|
|
|
|
|
11 Mbit/s |
|
Encrypted (but questionable security) |
|
|
|
|
|
|
|
InfraRed: Short range, slow connection |
|
Bluetooth: Short range, fast connection |
|
Cell/PCS: Wide Area Network |
|
CDPD: 10 Kbit/sec data on old
analog
cell systems (Cellular Digital Packet Data) |
|
GSM: 13 Kbit/sec data (European cell
standard) |
|
G3: High Speed (promised) |
|
|
|
|
|
Wavelength |
|
C = 3*108 m/sec |
|
F = frequency (Hz) |
|
Modulation |
|
Narrow Band (AM, FM) |
|
Wide Band (Spread Spectrum) |
|
|
|
|
|
|
Frequency Hopping:
Invented by Heddy
Lamar during WWII |
|
Direct Sequence :
Invented at ITT Labs
in Nutley NJ ~1950 |
|
|
|
|
|
Spread Spectrum Properties |
|
Difficult to jam |
|
Difficult to
eavesdrop |
|
Less interference
with other services |
|
|
|
|
|
|
Carrier Sense Multiple Access / Collision
Avoidance |
|
Notes