Abstract: A diversity receiver switches between at least two antennae when the noise level of a processed receiver signal exceeds a predetermined level. A diversity circuit extracts the noise from the receiver signal with a bandpass filter and compares the level of the noise to the predetermined level. When the noise exceeds the predetermined level, the diversity circuit sends a command signal to switching circuitry to switch from the antenna currently responsible for the receiver signal to another antenna. If the noise in the receiver signal indicative of the signal received by the now-coupled antenna still exceeds the predetermined level, then the switching circuitry continues to switch between antennae until an acceptable noise level is achieved. A sync separator circuit may be provided if antenna switching is desired during the vertical or horizontal blanking intervals.

Abstract: An improved Nuclear Magnetic Resonance (NMR)/Magnetic Resonance Imaging (MRI) Pulse Amplifier uses fast acting Radio Frequency (RF) switches with a fixed or programmable attenuator to achieve fast blanking speed, low blanked noise and a low power mode, previously unavailable with existing amplifiers.