Test on Analog-Digital Conversion and DSP Basics

Question 1: A simple analog low-pass filter is required to transform the 1s and 0s from a delta-sigma converter back into an analog signal.

A. Ano

B. Ne

Explanation: To transform the 1s and 0s from a delta-sigma converter back into an analog signal, a simple analog low-pass filter is required. This filter averages out the high and low voltages corresponding to the 1s and 0s to form the correct analog voltage.

Question 2: According to the study materials, in which applications are single-bit Analog-to-Digital Converters (ADC) and Digital-to-Analog Converters (DAC) primarily used?

A. Telecommunications and music reproduction

B. General purpose ADC for various signal types

C. High-resolution medical imaging equipment

D. Precision control systems in industrial automation

Explanation: The study materials state that 'Single bit ADC and DAC Used in telecommunications and music reproduction'.

Question 3: Increasing the allowed passband ripple in an analog filter results in a faster roll-off.

A. Ano

B. Ne

Explanation: A filter designed with more allowed passband ripple will achieve a faster roll-off. This characteristic is notably seen in Chebyshev filters, which obtain their excellent roll-off by permitting ripple in the passband.

Question 4: For applications where information is encoded in the time domain, using a Chebyshev antialias filter is recommended due to its excellent step response.

A. Ano

B. Ne

Explanation: When information is encoded in the time domain, the Chebyshev filter severely distorts the waveform and should not be used; the Bessel filter is best. The nasty step response of filters like Chebyshev does not affect information encoded in the frequency domain, but it does affect time domain encoding.

Question 5: Which of the following describes a key aspect of multirate data conversion techniques as applied to the digital voice recorder example?

A. It involves initially sampling at a lower rate, such as 8 kHz, and then digitally interpolating to a higher rate for analog conversion.

B. It uses more than one sampling rate within the same system to process signals, such as sampling at 64 kHz and then decimating to 8 kHz.

C. It replaces complex analog antialias and reconstruction filters with simpler RC networks and digital signal processing.

D. It primarily aims to eliminate the need for any analog filtering by relying solely on high-speed digital processing.

Explanation: Multirate techniques use more than one sampling rate in the same system. In the digital voice recorder example, the voice signal is passed through a simple RC filter and sampled at 64 kHz. Then, a digital low-pass filter removes unusable bands, and decimation resamples the digital signal from 64 kHz to 8 kHz. This approach allows 8-pole analog filters to be replaced with simple RC networks, simplifying the analog circuitry while still achieving the desired filtering.