While
the three towers, by 1959, were thus up and operating, all was not well
with them. One of the main difficulties centered on the FRC-56 tropospheric
scatter communications system. When functioning in the manual system, employing
voice communications, tropospheric radio proved sufficiently effective.
But faulty communications ensued after FST-2 equipment was installed to
automate communications for SAGE operations, wherein tower-to-shore communications
were transmitted and received, not by voice, but by pre-coded, digitally
computed electronic signals for automatic assimilation by SAGE computers.
Since SAGE shore computers were calibrated to reject all except perfectly
accurate inputs, the tropospheric system, as then in operation, simply could
not accomplish the task. It was decided about this same time not to replace
each FPS-20A search set and twin FPS-6 height finders with Frequency Diversity
FPS-27 search and FPS-26 height finder sets, as programmed theretofore,
because of the expense involved. The FPS-20A’s at TT-2 and TT-3, instead,
were later modified with GPA-103 equipment in late 1960, incorporating certain
ECCM devices that reshaped their FPS-20A to the FPS67
configuration.
Several remedies, meanwhile,
were suggested to correct the problem with communications. One proposal
reverted to ADC’s original plan: stretching a submarine cable from shore
to each tower. Another solution proposed by the MITRE Corporation looked
more toward refining the existing apparatus, so that tropospheric radio,
with the addition of Code Translation Data Service (CTDS),
would still bear the burden of primary tower-to-shore transmission
and reception. CTDS would tolerate greater signal level variations than
existing subsystems. American Telephone and Telegraph Company (AT&T), which
frowned on this idea, was approached with a proposal to take charge, on
a contract basis, of maintenance and operation responsibilities for the
tropospheric system. While solutions to this problem were under consideration,
the three Texas Towers reverted to operating as a manual adjunct, employing
voice communications, in the far-flung semi-automated SAGE network.14
In 1960, a proposal was advanced
that perhaps would have solved some part of the communications problem,
namely the installation aboard Texas Towers of ALRI (Airborne Long Range
Inputs) equipment designed to automate the communications process. This
plan was soon discarded, for several reasons, not least of which was the
dearth of available space for accommodating the ALRI equipment. The same
year, all further consideration was dropped of stringing submarine cables,
or adding CTDS, leaving only the prospect of AT&T taking charge of maintenance
and operations. Antenna realignments combined
with improved maintenance, supply, training and operating procedures
enhanced tropospheric communications appreciably during 1960, and to all
intents and purposes rendered them satisfactory for SAGE as well as for
manual operations.15