Subelement F: Receivers— Topic 45: IF Amplifiers
Question 3-45F3
Element 3 (GROL)A receiver selectivity of 2.4 kHz in the IF circuitry is optimum for what type of signals?
Explanation
A 2.4 kHz receiver selectivity is optimum for SSB (Single Sideband) voice because it closely matches the typical bandwidth of a human voice signal. SSB transmissions efficiently convey voice information within approximately 2.4 to 2.7 kHz, which includes the critical audio frequencies for clear communication. A 2.4 kHz filter effectively passes this full voice range while rejecting noise and interference from signals outside this bandwidth, maximizing the signal-to-noise ratio and audio fidelity.
For CW (Morse code), 2.4 kHz is far too wide; CW signals are very narrow, typically 50-500 Hz. Double-sideband AM voice signals require about 6 kHz of bandwidth (twice the audio bandwidth), so a 2.4 kHz filter would severely clip and distort them. FSK RTTY signals are also relatively narrow, ranging from a few hundred Hz to around 1 kHz, making 2.4 kHz generally too wide.
Related Questions
3-45F1 What degree of selectivity is desirable in the IF circuitry of a wideband FM phone receiver?3-45F2 Which one of these filters can be used in micro-miniature electronic circuits?3-45F4 A receiver selectivity of 10 KHz in the IF circuitry is optimum for what type of signals?3-45F5 What is an undesirable effect of using too wide a filter bandwidth in the IF section of a receiver?3-45F6 How should the filter bandwidth of a receiver IF section compare with the bandwidth of a received signal?