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# Electrical Engineering

### Transistor Minority Densities and Current Density

FIGURE 2(b) represents the carrier densities in the three neutral regions of the transistor under active conditions. The base-emitter junction is forward-biased by 0.6 volts and the base collector junction is reverse biased by 1 volt. The biased minority carrier densities are a function of distance x from the junction interfa

### Transistor Doping Concentrations

An npn transistor has the doping concentrations as given in TABLE A, where NDE and NDC are the emitter and collector donor concentrations and NAB the acceptor concentration of the base. FIGURE 2(a) represents the electron and hole carrier densities in the emitter, base and collector for the unbiased transistor. (a) Justify

### Proper Bridge Rectifier for PSU

FIGURE 1(a) shows a power supply using a full-wave bridge rectifier circuit. The main supply is stepped down by the transformer T1 and the secondary voltage Vs rectified by the four diodes D1 -D4; diodes D1 and D3 conduct on one half cycle and D2 and D4 on the other. The diodes are provided in a single 4-pin bridge-rectifier pac

### Murray Loop Test and Locating Faults

Hi there, Can anyone answer the following questions please? Q.1 (a) Using the Murray Loop test, determine the distance to an earth fault on one of the cores of a uniform three-core underground cable. Ra = 2 ohms, Rb = 1 ohm and the cable length is 300 m. (b) If the cable measurement is accurate to ±1% what length of

a. Frequency modulation is regarded as a much preferred modulation method over DSB-LC AM for sound radio broadcasting. Give two reasons why FM is preferred over AM in sound radio broadcasting. b. Do either or both of the reasons you gave in part (a) above also apply to a point to point voice link using frequency modulatio

### Demodulator for FM Stereo Signals

Multiplication of a carrier by a modulating signal generates an AM waveform known as DSB-SC, the waveform is v(t) DSB-SC = Ac cos W ct x Vm cos Wmt Where W = is the angular velocity a. Make a sketch of the DSB-SC waveform with Vm = 1 V and Ac = 10 V for a carrier frequency of 10 kHz and a modulating signal frequency

### Peak frequency deviation and Carson's rule bandwidth

A baseband signal has a frequency range from 50 Hz to 15.0 kHz. The signal is transmitted using frequency modulation. The FM transmitter has a modulation constant of 100 kHz per volt. a. A 1 volt peak sine wave signal at a frequency of 5 kHz is applied to the modulation terminal of the FM transmitter. What is the peak f

### Control Systems: Root-Locus Problems

Question 1: a) Construct the root-locus for the K > 0 for the transfer function GH = K / [s(s+1)(s^2+7s+12) b) If the design value for the gain is K = 6, calculate the gain margin. c) Determine the value of the gain factor K for which the system with the above open loop transfer has closed loop poles with a damping ra

### Modulating Radio Frequency Carriers to Carry Digital Data

Digital radio transmission requires the use of a carrier wave which is modulated by the digital data. a. What are the three possible ways in which a radio frequency carrier can be modulated to carry digital data? b. Write down the equation for the occupied bandwidth of a digital band pass (radio) link that h

### Parameter of the rectangular pulses has changed

A spectrum analyzer is connected to a signal that is known to consist of randomly occurring rectangular pulses. The vertical axis of the spectrum analyzer is calibrated in dBm. The spectrum analyzer has the following display: A continuous spectrum with magnitude 0 dBm at 0 Hz and zero magnitude at 2 kHz, 4 kHz, 6 kHz, 8 kHz..

### Filter characteristics

A filter has the following characteristics: Attenuation is 0 dB from 0 Hz to 2.5 kHz. Phase angle decreases linearly with increasing frequency above 2.5 kHz. Above 5 kHz the filter has steadily increasing attenuation. At 10 kHz attenuation is 6 dB and at 20 kHz attenuation is 24 dB. a. Is this a low pass, high pas

### Laplace Transform Method and Control Systems

See the attached document for the full problem set. 4.a) Using the Laplace transform technique, find the transient and steady state response of the system described by the differential equation (d^2*y)/dt^2) + 3dy/dx + 2y = 1 with initial conditions y(0^+) and dy | =1

### Routh Array Stability

a) Determine if the following characteristic equation represents a stable system? S^3 + 4s^2 + 8s + 12 = 0 b) The characteristic equation of a given system is: s^4 + 6s^3 + 11s^2 + 6s +K = 0 What restrictions must be placed upon the parameter K in order to ensure that the system is stable? C- A system is desi

### Control Systems and Laplace Transformations

What is the step response of a system whose transfer function has a zero at -1, a pole at -2 and a gain factor of 2? Determine the time response y(t) for the following transformed equation: Y(S) = (s + 4)/(s(s + 1)(s + 2)) What is the unit step response of a system whose transfer function is given by: P(s) = (S + 2) / (S

### Using Routh Criterion

Using Routh criterion: A) Determine the range of values of K such that the system is stable for s(s²+4s+10)+ k (s+5)=0 B) Investigate the stability of the characteristic equation: S5+ S4+ 2s³+ s²+ S + K=0 Notice: S5, S4 in the above means s^5 and s^4 (i.e. s is raised to these powers). Thanks.

