Radio frequency receiver for nmr-device

PURPOSE: To eliminate any unnecessary signal of a frequency which is not transmitting any information by performing an orthogonal detection by two digital signal processors for preparing the orthogonal signals of a normal (I) and (Q), and filtering digitally the waves of the signal samples of (I) and (Q). CONSTITUTION: The NMR-signal dispatched from a patient is picked up by a receiving coil 138, and impressed into the input of a receiver 207. The receiver 207 amplifies the NMR-signal, the NMR-signal is damped to the extent of a determined amount by a digital damping signal (RA) received through a link 103 from a main computer. The receiver 207 is made on-off according to a signal received from a pulse code modulation(PCM) through a line 211. By this, the NMR signal is obtained during the period of obtaining a specified signal under the operation. A received high frequency signal is filtrated and recovered by two step processes in a recovering device 208. An analogue/digital convertor 209 digitizes the sampling of the analogue signal by the rate of 250kHz. The output of the A/D convertor 209 is impressed into a digital orthogonal detector 210. COPYRIGHT: (C)1991,JPO