Tektronix TekRanger 2 TFS3031, Руководство по обслуживанию

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Performance Check – TekRanger 2 (serial nos. B052000 and above)
4–30
TFS3031 TekRanger/TekRanger 2 Service Manual
17. Identify the seven highest points and draw a line parallel with the distance
axis so the seven highest points fall above the line. See figure 4–14.
Seven noise spikes are above this line, 1.5 dB in this case
Figure 4–14: Singlemode Dynamic-Range Check, 500-m Pulse Width, 98% Noise
Level
18. Note where this line intersects the loss axis. This is the 98% noise level.
19. Subtract 1.5 dB from the number noted in the previous step to calculate the
SNR=1 noise level.
The SNR=1 noise level cannot be less than zero. If the 98% noise level is 1.5
dB or less, the SNR=1 noise level is zero.
20. To calculate the SNR=1 dynamic range level, subtract the SNR=1 noise level
from the zero-meter level. In the example shown here, the SNR=1 dynamic
range is 26.6 - 0 = 26.6 dB.
21. Verify that the measured dynamic range is equal to or greater than the
specification for the wavelength and pulse width being tested.
22. Repeat steps 3 through 21 at 1310 nm and 1625 nm if the unit is an
option 06, option 10, or option 12.