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TM 11-5821-333-12
1-17. FREQUENCY HOPPING OPERATION. Continued
late entry mode is selected, the search procedure is changed to permit a +59 second difference. A late entry RT
must receive the late entry sync data to synchronize with the net. Late entry sync data is included with the regular
synchronizing signal at a maximum of once every 30 seconds for the net. The RT also checks the cue frequency
during passive receive for any activity. When an RF signal with a 150 Hz squelch tone on the RF cue frequency is
detected, the RT displays “CUE” and the headset beeps.
The NCS uses the frequency hopping-master (FH-M) mode. It differs from FH in two ways, The NCS is the time
standard for the net, and the NCS RT is the only one that can transmit ERF data. When an RT receives a message,
it automatically adjusts its clock toward the transmitting RT clock. This adjustment can be a maximum of one-half
second for each received message. The NCS RT does not adjust its clock with a received message. When the
NCS is an active net member, all of the net member’s RT clocks will be synchronized with the NCS RT clock, All
the required FH data, except the TRANSEC key (Non-lCOM) may be sent from the NCS to net members using
ERF. The NCS loads its holding memory with the fill data to be transmitted, The fill data can be either a hopset or a
lockout set. When the ERF or SEnd button is pressed, the RT is keyed and the fill data
transmitted. The fill data is preceded by a synchronizing signal and the NCS FH sync time. An end-of-message
code is sent twice after the fill data. The receiving RT detects the codes in the message that identify it as fill data
and places the fill data in the holding memory. A typical net opening will use the cold start procedure, Operation
in the cold start mode is the same as normal FH operation except that the RT hops on a single frequency, The
frequency used is the one in the SC MAN preset.
When the RT is operating with the data or COMSEC equipment, the analog-to-digital and digital-to-analog conver-
ters are bypassed. When necessary, data is converted to 16 kb/s by the DRA. The DRA also adds a code to the
message to identify it as data.
When the radio set FUNCTION switch is set to OFF, the RT clock is kept running for 24 hours. After 24 hours, the
clock is turned off to preserve the holding battery life. All fill data is retained. The life of the holding battery can be
extended by supplying DC power to the RT when the RT is turned off.
1-18. VOICE OPERATION WITH KY-58 COMSEC EQUIPMENT.
ARRANGEMENT FOR VOICE OPERATION WITH KY-58 COMSEC EQUIPMENT
a. Introduction. The RT can be used with the VINSON COMSEC KY-58, The KY-58 provides security for
voice and data communications. It encrypts signals from the intercom and decrypts encoded signals received by
the RT. The optional Z-AHQ interface adapter is used to adapt the KY-58 to some aircraft, The Z-AHP remote
control unit is also a KY-58 option. When the Z-AHQ is not used, the RT and intercom are connected directly to
the KY-58, and the Z-AHP connects to the RT and the KY-58. Use of the KY-58 with data equipment is
discussed in paragraph 1-20. Plain-text voice and cipher-text voice are discussed here.
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