and operating areas remote from the
match a variety of impedances encountered in dif-
(supervisory. maintenance, or service areas). The
ferent types of multiplex equipment, including 600,
amount and type of equipment necessary to satisfy
150, and 135 ohms balanced and 75 ohms unbalanced.
this requirement is dependent on the TCF size and will
Not all of these will ordinarily be found in the same
vary from site to site.
(1) All alarm outputs are accessible at the main
(2) Level adjusting equipment is used to co-
frame. According to equipment types, alarms are des-
ordinate the levels of groups, supergroups, and base-
ignated as "go-no-go" or analog types (for adaptation t
bands of nonstandard multiplex with the standard
more sophisticated monitoring). The alarm display ix
levels. This equipment includes adjustable attenuators
cludes but is not limited to the following as applicable
to the station configuration:
feature described above may be combined with the at-
(a) All radio paths.
tenuators or amplifiers or both in integrated as-
(6) Cable carrier systems.
(c) Data circuits.
(3) Group pilot frequency conversion equipment
(d) Circuits having an alarm feature.
is used to change nonstandard group pilot frequencies
(e) Common equipment units which could affect
to the standard frequency without change in level.
This equipment removes the incoming group pilot,
(f) Low transmitter output.
converts it to the desired frequency, and reinserts it at
(g) Low receiver input.
the same level as the incoming pilot. The reinserted
(h) High received noise on the radio channel.
pilot level will track any variations in the incoming
(i) Failure of standby equipment.
pilot level with an accuracy of ±0.5 dB. Pilot alarm
(j) Failure of primary equipment.
equipment to indicate variation in pilot level beyond
(k) Signal level, high or low.
allowable limits is usually associated with the fre-
(l) Power being used <primary, secondary
quency conversion devices.
emergency, auxiliary, or battery).
2-20. Internal Systems
(m) High or low power voltage.
(n) Open fuse alarm.
Systems internal to the Technical
(o) High or low pilot frequency level.
Facility include all of the nontraffic handling
(p) Failure of line signalling supply.
subsystems, which include but not necessarily limited
(q) Low fuel supply for generator.
to those described in the following paragraphs.
(r) Open door or window (at unattended
b. Intercommunications (Intercom) System. The
intercom system provides technical coordination in-
(s) Failure of obstruction or warning light.
ternal to the Technical Control Facility and to support
(t) Change in waveguide pressurization.
ing and using agencies located in the vicinity of the
(u) Fire in equipment area.
TCF Intercom service is provided through the use of
existing administrative telephone circuits which con-
(v) Failure of environmental control system.
tain the intercom feature, and through the application
(2) The alarm system provides for incremental es
of a multistation intercom system. The intercom sys-
pansion. The system is usually so designed that activa-
tem shares common equipment and operator panels
tions, deactivations, and changes of transmission sys-
with the orderwire system. The number of intercom
tems, TCF subsystems, and circuits can be ac-
station locations varies with the operational mission
commodated without affecting the operation of the
and actual TCF configuration. The audio and dc patch
basic system. The system is usually broken down into
bays are equipped with a sufficient number of inter-
com stations to allow access from each working
(a) A local equipment and functions alarm sub-
location. As a minimum, one intercom station is pro
vided for every three patch bays.
(b) A remote station equipment and function
c. Alarm System. An alarm system is provided to
alert the Technical Controller and maintenance tech-
d. Orderwire System. An orderwire network is pro-
nicians of equipment degradations or failures that af-
vided for efficient TCF procedures. Information
regarding circuit and facility statu
fect communications circuit status. Information pro
sented by the alarm system initiates prompt action
work, and maintenance and trouble co
toward the restoration or rerouting of circuits and the
mitted over this network. Voice and da
repair of faulty equipment. Display of alarms is in a
up the orderwire network and provid
central location provided in the Technical Control Fa-
means of coordination between two or
tween a TCF and associated PTF, and
cility operating area. Parallel presentation of portions
and some special communicati
of the alarm display is also required in maintenance