[SOLVED] ultrasonic reading error

#include<stdio.h>
#include <string.h>
#include"uart.h"


#define _XTAL_FREQ 20000000
#define trigger RD2
#define echo RD3


void port_init()
{
   TRISA1=0;
   TRISD3=0XFF; //echo
   TRISD2=0X00; //trigger
   T1CON = 0x80; 
   TMR1IF = 0;
   TMR1=0; 
}
void delay(unsigned int de)
{
    unsigned int maxde,minde;
    for(maxde=0;maxde<de;maxde++)
        for(minde=0;minde<453;minde++);
}
void Delay10Us()
{
    int dCnt;
    for(dCnt=0;dCnt<3;dCnt++);
}
void trigger_US()
{
    trigger=1;
      __delay_us(10);
    trigger=0;
    __delay_us(10);
    while(echo == 0);
    TMR1=0;
    TMR1ON=1;
    while(echo == 1 && !TMR1IF);
    Time=TMR1;
    TMR1ON=0;
    Distance = ((float)Time/117.00); 
}




void main()
{
    port_init();
    port1_init();
    UART_init();


   while(1)
   {
       RA1=1;  //led on
       delay(2000);
       RA1=0;    // led off
       delay(2000);
       trans_string("\n test");   // test uart
       trigger_US();
       sprintf(Total_distance,"%.03f",Distance);
       trans_string(Total_distance);
   }
}