### Routh Array: Determine Which Planes the Roots of the Function Lie

Apply Routh criterion to determine the number of the roots lie in the right half plane for: a. sA^3+5sA^2+6s = 0 b. sA^3+2sA^2+4s+8 = 0 c. s4+5sA^3+5sA^2-5s-6 = 0

### BI-DIRECTIONAL OPTO COUPLER- PLCS

(c) The diagram of FIGURE 2 shows a bi-directional opto coupler input interface circuit. When a supply voltage of 20 V is applied the LED carries a current and 2 V is dropped across it. Calculate the value of the LED current and the value of current through the 3 k? resistance. FIG. 2 Please refer to the attachment.

### why developing software for wireless devices is challenging?

List and briefly describe the two (2) reasons given in your textbook for why developing software for wireless devices is challenging. Include and describe five (5) of the major software components associated with mobile computing in your response.

### Locating Cable Faults - The Murray Fisher method

FIGURE 1 shows a Wheatstone Bridge connection used to determine the location of a fault on a cable in which two cores are of different cross-sectional area (the Murray Fisher method). Ignoring test lead resistance, show that: a) For the first reading position, the resistance to the fault, Rx, is given by Rx = Rb1 /

### Model Building and Parameter Estimation

See the attached file. This problem refers to the model building and parameter estimation in the presence of noise. For full details, see the attachment. The task is to implement a simulation model that generates data (simulating real-world measurements), and then fit two types of models to these data. One of the models i

### A waveguide of rectangular cross-section

A waveguide of rectangular cross-section width a=4 cm length b=5 cm in which microwave signals of frequency f propagate solely in the TE10 mode. There are limits on the frequencies of microwaves that can propagate. For very high frequencies in which landa (?) is much smaller than both a and b, many modes exist that can car

### Finding the Error Patterns in a Code

The full problem is Consider a (5,2) linear block code C with generator matrix: G = [1 0 1 1 0; 0 1 0 1 1] 1. Determine the parity check matrix H of C; 2. How many error patterns of C; 3. How many errors can the code correct? 4. Construct the following table; 5. Use the table above to find the most likely codeword v,

### Electrostatic field

A long metal cylinder with radius a is coaxial with, and entirely inside, an equally long metal tube with internal radius 2a and external radius 3a. The space between the cylinder and the tube is filled with an LIH dielectric material with relative permittivity a. This space is also permeated by a uniform free charge distributio

### Select the best modulation/coding scheme for a target BER.

Design a modulation and coding scheme for a wireless communication system. The system requires spectral efficiency 2.4 bits/symbol. 8-PSK modulations and (n=63, k=51, t=2) linear code, (n=63, k=36, t=5) linear block code, (n=63, k=24, t=7) linear block code and (n=63, k=16, t=11) linear block code are to be considered, where t i

### Determine the channel matrix of the given binary erasure channel.

Assume that we are transmitting binary digits over a binary erasure channel which is shown in the following figure, where transmitted digits may be erased. An erasure occurs with probability ? for both inputs symbols. Let p(x = 0) = p and p(x =1) = 1- p. Determine the channel matrix.

### Word error probability

Consider a binary symmetric channel with error probability p = 0.1. Assume un-coded words of length n bits are transmitted over this channel. What is the word error probability? Suppose now a single error correcting code with length n is used. What is the word error probability?

### dc machines: 4 pole lap wound armature with 16 coils

A 4 pole lap wound armature has 16 coils each with a resistance of 0.1 ohms. Calculate the resistance of the armature

### Rlocus Function in MATLAB

Using the rlocus function, obtain the root locus for the following transfer function shown in Figure 1. ** Please refer to the attachment for full problem details ** 1. Comment on the stability of the system as k varies.

### What is the total capacity of the disk?

Consider a two-platter disk with the following parameters: Number of heads = 4 (one head for each surface of the platters) Rotation speed = 7200 rpm Number of tracks on one side of the platter = 30 000 Number of sectors per track = 600 Number of bytes per sector = 512 bytes Seek time = one ms for every hundred tracks trave

### Writing the signals as rect(t) convolutions

Considering the periodic pleural pressure source plotted. The negative going pressure pulse has a magnitude of -12 cm H2O and a duration of 0.3s. The positive going pressure pulse has a magnitude of 6 cm H2O and a duration of 0.15s and begins immediately after the negative going pressure pulse. Please refer to attachment f