What is the purpose of the preselector in a communications receiver?
To store frequencies that are often used
To provide broadband attenuation before the first RF stage to prevent intermodulation
To increase the rejection of signals outside the band being received✓الإجابة الصحيحة
To allow selection of the optimum RF amplifier device
الشرح
A preselector is a tunable or band-switched filter placed ahead of the receiver's first active stage that passes the band in use and attenuates everything outside it. It is selective rather than broadband attenuation, which is what lets it reject out-of-band signals without throwing away the wanted one.