Description : What are three advantages of adding an ac bias voltage to the input signal instead of adding a fixed dc bias voltage?
Last Answer : a. Reproduces a stronger output signal. b. Greatly improves the SNR. c. Greatly reduces the natural tape hiss.
Description : Why does using ac vice dc bias voltage result in a stronger output signal?
Last Answer : Because an ac bias voltage of the proper frequency and level places the input signal away from both steps in the magnetism curve. The result is two undistorted output signals that are combined into one strong output.
Description : Which performance parameter is the minimum amount of optical power required to achieve a specific bit-error rate (BER) in digital systems or a given signal-to-noise ratio (SNR) in analog systems?
Last Answer : Receiver sensitivity.
Description : How does dc bias added to the input signal correct the distortion in the output signal?
Last Answer : The dc bias moves the input signal away from the step in the magnetism curve. This prevents the input signal from crossing the zero-point of the magnetism curve.
Description : SNR is: A. Signal to Noise Ratio B. Signal to Net Ratio C. Signal to Noise Rate D. None of above
Last Answer : A. Signal to Noise Ratio
Description : An FET has a gate source bias of 2 V. The ac input signal is ± 1.2 V. The class of operation is A) A B) B C) C D) AB
Last Answer : D) AB
Description : What would be the output of a negative clamper with a bias potential of −5 volts and an input voltage swing from +50 to −50 volts?
Last Answer : -5 volts.
Description : A, when there is an increase in the input voltage, the forward bias of Q1 increases/decreases (which one).
Last Answer : Increases.
Description : Two tape recorders have signal-to-noise ratios (SNRs) of 25-dB RMS and 35-dB RMS respectively. Which of the SNRs can record and reproduce the widest range of input signals and why?
Last Answer : 35-dB RMS because the highest SNR can always record and reproduce the widest range of input signals.
Description : rid-leak biasing in effect rectifies the input ac signal. What feature
Last Answer : Unequal charge and discharge paths of the coupling capacitor Cc.
Description : Which of the following is not true: A) An oscillator is a circuit that converts DC to AC B) An oscillator is an amplifier that supplies its own input signal C) All oscillators generate sine waves D) In phase feedback is called positive Feedback
Last Answer : C) All oscillators generate sine waves
Description : To avoid objectionable noise in a microwave TV link, the SNR should be about:
Last Answer : 25 or more
Description : Technical manuals for tape recorders can state the SNR in what three different ways?
Last Answer : a. Root-mean-square (RMS) signal-to-RMS noise. b. Peak-to-peak signal-to-RMS noise. c. Peak signal-to-RMS noise.
Description : You plan to measure your tape recorder’s SNR. What test equipment will you need?
Last Answer : A VTVM and a signal generator.
Description : If the operating point of an NPN transistor amplifier is selected in saturation region, it is likely to result in A) Thermal runaway of transistor B) Clipping of output in the positive half of the ... for high dc collector supply D) Clipping of output in the negative half of the input signal
Last Answer : B) Clipping of output in the positive half of the input signal
Description : What component causes a generator to produce dc voltage rather than ac voltage at its output terminals?
Last Answer : A commutator
Description : What causes dc bias energy to be absorbed by avalanche electrons and given up to the microwave field applied to an avalanche transit-time diode?
Last Answer : The negative-resistance property.
Description : ECE Board Exam March 1996 What is the purpose of the receiver's squelch circuit? A. To overcome fluctuations in the level the RF signal arriving at the receiver antenna B. To prevent ... signals D. To prevent amplified noise from reaching the loudspeaker during the absence of an incoming signal
Last Answer : D. To prevent amplified noise from reaching the loudspeaker during the absence of an incoming signal
Description : What causes image interference? A. Low gain B. High IF C. Poor front-end selectivity D. Low signal-to-noise ratio
Last Answer : C. Poor front-end selectivity
Description : The threshold effect in demodulators is a) The rapid fall of output SNR when the input SNR falls below a particular value b) Exhibited by all the demodulators when the input SNR is low c) Exhibited by all AM suppressed carrier coherent demodulators d) Exhibited by correlation receivers
Last Answer : The threshold effect in demodulators is The rapid fall of output SNR when the input SNR falls below a particular value
Description : The purpose of the bias winding in figure 'B' shown in the illustration is for ____________. EL-0091 A. changing the direction of current in the control winding B. setting the operating point of the ... use of either AC or DC in the load circuit D. changing the direction of current through the load
Last Answer : Answer: B
Description : What is used to bias a magnetic amplifier so that the control winding remains free to accept control (input) signals?
Last Answer : A bias winding and associated circuitry.
Description : If the mu of a tube is 85 and the signal at the control grid is 4 volts ac, the plate voltage will vary by what amount?
Last Answer : 340 volts.
Description : The plate voltage of a tube will vary 126 volts when a 3-volt ac signal is applied to the control grid. What is the gain of this tube?
Last Answer : 42.
Description : In the inverting configuration, what is the voltage (for all practical purposes) at the inverting input to the operational amplifier if the input signal is a 1-volt, peak-to-peak sine wave?
Last Answer : 0 volts.
