II-D. Digital instrumentation Flashcards
Which of the following converts an analog signal into a series of digital binary numbers?
A) Fast Fourier Transform
B) Impedance Meter
C) Differential Amplifier
D) A/D Converter
A/D Converter
What happens when a 60 cycle sine wave is sampled at 100 hertz?
A) digital filtering
B) subharmonic responce
C) aliasing
D) overlap of data
aliasing
Clipping of the waveforms occurs when:
A) the sensitivity is set too low, i.e. 20 uV/mm
B) the signal is aliased
C) the sampling rate is too fast
D) the signal is outside the range of the digitizer
the signal is outside the range of the digitizer
Which of the following settings is most sensitive?
A) 2 mV/cm
B) 5 uV/mm
C) 2 uV/mm
D) 5 mV/cm
2 uV/mm
The waveforms contain frequencies as high as 100 hertz. What is the Nyquist sampling rate?
A) 50 samples/second
B) 25 samples/second
C) >200 samples/second
D) >100 samples/second
> 200 samples/second
VOLTAGE RESOLUTION
A) horizontal sampling rate
B) frequency resolution
C) Analog-to-digital converter
D) bandwidth
Analog-to-digital converter
Which of the following instrumentation setting change may result in the elimination of cortical spikes?
A) Change the LFF from 1 Hz to 0.1 Hz
B) Change the HFF from 70 Hz to 100 Hz
C) Change the LFF from 1 Hz to 5 Hz
D) Change the HFF from 70 Hz To 15 Hz
Change the HFF from 70 Hz To 15 Hz
Which of the following instruments magnifies the common-mode voltage difference between two inputs?
A) A/D Converter
B) Differential Amplifier
C) Fast Fourier Transform
D) Impedance Meter
Differential Amplifier
EEG amplifiers work on the principle(s) of
A) differential discrimination
B) differentiation and amplification
C) aliasing
D) amplification
differentiation and amplification.
The sharpness of the frequency response curve is determined by the filter
A) rolloff
B) capacitance
C) bandwidth
D) notch
rolloff.
Which of the following is the most appropriate sampling rate that should be used for a HFF setting of 70 Hz, according to ACNS 2016 Guidelines?
A) 210 samples per second
B) 140 samples per second
C) 30 samples per second
D) 256 samples per second
256 samples per second
With high frequency filtering, muscle artifact may become distorted and look like
A) lambda activity
B) theta activity
C) beta acitivity
D) alpha
beta activity
A 0.5 Hz wave is enhanced without affecting a spike by using
A) LF 0.3 Hz
B) LF 1 Hz
C) HF 35 Hz
D) LF 5 Hz
LF 0.3 Hz
According to the Guidelines, how many bits of resolution is required?
A) 10
B) 8
C) 16
D) 13
16
Which of the following is not useful in digital EEG recordings?
A) balance of electrode impedances
B) bio calibration
C) filters
D) system reference
bio calibration
All of the following factors favor cancellation or signals in the two inputs or an amplifier, except
A) shorter inter-electrode distance
B) cerebral potentials in common mode
C) equal impedances in the inputs
D) unequal impedances in the inputs
unequal impedances in the inputs
LONG TIME CONSTANT
A) HFF of 35 Hz
B) LFF of 0.1 Hz
C) HFF of 70 Hz
D) LFF of 1 Hz
LLF of 0.1 Hz
A time constant of 0.5 sec:
A) Low Filter 5.0 Hz
B) High Filter 35 Hz
C) Low Pass Filter 15 Hz
D) High Pass Filter 0.3 Hz
High Pass Filter 0.3 Hz
High data sampling rates in a digital EEG machine create
A) long EEG recordings
B) choppy, rigid lines
C) smooth, connected lines
D) low amplitude EEG activity
smooth, connected lines.
For low frequency filters (LFFs), the corresponding time constants for LFF cutoff frequency of 3 Hz would be
A) 0.03 sec
B) 0.016 sec
C) 0.06 sec
D) 0.05 sec
0.05 sec
Digital EEG montages are reformatted by using
A) system reference
B) the Nyquist theorem
C) referentially recorded data
D) Fourier analysis
system reference.
Which of the following sites is most commonly used for the ground electrode in EEG?
A) Oz
B) Pz
C) Fpz
D) Fz
Fpz
Low sampling rate may cause fast frequencies to appear slower:
A) overfiltering
B) long time constant
C) aliasing
D) low impact impedance
aliasing
Term used to describe the way a signal is sampled at intervals and assigned a numeric value:
A) Linear filtering
B) Aliasing
C) Sampling skew
D) Sampling Rate
Sampling Rate
Which of the following time constants would best display delta activity?
