spartans_in_darkness

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EO 1.4. (c)
EO 1.4. (d)
ing transmitting antennas a good distance from
command posts, limiting the tactical advantage of
DIF in producing targets for ground and air operations.
(SHSI) The various ASA ground-based short
range direction finding (SRDF) and mediumrange
direction finding (MRDF) systems had
their own unique problems to overcome.
Suitability for the target environment was one:
the jungle had a dampening effect on radio transmissions
which worsened during the monsoon or
rainy season. In the regions to the north of
Saigon, the hilly environment of the Central
Highlands and the area near the DMZ had a tendency
to shield communications from intercept,
or, at least degrade them. In addition, the VC
radio operators used low-power (as low as one
watt) HF radios.1
(s//sn The existing ASA D/F equipment was
inadequate for the envisioned operations from
fixed sites. For example, the MRDF equi ment,
AN TRD-4 s stem and its 4A variant
'--
......The principal
transmission band for VC communications was 5
to 7.5 MHz, a range not conducive to good ground
wave propagation. Unfortunately, this was the
only equipment available for the army when it
established its Whitebirch MRDF network, On
14 June, the first station (USM-9D), located at
Nha Trang, came on line. By the end of the
month, the net had increased to three stations
with a net control at Tan Son Nhut. Byearly 1962,
Whitebirch would include three more sites
manned by ARVN DjF operator trainees super::
vised by Americans.2'
(TS//SI) The Whitebirch MRDF network, as
it originally was established, was pretty much
ineffective." This was mostly due to the original
arrangement of the stations. At first, it was
thought that setting up D/F sites within the target
area itself would lead to better results. However,
this proximity of the DIF sites to the communist
radio stations usually placed the former within
the skip zones of the VC transmitters.
Communications among the stations in the
Whitebirch network were prone to equipment
failure and hampered by atmospherics.
Elementary analytic aids and equipment, such as
a plotting board for DIF returns, were lacking, so
that the net control station at Tan Son Nhut had
toforward its information to an ASA site in the
Philippines which, in turn, would plot the fixes
andtransmit them back. Through mid-1963, this
MRDF network, after several station relocations
and network communications upgrades, had
raged to fix nearly eighty Viet Cong transmit-I
(S//SI) \The early ASA DIF plan also had
called for all\SRDF program to complement the
less.than adequate array of fixed MRDF sites. The
standard SRDF equipment used by ASA, the
ANIPRD-1, had been developed during the
Korean WaLl
"---_---'IThis meant the equipment had to be
mounted on vehicles, usually a1/4-ton truck
(popularly knownas'thejeep)and driven out into
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