- Fact:
- It is common to combine the above 3 modulation methods to achieve a higher data rate
Example: combining amplitude and frequency
00 low amplitude and low frequency 01 low amplitude and high frequency 10 high amplitude and low frequency 11 high amplitude and high frequency
Graphical example:
Notice that:
- We can now transmit:
- 2 bits using 1 sine wave
- Historical fact:
- Modems
(which was used around 1990)
use a
combination of all
3 techniques
and
can achieve upto
56Kbps:
- which was the maximum possible data rate on a telephone line
- Modems
(which was used around 1990)
use a
combination of all
3 techniques
and
can achieve upto
56Kbps: