A receiver selectivity of 2.4 kHz in the IF circuitry is optimum for what type of signals?

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Multiple Choice

A receiver selectivity of 2.4 kHz in the IF circuitry is optimum for what type of signals?

The main idea is that receiver selectivity should match the signal’s bandwidth so the desired signal passes with minimal distortion while adjacent signals are suppressed. A 2.4 kHz IF filter is ideal when the signal occupies about 2.4 kHz of spectrum, as with SSB voice. This width preserves the intelligibility of the voice while still providing some protection against neighboring channels. For CW, the signal is much narrower—only a few hundred hertz—so a 2.4 kHz filter would be wider than necessary and allow more adjacent-channel interference. DSB AM voice needs roughly 6 kHz of bandwidth to carry the full audio spectrum, so a 2.4 kHz filter would truncate part of the sidebands and degrade quality. FSK RTTY generally uses far less than 2.4 kHz of bandwidth, so a 2.4 kHz filter is wider than needed and would not be optimal for that mode either. Thus, the 2.4 kHz selectivity best matches the bandwidth of SSB voice.

The main idea is that receiver selectivity should match the signal’s bandwidth so the desired signal passes with minimal distortion while adjacent signals are suppressed. A 2.4 kHz IF filter is ideal when the signal occupies about 2.4 kHz of spectrum, as with SSB voice. This width preserves the intelligibility of the voice while still providing some protection against neighboring channels.

For CW, the signal is much narrower—only a few hundred hertz—so a 2.4 kHz filter would be wider than necessary and allow more adjacent-channel interference. DSB AM voice needs roughly 6 kHz of bandwidth to carry the full audio spectrum, so a 2.4 kHz filter would truncate part of the sidebands and degrade quality. FSK RTTY generally uses far less than 2.4 kHz of bandwidth, so a 2.4 kHz filter is wider than needed and would not be optimal for that mode either.

Thus, the 2.4 kHz selectivity best matches the bandwidth of SSB voice.

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