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
To answer this question, we must consult the Nyquist Sampling Theorem.
This theorem states that in order for a continuous time signal to be distinguishable from a sample taken at discrete time intervals, we must choose a sampling rate over twice as fast as its highest frequency component.
Let's first calculate the frequency of our continuous harmonic data signal. Let's recall frequency is the inverse of the period:
We observe that from to , one full waveform exists, and this total time represents our period. Since we are given , and we know the time delta between to is twice this amount, our period must be equal to 2 seconds. Therefore, our frequency is:
Since .5Hz is our only, and highest, frequency, we multiply this by two to get our Nyquist frequency:
Therefore, the minimum sample frequency required to reconstruct the continuous signal is 1 sample per 1 second.
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
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.