Doppler frequency shift observation of ionospheric high frequency echo is an important method for studying ionospheric disturbances.
电离层高频反射回波的多普勒频移观测是研究电离层扰动的一个重要方法。
For this purpose they generate a high frequency ultrasonic pulse the echo of which is detected and evaluated by the sensor.
为此，他们产生高频率的超声波脉冲回波是由传感器检测和评估。
High frequency ground wave radar for near ocean inspection and ocean remote sensor is a method that use ocean echo wave Dopier spectrum to deduce the parameters of ocean situation.
高频地波雷达近海监测和海态遥感技术是一种利用海洋回波多普勒谱反演海态参数的方法。
Methods The manifestation, internal echo, the L/T ratio, CDFI and RI frequency spectrum feature of the superficial lymph nodes were studied with high frequency and color Doppler ultrasound 89 cases.
方法本组89例，应用高频率的彩色多谱勒超声检查肿大淋巴结的形态及内部回声、纵横比（L/T）、彩色多谱勒血流显像（CD FI）及阻力指数（RI）的频谱特征。
To suppress ionospheric clutter in the echo signal of high frequency surface wave radar (HFSWR), a method to suppress clutter based on time-frequency analysis and eigenvalue decomposition is proposed.
针对高频地波雷达回波信号中的电离层杂波，提出了利用时频分析与特征值分解抑制杂波的方法。
Besides, the target echo signal is often weak with strong noise, so data acquisition (DAQ) card should sustain high sampling frequency and resolution.
由于目标回波的低信杂比，需要采集卡具有较高的采样率和分辨率。
This paper analyzes the technology with intra-pulse chirp and inter-pulse stepped frequency to obtain high-resolution range profile. The echo expressions of static and moving targets are derived.
本文分析阐述了利用脉内调频、脉间跳频技术获取距离高分辨一维成像的可行性，导出了静止目标和运动目标的回波表达式。
This paper analyzes the technology with intra-pulse chirp and inter-pulse stepped frequency to obtain high-resolution range profile. The echo expressions of static and moving targets are derived.
本文分析阐述了利用脉内调频、脉间跳频技术获取距离高分辨一维成像的可行性，导出了静止目标和运动目标的回波表达式。
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