diff --git a/lark1fq/src/filter.c b/lark1fq/src/filter.c
index b8f57f6..2b4489f 100755
--- a/lark1fq/src/filter.c
+++ b/lark1fq/src/filter.c
@@ -78,8 +78,8 @@ void filter_quadratic_process(void)
     float rative, peak;
     uint32_t pos_ravine, pos_peak;
 
-    pos_ravine = data_ltc1867.pos_ravine + SAMPLES_PER_PERIOD / 4 - CALC_POINTS / 2;
-    pos_peak = data_ltc1867.pos_peak + SAMPLES_PER_PERIOD / 4 - CALC_POINTS / 2;
+    pos_ravine = (data_ltc1867.sample_falling + data_ltc1867.sample_rising - CALC_POINTS) / 2;
+    pos_peak = (data_ltc1867.sample_falling - CALC_POINTS) / 2;
     for (uint8_t i = 0; i < 4; i++) {
         calc_quadratic_fit(data_ltc1867.p_calc[i] + pos_ravine, &coeff, CALC_POINTS);
         rative = coeff.c - coeff.b * coeff.b / (4.0f * coeff.a);
diff --git a/lark1fq/src/ltc1867.c b/lark1fq/src/ltc1867.c
index 718935a..a468c93 100755
--- a/lark1fq/src/ltc1867.c
+++ b/lark1fq/src/ltc1867.c
@@ -10,7 +10,8 @@
 #include "stm32f4xx_tim.h"
 #include "stm32f4xx_spi.h"
 
-float data_ltc1867_raw[2][4][SAMPLES_PER_PERIOD * 2] __attribute__((section(".bss_ccm")));
+#define LTC1867_RAW_BUFF_SIZE (SAMPLES_PER_PERIOD / 4 * 5)
+float data_ltc1867_raw[2][4][LTC1867_RAW_BUFF_SIZE] __attribute__((section(".bss_ccm")));
 struct data_ltc1867_s data_ltc1867 __attribute__((section(".bss_ccm")));
 __attribute__((section(".data_ccm"))) uint16_t ltc1867_spi_data[LTC1867_CH_CNT] = {0xC400, 0x9400, 0xD400, 0xA400, 0x8400}; /* order: ch1, ch2, ch3, ch4, ch0 */
 
@@ -103,7 +104,7 @@ void ltc1867_init(void)
     data_ltc1867.calc_cnt = 0;
     data_ltc1867.calc_flag = 0; /* 2 period complete, need calc */
     data_ltc1867.ledir_cnt = 0; /* index of led count, for togglr IR led */
-    data_ltc1867.state_idx = 0; /* index for search point of 32768 */
+    data_ltc1867.sample_cnt = 0; /* index for search point of 32768 */
     for (uint8_t i = 0; i < 4; i++) {
         data_ltc1867.p_samp[i] = data_ltc1867_raw[0][i];
         data_ltc1867.p_calc[i] = data_ltc1867_raw[1][i];
@@ -173,19 +174,19 @@ uint16_t ltc1867_transfer(uint16_t data_send)
 
 void TIM2_IRQHandler(void)
 {
-    static uint16_t pre_ref = 0;
+    static uint16_t pre_ref = 65535;
     uint16_t val[LTC1867_CH_CNT];
+    float *p;
 
     TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
 
     /* for control led IR */
     data_ltc1867.ledir_cnt++;
-    if ((data_ltc1867.ledir_cnt == (SAMPLES_PER_PERIOD / 2)) || \
-        (data_ltc1867.ledir_cnt == (SAMPLES_PER_PERIOD / 2 * 3))) {
+    if (data_ltc1867.ledir_cnt == (SAMPLES_PER_PERIOD / 2)) {
         ltc1867_ledir_on();
-    } else if ((data_ltc1867.ledir_cnt == (SAMPLES_PER_PERIOD)) || \
-               (data_ltc1867.ledir_cnt == (SAMPLES_PER_PERIOD  * 2))) {
+    } else if (data_ltc1867.ledir_cnt >= SAMPLES_PER_PERIOD) {
         ltc1867_ledir_off();
+        data_ltc1867.ledir_cnt = 0;
     }
 
