Figure 2.

Scanner receiver dynamic response to a continuous RF signal from a synthesizer. a. The response of the ³¹P channel of the Siemens Trio 3T scanner receiver to which a continuous wave fixed amplitude signal was applied from a synthesizer. The attenuated output of the synthesizer was applied to the point at which the RF coil is connected, the transmitter was disconnected, and an acquisition was conducted. The receiver is completely blocked 185 μs after the receiver was turned on and is completely recovered after about 275 μs. b. Using the frequency converter scheme which detects the ³¹P signal via the proton channel of the scanner (see the text and Figure 3), receiver blocking is reduced to about 5 μs.