Data encoding converts data into a signal form for transmission. There are different encoding methods for digital-to-digital, digital-to-analog, analog-to-analog, and analog-to-digital conversion. Common digital encoding techniques include unipolar, bipolar, and polar encoding, which represent binary data using single or multiple voltage levels. Non-return-to-zero and return-to-zero are examples that represent bits through the signal remaining at a level or returning to zero between bits. Manchester encoding and differential Manchester encoding are biphase techniques that provide clocking through signal transitions.

1. •Data Encoding is a method to convert the data into
signal form because we cannot transmit data until it is
converted into signal.
•Whenever we transmit a data it is always in the form
of a signal. It can be in digital or analog form.

2. Encoding
Method
Digital to
Digital
Digital to
Analog
Analog to
Analog
Analog to
Digital

4. •It is logical to represent digital data with a digital
signal
•Signal changes value as the data changes value
from 0 to 1 and 1 to 0
• It involves various methods: Unipolar Encoding,
Bipolar Encoding and Polar Encoding.

5. •It uses only one polarity. The polarity of the pulse shows
whether it is positive or negative logic.
•Positive logic refers to binary 1.
•Negative logic refers to binary 0.

6. •It uses two voltage level a positive
and one negative.
•It includes :
1. NRZ: Non-Return to Zero
2. RZ: Return to Zero
3. Biphase

7. NRZ: Non-
Return to Zero
NRZ: Non-
Return to Zero
L-Type
NRZ: Non-
Return to Zero
Inversion

8. NRZ-L: Non-Return to Zero L-Type
•It is a Low or –ive logic encoding technique of
NZR.
•+ive voltage level is represented by 0 and –ive
voltage is represented by 1.

9. NRZ-I: Non-Return to Zero
Inversion
•In it bits are represented between +ive and –ive voltages.
•If bit is zero there is no change
•But if next bit is one the change take place.

10. Difference in NRZ-L and NRZ-I Signal

11. RZ: Return to Zero
•It uses three values +ive,-ive and zero.
•In RZ, Signal change not between bits but during each bits.
•In RZ, the signal is return to zero in midway of each duration.
•Bit 1 is represented by +ive to zero and 0 by –ive to zero.

12. Biphase Encoding
•In it signal does not return to zero instead it continues
to opposite polarity and the middle transition of each
bit is used for synchronization.
•It is of two types:
1.Manchester
2.Differential Manchester

13. Manchester:
•Transition in middle of each bit period
•Transition serves as clock and data
•Low to high represents one
•High to low represents zero
•Used by IEEE 802.3

14. Differential Manchester:
•Mid bit transition is clocking only
•Transition at start of a bit period represents zero
•No transition at start of a bit period represents one
•Note: this is a differential encoding scheme
•Used by IEEE 802.5

15. •It also uses three voltage level +ive,-ive and zero.
•Bit 0 is represented by voltage level zero.
•Bit 1 is represented by both +ive and –ive voltage level.
•If a bit is 1 and represents by +ive then the second bit 1
is represents by –ive voltage level

16. •In it digital binary data is converted into analog wave
form.
•Digital to analog techniques:
1. ASK: Amplitude Shift Keying
2. FSK: Frequency Shift Keying
3. PSK: Phase Shift Keying

17. •These are nothing but analog modulation techniques such
as:
1. Amplitude Modulation
2. Frequency Modulation
3. Phase Modulation