E7F: Frequency markers and counters: frequency divider circuits; frequency marker generators; frequency counters
What is the purpose of a prescaler circuit?
It divides a higher frequency signal so a low-frequency counter can display the operating frequency
It converts the output of a JK flip-flop to that of an RS flip-flop
It multiplies a higher frequency signal so a low-frequency counter can display the operating frequency
It prevents oscillation in a low-frequency counter circuit
Which of the following would be used to reduce a signal’s frequency by a factor of ten?
A marker generator
What is the function of a decade counter digital IC?
It produces one output pulse for every ten input pulses
It decodes a decimal number for display on a seven-segment LED display
It produces ten output pulses for every input pulse
It adds two decimal numbers together
What additional circuitry must be added to a 100-kHz crystal-controlled marker generator so as to provide markers at 50 and 25 kHz?
Two frequency multipliers
A voltage divider
Which of the following circuits can be combined to produce a 100 kHz fundamental signal with harmonics at 100 kHz intervals?
A 1 MHz oscillator and a decade counter
A 10 MHz oscillator and a flip-flop
A 1 MHz oscillator and a flip-flop
A 100 kHz oscillator and a phase detector
Which of these choices best describes a crystal marker generator?
A crystal-controlled oscillator that generates a series of reference signals at known frequency intervals
A low-stability oscillator that sweeps through a band of frequencies
An oscillator often used in aircraft to determine the craft's location relative to the inner and outer markers at airports
A crystal-controlled oscillator with an output frequency and amplitude that can be varied over a wide range
Which type of circuit would be a good choice for generating a series of harmonically related receiver calibration signals?
A crystal oscillator followed by a frequency divider
A Wein-bridge oscillator followed by a class-A amplifier
A Foster-Seeley discriminator
A phase-shift oscillator
What is one purpose of a marker generator?
To provide a means of calibrating a receiver's frequency settings
To add audio markers to an oscilloscope
To provide a frequency reference for a phase locked loop
To add time signals to a transmitted signal
What determines the accuracy of a frequency counter?
The accuracy of the time base
The speed of the logic devices used
Accuracy of the AC input frequency to the power supply
Proper balancing of the mixer diodes
How does a conventional frequency counter determine the frequency of a signal?
It counts the number of input pulses occurring within a specific period of time
It counts the total number of pulses in a circuit
It monitors a WWV reference signal for comparison with the measured signal
It converts the phase of the measured signal to a voltage which is proportional to the frequency
What is the purpose of a frequency counter?
To provide a digital representation of the frequency of a signal
To generate a series of reference signals at known frequency intervals
To display all frequency components of a transmitted signal
To provide a signal source at a very accurate frequency
What alternate method of determining frequency, other than by directly counting input pulses, is used by some frequency counters?
What is an advantage of a period-measuring frequency counter over a direct-count type?
It provides improved resolution of signals within a comparable time period
It can run on battery power for remote measurements
It does not require an expensive high-precision time base
It can directly measure the modulation index of an FM transmitter
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