The process and conversion of analog to digital signal conversions lecture in PowerPoint.

1. OSI ModelDNA Lecture
Analog and Digital Signal Conversion and Processing

2. Physical – Layer 1 Protocol Data Unit
Technical: Layer 1 is where data is transmitted over
various physical media types via analog, digital and
optical signals to a signal decoder.
• Analog Wave Signal (Orange) Voltage + Time as a continuous
wave form
• Digital Wave Signal (Blue) Binary Bits 0's and 1's
Sampling time is generally between 1µs to 14 µs while the
holding time can assume any value as required in the
application. It will not be wrong to say that capacitor is
the heart of sample and hold circuit. This is because the
capacitor present in it charges to its peak value when the
switch is opened, i.e. during sampling and holds the
sampled voltage when the switch is closed.
• µs = microsecond
Analog and Digital Signal Conversion and Processing

3. Physical – Layer 1 Protocol Data Unit
Analog vs Digital Signal Comparison

4. Physical – Layer 1 Protocol Data Unit
Analog to Digital Conversion
• Stage 1 analog wave enters input S/H sampling and hold
and the analog wave signal is held and sampled
• Sample and hold circuit stores a electric charge in a
capacitor
• Capacitor is a device that stores electrical energy
in an electric field. It is a passive electronic component
with two terminals.

5. Physical – Layer 1 Protocol Data Unit
Analog to Digital Conversion
• An analog signal is described using amplitude, period
or frequency and phase. Amplitude marks the maximum
height of the signal. Frequency marks the rate at which
signal is changing. Phase marks the position of the wave
with respect to time zero.
• An analog signal is not immune to noise hence,
it faces distortion and decrease the quality
of transmission.
• Digital signal can be further decomposed into simple
sine waves called harmonics. Each simple wave has
different amplitude, frequency and phase.
• Bit interval describes the time require
for sending a single bit. Bit rate describes the frequency
of bit interval.

6. Physical – Layer 1 Protocol Data Unit
Analog to Digital Conversion
• Digital signal is more immune to the noise; hence, it
hardly faces any distortion. Digital signals are easier
to transmit and are more reliable when compared to
analog signals. Digital signal has a finite range of values.
The digital signal consists 0s and 1s.
• Digital signal represents a noncontinuous wave that
carries information in a binary format and has discrete
values.
• Analog signal is always represented by the continuous
sine wave whereas, a digital signal is represented by
square waves.
• Digital signal is nowadays replacing the analog signal, but
analog signal is still best for audio transmission.

7. Physical – Layer 1 Protocol Data Unit
“ADC” Analog to Digital Conversion Process
• V in = Voltage in |
C = Control Signal / Holding Capacitor
• When switch is closed sampling process will find a
measurement and when the switch is opened holding
effect will occur.
Capacitor

8. Physical – Layer 1 Protocol Data Unit
“ADC” Analog to Digital Conversion Process
Q/E: Quantizing and Encoding
• Voltage In as a sine analog wave inside the S/H
Sampling and hold circuit, the gate is open allowing
the holding effect of the analog sine wave in the
holding capacitor to be quantized & encoded into
a binary digital wave format, outputs digital signal.
A sine wave or sinusoid is a mathematical curve that describes a smooth periodic oscillation, a
a continuous wave. It is named after the function sine (sin), of which it is the graph.
u is a function of time t, and u has value zero when
time is negative (before we flip the switch); and value
one when time is positive (from when we flip the switch).

9. Physical – Layer 1 Protocol Data Unit
“ADC” Analog to Digital Conversion ProcessQ/E: Quantizing and Encoding
• We could measure the signal repeatedly and very fast,
and then find out the right time scale.
• We could measure the signal at different timings and
then average it. Or preferably we can hold the signal
for a specific duration and then digitize the signal and
sample the value. This is done by a sample and hold
circuit.
• On the output of (S/H), a certain voltage level is present.
We assign a numerical value to it.
• Following table shows the performance of different ‘n’
Bit ADCs. If the number of bits is greater, then the
Frequency is lesser and time consumed is also greater.

10. Physical – Layer 1 Protocol Data Unit
Credits
ANALOG TO DIGITAL CONVERTER - How ADC Works
- https://microcontrollerslab.com/analog-to-digital-adc-converter-working/
Difference Between Analog and Digital Signal (with Comparison Chart)
- https://techdifferences.com/difference-between-analog-and-digital-signal.html
Laplace Transforms - 1a. The Unit Step Function (Heaviside Function)
- https://www.intmath.com/laplace-transformation/1a-unit-step-functions-definition.php
What is Sample and Hold Circuit - Circuit Diagram, Working & Applications - Electronics Coach
- https://electronicscoach.com/sample-and-hold-circuit.html