G8B-2011: Frequency mixing; multiplication; HF data communications; bandwidths of various modes; deviation
What receiver stage combines a 14.250 MHz input signal with a 13.795 MHz oscillator signal to produce a 455 kHz intermediate frequency (IF) signal?
If a receiver mixes a 13.800 MHz VFO with a 14.255 MHz received signal to produce a 455 kHz intermediate frequency (IF) signal, what type of interference will a 13.345 MHz signal produce in the receiver?
What is another term for the mixing of two RF signals?
What is the name of the stage in a VHF FM transmitter that generates a harmonic of a lower frequency signal to reach the desired operating frequency?
Why isn't frequency modulated (FM) phone used below 29.5 MHz?
The wide bandwidth is prohibited by FCC rules
The transmitter efficiency for this mode is low
Harmonics could not be attenuated to practical levels
The frequency stability would not be adequate
What is the total bandwidth of an FM-phone transmission having a 5 kHz deviation and a 3 kHz modulating frequency?
What is the frequency deviation for a 12.21-MHz reactance-modulated oscillator in a 5-kHz deviation, 146.52-MHz FM-phone transmitter?
Why is it important to know the duty cycle of the data mode you are using when transmitting?
Some modes have high duty cycles which could exceed the transmitter's average power rating.
To aid in tuning your transmitter
To allow time for the other station to break in during a transmission
All of these choices are correct
Why is it good to match receiver bandwidth to the bandwidth of the operating mode?
It results in the best signal to noise ratio
It is required by FCC rules
It minimizes power consumption in the receiver
It improves impedance matching of the antenna
What does the number 31 represent in PSK31?
The approximate transmitted symbol rate
The version of the PSK protocol
The year in which PSK31 was invented
The number of characters that can be represented by PSK31
How does forward error correction allow the receiver to correct errors in received data packets?
By transmitting redundant information with the data
By controlling transmitter output power for optimum signal strength
By using the varicode character set
By using a parity bit with each character
What is the relationship between transmitted symbol rate and bandwidth?
Higher symbol rates require higher bandwidth
Symbol rate and bandwidth are not related
Lower symbol rates require higher bandwidth
Bandwidth is constant for data mode signals
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