2015-G4C: Interference with consumer electronics; grounding; DSP
Which of the following might be useful in reducing RF interference to audio frequency devices?
Which of the following could be a cause of interference covering a wide range of frequencies?
Arcing at a poor electrical connection
Not using a balun or line isolator to feed balanced antennas
Lack of rectification of the transmitter's signal in power conductors
Using a balun to feed an unbalanced antenna
What sound is heard from an audio device or telephone if there is interference from a nearby single sideband phone transmitter?
A steady hum whenever the transmitter is on the air
On-and-off humming or clicking
Clearly audible speech
What is the effect on an audio device or telephone system if there is interference from a nearby CW transmitter?
On-and-off humming or clicking
A CW signal at a nearly pure audio frequency
A chirpy CW signal
Severely distorted audio
What might be the problem if you receive an RF burn when touching your equipment while transmitting on an HF band, assuming the equipment is connected to a ground rod?
The ground wire has high impedance on that frequency
Flat braid rather than round wire has been used for the ground wire
Insulated wire has been used for the ground wire
The ground rod is resonant
What effect can be caused by a resonant ground connection?
High RF voltages on the enclosures of station equipment
Overheating of ground straps
Corrosion of the ground rod
A ground loop
What is one good way to avoid unwanted effects of stray RF energy in an amateur station?
Connect all equipment grounds together
Install an RF filter in series with the ground wire
Use a ground loop for best conductivity
Install a few ferrite beads on the ground wire where it connects to your station
Which of the following would reduce RF interference caused by common-mode current on an audio cable?
Placing a ferrite choke around the cable
Adding series capacitors to the conductors
Adding shunt inductors to the conductors
Adding an additional insulating jacket to the cable
How can a ground loop be avoided?
Connect all ground conductors to a single point
Connect all ground conductors in series
Connect the AC neutral conductor to the ground wire
Avoid using lock washers and star washers when making ground connections
What could be a symptom of a ground loop somewhere in your station?
You receive reports of "hum" on your station's transmitted signal
The SWR reading for one or more antennas is suddenly very high
An item of station equipment starts to draw excessive amounts of current
You receive reports of harmonic interference from your station
Which of the following is a function of a digital signal processor?
To remove noise from received signals
To provide adequate grounding
To increase antenna gain
To increase antenna bandwidth
Which of the following is an advantage of a receiver DSP IF filter as compared to an analog filter?
A wide range of filter bandwidths and shapes can be created
Fewer digital components are required
Mixing products are greatly reduced
The DSP filter is much more effective at VHF frequencies
Which of the following can perform automatic notching of interfering carriers?
A Digital Signal Processor (DSP) filter
A noise limiter
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