Sampling
Questions
The following frequencies are present in a continuous time signal: 20 Hz, 60 Hz, 110 Hz. The signal is sampled in discrete time. To avoid aliasing, the signal should be sampled at a rate (Hz) of at least most nearly:
A. 40
B. 120
C. 160
D. 220
The continuous harmonic data signal is given below:
The minimum sample frequency $$f_s$$ required to properly reconstruct the continuous signal is:
A. 1 sample per 4 sec
B. 1 sample per 2 sec
C. 1 sample per 1 sec
D. 2 samples per 1 sec
You are designing a digital speed-monitoring system for the cruise control of a new automobile. A tachometer sensor produces a square wave signal with a 50% duty cycle. Each pulse corresponds to one full rotation of the rear right tire, The tires are 24 inches in diameter. The vehicle’s absolute top speed is 100 mph.
The sensor signal is low-pass filtered with a cutoff frequency between the tenth and eleventh harmonic of the signal. The minimum sampling frequency (samples per second) required to avoid aliasing when the vehicle is at its top speed is most nearly.
A. 23.4
B. 234
C. 467
D. 1,000
Two waveforms are represented by the following equations:
$$i_1=10cos(omegat)-7cos(3omegat)-3sin(5omegat)$$
$$i_2=10sin(omegat)+3cos(3omegat)+7cos(5omegat)$$How do their RMS values compare?
A. RMS values of $$i_1(t)$$ and $$i_2(t)$$ are nonzero and equal.
B. RMS value of $$i_1(t)$$ is larger than that of $$i_2(t)$$.
C. RMS value of $$i_1(t)$$ is smaller than that of $$i_2(t)$$.
D. RMS values of $$i_1(t)$$ and $$i_2(t)$$ are each zero.