Description : The device in figure 'B' shown in the illustration can be used to control an AC load yet maintain its high gain by ______________. EL-0091 A. connecting the load to the output side of the ... connecting the load to the input side of the bridge D. reversing the current flow through the bias winding
Last Answer : Answer: C
Description : Indicate the false statement. Noise figure is defined as A. the ratio of the S/N power supplied at the input terminal of a receiver or amplifier to the S/N power supplied to the output or ... under test, both working at the same temperature over the same bandwidth and fed from the same source
Last Answer : C. an unwanted form of energy tending to interfere with the proper and easy reception and reproduction of wanted signals
Description : Each connection link in ANN is associated with ________ which has information about the input signal. A. neurons B. weights C. bias D. activation function
Last Answer : B. weights
Description : To properly bias an NPN transistor, what polarity voltage is applied to the collector, and what is its relationship to the base voltage?
Last Answer : Positive, more positive.
Description : In the illustrated circuit, what is the phase relationship of the amplifier output compared to the input? EL-0022 A. 0° in-phase B. 180° out of phase C. phase angle of the input divided by power factor D. unable to determine without the value of the bias voltage
Description : Define: i) Input Offset Voltage ii) Input offset Current iii) Input Bias Current iv) Output offset voltage
Last Answer : Definition of parameters of OPAMP is follows: i) Input Offset Voltage: Input offset voltage is defined as the voltage that must be applied between the two input terminals of an OPAMP to null or ... to ground) and output voltage is obtained non zero such voltage is output offset voltage of opamp.
Description : if noise voltage =120 mv and signal voltage = 80 v , S/N ratio in dB is?
Last Answer : Answers is the place to go to get the answers you need and to ask the questions you want
Description : An AC supply of 230 V is applied to half wave rectifier circuit. A transformer turns ratio is 20 : 1. Find i) Output DC voltage (ii) Peak Inverse Voltage (PIV)
Last Answer : Solution:
Description : A loud buzzing noise in an AC controller is probably caused by _____________. A. poor contact with the overload relay B. an incorrectly sized heater C. a broken shading coil D. abnormal starting current
Description : One of the following is a possible cause of an abrupt frequency variation in a self exited transmitter oscillator circuits resulting to a poor frequency stability to hold a constant frequency ... capacitor in the oscillator D. Loose connections in the oscillator, amplifier, or antenna circuits.
Last Answer : D. Loose connections in the oscillator, amplifier, or antenna circuits.
Description : What type of tape error causes noise to appear on the tape when no signal should appear? What causes this type of tape error?
Last Answer : Noise error is usually caused by a cut or a scratch on the magnetic tape.
Description : What effect does noise have on the fiber optic signal?
Last Answer : Noise obscures or reduces the quality of the signal.
Description : Deemphasis in the receiver in effect attenuates modulating signal components and noise in what frequency range? A. dc B. low C. intermediate D. high
Last Answer : D. high
Description : What is the basic difference between the primaries of ac and dc rate generators?
Last Answer : The method of primary excitation (ac and permanent magnet).
Description : Why is the dc scale on a multimeter different than the ac scale?
Last Answer : The meter movement reacts to average ac voltage and current and the effective value is desired.
Description : List three meter movements that can measure either ac or dc without the use of a rectifier.
Last Answer : Electrodynamic, moving vane, and hot-wire or thermocouple.
Description : Negative feedback amplifier has a signal corrupted by noise as its input. The amplifier will (A) Amplify the noise as much as the signal (B) Reduce the noise (C) Increase the noise (D) Not effect the noise
Last Answer : Negative feedback amplifier has a signal corrupted by noise as its input. The amplifier will Reduce the noise
Description : The input to a coherent detector is DSB-SC signal plus noise. The noise at the detector output is: (1) The in-phase component (2) The quadrature-component (3) Zero (4) The envelope
Last Answer : The input to a coherent detector is DSB-SC signal plus noise. The noise at the detector output is: Zero.
Description : Which of the following statement is correct ? (A) Modem is a software (B) Modem helps in stabilizing the voltage (C) Modem is the operating system (D) Modem converts the analog signal into digital signal and vice-versa
Last Answer : (D) Modem converts the analog signal into digital signal and vice-versa
Description : A transformer works with (1) alternating current only (2) direct current only (3) both AC and DC (4) any signal
Last Answer : alternating current only
Description : Differentiate AC and DC signal conditioning.
Last Answer : AC signal conditioning DC signal conditioning Excitation source is only AC for AC signal conditioning. Excitation source can be ac or dc for DC signal conditioning. AC signal conditioning ... low frequency. Demodulation is present in AC. Demodulation is absent in DC.
Description : How can a series-positive limiter be modified to limit unwanted negative portions of the input signal?
Last Answer : Biasing.
Description : What components form the input-signal-developing impedance for the amplifier?
Last Answer : C2 and the secondary of T1.
Description : If the input-signal-developing impedance of an amplifier is increased, what is the effect on the gain?
Last Answer : The gain increases.
Description : . When you select the time base to display a signal, should the time base be the same, higher, or lower than the input signal?
Last Answer : Lower.