The  Barrett  974 system is designed to make major HF turnkey projects
simple to design, install and maintain. Where the main emphasis of the
974 system is towards fully automated HF telephone interconnected base
stations,  using  multiple  frequencies,  with remote transmitters and
receivers,  the sub-assemblies that comprise the system can be used to
manage many other configurations.

Barrett  Communications,  using 974 sub-assemblies, can design turnkey
systems tailored to exact client requirements.

Features that can be offered within turnkey systems include :

-CCIR 493-2 standard digital selective call systems.
-HF Vehicle tracking.
-HF Fax, data and E-mail.
-HF Automatic telephone interconnect.
-ICAO standard selective call systems.
-Remote transmitters and receivers.
-Microwave, VHF, UHF or landline links to remote sites.
-BC97400 HF Radio Telephone Interconnect Router.

The  BC97400  is  a  3U  high EUROCARD rack containing 12 modules. The
first  4  modules are interconnect Switch Matrix Cards that allows the
interconnect  connected  to each card to select individual receive and
transmit  audios  from  up  to 8 receivers or transmitters.

The   Switch   Matrix   Card  also  provides  a  busy  signal  to  the
interconnect, indicating which channels are in use by any of the other
interconnects.

The  remaining 8 cards in the sub rack are Channel Cards. Each Channel
Card   has  the  facilities  to  input  one  receiver  audio  and  one
transmitter  audio to the interconnect router bus. Jumpers are used on
the   card  to  alloc  ate  these  receiver  and  transmitter  audio’s
individual  channel  positions.  In addition the Channel Card provides
level trim for the transmitter audio going to line and level and slope
trim for incoming receiver audio from line.

BC97403 Line Interface Panel

The  line  interface  panel  is  a 2U physical routing panel using IDC
connectors that allows easy interconnection of the Interconnect Router
(BC97400)  to  either  local  or remote transmitters and receivers via
microwave  or  landline  systems.  Krone connectors on the front panel
enable  monitoring  of  line  levels  or injection of test tones using
standard  Krone  test  cords in conjunction with the Monitor panel P/N
BC97505

BC97405 Monitor Panel

The  Barrett 974 monitor panel is a 2U rack mount unit consisting of a
line  monitor  amplifier,  line level measuring display which covers a
60dB  range and test tone generator, providing three tones 400Hz, 1kHz
and  2.6kHz.  Test  lead  connection to the unit is made by a standard
Krone  connector  on  the panel front using standard Krone test leads.
The panel circuitry is fully isolated from chassis ground and will run
with an input voltage from 12VDC to 48VDC.

BCA90037 Line Interface Module

The  line  interface  module plugs into the auxiliary connector of the
either 550/ 950 transceiver or 550/950 receiver and is used to provide
an adjustable interface to 600ohm lines.