Figure 1-9.-UHF-2 antenna select panel.
Figure 1-10.-UHF block diagram.
accomplished through the control box and the A516
communications system selector. Some of the peripheral
equipment include the AN/AIC-22 intercommunication
system, the AN/AGC-6 teletypewriter set (TTY), the
AN/ACQ-5 data terminal set (DTS), the AN/ASA-76
generator transmitter group (CASS), and the security
equipment TSEC/KY-28 or TSEC/KY-58.
In general, both radio sets are UHF transceivers that
provide two-way voice and data communication in the
frequency range of 225.000 to 399.975 MHz. They
automatically tune 7,000 channels at 0.025-MHz
intervals. Built in self-test circuits detect the presence or
absence of required operation signals and voltages, then
illuminate fault indicators upon detection of faults.
Voice and Data Signals
Voice and data signals at the UHF-2 radio set are
linked to the TTY, ICS, and DTS. The UHF security unit
is linked between both radio sets and the ICS. This
security unit ciphers and deciphers secure voice
information. The UHF-2 radio set is used as a backup
transmitter for sonobuoy command signals for the
CASS system. The secure switching matrix controls the
signal flow between the signal processing equipment
and the voice, data source, and monitoring equipment.
Transmit Functions
During transmit, the keying and transmit signals
from the voice or data source are coupled by the COMM
switching matrix to the UHF RT. In the UHF-1 set, the
keying signal is interlocked by the UHF-1 RF switch.
The voice or data signal modulates the carrier signal
generated in the RT, and the output signal is amplified
and coupled to the antenna. The UHF-1 output goes
through the UHF falter and UHF-1 RF switch to the
antenna. UHF-2 output goes through the UHF filter and
the UHF-2 RF switch. To provide operating frequency
and mode control information, both radio set control
boxes generate a digital bit stream that is decoded in the
radio’s RT. This decoded stream gates the appropriate
selected carrier modulation mode and operating
frequency. It also gates input voice or data signals by
activating the appropriate lines in the RT for the selected
operating mode.
The COMM system selector interfaces the UHF-2
radio set with the other systems by controlling the
keyline and voice or data signal relay gates in the
COMM switching matrix. The UHF-1 set control and
the UHF- 1 voice selector interface the UHF-1 radio set
with the voice or data sources.
The satellite communications (SATCOM) relay
panel is activated to the SATCOM mode of operation by
the UHF-1 control box. The control sends an FM select
signal to the relay panel, and this switches the panel to
the SATCOM mode. The UHF-1 RT is connected to the
top antenna through the internal preamplifier to receive
the UHF RF signals.
UHF-DF Operation
The UHF-DF operation is accomplished by
connecting the UHF-1 radio set to the AN/ARA-50
automatic direction finder set. The ADF received signals
are routed through the UHF-1 RT, complete with
sidetone to the ICS system for monitoring. During
UHF-DF operations, the operator can break in to the
mode to transmit. When the mike is keyed to transmit,
the UHF-1 RT is automatically connected to the top
UHF antenna for transmission. When the mike key is
released, the UHF-1 RT is automatically switched back
to the ARA-50 antenna for resumption of DF operations.
UHF-1 Receive
During receive, the RF from the top antenna is
coupled through the SATCOM relay panel, the RF
SWITCH, and the UHF filter to the RT. In the RT, the
signal is applied to both the main receiver and the guard
receiver. The main receiver consists of two modules-the
receiver and a 70-MHz I/O. The receiver is capable of
providing reception of 7,000 channel frequencies. The
1-15
