E4E01:

What problem can occur when using an automatic notch filter (ANF) to remove interfering carriers while receiving CW signals?

1. Removal of the CW signal as well as the interfering carrier
2. Any nearby signal passing through the DSP system will overwhelm the desired signal
3. Received CW signals will appear to be modulated at the DSP clock frequency
4. Ringing in the DSP filter will completely remove the spaces between the CW characters

E4E02:

Which of the following types of noise can often be reduced with a digital signal processing noise filter?

1. Broadband white noise
2. Ignition noise
3. Power line noise
4. All these choices are correct

E4E03:

Which of the following signals might a receiver noise blanker be able to remove from desired signals?

1. Signals that are constant at all IF levels
2. Signals that appear across a wide bandwidth
3. Signals that appear at one IF but not another
4. Signals that have a sharply peaked frequency distribution

E4E04:

How can conducted and radiated noise caused by an automobile alternator be suppressed?

1. By installing filter capacitors in series with the DC power lead and a blocking capacitor in the field lead
2. By installing a noise suppression resistor and a blocking capacitor in both leads
3. By installing a high-pass filter in series with the radio's power lead and a low-pass filter in parallel with the field lead
4. By connecting the radio's power leads directly to the battery and by installing coaxial capacitors in line with the alternator leads

E4E05:

How can radio frequency interference from an AC motor be suppressed?

1. By installing a high-pass filter in series with the motor's power leads
2. By installing a brute-force AC-line filter in series with the motor leads
3. By installing a bypass capacitor in series with the motor leads
4. By using a ground-fault current interrupter in the circuit used to power the motor

E4E06:

What is one type of electrical interference that might be caused by a nearby personal computer?

1. A loud AC hum in the audio output of your station receiver
2. A clicking noise at intervals of a few seconds
3. The appearance of unstable modulated or unmodulated signals at specific frequencies
4. A whining type noise that continually pulses off and on

E4E07:

Which of the following can cause shielded cables to radiate or receive interference?

1. Low inductance ground connections at both ends of the shield
2. Common-mode currents on the shield and conductors
3. Use of braided shielding material
4. Tying all ground connections to a common point resulting in differential-mode currents in the shield

E4E08:

What current flows equally on all conductors of an unshielded multi-conductor cable?

1. Differential-mode current
2. Common-mode current
3. Reactive current only
4. Return current

E4E09:

What undesirable effect can occur when using an IF noise blanker?

1. Received audio in the speech range might have an echo effect
2. The audio frequency bandwidth of the received signal might be compressed
3. Nearby signals may appear to be excessively wide even if they meet emission standards
4. FM signals can no longer be demodulated

E4E10:

What might be the cause of a loud roaring or buzzing AC line interference that comes and goes at intervals?

1. Arcing contacts in a thermostatically controlled device
2. A defective doorbell or doorbell transformer inside a nearby residence
3. A malfunctioning illuminated advertising display
4. All these choices are correct

E4E11:

What could cause local AM broadcast band signals to combine to generate spurious signals in the MF or HF bands?

1. One or more of the broadcast stations is transmitting an over-modulated signal
2. Nearby corroded metal joints are mixing and re-radiating the broadcast signals
3. You are receiving skywave signals from a distant station
4. Your station receiver IF amplifier stage is defective