| 摘要 |
PURPOSE:To obtain a DC zero level without DC regeneration by inverting the output of a balanced modulator in place by 180 deg. every time a transmit pulse is supplied, and inverting a base band signal in polarity in every transmit sequence in response to said inversion. CONSTITUTION:The output of the 3rd balanced modulator 5 is inverted by 180 deg. every time a transmit trigger is supplied, and the polarity of the base band signal is inverted in every transmit wave sequence. Consequently, DC cutting is performed by CR coupling, etc., with performing DC regeneration specially to stabilize a DC level automatically or make the DC zero level clear in a long period of repetition. When an echo signal is used as a Doppler signal, outputs of LPFs 9a and 9b are used, but a Doppler module side fetches the output signal of an FF8 at the same time to shift in phase by 180 deg. to return to the original phase, line by line, by referring to it before use. Therefore, there is no trouble occurring when a bipolar logarithmic amplifier is used. |
