HP 8753E manual Front panel keypad after each key press, 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 .:.:_...Aw.A..~~.~.~~..~.~.~.~.~.~..~ ..A........i> ’

front panel keypad after each key press.

CHI JSTHRT 10 t

1

STclP I35 n*I aw000026

Figure 2-65. Device Response in the Time Domain

2-80 Making Measurements