ABRET Digital Instrumentation Questions and Answers 100% Pass

ABRET Digital Instrumentation Questions and Answers 100% Pass A LFF setting of 5 Hz will attenuate a 5 Hz wave by approximately: a. 0.3 b. 30 mm c. 0.05 d. 5 mm 0.3 (LFF of 5 Hz will attenuate a 5 Hz wave by 30%) Gradual changes in amplitude , frequency, or spatial distribution of rhythms is known as: a. asymmetry b. attenuation c. background activity d. evolution evolution Vertical resolution a. bits b. frequencies c. amplitude d. duration amplitude The ability of an amplifier to reject like signals a. amplifier gain b. phase reversal c. common mode rejection d. sensitivity common mode rejection Which of the following principles best applies to the EEG amplifiers? a. aliasing b. sampling c. common mode rejection d. filtering common mode rejection Increasing the number of seconds displayed on the monitor a. decreases spike duration b. increases spike amplitude c. does not change spike amplitude or duration d. increases spike duration does not change spike amplitude or duration Which of the following is the most appropriate sampling rate that should be used for a HFF setting of 70 Hz, according to Nyquist theory? a. 20 p/sec b. 210 p/sec c. 10 p/sec d. 140 p/sec 140 p/sec (Nyquist theory is 2x the setting, ACNS Guidelines is 3x the setting) For low frequency filter (LFF), the corresponding time constants for LFF cutoff frequency of 3 Hz would be a. 0.05 sec b. 0.03 sec c. 0.06 sec d. 0.016 sec 0.05 sec A device that alters the frequency composition of a signal: a. conductor b. filter c. transducer d. capacitor filter With high frequency filtering, muscle artifact may become distorted and look like: a. theta activity b. beta activity c. lambda activity d. alpha activity beta activity Which mathematically converts the time function into a sine wave of different functions? a. fast fourier transform b. A/D converter c. impedance meter d. differential amplifier fast fourier transform 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 downward b. 50 upward c. 50 downward d. 150 upward 150 downward (different signs, add numbers together) Common mode rejection a. half cycle amplifier b. differential amplifier c. bipolar amplifier d. referential amplifier differential amplifier Input impedance should be a. less than the common rejection ratio b. very high c. equal to the common mode rejection ratio d. very low very high (input impedance should be high, electrode impedance should be low) Long time constant a. LFF of 0.1 Hz b. LFF of 1 Hz c. HFF of 70 Hz d. HFF of 35 Hz LFF of 0.1 Hz Term used to describe the way a signal is sampled at intervals and assigned a numeric value: a. sampling rate b. linear filtering c. sampling skew d. aliasing sampling rate (the way a signal is SAMPLED and NUMERIC VALUE=rate) All of the following factors favor cancellation of signals in the two inputs of an amplifier, EXCEPT a. shorter interelectrode distances b. unequal impedances in the inputs c. equal impedances in the inputs d. cerebral potentials in common mode unequal impedances in the input According to the guidelines, how many bits of resolution is required? a. 10 b. 13 c. 16 d. 8 16 What happens when a 60 cycle sine wave is sampled at 100 Hz? a. overlap of data b. aliasing c. subharmonic response d. digital filtering aliasing Which of the following is the most appropriate sampling rate that should be used for a HFF setting of 70 Hz, according to ACNS guidelines? a. 30 p/sec b. 210 p/sec c. 140 p/sec d. 10 p/sec 210 p/sec (ACNS guidelines is 3x the setting, Nyquist theory is 2x the setting) Voltage Resolution a. analog to digital converter b. horizontal sampling rate c. bandwidth d. frequency resolution analog to digital converter Which of the following most closely relates the ratio of an amplifiers output to input signal? a. system gain b. impedance c. display sensitivity d. CMRR (common mode rejection ratio) system gain 2016 ACNS Guidelines recommends a CMRR of at least: a. 70 Hz b. 90 Hz c. 70 dB d. 90 dB 90 dB The 60 Hz notch filter will have the greatest effect on a waveform having a duration