SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL
MCS--4200/7200 Multi--Channel SATCOM System
23--20--35
15 Jul 2006
Honeywell International Inc. Do not copy without express permission of Honeywell.
Page 5--71
(b) This configuration pin specifies the functionality of the SDU Cockpit Voice
Mic-On Input No. 1 (and No. 2) discrete inputs (referred to as the mic-on
inputs). When TP13K is wired to the one state, the SDU utilizes the switched
PTT and/or MCDU/SCDU line switch(es) (referred to as switched PTT) method
for cockpit hookswitch signaling on the mic-on inputs. When TP13K is wired to
the zero state, the SDU utilizes the latched audio control panel SATCOM
microphone switch (referred to as the latched ACP) method. These two
methods are described below.
(2) Switched PTT Method
(a) With the switched PTT method, the SDU assumes the mic-on inputs are wired to
conventional microphone momentary push-to-talk switches (i.e., they are
dynamically active [on/off] throughout the duration of the call). The SDU
assumes the air- or ground-initiated call annunciation to have been
acknowledged (i.e., the call to be in the off-hook state) when the appropriate
mic-on input is activated (connected to ground) for the first time after the call
annunciation for a particular channel. Successive activations of that mic-on input
for the duration of that call have no effect on the status of that call until the call
has been cleared.
(b) With the switched PTT method, the off-hook state is also entered following
activation of the Answer Call line select switch on the MCDU/SCDU. The
on-hook state is entered following activation of the End Call line select switch on
the MCDU/SCDU that results in call clearing.
(c) This method also allows usage of the place/end call discrete input and
associated switch to initiate calls to preselected numbers, as well as to terminate
existing calls.
(3) Latched ACP Method
(a) With the latched ACP method, the SDU assumes the mic-on inputs are wired to
SATCOM microphone select switches on the ACP that are latched on
(connected to ground) for the entire duration of a call. The SDU considers the
air- or ground-initiated call annunciation to have been acknowledged (i.e., the
call to be in the off-hook state) when the appropriate mic-on input is active
(connected to ground) for a particular channel. The call is cleared and the
channel is considered to be in the on-hook state when the mic-on input is in the
open-circuit state.
(b) With the latched ACP method, all hookswitch signaling for answering and
terminating all air- and ground-initiated calls is handled by the mic-on inputs; the
MCDU/SCDU Answer Call and End Call options are blanked (the MCDU/SCDU
is only necessary for specifying the called-party number and initiating the call
process for air-to-ground calls).
(c) This method also allows usage of the mic--on discrete input and switch to initiate
calls to preselected numbers.
