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# Electrical Engineering

### Why is a spreading code used in a CDMA radio system?

A terrestrial radio link transmits a CDMA signal from a base station using a spreading code with a chip rate of 1.0 Mchips per seconds. The message data rate of the signal is 10 kbps. a. Why is a spreading code used in a CDMA radio system? b. What is the coding gain of the correlator in a CDMA receiver when it is synchroni

### SNR Ratio for Next Generation Transmission

You are required to determine that this next generation transmission system will require a spectral efficiency of 5 bits/sec per Hertz. In other words, the total capacity of your system, given in bits/sec, divided by the total channel bandwidth, given in HZ, must be 5. Determine the minimum signal to noise ratio in dB required f

### Determining the Wavelength and Frequency

The downstream information (from the network to the customer) is transmitted at a wavelength of 1550 nanometers and the upstream information (from the customer to the network) is transmitted at a wavelength of 1310 nanometers. What is the separation in frequency between 1550 and 1310 nanometers?

### Minimum Signal to Noise Ratio in dB

15 Mhz of total spectrum is divided into 75 separate communication channels of equal bandwidth. Each of the 75 separate communication channels will have a data rate of 270 kbps. Determine the minimum signal to noise ratio (s/n) in dB required in each communication channel to achieve a data rate of 270 kbps?

### Required Channel Bandwidth

In a given communications system, one signaling element is used to represent 64 bits. The required data rate is 1.789 Mbps. Determine the minimum required channel bandwidth to support this communication.

### Examing Z Transform, Poles and Zeros

We examine the z transform X(z) = (1 - z^-10)/(1 - z^-1) and use properties of the general z transform to find the discrete time signal x(n). We also expand X(z) into its polynomial in terms of z^-1 and find the polynomials degree and the coefficients We finally plot the poles and zeros of X(z) in the xz plane and examine

### Mapping of discrete functions in the z and s planes

The transform from the s to the z plane using the transform z = e^sT(s) is used to obtain an inverse transform in terms of s , namely s = Ln(z)/T(s) This is then used to find the s plane mapping of z = e^jw The s palne plot is then made for -pi <= w <= pi and the poles and zeros plotted

### Mapping of poles/zeros in s and z planes, discrete time sigma

Mapping of poles/zeros in s and z planes for given discrete time signals

### Analysis of digital signal over twisted pair cable

A data transmission system transmits data at 0.772 Mbps over a twisted pair cable. The line is equalized such that the transfer function of the line from 0 Hz to 500 kHz has constant attenuation and linear phase shift with frequency. The transmitter and receiver have ideal baseband RRC filters with filter rolloff = 0.25. At

### Examination of a Terrestrial Communications Link

See the attached file. A terrestrial radio link is used to send digital data over a long distance. The RF channel has a bandwidth of 250 kHz. The transmitter and receiver have ideal RRC filters with Rolloff = 0.25. a. What is: i. The maximum symbol rate that can transmitted over this link without ISI? ii. The bit rat

### A low definition television signal is transmitted over a radio link using frequency modulation. The baseband video signal extends from 0 Hz to 1.0 MHz, and the signal voltage varies between 0 V and +1V. The modulation constant of the transmitter is 1 MHz per volt. The following are answered a. What is the peak frequency deviation of the FM signal and bandwidth of the FM signal? b. The signal is received with CNR = 30.0 dB. What is the SNR of the recovered video signal at the radio receiver output? c. The signal could have been sent using DSB-LC modulation. What bandwidth would be required to transmit the signal with DSB-LC? d. Give two reasons why FM is used in this application rather than AM

A low definition television signal is transmitted over a radio link using frequency modulation. The baseband video signal extends from 0 Hz to 1.0 MHz, and the signal voltage varies between 0 V and +1V. The modulation constant of the transmitter is 1 MHz per volt. a. What is the peak frequency deviation of the FM signal and

### RLC Circuit using maxwells circulating current

PFA Question in word format.

