In digital television, what does a coding rate of 3/4 mean?
Answer25% of the data sent is forward error correction data
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Ham Feed
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ONLY THE RIGHT ANSWER //No distractors. No scoring. No account. Just repeated exposure to what you need to know.
What is the function of a reactance modulator?
AnswerProduce PM or FM signals by varying a capacitance
What is the difference between direct FSK and audio FSK?
AnswerDirect FSK modulates the transmitter VFO
What challenge is presented by a small wire-loop antenna for direction finding?
AnswerIt has a bidirectional null pattern
What is a use for a Wilkinson divider?
AnswerTo divide power equally between two 50-ohm loads while maintaining 50-ohm input impedance
What is the purpose of adding an inductor to a Pi-network to create a Pi-L-network?
AnswerGreater harmonic suppression
What term describing total radiated power takes into account all gains and losses?
AnswerEffective radiated power
What is the most useful characteristic of a Zener diode?
AnswerA constant voltage drop under conditions of varying current
What is the purpose of connecting Zener diodes between a MOSFET gate and its source or drain?
AnswerTo protect the gate from static damage
What is the photovoltaic effect?
AnswerThe conversion of light to electrical energy
What do the subscripts of S parameters represent?
AnswerThe port or ports at which measurements are made
What is Quadrature Amplitude Modulation or QAM?
AnswerTransmission of data by modulating the amplitude of two carriers of the same frequency but 90 degrees out of phase
What must the control operator of a repeater operating in the 70-centimeter band do if a radiolocation system experiences interference from that repeater?
AnswerCease operation or make changes to the repeater that mitigate the interference
Why are odd-order intermodulation products, created within a receiver, of particular interest compared to other products?
AnswerOdd-order products of two signals in the band being received are also likely to be within the band
What undesirable effect can occur when using a noise blanker?
AnswerStrong signals may be distorted and appear to cause spurious emissions
How does DC input impedance at the gate of a field-effect transistor (FET) compare with that of a bipolar transistor?
AnswerAn FET has higher input impedance
What do the terms “L band” and “S band” specify?
AnswerThe 23- and 13-centimeter bands
What limitations may the FCC place on an amateur station if its signal causes interference to domestic broadcast reception, assuming that the receivers involved are of good engineering design?
AnswerThe amateur station must avoid transmitting during certain hours on frequencies that cause the interference
What are “extraordinary” and “ordinary” waves?
AnswerIndependently propagating, elliptically polarized waves created in the ionosphere
How is impedance in polar form converted to an equivalent admittance?
AnswerTake the reciprocal of the magnitude and change the sign of the angle
What parasitic characteristic creates an inductor’s self-resonance?
AnswerInter-turn capacitance