Outline of modulation methods

1. CSN08704
Data, Audio, Video and Images
http://asecuritysite.com/comms
Telecommunications
Prof Bill Buchanan
3. Modulation and Multiplexing

2. CSN08704
Data, Audio, Video and Images
http://asecuritysite.com/comms
Telecommunications
Prof Bill Buchanan
3. Modulation and Multiplexing:
Modulation

3. Amplitude Modulation
carrier
signal
V
V
m 

4. AM
• 10Hz carrier.
• 1Hz signal.
• m=0.5.
• Link.

5. FM
• 10Hz carrier.
• 1Hz signal.
• Link.

6. CSN08704
Data, Audio, Video and Images
http://asecuritysite.com/comms
Telecommunications
Prof Bill Buchanan
3. Modulation and Multiplexing: Digital
Modulation

7. ASK, PSK and FSK
1 1 0 1 0
ASK
PSK
FSK

8. ASK
• 15Hz.
• Link.

9. FSK
• 10/20Hz .
• Link.

10. PSK
• 15Hz.
• Link.

11. M-ary modulation
Amplitude 1
Amplitude 2
Amplitude 3
Amplitude 4
Phase 1
Phase 2Phase 3
90°
0°180°
270°

12. FDM and TDM
Radio
station 3
Radio
receiver
Receiver tuned to
pick-up only in a range
of carrier frequencies
Radio
station 1
Radio
station 2
Time slot
1
Time slot
2
Time slot
3
Time-division
multiplexor
Source
1
Source
2
Source
3

13. CSN08704
Data, Audio, Video and Images
http://asecuritysite.com/comms
Telecommunications
Prof Bill Buchanan
3. Modulation and Multiplexing: Digital
Carrier Frequencies

14. Carrier Frequencies
f
u

Cosmic
rays
Gamma
rays
X-rays Ultra-
violet
Light Infra-
red
Micro-
waves
Radio
waves
0.3-3 GHz UHF (ultra-high frequencies)
3-30 MHz SHF (super-high frequencies)
30-300 GHz EHF (extremely high frequencies)
400 nm 700 nm3 nm
30-300 Hz ELF (extremely low frequencies)
0.3-3 kHz VF (voice frequencies)
3-30 kHz VLF (very low frequencies)
30-300 kHz LF (low frequencies)
0.3-3 MHz MF (medium frequencies)
3-30 MHz HF (high frequencies)
30-300 MHz VHF (very high frequencies)
30 Hz300 MHz300 GHz3 pm
r
c
u



15. Circuit and Packet Switching
Circuit-
switching
Packet-
switching
possible routes
fixed routePSE

16. CSN08704
Data, Audio, Video and Images
http://asecuritysite.com/comms
Telecommunications
Prof Bill Buchanan
3. Modulation and Multiplexing