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A comprehensive set of questions and answers related to radio communication fundamentals. It covers various aspects of radio communication, including modulation techniques, receiver design, frequency bands, and hf systems. Valuable for students and professionals seeking to understand the principles and applications of radio communication.
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When the carrier is modulated, where is the information located? --------- CORRECT ANSWER-----------------Upper and lower sidebands of composite signal What is the difference frequency known as? ---------CORRECT ANSWER--- --------------Intermediate Frequency What is the receivers ability to faithfully reproduce a desired signal is based on what two things? ---------CORRECT ANSWER-----------------Its sensitivity and selectivity What does Phase Lock Loop do? ---------CORRECT ANSWER----------------- Compares output of VCO with a reference frequency What happens if the output of VCO is different than the reference frequency? ---------CORRECT ANSWER-----------------DC controlling voltage is generated to steer VCO to correct output What frequency range do AM broadcasts use? ---------CORRECT ANSWER----------------- 535 - 1605 kHz
What are two types of AM receiver tuning? ---------CORRECT ANSWER----- ------------Synthesized and manual What are two types of synthesized tuning? ---------CORRECT ANSWER----- ------------Direct and indirect synthesis What are 4 components of PLL? ---------CORRECT ANSWER----------------- Phase detector, loop filter, VCO, and frequency counter/divider What are 3 benefits of synthesized tuning? ---------CORRECT ANSWER---- -------------Greater freq stability, freq changed electronically, reduced cost, smaller size What type of tuning incorporates PLL and VCO to provide desired frequency? ---------CORRECT ANSWER-----------------Indirect synthesis What is amplitude modulation? ---------CORRECT ANSWER----------------- Information is encoded into carrier wave by varying RF carriers amplitude and maintaining constant frequency AM IF signal is at what frequency? ---------CORRECT ANSWER--------------- --455 kHz FM IF signal is at what frequency? ---------CORRECT ANSWER--------------- --10 MHz
What type of SSB has two sidebands that can each carry completely different intelligence? - --------CORRECT ANSWER-----------------ISB What is the purpose of balanced modulator? ---------CORRECT ANSWER-- ---------------Eliminates/suppresses carrier What is the heart of sideband generation? ---------CORRECT ANSWER----- ------------Balanced modulator What are 3 methods for SSB generation? ---------CORRECT ANSWER------ -----------Filter method, phase method, Third/Weaver method What is a unique aspect of SSB? ---------CORRECT ANSWER----------------- Must recreate carrier in order for intel to be detected What frequency range is used by CB? ---------CORRECT ANSWER----------- ------26.965-27.405 MHz What is heterodyning? ---------CORRECT ANSWER-----------------Combining 2 frequencies to convert to new frequency without altering intel in original SSB is not _____ dependent ---------CORRECT ANSWER----------------- Phase
What are two types of AGC? ---------CORRECT ANSWER----------------- Carrier and Audio derived What is the bandwidth of HF? ---------CORRECT ANSWER----------------- 3MHz to 30MHz What is the purpose of the HF system? ---------CORRECT ANSWER--------- --------Allows long range high frequency surface to surface, surface to air, air to air, air to surface, two way comms and data comms at LOS and over horizon What are 4 modes of operation of HF system? ---------CORRECT ANSWER-----------------AM, AME, USB, LSB What is the most common HF mode of operation? ---------CORRECT ANSWER-----------------USB What type of HF causes large bandwidth and large power consumption? --- ------CORRECT ANSWER-----------------AM What type of HF has the carrier reinserted prior to transmission? --------- CORRECT ANSWER-----------------AME
FM guard bands are _____ kHz at upper and lower boundary of each channel and guard against interference ---------CORRECT ANSWER--------- --------24kHz What are two types of FM generation? ---------CORRECT ANSWER---------- -------Direct (capacitor) and indirect (phase modulation) What are the primary advantages of FM? ---------CORRECT ANSWER------- ----------Greater noise suppression, high fidelity (stereo) reception, less interference (limits capture effect), reduced transmitter power to cover assigned area What are two types of phase detectors? ---------CORRECT ANSWER-------- ---------Sequential (digital) and Multiplier (no memory) What is the a general rule of thumb regarding the sun and frequency? ------- --CORRECT ANSWER-----------------The higher the sun the higher the frequency FM has a carrier and a _____ number of sidebands ---------CORRECT ANSWER-----------------Infinite FM sidebands have _____ amplitudes and are always an _____ distance from center (carrier) frequency ---------CORRECT ANSWER----------------- equal amplitude, equal distance from carrier
What is the bandwidth of narrow band FM? ---------CORRECT ANSWER---- -------------10 to 30 kHz Why is NBFM reduced bandwidth? ---------CORRECT ANSWER--------------- --To accommodate signal/voice transmissions What is primary advantage of NBFM? ---------CORRECT ANSWER----------- ------RF spectrum conservation What are four steps of TS NBFM? ---------CORRECT ANSWER----------------