset in VSB systems when the residual carrier phase offset is contained in the signal. We use the conjugate multiplication of received signals for cancelling out the carrier phase offset. Then Gardner algorithm is employed for extracting the spectral line. The proposed method generates a consistent timing error even in the presence of the carrier phase offset. Keyword : VSB, Symbol timing recovery, Timing error detection, Carrier phase, Timing offset estimation. DTV(Digital Television) 1997 11 a) Department of Electronics Engineering, Konkuk University : (jtkim@konkuk.ac.kr) IT (NIPA-2010-C1090-1001-0006) (20101026),(2011120),(2011120) ATSC(Advanced Television Systems Committee) [1], 2001 10 TV. 2012 TV (NTSC)TV. ATSC DVB-T(Digital Video Broadcasting-Terrestrial) ISDB-T(Integrated Service Digital Broadcasting- Terrestrial) DTV 1996
8-VSB (Vestigial Sideband Modulation)., (Carrier Phase Offset, CPO) (Timing Frequency Offset),. VSB, 8-PAM(pulse amplitude modulation,, ) DC 1.25V, [2]. (Symbol Timing Recovery),,.,,. DTV VSB, [3]. QAM(Quadrature Amplitude Modulation) DSB (Double Side Band) ( In-phase) ( Quadrature-phase). QAM VSB, [3] (Timing Error Detector, TED),. VSB, (Hilbert Transform) QAM., VSB,. QAM, VSB. VSB,., VSB (robust),, (Spectral line). [4], 2 (, conjugate) (Overlap). [4] S- 1/4 (0.25 ), 0.25T. [5] [4], (Bandedge Pre-filter). [4], [5]. [4], [5], VSB., [3]., [4] S-,,,.. 1. ATSC 8-VSB DTV ATSC-8VSB[1]. 8VSB 6MHz 19.39Mbps 188 MPEG2-TS(Transport Stream).
1. ATSC-8VSB Fig. 1. A structure of ATSC-8VSB systems 20 RS(Reed Solomon) RS, 2/3 (FEC).,. ATSC- 8VSB 1,,, 2., VSB,. (Hilbert Transform).. VSB,, 3, DSB 1/2. [4], [5]. 2.. [4] [5] (Spectral line). [4] [5], VSB. VSB 8-PAM, PAM. (PSF : Pulse Shaping Filter) 2. DSB VSB Fig. 2. Spectral overlap of the DSB and VSB 3 [4],
3. [4] Fig. 3. Introduced Timing offset estimation Scheme in [4]. VSB.. [5] [4].,,. 4,.. [5] [4],. 4 [5]. ], exp (Bandedge Prefilter),.,.,,.. [2] 4. [5] Fig. 4. Introduced Timing offset estimation Scheme in [5], [4], [5] S- 5 1/4 (0.25 ), 0.25. [4], [5]..
5. [4] S- Fig. 5. S-curve plot of kim's[4] TED for timing phase offset, [3] (3).., cos sin sin cos,, 2,. I Q. (3), 1/2. DSB,. (4),. (3). k, (6) (5),, sin cos.
, (7). VSB,,.. sin sin (8) 6,., VSB. 3. 7 VSB 2,.., VSB 6. (DSB ) Fig. 6. Gardner algorithm's a diagram of spectral overlap 7. Fig. 7. A structure of proposed Timing Error Detector
, [4], [5] S- 0.25T. VSB,. VSB, (9)., VSB,,,. 8.,, DSB.,, VSB (Complex Pulse Shaping Filter) (Impulse Response). T, n(t)., =,,. 8. VSB Fig. 8. A spectral overlap for conjugate multiplication of VSB. (13).. (10), (Poisson's sum formula), (11).,., * (Complex Conjugate).., sin sin. (14),. 9 VSB,.
9. VSB(a) (b), (c) Fig. 9. A spectral overlap for VSB signals(a), conjugate multiplication of VSB signals(b), and after the proposed algorithm(c) 9-(a) VSB. 9-(b), (11), (12). 9-(b),.,, 9-(c),.,, 4., VSB., VSB (Band Pass Filter) DC component,, (High Pass Filter),. 10 S-. 1000ppm VSB, 10., [4], S- 1/4 (0.25 ),,. 11 AWGN(Additive White Gaussian Noise)., 10. S- Fig. 10. S-curve plot of two TEDs for timing phase offset
,. 1000ppm,. 7,. 12 1000Hz S-.,. S-, VSB,. VSB, 10, 11, 12. 11. VSB (AWGN, 1000ppm ) Fig. 11. performance of the TED's variance(awgn channel) 12. S- Fig. 12. S-curve plot of two TEDs for carrier phase offset
13. Fig. 13. Symbol timing frequency recovery scheme VSB. 13. 1. Table 1. Number of operations of timing frequency offset estimators ATSC-8VSB 8-VSB 1.0 % 1.0 % 10.0 db VSB (Interpolator).. DTV ATSC 8-VSB [1]. AWGN. 14. 1KHz Fig. 14. Acquisition and tracking performance of timing recovery systems for 1KHz timing offset
1, 1. 14,.,... VSB,,,. [4] S-,.. ATSC-8VSB DTV. VSB,., [1] ATSC A/43, Guide to the use of the ATSC digital television standard, Dec. 2003. [2] Grand Alliance HDTV system Specification, Ver. 2.0, Dec. 7, 1994. [3] F.M. Gardner, "A BPSK/ QPSK timing error detector for sampled receiver," IEEE Trans. On Comm., COM-34, pp. 423-429, May 1986. [4] J.T. Kim, " Carrier phase independent timing recovery methods for VSB receivers, " IEEE Trans. On Consumer Electron, Vol.52, No. 1, Feb. 2006. [5] Huang. Lou., " Timing recovery Methods for VSB Receivers." IEEE Trans. On Consumer Electronics, Vol. 53, No. 2, pp. 265-269, May 2007. - 2007 : - 2010 ~ : - :, - 1990 : - 1993 : - 1998 : - 1998 ~ 2003 : LG DTV - 2003 ~ : - :,,