A-005 — Transmitters, modulation and processing

Transmitters, modulation and processing: AM, FM, SSB, keying, speech processing, and the numbers behind occupied bandwidth.

All 99 questions

• A-005-001-001 How is the positive feedback coupled to the input in a Hartley oscillator?
• A-005-001-002 How is positive feedback coupled to the input in a Colpitts oscillator?
• A-005-001-003 How is positive feedback coupled to the input in a Pierce oscillator?
• A-005-001-004 Why is the Colpitts oscillator circuit commonly used in a VFO?
• A-005-001-005 Why must a very stable reference oscillator be used as part of a phase-locked loop (PLL) frequency synthesizer?
• A-005-001-006 Positive feedback from a capacitive divider indicates the oscillator type is:
• A-005-001-007 In an RF oscillator circuit designed for high stability, the positive feedback is drawn from two capacitors connected in series. These two capacitors would most likely be:
• A-005-001-008 In an oscillator circuit where positive feedback is obtained through a single capacitor in series with the crystal, the type of oscillator is:
• A-005-001-009 A circuit depending on positive feedback for its operation would be a:
• A-005-001-010 An apparatus with an oscillator and a class C amplifier would be:
• A-005-001-011 In an oscillator where positive feedback is provided through a capacitor in series with a crystal, that type of oscillator is a:
• A-005-002-001 The output tuning controls on a transmitter power amplifier with an adjustable PI network:
• A-005-002-002 The purpose of using a centre-tap return connection on the secondary of transmitting tube's filament transformer is to:
• A-005-002-003 In a grounded grid amplifier using a triode vacuum tube, the input signal is applied to:
• A-005-002-004 In a grounded grid amplifier using a triode vacuum tube, the plate is connected to the pi-network through a:
• A-005-002-005 In a grounded grid amplifier using a triode vacuum tube, the plate is connected to a radio frequency choke. The other end of the radio frequency choke connects to the:
• A-005-002-006 In a grounded grid amplifier using a triode vacuum tube, the cathode is connected to a radio frequency choke. The other end of the radio frequency choke connects to the:
• A-005-002-007 In a grounded grid amplifier using a triode vacuum tube, the secondary winding of a transformer is connected directly to the vacuum tube. This transformer provides:
• A-005-002-008 In a grounded grid amplifier using a triode vacuum tube, what would be the approximate B+ voltage required for an output of 400 watts at 400 mA with approximately 50 percent efficiency?
• A-005-002-009 In a grounded grid amplifier using a triode vacuum tube, each side of the filament is connected to a capacitor whose other end is connected to ground. These are:
• A-005-002-010 After you have opened a VHF power amplifier to make internal tuning adjustments, what should you do before you turn the amplifier on?
• A-005-002-011 Harmonics produced in an early stage of a transmitter may be reduced in a later stage by:
• A-005-003-001 In a simple 2 stage CW transmitter circuit, the oscillator stage and the class C amplifier stage are inductively coupled by a RF transformer. Another role of the RF transformer is to:
• A-005-003-002 In a simple 2 stage CW transmitter, current to the collector of the transistor in the class C amplifier stage flows through a radio frequency choke (RFC) and a tapped inductor. The RFC, on the tapped inductor side, is also connected to grounded capacitors. The purpose of the RFC and capacitors is to:
• A-005-003-003 In a simple 2 stage CW transmitter, the transistor in the second stage would act as:
• A-005-003-004 An advantage of keying the buffer stage in a transmitter is that:
• A-005-003-005 As a power amplifier is tuned, what reading on its grid current meter indicates the best neutralization?
• A-005-003-006 What does a neutralizing circuit do in an RF amplifier?
• A-005-003-007 What is the reason for neutralizing the final amplifier stage of a transmitter?
• A-005-003-008 Parasitic oscillations are usually generated due to:
• A-005-003-009 Parasitic oscillations would tend to occur mostly in:
• A-005-003-010 Why is neutralization necessary for some vacuum-tube amplifiers?
• A-005-003-011 Parasitic oscillations in an RF power amplifier may be caused by:
• A-005-004-001 What type of signal does a balanced modulator produce?
• A-005-004-002 How can a single-sideband phone signal be produced?
• A-005-004-003 Carrier suppression in a single-sideband transmitter takes place in:
• A-005-004-004 Transmission with SSB, as compared to conventional AM transmission, results in:
• A-005-004-005 The peak power output of a single-sideband transmitter, when being tested by a two-tone generator is:
• A-005-004-006 What kind of input signal is used to test the amplitude linearity of a single-sideband phone transmitter while viewing the output on an oscilloscope?
• A-005-004-007 When testing the amplitude linearity of a single-sideband transmitter what audio tones are fed into the microphone input and on what kind of kind of instrument is the output observed?
• A-005-004-008 What audio frequencies are used in a two-tone test of the linearity of a single-sideband phone transmitter?
• A-005-004-009 What measurement can be made of a single-sideband phone transmitter's amplifier by performing a two-tone test using an oscilloscope?
• A-005-004-010 How much is the carrier suppressed below peak output power in a single-sideband phone transmission?
• A-005-004-011 What is meant by "flat topping" in a single-sideband phone transmission?
• A-005-005-001 In an FM phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency, what is the modulation index, when the modulating frequency is 1000 Hz?
• A-005-005-002 What is the modulation index of an FM phone transmitter producing an instantaneous carrier deviation of 6 kHz when modulated with a 2 kHz modulating frequency?
