[1] [1] WERNER W,ROMAN K.High-resolution monitoring of the gastrointestinal transit of a magnetically marked capsule[J].Journal of Pharmaceutical Sciences,1997,86(11):1218-1222.

[2] [2] PRAKASH N M,SPELMAN F A.Location of a magnetic marker for GI motility studies:an in vitro feasibility study[C].Proceeding-19th international conference-IEEE/EMBS,Chicago,USA,1997.

[3] [3] RAAB F,BLOOD E,STENINER T,et al..Magnetic position and orientation tracking system[J].IEEE Transaction on Instrumentation and Measurement,1980,29(4):462-467.

[4] [4] PAPERNO E,KEISAR P.Three dimensional magnetic tracking of biaxial sensors[J].IEEE Transaction on Magnetics,2004,40(3):1530-1536.

[5] [5] CHAO H,MAX Q H M,MRINAL M,et al..3-axis magnetic sensor array system for tracking magnets position and orientation[C].Proceedings of the 6th World Congress on Intelligent Control abd Automation,Dalian,China,2006.

[6] [6] HE W H,YAN G Z,GUO X D.A novel localization method for noninvasive monitoring capsule[J].High Technology Letters,2006,12(3):255-259.

[7] [7] WANG J S,SHEN Z X.An improved music TOA estimator for RFID positioning[C].IEEE proceeding on RADAR,Long Beach,CA,2002.

[8] [8] FEUERSTEIN M J,BEKUVEAU Y J.Distribution of phase errors in UHF position location sysfem[J].Electronics Letters,1989,25(16):1086-1088.

[11] [11] NARA T,SUZUKI S,ANDO S.A closed-form formula for magnetic dipole localization by measurement of its magnetic field and spatial gradients[J].IEEE Transactions on Magnetics,2006,42(10):3291-3293.

[12] [12] WANG X N,MENG M.Q-H,HU CH.A localization method using 3-axis magnetoresistive sensors for tracking of capsule endoscope[C].Proceeding of 28th Conference of Engineering in Medicine and Biology SociPty,New york,USA,2006.