The discrete-time signal x(n) = 6.35 cos(π/10)n is quantized with a resolution (a) = 0.1 or (b) = 0.02. How many bits are required in the A/D converter in each case?
Consider the discrete-time signal \(x(n)\).
\(x(n)=6.35 \cos \left(\frac{\pi}{10}\right)\)
Identify the maximum and minimum values of \(x(n)\).
\(x_{\max }=+6.35 \mathrm{~V}\)
\(x_{\min }=-6.35 \mathrm{~V}\)
(a)
Write the expression of the resolution of the quantizer.
\(\Delta=\frac{x_{\max }-x_{\min }}{N}\)
Here, \(N\) is the number of bits.
Substitute \(6.35 \mathrm{~V}\) for \(x_{\max },-6.35 \mathrm{~V}\) for \(x_{\min }\) and \(0.1\) for \(\Delta\).
\(0.1=\frac{6.35-(-6.35)}{2^{N}-1}\)
\(2^{N}-1=\frac{12.7}{0.1}\)
\(2^{N}=128\)
\(N=7\) bits
Thus, the number of bits required in the A/D convertor are 7 .
(b)
Write the expression of the resolution of the quantizer.
\(\Delta=\frac{x_{\max }-x_{\min }}{N}\)
Here, \(N\) is the number of bits.
Substitute \(6.35 \mathrm{~V}\) for \(x_{\max },-6.35 \mathrm{~V}\) for \(x_{\min }\) and \(0.02\) for \(\Delta\).
\(0.02=\frac{6.35-(-6.35)}{2^{N}-1}\)
\(2^{N}-1=\frac{12.7}{0.02}\)
\(2^{N}=636\)
\(N=10\) bits
Thus, the number of bits required in the A/D convertor are 10 .