     /* sample 5 channel adc data */
@@ -199,77 +200,39 @@ void TIM2_IRQHandler(void)
     /* ltc1867 original sample data */
     for (uint8_t i = 0; i < 4; i++) {
         float val_f = (float)val[i]; /* convert to float */
-        data_ltc1867.p_samp[i][data_ltc1867.ledir_cnt - 1] = val_f;
+        data_ltc1867.p_samp[i][data_ltc1867.sample_cnt] = val_f;
         debug_write_data(DEBUG_CH_RAW + i, val_f);
     }
+    data_ltc1867.sample_cnt++;
+    if (data_ltc1867.sample_cnt >= LTC1867_RAW_BUFF_SIZE) {
+        data_ltc1867.sample_cnt = 0;
+    }
+
+    /* search point of 32768 */
+    if ((pre_ref < 32768) && (val[0] >= 32768)) {
+        data_ltc1867.calc_cnt++;
+        data_ltc1867.sample_rising = data_ltc1867.sample_cnt;
+        data_ltc1867.sample_cnt = 0;
+        if ((data_ltc1867.sample_falling > SAMPLES_PER_PERIOD / 16 * 7) && \
+            (data_ltc1867.sample_falling < SAMPLES_PER_PERIOD / 16 * 9) && \
+            (data_ltc1867.sample_rising > SAMPLES_PER_PERIOD / 16 * 15) && \
+            (data_ltc1867.sample_rising < SAMPLES_PER_PERIOD / 16 * 17)) {
+            /* exchange pointor of calc/samp data */
+            for (uint8_t i = 0; i < 4; i++) {
+                p = data_ltc1867.p_calc[i];
+                data_ltc1867.p_calc[i] = data_ltc1867.p_samp[i];
+                data_ltc1867.p_samp[i] = p;
+            }
+            data_ltc1867.calc_flag++; /* trig calc */
+        }
+    } else if ((pre_ref >= 32768) && (val[0] < 32768)) {
+        data_ltc1867.sample_falling = data_ltc1867.sample_cnt;
+    }
+    pre_ref = val[0];
 
     /* channel 4 for ltc1867 detector temperature sample data */
     adc_det_temp_from_ltc1867 = val[4];
 
