Some microphones have an adjustable gain control. Some radios have an internal gain control to trim the audio gain of the microphone. If the gain is set too high it can exceed the range that circuitry can handle and will cause the audio signal to be distorted. Distortion might be fine for your old tube type guitar amplifier but it will render your signal quality as unreadable.

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Tags: troubleshooting noise and interference arrl chapter 5 arrl module 11

VFO means Variable Frequency Oscillator; back in the time of crystals you often had to "program" a radio by changing crystals in the radio and then using a knob to select them. Modern radios are much easier to set up; most of them you can simply type in the frequency you want on the keypad. Some lack a keypad, but have a "tuning knob", or "VFO knob". Many have both options, since each has its uses.

CTCSS refers to a subaudible tone (also called a PL tone or a privacy code by FRS manufacturers) and DTMF tones are the tones generated when you press a key on your telephone; neither has anything to do with entering the operating frequency. Automatic Frequency Control keeps the receiver tuned to an incoming signal - thus it is not a method of entering an operating frequency.

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Tags: radio operation arrl chapter 5 arrl module 11

The squelch option on a radio is meant to suppress or mute sound when transmissions are not being received. This works by muting the receiver until a received signal strength exceeds the squelch setting. If the squelch is all the way down (i.e. receiver is never muted), then received transmissions of any strength will be heard on your transceiver, including weak FM signals with low output power.

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The ability of most radios to store/program and recall our favorite frequencies gives us quick access to them. These memories can be programmed with more than just the frequency that is needed. For example to reach a repeater we need the correct frequency, input offset frequency and CTCSS tone.

The distractor answers may sound right but remember the key words here are frequency, which is found in the question and correct answer, quick and memory. A good memory is important to get the right frequency recalled quickly.

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Tags: radio operation arrl chapter 5 arrl module 11

A scanning function is useful for scanning through a range of frequencies to check for activity. None of the other options have anything to do with scanning.

The scanning feature on a radio will rapidly switch receive frequencies automatically, pausing on each frequency for only a fraction of a second to see if a carrier signal is present indicating that someone is actively transmitting on that frequency. If no carrier is present on a frequency it continues to the next one.

If a carrier is present on a frequency then the action taken is usually user-configurable. Scanning features can typically be configured to stop on the frequency until manually told to continue, to stop for only a few seconds, or stop for as long as the carrier signal remains then continue. More sophisticated scanning features may have more advanced options. Scanners can often be configured to scan a list of specific frequencies (such as repeaters) rather than an incremental range.

As you can imagine, this can be very useful for finding other operators to communicate with when you have no idea what frequency they might be transmitting on.

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RIT stands for Receiver Incremental Tuning. It is a fine tuning control to adjust the receiver frequency without adjusting the transmitter frequency.

While SSB is a very efficient transmission mode, everyone ends up sounding somewhat like Donald Duck. This is due to the fact that the transmit carrier frequency is missing. RIT Stands for Receiver Incremental Tuning which in effect, recreates the signal's missing carrier transmit frequency. When the RIT adjustment is misadjusted, the result can be a voice which is too high or too low sounding. Adjust the RIT until the voice sounds correct. Keep in mind some people have naturally higher voices than others. The direction you adjust the RIT will be in opposite directions for upper sideband (USB) vs. lower sideband (LSB), SSB signals.

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Tags: radio operation hf arrl chapter 5 arrl module 11

A "code plug" contains the programming information for a DMR-capable radio. This programming information contains programmed channels, frequencies, and tones required to communicate through a repeater and into talkgroups. A code plug is generally unique to a specific model of radio.

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What is the advantage of having multiple receive bandwidth choices on a multimode transceiver?

Different modes use different amounts of bandwidth; if you are using a narrow receive bandwidth and the mode is wide FM, you will only "hear" a portion of the signal. On the other hand if you're using a wide FM receive bandwidth and the mode is narrow FM, you may not be able to make out the signal at all and there could be interference from other stations on nearby frequencies. The best signal will be experienced when the receiver is expecting the same amount of bandwidth that the transmitter is transmitting.

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Tags: radio operation bandwidth noise and interference hf arrl chapter 5 arrl module 11

There is probably some room for argument on this question, since it tries to be generic to all digital voice modes -- but keep in mind it's talking about the most common case.

The key here is "digital voice", so selecting stations is not usually going to be just a question of checking frequencies. Similarly since it's digital you don't use a CTCSS tone -- those are used for analog conversations. Automatic identification is a real and a cool thing with digital voice, but it is not going to affect what stations you are talking to!

Digital Voice indicates a mode where the audio (voice) is encoded into a digital format and transmitted using some kind of digital modulation -- think old-school modems, though it's a bit more advanced than that. If you listen with an analog transceiver you'll hear "computer tones" that you can't understand. Because it's digital the transmitter can encode a lot of extra information with the signal, including things like a group code, your call sign, etc.

Common practice for digital voice operation is to have some kind of group identification code which is entered into the transmitter and sent with the signal; whatever is listening on the other side (usually a repeater or hotspot) then looks at that and decides where to send the signal.

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SSB is Single Sideband From HamUniverse.com

The information contained in the average human voice needed to understand the voice is contained within about the first 3000hz of the human hearing range. Frequencies of the human voice beyond this range are not needed for communication purposes and are filtered out in the modulation process. So the average bandwidth of a SSB signal is about 3000hz wide with all of the voice characteristics needed within that range to be understandable.

Hearing Frequency Range Starting with the main frequency range, it is the frequency range of human hearing, which is responsible for the perception of speech. It covers the frequencies from 300 to 3000 Hz. The range of frequencies in which the intelligibility and the recognition of the tuning characteristics are concerned is between the above mentioned frequency. This frequency range is used for voice communication in telephony and is the range the human ear is the most sensitive. Because of this, a 2400Hz filter will generally leave enough of the voice characteristics to be understandable but filter out much of the noise. (See also http://www.seaindia.in/blog/human-voice-frequency-range/)

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Tags: filters ssb noise and interference hf arrl chapter 5 arrl module 11

D-Star is a digital protocol and encodes your call sign into every transmission, which technically means that voice identification is not needed. Because of this you must program the call sign before transmitting because otherwise you're transmitting without identifying.

That is clear to most people, but many get thrown off thinking that all of the answers may be correct, so let's look at the distractors:

• D-Star always uses the same codec, it can't be changed -- just that is enough to show that it can't be "all these choices". The codec is the component (software or hardware) which encodes your analog voice audio into digital data for transmission.
• The output power is something you may want to set, but it's not something you must set -- any output power that a d-star capable radio can put out will be legal to use.

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If you've ever used a manually tuned FM radio receiver (e.g. in a vehicle) you've experienced this where as you tune up the signal becomes more clear the closer to the exact frequency you get. Other types of modulation give you a change in audio pitch (such as AM or SSB) but with FM it just affects how much of the full signal you receive -- the more you receive the more clear the signal is.

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