Absolute Psophometrically Weighted Level L 0P [Dbm0P]; Conversion Between Power And Voltage Levels - ABB ETL600 Instruction Manual

ETL600
Absolute mean or RMS level:
[
L dBm
Absolute peak level:
[
L dBm
Absolute peak envelope level:
[
L dBm
As the signal samples X(n) are dimensionless values, the levels given
above are neither voltage nor power levels. But in analogy to the levels
defined for analog signals, we use the terms "voltage level" or "power
level" according to the above formulas also for digital signals.
5.2.5.

Absolute psophometrically weighted level L 0p [dBm0p]

This is basically the same as L
psophometrically-weighted level, which is generally defined according
to ITU-T. This weighting is only used in connection with the
specification of noise levels on speech channels. The equivalent noise
bandwidth of the psophometrically-weighted filter is 1.74 kHz.
5.2.6.

Conversion between power and voltage levels

For digital signals, no conversion is necessary, because power and
voltage levels are not distinguished.
For analog signals, the following formula applies:
[
L dBu
u
where R
Thus for an impedance of 600 Ohms, the voltage level L
the power level L.
Configuration and Set-up
1KHW001489-EN
⎛
⎧
] ⎜
= ∗
⎨
20 log lim
⎜
→∞
⎩
n
⎝
⎛
⎧
1
⎜
= ∗
⎨
10 log lim
⎜
→ ∞
⎩ n
⎝ n
]
= ∗
peak 20 log
(
=
10 * log
]
= − + ∗
PE 3 20 log
= − +
3 10 * log
] [ ]
= + ∗
L dBm 10 log
[ ]
= + ∗
L dBm 10
is the impedance of the measuring point.
0
⎞
⎫
n 2
⎟
1
∑
2 ⎬
X ( n )
⎟
n ⎭
− ⎠
n 2
⎞
⎫
n 2
∑
⎟
2 ⎬
X ( n )
⎟ .
⎭
⎠
−
n 2
( {
−∞
max X ( n , )
{
− ∞
2
max X ( n , )
( {
max X ( n , )
( {
−
2
max X ( n , )
, but the index "p" indicates a
0
⎛ ⎞
∗
1 mW R
⎜ ⎜ ⎟ ⎟
0
2
⎝ ⎠
( 775 mV )
⎛ ⎞
R
⎜ ⎜ ⎟ ⎟
0
log
.
⎝ ⎠
600 Ohm
November 2005
ABB Switzerland Ltd
(13)
} )
< < ∞
n
} )
< < ∞
(14)
n
.
} )
− ∞ < < ∞
n
} )
∞ < < ∞
n . (15)
(16)
is equal to
u
5-5