TriPoint VertexRSI 7200, Руководство по эксплуатации и обслуживанию

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7 2 0 0 A /D C ARD C ALIBRA TIO N
D - 2
4. Note the read i ngs on channe l s 1 and 2; ad j ust R2 (channe l 1) and R1 6
(channe l 2) unt il the vo l tage i nd i cated on the 7 2 0 0 A C U matches that of the
DM M.
5. V ary the po w er supp l y output vo l tage and take severa l read i ngs at the l o w ,
m i dd l e, and h i gh ends of the i nput vo l tage range to make sure there are no
non- li near i ty (vo l tage shou l d match to 1 0 m V).
3.0 AGC Mod e Offs e t Ad j ustm e nt
Because most A G C vo l tage outputs are not ca li brated and have a w i de v i deo s i gna l
dynam i c range, i t i s often necessary to ’t w eak’ the A G C mode offset on the
assemb l y.
If proceed i ng from paragraph 2.0, po w er do w n the 7 2 0 0 A C U and reconf i gure the
appropr i ate j umpers (JP1/2) i nto the ’ A ’ pos i t i on for A G C mode. Po w er up the
7 2 0 0 A C U.
1. On the 7 2 0 0 A C U M a i n m e nu , se l ect D i sp l a y syst e m st a tus... and A/D st a t e s .
2. To effect i ve l y a li gn the A G C offset, acqu i re and peak the des i red v i deo s i gna l
A G C vo l tage from the v i deo rece i ver and p i pe i t i nto the converter card. If th i s
method i s i nconven i ent, then the D C vo l tage po w er supp l y can be ad j usted to
the appropr i ate vo l tage to s i mu l ate the rece i ver.
3. A d j ust R1 4 for channe l 1 and/or R2 6 for channe l 2 A G C offsets. Note that i t
may take severa l revo l ut i ons of the tr i mmer to sca l e the vo l tage proper l y due
to the h i gh ga i n of the rest of the c i rcu i t. Th i s i s because the typ i ca l vo l ts/dB
sca l e on an A G C c i rcu i t i s on the order of severa l m V , so there i s not enough
reso l ut i on on the 1 2 b i t A D C ’s to use i n steptrack operat i on.
Th i s comp l etes the ca li brat i on/ad j ustment procedure for the 8 0 0 2 2 1 assemb l y.