Digital Signal Processing Reference
In-Depth Information
APPENDIX A
USEFUL FORMULAS, IDENTITIES,
UNITS, AND CONSTANTS
Constants
10
8
m
/
s
Speed of light in a vacuum :
c
=
2
.
99792
×
10
−
12
F
/
m
Permittivity of free space :
ε
0
=
8
.
854
×
10
−
7
H
/
m
Permeability of free space :
=
4
π
×
µ
0
Decibels
20 log
10
v
2
v
1
Voltage:
dB
=
20 log
10
i
2
i
1
Current:
dB
=
10 log
10
P
2
P
1
Power:
dB
=
Units
Time
10
−
12
s
picosecond
(
ps
)
=
1
×
10
−
9
s
nanosecond
(
ns
)
=
1
×
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