| 摘要 |
A radio frequency receiver wherein received signals are directed to a mixer through a pair of signal channels, the bandwidth of one of the pair of signal channels being a selected narrow portion of the bandwidth of the other one of the pair of signal channels. With such arrangement a received signal within a wide band of frequencies is passed to the mixer through both channels to become homodyned to a fixed intermediate frequency signal. Noise received by the wide bandwidth receiver while also passed through the both channels is mixed with only a narrow portion of itself, and hence the amount of noise at the fixed intermediate frequency is reduced with the result that the sensitivity of the receiver is correspondingly increased. An instantaneous frequency measuring unit is also fed by the selected narrow portion of the wide bandwidth signal channel to determine the frequency of the received signal with improved sensitivity.
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