串口超声测距系统工作程序，0KHz超声收发头，超声波速度补偿，温度范围：0-60度-Serial ultrasonic ranging system procedures, 0KHz ultrasonic transceiver head, ultrasonic velocity compensation, the temperature range :0-60 degree

回归轨道卫星，回归周期1天，倾角分别为60度，周期为4h。-Orbit satellites, one day return period, inclination of 60 degrees and a period of 4h.