An analog signal is to be coded by an ADC. The signal contains significant frequencies up to 900Hz. If the system is operated at a bit rate of 180kbps and each input sample is quantized into 1024 levels, answer the following: a) What must be the minimum sampling frequency to avoid aliasing? samples/sec b) What is the Nyquist rate? c) What must be the number of bits per sample? kHz Hz bits d) If the sampling frequency is 10% above the Nyquist rate, what is the Nyquist frequency?

1- A music signal has frequency content from 0 Hz up to 8.75 kHz. (a) What sampling frequency must be exceeded for successful A/D conversion? (b) What is another name for the minimum sampling frequency?

Pulse-code modulation (PCM) is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications. Figure 3 shows the 3bit PCM system that transmit the 250 kHz analog signal with the voltage range from -6 mV to 6 mV. i) Identify the quantized value, voltage range and binary code for each level by building your own quantization table. ii) Calculate the minimum sampling rate and sampling time. ii) Identify the corresponding sampled voltage, the quantized voltage and binary code if the input signal is sampled at time t1 = 2us, t2 = 4us, t3 = 6us, t4 = 8µs. iv) Sketch the output in (iii) if it is fed to Manchester coding line encoder with bit rate of 20000 bit/sec and amplitude of +4 V. 5 4 3 2 10 Timel(usec) Figure 3 Amplitude (mV)

2a. Assume a digital to analog conversion system uses a 10-bit integerto represent an analog temperature over a range of -25oF to 125oIf the actual temperature being read was 65.325oF, what would bethe closest possible value that the system could represent?   2b. What is the minimum sampling rate needed in order to successfullycapture frequencies up to 155 KHz in an analog signal?