### A single hop microwave line of sight link transmits a 16-QAM signal in clear air conditions at a bit rate of 40 Mbps. The transmitter and receiver have ideal RRC filters with Rolloff = 0.5. The receiver has an implementation margin of 1.0 dB. The following are addressed to find a. What is the symbol rate and what is the bandwidth occupied by the 16-QAM signal? b. The link must maintain a BER no higher than 10^-6. What is the minimum CNR in the receiver to meet this requirement? c. When rain causes attenuation on the link the BER will eventually increase to 10^-6. The modulation at the transmitter automatically changes to QPSK, and the bit rate is reduced. What is the new bit rate on the link. d. How much additional rain attenuation can occur when the link is using QPSK modulation, compared to 16-QAM?

A single hop microwave line of sight link transmits a 16-QAM signal in clear air conditions at a bit rate of 40 Mbps. The transmitter and receiver have ideal RRC filters with Ã?± = 0.5. The receiver has an implementation margin of 1.0 dB. a. What is the symbol rate and what is the bandwidth occupied by the 16-QAM signal?

### A T1 data transmission system transmits data at 1.544 Mbps over a GEO satellite link. At the receiving terminal the clear air value of overall (CNR)o is 19.0 dB. The modulation used on the link is QPSK and the implementation margin of the QPSK demodulator is 0.5 dB. a. Find the BER at the receiver output and the average time between errors. b. Rain affects the downlink from the satellite and the overall CNR ratio in the receiver falls by 6.0 dB to 13.0 dB. What is the bit error rate and the time between errors now? c.If the modulation were changed to BPSK and the bit rate reduced by a factor of two when CNR overall is 13.0 dB, what BER would you expect from the link?

A T1 data transmission system transmits data at 1.544 Mbps over a GEO satellite link. At the receiving terminal the clear air value of overall (CNR)o is 19.0 dB. The modulation used on the link is QPSK and the implementation margin of the QPSK demodulator is 0.5 dB. a. Find the BER at the receiver output and the average ti

### Twisted Pair Telco Line

A twisted pair telephone line one mile in length is used to carry digital data at a rate Rb bit/s. The line is equalized so that the attenuation is constant at 50 dB over the frequency range 0 Hz to 400 kHz. The phase response of the line is equalized so that it is linear with frequency over this range. Data is transmitted ov

### BPSK/QPSK Line of Sight

A line of sight wireless link is established between two points at a distance of 1.0 km using a frequency of 2.40 GHz. Digital data is to be transmitted over the link at a rate of 200 kbps. The transmitter and receiver have ideal RRC bandpass filters with ? = 0.25. a. What RF bandwidth is required to send the data using

### RF Signals

A Ku band satellite link has a carrier frequency of 14.125 GHz and carries a symbol stream at Rs = 40 Msps. The transmitter and receiver have ideal RRC filters with ? = 0.25. a. What is the RF bandwidth occupied by signal? b. What is the frequency range of the transmitted RF signal?

### Microwave line of sight link

A microwave line of sight link has a single hop.. The link has an RF channel with a bandwidth 10 MHz. The transmitter and receiver have ideal RRC filters with ? = 0.25. a. What is correct symbol rate (pulse rate) for this link? b. What is the bit rate with BPSK modulation? c. What is the bit rate with QPSK mod

### Telecommunications Base Station

Problem 1: In a typical mobile communications base station (or cell site), a radio frequency (RF) signal is amplified in the base station and then sent (over cable) to the antennas at the top of the tower. Consider the case where a RF signal is applied to a 20 dB amplifier in the base station. The cable loss between this ampl

### Data math channels

1st problem: What is the channel capacity for a channel with a 300 Hz bandwidth and as S/N = 3? 2nd problem: Given a channel with a 50 kHz bandwidth and a S/N = 127, determine: â?¢ Maximum signaling rate in baud â?¢ Maximum channel capacity in bps 3rd problem: Consider a communications channel with a bandwid

### MATLAB Problem for Temperature Measuring system

Please see attachment. Only need to do letter (B) and (C) and include MATLAB CODE.

### Amplitude Modulation

Amplitude modulation is obsolete but still in widespread use. a. A baseband sine wave signal with frequency 4.0 kHz is modulated onto a carrier at 1.050 MHz using DSB-LC AM. What are the frequencies of the sidebands of the RF signal? b. In part (a) above, what bandwidth is required to transmit the RF signal? c.