of a. 16 msec b. 25 msec c. 50 msec d. 10 msec 16 msec Undersampling a. common mode rejection b. aliasing c. impedance d. fast fourier transform aliasing Clipping of the waveforms occurs when a. the signal is aliased b. the sensitivity is set too low 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 converts an analog signal into a series of digital binary numbers? a. A/D converter b. fast fourier transform c. differential amplifier d. impedance meter A/D converter (analog to digital converter) Frequency response curve a. sensitivity b. duration c. input impedance d. filters filters Which of the following instrumentation setting change may result in the elimination of cortical spikes? a. change the HFF from 70 Hz to 100 Hz b. change the LFF from 1 Hz to 0.1 Hz c. change the HFF from 70 Hz to 15 Hz d. change the LFF from 1 Hz to 5 hz change the HFF from 70 Hz to 15 Hz What percentage of actual amplitude will be visible of a 15 Hz wave when using a HFF setting of 15 Hz? a. 0.15 b. 0.7 c. 0.3 d. 0.5 0.7 Time constant a. low frequency filter b. sensitivity c. gain d. time axis low frequency filter EEG amplifiers work on the principles of a. both differential and amplification b. differential discrimination c. amplification d. aliasing both differential and amplification Low sampling rate may cause fast frequencies to appear slower a. long time constant b. aliasing c. overfiltering d. low impact impedance aliasing (undersampling) The amount by which the differential amplifier increases the magnitude of the input signal is its a. resistance b. filter c. sensitivity d. input impedance sensitivity Which of the following instruments magnifies the common-mode voltage difference between two inputs? a. impedance meter b. A/D converter c. fast fourier transform d. differential amplifier differential amplifier The sharpness of the frequency response curve is determined by the filter a. bandwith b. rolloff c. notch d. capacitance rolloff 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 attenuated d. it will be accentuated it will be significantly attenuated Digital EEG montages are reformatted by using a. the Nyquist theorem b. fourier analysis c. referentially recorded data d. system reference system reference The waveforms contain frequencies as high as 100 Hz. What is the Nyquist sampling rate? a. 200 samples/second b. 50 samples/second c. 25 samples/second d. 100 samples/second 200 samples/second What is the specification of the minimum sampling rate used, in relation to the highest frequency signal recorded? a. Ohm's theory b. Coulombs law c. Paley-Winer theorem d. Nyquist theory Nyquist theory Which of the following time constants would best display delta activity? a. 0.5 sec b. 0.3 sec c. 1.0 sec d. 0.1 sec 1.0 sec Signals common to both inputs of a differential amplifier a. cancelled b. amplified c. attenuated 37 % d. attenuated 63 % cancelled Doubling the interelectrode distances will have what effect on the waveforms? a. increase amplitude b. increase slow activity c. decrease muscle artifact d. no effect increase amplitude 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 influence by sampling rate and measured in hertz 2016 ACNS Guidelines recommends a minimal horizontal resolution of: a. 16 bits b. 8 bits c. 16 Hz d. 8 Hz 16 bits High data sampling rates in a digital EEG machine create: a. smooth, connected lines b. low amplitude EEG activity c. long EEG recordings d. choppy, rigid lines smooth, connected lines Which of the following sites is most commonly used for the ground electrode in EEG? a. FPz b. Pz c. Oz d. Fz FPz Which of the following is not useful in digital EEG recordings? a. system reference b. bio calibration c. balance of electrode imbalances d. filters bio calibration Which of the following is most sensitive? a. 2 uV/mm b. 5 mV/cm c. 5 uV/mm d. 2 mV/mm 2 uV/mm A time constant of 0.5 sec: a. high filter 35 Hz b. low filter 5.0 Hz c. low pass filter 15 Hz d. high pass filter 0.3 Hz high pass filter 0.3 Hz A 0.5 Hz wave is enhanced without affecting a spike by using a. LF 0.3 Hz b. HF 35 Hz c. LF 1 Hz d. LF 5 Hz LF 0.3