Issue 1, Section 150-231-164
Revision 04
Page 35
3.10
Depressing both the MODE and SEL push-
buttons on the front panel for at least three
seconds initiates a MANUAL loopback session. This
session allows the user to SEL one of eight HiGain
system loopbacks. The message, “MAN LPBK”,
appears on the front panel display followed by the
message “NLO?”. If the SEL push-button is now
pressed, an “NLOC” loopback is executed and the
message changes from “NLO?” to “NLOC”. If the
MODE button is pressed instead of the SEL push-
button, “NLO?” is replaced by “ND1?”. This now allows
an ‘NDU1’ loopback to be executed (if it is a Doubler
application) with the SEL push-button. If this same
routine is followed, all eight loopbacks (NLOC, NDU1,
NDU2, NREM, CLOC, CDU2, CDU1 & CREM) are
presented and can be initiated in the sequence listed.
Pressing the MODE push-button two more times yields
the CRE and CLO loopback options in the sequence
listed. This interactive push-button procedure permits
any of the four HiGain loopbacks to be
executed/activated. The next loopback option can be
presented by pressing the MODE push-button however,
the previously executed loopback will remain active until
the SEL push-button is pressed and a different loopback
is activated. If neither button is pressed for a period of
30 seconds and no loopback is in effect, the manual
loopback session terminates and the normal margin
displays reappear. If any loopback is in effect, the 30-
second time-out is inhibited. The active loopback and
the manual loopback session continue until the loopback
times out in accordance with the user selected LBTO
setting. Only one loopback can exist at any given time.
Pressing both buttons again for three seconds,
terminates any active loopback, ends the MANUAL
loopback session and returns the display to normal
mode. Note that these same loopbacks can be initiated
from the RS-232 maintenance port by choosing the
LOOPBACK MODE, option D, from the MAIN MENU.
This displays the Loopback Menu (Figure 22), from
which any of the eight loopbacks can be
initiated/terminated.
