18 Questions
What is the relationship between the input signals I(t) and Q(t) on the quadrature modulator and the output signal s(t)?
s(t) = I(t) * cos(2πfIF t) - Q(t) * sin(2πfIF t)
What is the advantage of using a quadrature modulator compared to a single D/A converter and lowpass filter?
The quadrature modulator has a lower data conversion time.
What is the drawback of using a quadrature modulator compared to a single D/A converter and lowpass filter?
The quadrature modulator requires more hardware components.
What is the spectrum of the D/A converted signal xs(t)?
The spectrum is periodic and repeated every 1/ΔT = 800 MHz.
What is the required cut-off frequency of the lowpass (aliasing) filter?
400 MHz
What is the significance of the parameter ΔT in the context of the digital pulse generation system?
ΔT is very small and depends on both the IF frequency fIF and the bandwidth B.
What does the impulse response h(t) of the latching filter represent?
The modulation function
What is the transfer function H(f) used for in the given context?
Describing the performance of a practical D/A converter
What is the maximum deformation caused by the sinc-function in a practical D/A converter?
3.9 dB
In digital pulse coding, how is the quantization step eo calculated?
(xmax - xmin) * 2^(-n)
What does the error signal e(n) represent in digital pulse coding?
The error from quantization
What characteristic does the transfer function H(f) describe for a practical D/A converter?
Maximum deformation of the spectrum
What is the primary difference between the output signal of a practical D/A-converter and an ideal D/A-converter?
The output signal of a practical D/A-converter is a sequence of rectangular pulses, while the output signal of an ideal D/A-converter is a sequence of delta functions.
What is the effect of the finite number of bits in the binary numbers on the output signal of a practical D/A-converter?
It results in a noise contribution due to rounding of the binary numbers.
How can the difference between the output signal of a practical D/A-converter and an ideal D/A-converter be described?
As a simple latching filter.
What is the mathematical expression for the output signal of a practical D/A-converter?
$y_p(t) = \sum_n x(n)p(t - n\Delta T)$
What is the relationship between the convolution in the time domain and the multiplication in the frequency domain for the output signal of a practical D/A-converter?
The convolution in the time domain is equivalent to a multiplication in the frequency domain.
What is the purpose of the rectangular pulse $p(t)$ in the expression for the output signal of a practical D/A-converter?
To model the finite duration of the output signal in the practical D/A-converter.
Test your knowledge on signal processing, digital-to-analog conversion, and the use of quadrature modulators. Learn about periodic signal spectra, aliasing filters, bandwidth, and data conversion time.
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