Tektronix TekRanger 2 TFS3031, Service Manual

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Performance Check – TekRanger 2 (serial nos. B052000 and above)
4–26
TFS3031 TekRanger/TekRanger 2 Service Manual
16. Identify the ten highest points and draw a line parallel with the distance axis
so the ten highest points fall above the line. See figure 4–11.
Ten noise spikes fall above this line, 0dB in this case
Figure 4–11: Singlemode Dynamic-Range Check, Longest Pulse Width, 98% Noise
Level
17. Note where this line intersects the loss axis. This is the 98% noise level.
18. 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.
19. 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 29.75 - 0 = 29.75 dB.
20. Verify that the measured dynamic range is equal to or greater than the
specification for the wavelength and pulse width being tested.
21. Repeat steps 3 through 20 at 1310 nm and 1625 nm if the unit is an option
06, option 10 or option 12.