Image rejection is an important factor in choosing the intermediate frequency of a receiver.
2.
IF increases the receiver's " image rejection " without requiring additional selectivity in the RF stage.
3.
The ability of a receiver to reject interfering signals at the image frequency is measured by the image rejection ratio.
4.
The ability of the receiver to reject this image gives the image rejection ratio ( IMRR ) of the system.
5.
IF "', the higher the IF, the farther apart these two frequencies are, and the better the image rejection.
6.
In order to suppress local oscillator leakage and provide a slight amount of image rejection, a varactor and a coil provide one stage of tracking bandpass filtering.
7.
Since the frequency separation between the bandpass and the image frequency is 2f _ \ mathrm { IF } \ !, a higher intermediate frequency improves image rejection.
8.
This image rejection filter does not need great selectivity, but as the receiver is tuned to different frequencies it must " track " in tandem with the LO.
9.
"' Double-conversion superheterodyne "': In choosing the intermediate frequency ( IF ) used in a superhet, there is a tradeoff between image rejection and selectivity.
10.
RF, but in some modern receivers ( e . g . scanners and spectrum analyzers ) a higher IF frequency is used to minimize problems with image rejection or gain the benefits of fixed-tuned stages.
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