Tektronix CSA8000B, TDS8000B B-38 CSA8000B & TDS8000B User Manual

Appendix B: Automatic Measurements Reference

B-38 CSA8000B & TDS8000B User Manual

Table B- 7: NRZ Measurements - Amplitude (cont.)

Name Definition

NRZ Average Optical

Power (dBm)

The true average component of an optical signal, expressed in decibels. This measurement

results from the use of a hardware average power monitor circuit rather than from the

calculation of digitized waveform data.

Note: Average optical power measurements return valid results only on channels that contain

average power monitors. In general, all optical sampling module channels contain average

power monitors.

To determine NRZ Average Optical Power (dBm), this measurement simply converts average

optical power (watts) to decibels using a log10 function referenced to 1mW. To determine

average optical power in watts, see the NRZ Average Optical Power (Watts) measurement. See

below.

For best average optical power measurement results:

HUse a factory-calibrated wavelength. If using the USER wavelength setting, ensure that it

is properly compensated by performing the User Wavelength Gain compensation found by

clicking the Optical button in the Vertical Setup dialog box.

HCompensate the optical channel, which corrects for minor DC variances in the average

power monitor as part of the compensation routine. To access, choose Compensation in

the Utilities menu of the application.

NRZ Average Optical

Power (watts)

where:

HDC Signal Current is the O/E-converter photo detector current in DC amps

HConversion Gain is the O/E-converter photo detector gain in amps/watts