HP 8753E - Device Response in the Time Domain

7. To enter the relative velocity of the cable under test, press:
i ,; :...... ,.
:.:: : / .:> .<.~~;~~;<.
Lcal] gg#q ;:~~~~:~~~~~~~~~~~
and enter a velocity factor for your cable under test.
Note
Most cables have a relative velocity of 0.66 (for polyethylene dielectrics) or 0.7
(for teflon dielectrics). If you would like the markers to read actual one-way
distance rather than return trip distance, enter one-half the actual velocity
factor. Then the markers will read the actual round trip distance to the
reflection of interest rather than the “electrical length” that assumes a relative
velocity of 1.
Velocity Factor = -
i,
where cr is the relative permittivity of the cable dielectric
8.
lb position the marker on the reflection of interest, press:
@GiGJ and turn the front panel knob, or enter a value from the front panel keypad.
In this example, the velocity factor was set to one-half the actual value, so the marker reads
the time and distance to the reflection.
9.
To
position a marker at each reflection of interest, as shown in Figure 2-65, press:
..a:.>: “.~.:.:.:.:.:.:.:.::.:: :‘.:: . . . . _.“‘....
;-I.;;$ ~~~~~~,~ ~~~~,~;~,~ t-g the front panel knob or entering a value from the
L: // ::.~>>,:.$:.,.: .,... ,._,,,, ;:.::%>>:..I..
.._........ i . . . ..Z! . . . . . . . . ;...:.<m:...
:s .:.: _...A w .A.. ~~.~.~~..~.~.~.~.~.~..~ ..A.. . . . . . . ..i>
’
front panel keypad after each key press.
J
1
1 1
I I
CHI STHRT
0 t
STclP
35 n*
aw000026
Figure 2-65. Device Response in the Time Domain
2-80 Making Measurements