The practice of doppler frequency - shift signal extraction in ultrasonic blood flow detector 多普勒頻移信號提取技術在超聲血流檢測中應用
Because frequency - shift signal is a kind of modulation signal , it ' s waveform is two ac sine signal of alternating i . e . upper frequency and lower frequency which was generated by low frequency modulating middle frequency 由于移頻信號是一種調頻信號,其波形為低頻信號調制中心載頻信號后產(chǎn)生的低端載頻(下邊頻)和高端載頻(上邊頻)兩個交替變化的正弦交流信號。