• A-005-005-003 What is the deviation ratio of an FM phone transmitter having a maximum frequency swing of plus or minus 5 kHz and accepting a maximum modulation rate of 3 kHz?
• A-005-005-004 What is the deviation ratio of an FM phone transmitter having a maximum frequency swing of plus or minus 7.5 kHz and accepting a maximum modulation rate of 3.5 kHz?
• A-005-005-005 When the transmitter is not modulated, or the amplitude of the modulating signal is zero, the frequency of the carrier is called its:
• A-005-005-006 In an FM transmitter system, the amount of deviation from the centre frequency is determined solely by the:
• A-005-005-007 Any FM wave with single-tone modulation has:
• A-005-005-008 Some types of deviation meters work on the principle of:
• A-005-005-009 When using some deviation meters, it is important to know:
• A-005-005-010 What is the significant bandwidth of an FM-phone transmission having a +/- 5-kHz deviation and a 3-kHz modulating frequency?
• A-005-005-011 What is the frequency deviation for a 12.21- MHz reactance-modulated oscillator in a +/- 5-kHz deviation, 146.52-MHz FM-phone transmitter?
• A-005-006-001 If the signals of two repeater transmitters mix together in one or both of their final amplifiers and unwanted signals at the sum and difference frequencies of the original signals are generated and radiated, what is this called?
• A-005-006-002 How does intermodulation interference between two repeater transmitters usually occur?
• A-005-006-003 How can intermodulation interference between two repeater transmitters in close proximity often be reduced or eliminated?
• A-005-006-004 If a receiver tuned to 146.70 MHz receives an intermodulation product signal whenever a nearby transmitter transmits on 146.52, what are the two most likely frequencies for the other interfering signal?
• A-005-006-005 What type of circuit varies the tuning of an amplifier tank circuit to produce FM signals?
• A-005-006-006 What audio shaping network is added at an FM transmitter to attenuate the lower audio frequencies?
• A-005-006-007 Which type of filter would be best to use in a 2-metre repeater duplexer?
• A-005-006-008 The characteristic difference between a phase modulator and a frequency modulator is:
• A-005-006-009 In most modern FM transmitters, to produce a better sound, a compressor and a clipper are placed:
• A-005-006-010 Three important parameters to be verified in an FM transmitter are:
• A-005-006-011 Intermodulation interference products are not typically associated with which of the following:
• A-005-007-001 Maintaining the peak RF output of a SSB transmitter at a relatively constant level requires a circuit called the:
• A-005-007-002 Speech compression associated with SSB transmission implies:
• A-005-007-003 Which of the following functions is not included in a typical digital signal processor?
• A-005-007-004 How many bits are required to provide 256 discrete levels, or a ratio of 256:1?
• A-005-007-005 Adding one bit to the word length, is equivalent to adding ____ dB to the dynamic range of the digitizer:
• A-005-007-006 What do you call the circuit which employs an analog to digital converter, a mathematical transform, a digital to analog converter and a low pass filter?
• A-005-007-007 Which principle is not associated with analog signal processing?
• A-005-007-008 Which of the following is not a method used for peak limiting, in a signal processor?
• A-005-007-009 What is the undesirable result of AF clipping in a speech processor?
• A-005-007-010 Which description is not correct? You are planning to build a speech processor for your transceiver. Compared to AF clipping, RF clipping:
• A-005-007-011 Automatic Level Control (ALC) is another name for:
• A-005-008-001 What digital code consists of elements having unequal length?
• A-005-008-002 Open Systems Interconnection (OSI) model standardizes communications functions as layers within a data communications system. Amateur digital radio systems often follow the OSI model in structure. What is the base layer of the OSI model involving the interconnection of a packet radio TNC to a computer terminal?
• A-005-008-003 What is the purpose of a Cyclic Redundancy Check (CRC)?
• A-005-008-004 What is one advantage of using ASCII rather than Baudot code?
• A-005-008-005 What type of error control system is used in AMTOR ARQ (Mode A)?
• A-005-008-006 What error-correction system is used in AMTOR FEC (Mode B)?
• A-005-008-007 APRS (Automatic Packet Reporting System) does NOT support which one of these functions?
• A-005-008-008 Which algorithm may be used to create a Cyclic Redundancy Check (CRC)?
• A-005-008-009 The designator AX.25 is associated with which amateur radio mode?
• A-005-008-010 How many information bits are included in the Baudot code?
• A-005-008-011 How many information bits are included in the ISO-8859 extension to the ASCII code?
• A-005-009-001 What term describes a wide-band communications system in which the RF carrier varies according to some predetermined sequence?
• A-005-009-002 What is the term used to describe a spread spectrum communications system where the centre frequency of a conventional carrier is changed many times per second in accordance with a pseudorandom list of channels?
• A-005-009-003 What term is used to describe a spread spectrum communications system in which a very fast binary bit stream is used to shift the phase of an RF carrier?
• A-005-009-004 Frequency hopping is used with which type of transmission?
• A-005-009-005 Direct sequence is used with which type of transmission?
• A-005-009-006 Which type of signal is used to produce a predetermined alteration in the carrier for spread spectrum communication?
• A-005-009-007 Why is it difficult to monitor a spread spectrum transmission?
• A-005-009-008 What is frequency hopping spread spectrum?
• A-005-009-009 What is direct-sequence spread spectrum?
• A-005-009-010 Why are received spread-spectrum signals so resistant to interference?
• A-005-009-011 How does the spread-spectrum technique of frequency hopping work?