ECE 5/4625 ⢠Quiz 12a ⢠May 7, 2013
ECE 5/4625 ⢠Quiz 12a ⢠May 7, 2013
ECE 5/4625 ⢠Quiz 12a ⢠May 7, 2013
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Topic: Physical Noise Sources<strong>ECE</strong> 5/<strong>4625</strong> • <strong>Quiz</strong> <strong>12a</strong> • <strong>May</strong> 7, <strong>2013</strong>Name: ___________________________A true rms voltmeter (assumed noiseless) with an effective bandwidth of 30 MHz is used to measurethe noise voltage produced by the following devices. Calculate the meter reading in eachcase.a.) A 10-k Ω resistor at room temperature, T 0= 290 K.b.) A 10-k Ω resistor at room temperature, T 0 = 29 K.c.) A 10-k Ω resistor at room temperature, T 0 = 2.9 K.d.) What happens to all of the preceding results if the bandwidth is decreased by a factor of 4?a factor of 10? a factor 100?
Topic: Physical Noise Sources<strong>ECE</strong> 5/<strong>4625</strong> • <strong>Quiz</strong> 12b • <strong>May</strong> 7, <strong>2013</strong>Name: ___________________________Assuming a bandwidth of 2 MHz, find the rms noise voltage across the output terminals of the circuitshown below if the temperature is 400 K.5 k10 k20 k 50 kT 0= 400 K5 k
<strong>ECE</strong> 5/<strong>4625</strong> • <strong>Quiz</strong> 12c • <strong>May</strong> 7, <strong>2013</strong>Topic: Physical Noise Sources Name: ___________________________A source with equivalent noise temperature T s= 1000 K is followed by a cascade of three amplifiershaving the specifications shown in the table below. Assume a bandwidth of 50 kHz.Amplifier No. F Gain1 300 K 10 dB2 6 dB 30 dB3 11 dB 30 dBa.) Find the noise figure of the cascadeT 0b.) Find the noise temperature of the system
<strong>ECE</strong> 5/<strong>4625</strong> • <strong>Quiz</strong> 12d • <strong>May</strong> 7, <strong>2013</strong>Topic: Physical Noise Sources Name: ___________________________An antenna with a temperature of 300 K is fed into a receiver with a total gain of 80 dB,T e= 1500 K, and a bandwidth of 3 MHz.a.) Find the available noise power at the output of the receiver.b.) Find the necessary power50 dB.P rin dBm at the antenna terminals such that the output SNR is
<strong>ECE</strong> 5/<strong>4625</strong> • <strong>Quiz</strong> 12e • <strong>May</strong> 7, <strong>2013</strong>Topic: Physical Noise Sources Name: ___________________________Given a relay-user link as described in text Section A.3 with the following parameters:Average transmit power of relay satellite: 35 dBWTransmit frequency: 7.7 GHzEffective antenna aperture of relay satellite: 1m 2Noise temperature of user receiver including antenna: 1000 KAntenna gain of user: 6 dBTotal system losses: 5 dBSystem bandwidth: 1 MHzRelay-user separation: 41,000 kma.) Find the received signal power level at the user in dBW.b.) Find the receiver noise level in dBW.c.) Compute the SNR at the receiver in dB.
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