ECET 497 Final Exam Latest Version

ECET 497 Final Exam Latest Version

Author: Abraham Nolito


1. What is the signal-to-noise ratio, in decibels, for a system in which the signal power is 15 mW and the noise power is 50 nW? (Points : 1)

2. Two RF signals of equal power -1.8 dBm are combined in a power combiner, what is the output power of the combiner? (Points : 1)

3. A periodic waveform has 1.2 ms time period. What is the frequency of its 3rd harmonic? (Points : 1)

4. The Noise Figure of a LNA is 2.5 dB, what is the equivalent noise temperature of this amplifier? (Points : 1)

5. A 1 M resistor is at room temperature (22 C), what is the maximum thermal noise power that can be absorbed by an amplifier with 455 kHz bandwidth?(Points : 1)

6. An Amateur Radio Operator (HAM) is operating at 180 meters. What frequency is this? (Points : 1)

7. An amplifier with 10 dB of gain is followed by a filter with 6 dB of LOSS, which in turn is followed by an amplifier with 15 dB of GAIN and another filter with 9 dB of LOSS. The power measured at the last filter output is 10 mW. What must be the power at the input of the first amplifier? (Points : 1)

9. What is the minimum level of the positive envelope for an AM signal with an unmodulated peak carrier level of 50 V and 75% modulation? (Points : 1)

10. Given the AM signal defined by: , what is the total AM signal power in dBm? (System impedance 50 Ohms) (Points : 1)

11. Considering the system in the following figure, which of the following is the correct frequency spectrum of the signal at point A?
13. In a simple radio mixer circuit, assume that the selection of the input signal frequency of 110.7 MHz is achieved by tuning the LO frequency to 100 MHz. If you wanted to tune to another radio channel that is at 140.7 MHz, what would the LO have to be changed to in order to maintain the IF frequency? (Points : 1)

14. An FM tone-modulated source has a center frequency of 100 MHz, a modulating frequency of 4 kHz and a frequency deviation of 500 Hz. Determine the transmission bandwidth. (Points : 1)

15. A quantizer is using 16-bit output binary words. What is the best signal-to-noise ratio of quantization? (Points : 1)

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