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論文網址：
http://mimic.physionet.org/Archive/Publications/Zong03b.pdf
摘要
1 引言
2 方法
2.1 低通濾波
2.2 曲線長度變換
單通道ECG曲線長度變換
多通道ECG曲線長度變換 ---------------------使用多導聯信號檢測QRS的例子
窗口寬度 ---------------130 ms
尺度因子C 的作用，具體的選取值未講。
（------------橫座標u表示的是信號幅度單位時間的變化率，縱座標表示曲線長度對u的變化率或敏感性。 當C 不等於0 時，u趨於0 dl/du 趨於0，對單位時間幅度變化較小低頻成分如基線漂移，P, T波有抑制作用。對固定的非零的u，C 值選取越大麴線長度對幅度變化率敏感性變小，對同一個P或T波抑制作用變強但對同一個QRS波增強作用會減弱，所以要折中選C值。u表示一個採樣間期的幅度變化，自然既和採樣間隔（採樣率）又和分辨率有關係。）
2.3
2.3. Decision rule -------------判定準則
The decision rule consists of two procedures: (I) thresholding on the LT signal to find a possible QRS position; (2) searching locally to find the QRS onset and duration.
判定準則包含兩個過程：（1）在長度變換信號上用閾值法找到可能的QRS波位置；（2）局部搜索找到QRS起點和時限。
(1) Adaptive thresholding ------------自適應閾值
A threshold base value is established and is initially assigned as three times the mean value of the LT signal for the initial 10-second period. The actual threshold is set to 1/3 of the threshold base value. The threshold base value is then adaptively adjusted, based on the maximum LT value of each detected QRS complex.
建立閾值基礎值，對初始的10秒，基礎閾值賦值爲長度變換信號均值的三倍。實際閾值置爲基礎閾值的1/3。接下來基礎閾值自適應調整，以檢到的每個QRS波在LT上的最大值爲調整基礎。
(2) Local search strategies ----------局部搜索方法
When the LT signal crosses the threshold, a probable QRS is noted. From the threshold-crossing point, tc_i, the algorithm searches backward for 125 ms to get a minimum value, Lmin_i, and forward for 125ms to get a maximum value, Lmax_i. The difference, LAi = Lmax_i - Lmin_i is obtained. Then, from tc_i , again, the algorithm searches backward to find the location, Qb_i. where the LT value drops monotonically to Lmin_i = LAi/100 , and searches forward to find the location, Sb_i, where the LT increases to Lmax_i - LA_i / 20. Qb_i and Sb_i are considered the base values of QRS onset and end, respectively. The actual QRS onset is adjusted by -20 ms or -5 samples and the actual end is adjusted by +20ms or +5 samples. This widening adjustment compensates for the time interval loss caused by the onsetlend thresholds. The adjustments are based on statistical Observation of the differences between the algorithm's onset / end estimates and human expert judgments. Finally, a 250ms eyeclosing period is applied after each detected QRS to avoid possible double detection of the same beat.
（1） LT 信號與閾值相交時，一個可能的QRS波被發現。和閾值焦點記爲tc_i；
（2）在LT信號上，從tc_i 向後125 ms 內搜索最小值，記爲Lmin_i；
（3）從tc_i向前125 ms內搜索最大值，記爲Lmax_i，差值LA_i = Lmax_i - Lmin_i；
（4）再次從tc_i 向前或向後搜索過相應閾值點，檢測到Qb_i 或 Sb_i；
（5）對檢測位置進行補償。調整是基於算法定位和專家判斷差別的統計觀察；
（6）使用不應期。
3. 結果
4. 總結與討論
------------有對應本文算法的開源程序。
收藏於 2011-05-20
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