Digital Signal Processing Reference
In-Depth Information
max(|
error
_
vector
|)
MER
=
⋅
100
%;
PEAK
U
RMS
1
∑
−
=
N
1
2
(|
error
_
vector
|
N
n
0
MER
=
⋅
100
%;
RMS
U
RMS
The reference U
RMS
is here the RMS value of the QAM signal. Usually,
however, a logarithmic scale is used:
[]
MER
%
⎛
⎞
[]
MER
dB
=
20
lg
;
dB
⎝
⎠
100
The MER value is thus an aggregate quantity which includes all possi-
ble individual errors and thus completely describes the performance of the
transmission link.
In principle:
MER [dB] ≤ S/N [dB];
Table 18.1.
MER and EVM
QAM
MER>EVM
[%]
EVM>MER
[%]
MER>EVM
[dB]
MER>EVM
[dB]
4
EVM=MER
MER=EVM
|EVM|=MER
MER=|EVM|
16
EVM=
MER/1.342
EVM=
MER•1.342
|EVM|=
MER
+2.56dB
MER=
|EVM|
-2.56dB
32
EVM=
MER/1.304
EVM=
MER•1.304
|EVM|=
MER
+2.31dB
MER=
|EVM|
-2.31dB
64
EVM=
MER/1.527
EVM=
MER•1.527
|EVM|=
MER
+3.68dB
MER=
|EVM|
-3.68dB
128
EVM=
MER/1.440
EVM=
MER•1.440
|EVM|=
MER
+3.17dB
MER=
|EVM|
-3.17dB
256
EVM=
MER/1.627
EVM=
MER•1.627
|EVM|=
MER
+4.23dB
MER=
|EVM|
-4.23dB
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