### Frequency Modulation

Double sideband suppressed carrier AM (DSB-SC AM) is used in the transmission of stereo signals in sound broadcasting using frequency modulation. The transmitted stereo signal is a voltage proportional to L-R, where L and R are the left and right audio signals. a. A DSB-SC AM waveform is generated by modulating a 38 kHz carr

### Modulation of the NTSC TV signal and questions around DSB-LC FM

The NTSC television signal format uses frequency modulation of a 4.5 MHz sub carrier to attach the TV audio signal to the baseband video signal which extends from 0 Hz to 4.2 MHz. The maximum frequency of the baseband audio signal is 10 KHz and the bandwidth allocated to the FM audio signal is 100 kHz. a. What is the peak fr

### A spectrum analyzer is connected to an unknown signal. The spectrum analyzer displays the power level of signals in dBm vertically and frequency horizontally. The spectrum of the unknown signal creates the following display: A continuous spectrum that is completely filled so no lines are visible. The spectrum has a sin X / X (sinc X) shape. The spectrum has maximum power spectral density at 0 Hz and falls to zero at 2 kHz, 4 kHz, 6 kHz and other even kHz frequencies. a. What is the input waveform? b. Is the input signal periodic or non-periodic? c. What is the pulse width? d. If the spectrum suddenly changes to have zeroes at 5 kHz, 10 kHz, 15 kHz, etc, what is the new pulse width?

A spectrum analyzer is connected to an unknown signal. The spectrum analyzer displays the power level of signals in dBm vertically and frequency horizontally. The spectrum of the unknown signal creates the following display: A continuous spectrum that is completely filled so no lines are visible. The spectrum has a sin X

### Analysis of bandwidth of an amplifier and output power signal

An audio amplifier has the following frequency response (transfer function): At 20 Hz, gain = 30 dB. At 60 Hz, gain = 37 dB. At 120 Hz, gain = 40 dB. At 10,000 Hz, gain = 40 dB. At 12,000 Hz, gain = 37 dB. At 16,000 Hz, gain = 30 dB. The gain of the amplifier is constant from 120 Hz to 10 kHz at 40 dB. a. Wh

### PLC interface question

5 (d) The circuit shown in FIGURE 3 is part of the interface of a relay output module. Ib is 1 mA and Vcc is 9 V. The relay requires a minimum of 50 mA to energise. Complete the values of the assumptions listed below in order to calculate: • Voltage across R1 • value of Ri • voltage across the relay coil • voltag

### Convert the following numbers to dB with the correct dB units

Convert the following numbers to dB with the correct dB units a. A transmitter power of 250 watts b. A received power of 2 x 10^6 watts c. A noise temperature of 100 K d. A bandwidth of 4.0 MHz e. A radio receiver has a noise power N = kTB watts, with T = 100 K and B = 1.0 MHz. The value of k is 1.38 x 10^

### Moore sequential circuit

A Moore sequential circuit has one input and one output.The output goes to 1 when the input sequence 111 has occurred and the output goes to 0 if the input sequence 000 occurs. At all other times, the output holds its value. Example: X 0 1 0 1 1 1 0 1 0 0 0 1 1 1 0 0 1 0 0 0 Z 0 0 0 0 0 0 1 1 1 1 1 0 0 0 1 1 1

### A two part question and solution PART1 Finding the periodicity in N of the discrete time signal x(n) = Cos(3pi*Ts.n + pi/4) and then plotting the discrete signal. From this the condition on the sampling period is determined PART2 It is shown also how to determine the z transform of the composite discrete time signal given by y(n) = y(n-1) -0.5*y(n-2) +x(n) + x(n-1) From this the output function due to a step input x(n) = u(n) = 1 is determined as Y(z) = z^2*(z + 1)/{(z - 1)*(z^2 - z + 0.5)} Further it is shown how to do the partial expansion of Y(z) into its partial fractions. From this the inverse z transform to find the output in the time domain due to the step input is determined

two part question and solution PART1 Finding the periodicity in N of the discrete time signal x(n) = Cos(3pi*Ts.n + pi/4) and then plotting the discrete signal. From this the condition on the sampling period is determined PART2 It is shown also how to determine the z transform of the composite discrete time signal given