Tektronix TekRanger 2 TFS3031, Руководство по обслуживанию

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Performance Check – TekRanger 2 (serial nos. B052000 and above)
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TFS3031 TekRanger/TekRanger 2 Service Manual
15. Identify the seven highest points and draw a line parallel with the distance
axis so the seven highest points fall above the line. If the trace has no noise,
the 98% noise level is zero. See figure 4–30.
Figure 4–30: Multimode Dynamic-Range Check 98% Noise Level, 1-m Pulse Width
16. Note where this line intersects the loss axis. This is the 98% noise level.
17. 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.
18. To calculate the SNR=1 dynamic range level, subtract the SNR=1 noise level
from the zero-meter level obtained in step 10. In the example shown here,
the SNR=1 dynamic range is 19.6 - 0 = 19.6 dB.
19. Verify that the measured dynamic range is equal to or greater than the
specification for the wavelength and pulse width being tested.
20. Repeat steps 3 through 19 at 850 nm if the unit is an option 03.