Technical information
Table Of Contents
- TITLE PAGE
- TABLE OF CONTENTS
- INTRODUCTION
- SECTION I
- CHARACTERISTICS OF HF SSB
- ACRONYMS AND DEFINITIONS
- REFERENCES
- HF SSB COMMUNICATIONS
- FREQUENCY
- SKYWAVE PROPAGATION - WHICH FREQUENCY TO
- WHY SINGLE SIDEBAND IS IMPORTANT IN HF
- AMPLITUDE MODULATION (AM)
- SINGLE SIDEBAND OPERATION
- SINGLE SIDEBAND (SSB)
- SUPPRESSED CARRIER VS. REDUCED CARRIER
- SIMPLEX AND SEMI-DUPLEX OPERATION
- AUTOMATIC LINK ESTABLISHMENT (ALE)
- FUNCTIONS OF HF RADIO AUTOMATION
- HOW ALE ASSURES THAT THE BEST COMMUNICA-TIONS
- CHARACTERISTICS OF HF SSB
- SECTION II
- SECTION III
- SECTION IV
- SECTION V
- SECTION VI
- SECTION VII
- ITU MARITIME RADIOTELEPHONE STATIONS
- DESCRIPTION OF SERVICES
- AT&T HIGH SEAS RADIOTELEPHONE SERVICE
- AT & T COAST STATION COVERAGE MAP
- COAST STATION COVERAGE & INFORMATION
- AIRCRAFT REGISTRATION
- OPERATING PROCEDURES FOR USING THE HIGH SEAS RADIOTELEPHONE NETWORK
- AT&T HIGH SEAS COAST STATIONS
- MOBILE MARINE RADIO, INC.
- WORLDWIDE LISTING OF PUBLIC CORRESPONDENCE STATIONS
- MARITIME RADIOTELEPHONE CHANNEL DESIGNATIONS
- SECTION VIII
- SECTION IX
- SECTION X
- SECTION XI
- SECTION XII
- SECTION XIII
Description
1-10
KHF 950/990 Pilots Guide
Rev. 0
Dec/96
SINGLE SIDEBAND OPERATION
By electronically eliminating the carrier wave and one sideband, a
single sideband transmitter manages to pack all of its power in trans-
mitting the remaining single sideband. (Figure 1-3). Either the upper
sideband (USB) or the lower sideband (LSB) can be used since each
sideband contains all the required intelligence. However, from a prac-
tical standpoint the USB is used almost exclusively in airborne HF
SSB operations and the LSB may be disabled. Upon receiving this
SSB signal, the receiver then generates the carrier frequency inter-
nally and combines it with the one sideband in such a way that the
intelligence (voice) can be heard and understood by the pilot.
SINGLE SIDEBAND (SSB)
The result is that an SSB system has the effective transmit power of
AM units having many more times the transmitter power. Also, SSB
communications allow the frequency band to be utilized more effi-
ciently since the space or “bandwidth” of only one sideband rather
than two sidebands is required to transmit the message.
SUPPRESSED CARRIER VS. REDUCED CARRIER
The single sideband (SSB) operation just described with the carrier
frequency virtually eliminated is actually referred to as single side-
band suppressed carrier and is designated A3J. If just a small portion
of the carrier is transmitted along with the sideband, the operation is
referred to as single sideband reduced carrier and is designated A3A.
A3A was previously used in maritime radiotelephone but is not used
currently. Regulations still require its inclusion in equipment used in
conjunction with maritime radiotelephone. A3A is normally disabled
on the KCU 1051, but is harness selectable. A3A is normally inter-
nally disabled on the KCU 951 Control Display Unit. If it has been
enabled it is annunciated when both “AM” and “USB” are simultane-
ously displayed. The KFS 594 miniature control display unit allows
the A3A mode to be selected by rotating the mode selector to the
“A3A” position.
SINGLE SIDEBAND (SSB)
fc = carrier frequency
fm = modulating frequency (voice)
fc-fm
LSB
fc fc+fm
USB
Figure 1-3 Single Sideband