-    /* search point of 32768 */
-    if ((pre_ref < 32768) && (val[0] >= 32768)) {
-        data_ltc1867.state_pos[data_ltc1867.state_idx] = data_ltc1867.ledir_cnt - 1;
-        data_ltc1867.state_edge[data_ltc1867.state_idx++] = 1; /* 1 for rising edge */
-    } else if ((pre_ref >= 32768) && (val[0] < 32768)) {
-        data_ltc1867.state_pos[data_ltc1867.state_idx] = data_ltc1867.ledir_cnt - 1;
-        data_ltc1867.state_edge[data_ltc1867.state_idx++] = 0; /* 0 for falling edge */
-    }
-    pre_ref = val[0];
-
-    /* 2 cycle complete */
-    if (data_ltc1867.ledir_cnt >= SAMPLES_PER_PERIOD * 2) {
-        float *p;
-        /* exchange pointor of calc/samp data */
-        for (uint8_t i = 0; i < 4; i++) {
-            p = data_ltc1867.p_calc[i];
-            data_ltc1867.p_calc[i] = data_ltc1867.p_samp[i];
-            data_ltc1867.p_samp[i] = p;
-        }
-
-        /* ledir count need empty */
-        data_ltc1867.ledir_cnt = 0;
-        data_ltc1867.calc_cnt++;
-
-        /* check whether the data meets requirements */
-        if (data_ltc1867.state_idx == 4) {
-            if ((data_ltc1867.state_pos[0] < SAMPLES_PER_PERIOD / 4)      && \
-                (data_ltc1867.state_pos[1] >= SAMPLES_PER_PERIOD / 2)     && (data_ltc1867.state_pos[1] < SAMPLES_PER_PERIOD / 4 * 3) && \
-                (data_ltc1867.state_pos[2] >= SAMPLES_PER_PERIOD)         && (data_ltc1867.state_pos[2] < SAMPLES_PER_PERIOD / 4 * 5) && \
-                (data_ltc1867.state_pos[3] >= SAMPLES_PER_PERIOD / 2 * 3) && (data_ltc1867.state_pos[3] < SAMPLES_PER_PERIOD / 4 * 7)) {
-                /* pos is head */
-                if ((data_ltc1867.state_edge[0] == 0) && (data_ltc1867.state_edge[1] == 1) && (data_ltc1867.state_edge[2] == 0) && (data_ltc1867.state_edge[3] == 1)) {
-                   data_ltc1867.state = 1;  /* first ravine late */
-                   data_ltc1867.pos_peak = data_ltc1867.state_pos[1];
-                   data_ltc1867.pos_ravine = data_ltc1867.state_pos[2];
-                   data_ltc1867.calc_flag++; /* trig calc */
-                } else if ((data_ltc1867.state_edge[0] == 1) && (data_ltc1867.state_edge[1] == 0) && (data_ltc1867.state_edge[2] == 1) && (data_ltc1867.state_edge[3] == 0)) {
-                   data_ltc1867.state = 3;  /* first peak late */
-                   data_ltc1867.pos_ravine = data_ltc1867.state_pos[1];
-                   data_ltc1867.pos_peak = data_ltc1867.state_pos[2];
-                   data_ltc1867.calc_flag++; /* trig calc */
-                }
-            } else if ((data_ltc1867.state_pos[0] >= SAMPLES_PER_PERIOD / 4)     && (data_ltc1867.state_pos[0] < SAMPLES_PER_PERIOD / 2)     && \
-                       (data_ltc1867.state_pos[1] >= SAMPLES_PER_PERIOD / 4 * 3) && (data_ltc1867.state_pos[1] < SAMPLES_PER_PERIOD)         && \
-                       (data_ltc1867.state_pos[2] >= SAMPLES_PER_PERIOD / 4 * 5) && (data_ltc1867.state_pos[2] < SAMPLES_PER_PERIOD / 2 * 3) && \
-                       (data_ltc1867.state_pos[3] >= SAMPLES_PER_PERIOD / 4 * 7) && (data_ltc1867.state_pos[3] < SAMPLES_PER_PERIOD *2)) {
-                /* pos is later */
-                if ((data_ltc1867.state_edge[0] == 0) && (data_ltc1867.state_edge[1] == 1) && (data_ltc1867.state_edge[2] == 0) && (data_ltc1867.state_edge[3] == 1)) {
-                   data_ltc1867.state = 2;  /* first peak ahead */
-                   data_ltc1867.pos_ravine = data_ltc1867.state_pos[0];
-                   data_ltc1867.pos_peak = data_ltc1867.state_pos[1];
-                   data_ltc1867.calc_flag++; /* trig calc */
-                } else if ((data_ltc1867.state_edge[0] == 1) && (data_ltc1867.state_edge[1] == 0) && (data_ltc1867.state_edge[2] == 1) && (data_ltc1867.state_edge[3] == 0)) {
-                   data_ltc1867.state = 0;  /* first ravine ahead */
-                   data_ltc1867.pos_peak = data_ltc1867.state_pos[0];
-                   data_ltc1867.pos_ravine = data_ltc1867.state_pos[1];
-                   data_ltc1867.calc_flag++; /* trig calc */
-                }
-            }
-        }
-
-        data_ltc1867.state_idx = 0;
-    }
-
     cali_flash_write();
     debug_send_frame();
 }
diff --git a/lark1fq/src/ltc1867.h b/lark1fq/src/ltc1867.h
index 36d1a68..e53c9b8 100755
--- a/lark1fq/src/ltc1867.h
+++ b/lark1fq/src/ltc1867.h
@@ -25,17 +25,14 @@
 #define PIN_SPI_SDI         (GPIO_Pin_7)
 
 struct data_ltc1867_s {
-    uint32_t calc_flag;    /* double period complete, need calc */
-    uint32_t calc_cnt;     /* totle count of double period complete */
-    uint16_t ledir_cnt;    /* index of led count, for togglr IR led */
-    uint8_t state;         /* 0~3 is available, 0:first ravine ahead, 1:first ravine late, 2:first peak ahead, 3:first peak late */
-    uint8_t state_idx;     /* 0~3 is available, sample 4 times of  point 32768 */
-    uint8_t state_edge[4]; /* 0 or 1 is available, 0:falling edge, 1:rising edge */
-    uint16_t state_pos[4]; /* position of every edge, 0~(SAMPLES_PER_PERIOD*2-1) is available */
-    uint16_t pos_ravine;   /* position of ravine */
-    uint16_t pos_peak;     /* position of peak */
-    float *p_calc[4];      /* pointor for calculation */
-    float *p_samp[4];      /* pointor for store sample data */
+    uint32_t calc_flag;      /* double period complete, need calc */
+    uint32_t calc_cnt;       /* totle count of double period complete */
+    uint16_t ledir_cnt;      /* index of led count, for togglr IR led */
+    uint16_t sample_cnt;     /* index of sample */
+    uint16_t sample_falling; /* position of falling edge */
+    uint16_t sample_rising;  /* position of rising edge, is also total sample count */
+    float *p_calc[4];        /* pointor for calculation */
+    float *p_samp[4];        /* pointor for store sample data */
 };
 
 extern struct data_ltc1867_s data_ltc1867;