Appendix A: Specifications
RFA300A Measurement Set 8VSB
A- 5
Table A- 2: Measurement specifications (Cont.)
Characteristic
Description
EVM (Error vector magnitude)
EVM is the square root of the mean of the squares (RMS) of the magnitudes of the real
axis symbol error vectors, divided by the magnitude of the real (in-phase) part of the
outermost ideal constellation state.
The symbol error is the difference between the received real axis symbol and its ideal
value. EVM is often expressed as a percent.
Error Vector Magnitude (EVM) is defined by the following formula:
EVM
RMS
=
1
N
N
j
=
1
δ
I
2
j
S
max
2
Ꭹ
x
100%
EVM
RMS
= Error Vector Magnitude (%).
δ
I
j
= The error in the real axis received signal value.
S
max
= Magnitude of the real (in-phase) part of the vector to the outermost state of the
constellation.
EVM can also be expressed in terms of dB, where EVMdB = 20*log(100/EVM%).
Note that the ratio is intentionally inverted to make the value in dB positive.
Where:
EVM Accuracy
12% of the correct reading.
When S/N
≥
25 dB with high smoothing.
n
Residual EVM
≤
1%.
Residual EVM is created within the RFA300A measurement set.
Содержание RFA300A
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