A) 0.1 second
B) 1.0 second
C) 0.3 second
D) 0.5 second
1.0 second
In a differential amplifier, if input 1 received a voltage of + 50 microvolts and input 2 a voltage of - 100 microvolts, the output voltage and deflection would be approximately
A) 150 upward
B) 50 downward
C) 150 downward
D) 50 upward
150 downward
Input impedance should be
A) equal to the common mode rejection ratio
B) less than common mode rejection ratio
C) very high
D) very low
very high
Doubling the inter-electrode distances will have what effect on the waveforms?
A) Decrease muscle artifact
B) Increase slow activity
C) Increase amplitude
D) No effect
Increased amplitude
UNDERSAMPLING
A) Impedance
B) Common Mode Rejection
C) Aliasing
D) Fast Fourier transform
Aliasing
2016 ACNS guidelines recommends a CMRR of at least:
A) 90 dB
B) 70 Hz
C) 90 Hz
D) 70 dB
90 dB
Increasing the number of seconds displayed on the monitor
A) increases spike amplitude
B) decreases spike duration
C) increases spike duration
D) does not change spike amplitude or duration
does not change spike amplitude or duration
Which of the following principles best applies to the EEG amplifiers?
A) Filtering
B) Sampling
C) Aliasing
D) Common mode rejection
Common mode rejection
What is the specification of the minimum sampling rate used, in relation to the highest frequency signal recorded?
A) Nyquist theory
B) Ohm’s theory
C) Coulombs law
D) Paley-Winer therorem
Nyquist theory
What percentage of actual amplitude will be visible of 15 Hz. wave when using a HFF setting of 15 Hz.?
A) 0.15
B) 0.3
C) 0.7
D) 0.5
0.7
The amount by which the differential amplifier increases the magnitude of the input signal is its
A) resistance
B) filter
C) input impedance
D) sensitivity
sensitivity
VERTICAL RESOLUTION
A) Frequencies
B) Bits
C) Amplitude
D) Duration
Amplitude
The 60 Hz notch filter will have the greatest effect on a waveform having a duration of
A) 25 msec
B) 16 msec
C) 50 msec
D) 10msec
16 msec
Which of the following most closely relates to the ratio of an amplifiers output to input signal?
A) System Gain
B) Display sensitivity
C) CMRR
D) Impedance
System Gain
A 0.3 Hz wave would be attenuated by what percentage with a 0.3 Hz filter?
A) 0.7
B) 0.3
C) Unaffected
D) 0.5
0.3
A device that alters the amplitude of specific frequencies of a signal:
A) capacitor
B) transducer
C) filter
D) conductor
filter
FREQUENCY RESPONSE CURVE
A) Input impedance
B) Filters
C) Sensitivity
D) Duration
Filters
FREQUENCY
A) influenced by CMRR and measured in microvolts
B) influenced by sensitivity and measured in cycles per second
C) influenced by sampling rate and measured in hertz
D) influenced by impedance and measured in millimeters
influenced by sampling rate and measured in hertz
If the Low Frequency Filter is changed from 1 Hz to 5 Hz, how will a 2 Hz slow wave be affected?
A) It will be significantly attenuated
B) It will not be affected
C) It will be minimally (insignificantly attenuated
D) It will be accentuated
It will be significantly attenuated
Gradual changes in amplitude, frequency, or spatial distribution of rhythms is known as:
A) Evolution
B) Background activity
C) Attenuation
D) Asymmetry
Evolution
The ability of an amplifier to reject like signals.
A) amplifier gain
B) phase reversal
C) sensitivity
D) common mode rejection
common mode rejection
TIME CONSTANT
A) Low frequency filter
B) Sensitivity
C) Gain
D) Time axis
Low frequency filter
Which mathematically converts the time function into a sine wave of different frequencies?
A) Differential Amplifier
B) Impedance Meter
C) A/D converter
D) Fast Fourier Transform
Fast Fourier Transform
Signals common to both inputs of a differential amplifier with like frequency, amplitude and phase are:
A) canceled
B) attenuated 37%
C) amplified
D) attenuated 63%
canceled
2016 ACNS Guidelines recommends a minimum horizontal resolution of:
A) 16 Hz
B) 8 bits
C) 16 bits
D) 8 Hz
16 bits
A LFF setting of 5 Hz. will attenuate a 5 Hz. wave by approximately:
A) 30 mm
B) 0.05
C) 5 mm
D) 0.3
0.3
For a high frequency filter setting of 70 Hz, the Nyquist frequency is?
A) 210 samples per sec
B) 140 samples per sec
C) 10 samples per sec
D) 20 samples per sec
140 samples per sec
COMMON MODE REJECTION
A) Half cycle amplifier
B) Differential amplifier
C) Referential amplifier
D) Bipolar amplifier
Differential amplifier
