Measurements
R&S
®
RTP
367User Manual 1337.9952.02 ─ 12
Table 8-6: Eye measurements
Meas. type Description/Result
Extinction ratio (%) The extinction ratio is an indication of efficiency. It describes the ratio of
the power used to transmit a logic level 1, to the energy used to trans-
mit a logic level 0. The R&S RTP provides extinction ratio measure-
ments as a percentage, and in decibels:
ER (%) = Eye base / Eye top *100
Prerequisite: Eye base > 0 and Eye top > 0 because extinction ratio is
defined only for positive values.
Extinction ratio (dB) ER (dB) = 10*log (Eye top / Eye base)
Eye height The vertical eye opening indicates the sensitivity of the transmission to
noise.
(Eye top – 3 * σtop) – (Eye base + 3 * σbase)
Eye width The horizontal eye opening indicates the time range during which the
sampling of the logical state is possible.
(Tcrossing2 – 3 * σcrossing2) – (Tcrossing 1 – 3 * σcrossing1)
Eye top Mean of the upper vertical histogram
Eye base Mean of the lower vertical histogram
Q factor Q factor = (Eye top – Eye base) / (σtop + σbase)
Noise (RMS) Quadratic mean of the noise of eye top and eye base
S/N ratio Signal-to-noise ratio
SNR = 10 * log (Eye amplitude / Noise RMS)
Duty cycle distortion Duty cycle distortion = 20 * log (Eye amplitude / Noise RMS)
Eye rise time Duration for signal to rise from 10% to 90% of the high signal level
Eye fall time Duration for signal to fall from 90% to 10% of the high signal level
Eye bit rate Frequency between two crossings
Automatic measurements
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