Teledyne LeCroy QPHY-UWB - Manual (Page 24)

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QPHY-UWB-OM-E Rev C
When EVM is computed, the frequency of the signal has been matched; that is, the overall slope of CPE from
start to end of each PSDU has been eliminated. Therefore it is only variation of CPE from symbol to symbol that is
filtered and causes degradation of EVM values.
The inclusion choices are:
For compliance testing the appropriate choice is Data and Pilot Tones.
Selected Tone
In each symbol, there are (-61 to + 61) tones. Tones +/- 5, 15, 25, 35, 45, 55 are pilot tones.
If any pilot tone is selected, the constellation display will show only two points in the constellation.
If any data tone is selected points will be displayed in all of the points of the constellation, four points (QPSK) or
16 points (DCM). Data tones are distributed across the possible points of the constellation.
In this mode of operation, you can select a specific tone among the available tones (12 pilot tones and 100 data
tones) in each symbol.
Include Header
The Include Header checkbox makes the EVM calculation begin with Header symbols, before the PSDU. This is
not used in compliance testing. It can be used to diagnose a discontinuity of phase or power between the header
and the PSDU.
Selected Packets and Selected Symbol
The two control boxes below allow you to select packets and a specific symbol within the selected packet.
Selected symbol only can be checked at the same time as Selected Tone is chosen, in which case the EVM
value and the constellation are from only the selected tone in the selected symbol.