TB 9-6625-2309-24
(7) Set FOCUS-SWCM SWITCHED ATTN switch to IN and record lightwave
multimeter indication in Power Low Ref column on TD-260C (850 nm) Reference
Attenuation Data Sheet (appendix A).
(8) Repeat steps a (6) and (7) above recording lightwave multimeter indication for
each remaining column (three total) on TD-260C (850 nm) Reference Attenuation Data Sheet.
(9) Set digital delay/pulse generator controls as indicated in (a) through (m) below:
(a) Press MENU TRIG pushbutton to cycle through steps (b) through (e) below.
(b) TRIG to EXT.
(c) THRESHOLD to +0.50 V.
NOTE
Some TI/FOCUS combinations will not produce proper external
triggering of digital delay/pulse generator at a trigger
threshold of +0.05 V. Reduction of trigger threshold in this
case to obtain a good trigger is acceptable for attenuation scale
non-linearity measurements only.
(d) SLOPE (+/-) to +.
(e) TRIGGER TERM to 50 OHM.
(f) Press MENU OUTPUT pushbutton to cycle through steps (g) through (k) below.
(g) OUTPUT to AB.
(h) AB & -AB LOADS to 50 OHMS.
(i) AB: VAR.
(j)
AB: AMPLITUDE to +2.00 V.
(k) AB: OFFSET to -1.60 V.
(l) Press MENU DELAY pushbutton to set A Delay to A=T+ 0.000050000000
(50 sec).
(m) Press MENU DELAY pushbutton to set B Delay to B=A+ 0.000010000000
(10 sec).
(10) Carefully remove optical fiber jumper cable connection from lightwave
multimeter optical input (fig. 3) and connect to TI fiber connector.
(11) Press TI DISPLAY FROM pushbutton to select ORIGIN.
(12) Use technique of 8 a (2) above to set TI NEW LEN/RES to 8.0 km/0.5m.
(13) Press PULSE WIDTH pushbutton to select LONG.
(14) Set FOCUS-SWCM SWITCHED ATTN switch to OUT.
(15) Press REAL TIME pushbutton.
(16) Adjust FOCUS-SWCM VAR ATTN 1 control until FOCUS GENERATED
PULSE has approximately same amplitude as dead zone pulse as displayed on TI (fig. 8).
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