Electronics Test Questions
1 ECE 402 TEST 2 SUMMER 2009 July 23, 2009
NAME:
INSTRUCTIONS: Please Read If you need more room, write on the back side of the PREVIOUS page, not the back of the current page!! Please do not use your paper. Open book(s) and notes, including any lab related material. Cell phones off and out of sight. Be sure what you have written down is correct. YOU COULD LOSE POINTS FOR INCORRECT STATEMENTS. There are 6 problems on 4 total pages, including this page, make sure you have all pages now. The tests must be turned in by the time announced for full credit. KEEP YOUR ANSWERS BRIEF AND TO THE POINT. DON’T WASTE TIME WRITING LONG DISCUSSIONS. SOME Useful Facts • xn = f0 G(nf0 ), where xn are the Fourier Series coefficients of periodic signal x(t), and G(f ) is the Fourier Transform of a single period of x(t). • “Convolution of a signal of width w1 with a signal of width w2 results in a signal of width w1 + w2 .” • From the Fourier Transform table: k=∞ n=∞
w(t) = k=−∞ δ(t − kT )
⇐⇒
W (f ) = 1/T n=−∞ δ(f − n/T )
2 1. 10% dB problem: The output signal power of an ideal amplifier is 17 dBm. The input signal power is 2 milliWatts. Find the power gain of the amplifier in dB.
2. 20% For all parts, consider a uniform quantizer, with 32 levels, designed for an amplitude range of [−8, +8] volts (in other words, 8 volts peak amplitude, or (±8 volts)). The input is a stationary random signal. (a) Assume the input signal has amplitudes ranging between ±8 volts. Compute the PEAK signal to quantization noise ratio (SQNR) in dB. (b) Assume for this part that the quantizer input signal has amplitude PDF given in the figure below. Compute the PEAK SQNR of the output signal in dB. (c) Assume for this part that the signal from part (b) is processed by the simple block diagram shown below to form the signal Z(t). Z(t) is input to the quantizer. Determine the maximum and minimum amplitudes for Z(t) in volts. Compute the PEAK SQNR of the quantizer output in dB.
PDF of
NAME:
INSTRUCTIONS: Please Read If you need more room, write on the back side of the PREVIOUS page, not the back of the current page!! Please do not use your paper. Open book(s) and notes, including any lab related material. Cell phones off and out of sight. Be sure what you have written down is correct. YOU COULD LOSE POINTS FOR INCORRECT STATEMENTS. There are 6 problems on 4 total pages, including this page, make sure you have all pages now. The tests must be turned in by the time announced for full credit. KEEP YOUR ANSWERS BRIEF AND TO THE POINT. DON’T WASTE TIME WRITING LONG DISCUSSIONS. SOME Useful Facts • xn = f0 G(nf0 ), where xn are the Fourier Series coefficients of periodic signal x(t), and G(f ) is the Fourier Transform of a single period of x(t). • “Convolution of a signal of width w1 with a signal of width w2 results in a signal of width w1 + w2 .” • From the Fourier Transform table: k=∞ n=∞
w(t) = k=−∞ δ(t − kT )
⇐⇒
W (f ) = 1/T n=−∞ δ(f − n/T )
2 1. 10% dB problem: The output signal power of an ideal amplifier is 17 dBm. The input signal power is 2 milliWatts. Find the power gain of the amplifier in dB.
2. 20% For all parts, consider a uniform quantizer, with 32 levels, designed for an amplitude range of [−8, +8] volts (in other words, 8 volts peak amplitude, or (±8 volts)). The input is a stationary random signal. (a) Assume the input signal has amplitudes ranging between ±8 volts. Compute the PEAK signal to quantization noise ratio (SQNR) in dB. (b) Assume for this part that the quantizer input signal has amplitude PDF given in the figure below. Compute the PEAK SQNR of the output signal in dB. (c) Assume for this part that the signal from part (b) is processed by the simple block diagram shown below to form the signal Z(t). Z(t) is input to the quantizer. Determine the maximum and minimum amplitudes for Z(t) in volts. Compute the PEAK SQNR of the quantizer output in dB.
PDF of