CDM-750 Advanced High-Speed Trunking Modem
Revision 2
Appendix C
MN-CDM750
C–6
C.3
ACM System Description
A
generic
example
of
ACM
‐
over
‐
Satellite
is
shown
in
There
are
a
number
of
essential
requirements
to
enable
this
scheme:
•
A
near
side
modulator
and
FEC
encoder
that
can
instantaneously,
when
commanded,
change
either
modulation
type,
FEC
encoder
rate
or
both.
This
needs
to
be
accomplished
without
the
corruption
of
data
anywhere
in
the
path.
The
ModCod
must
remain
fixed
throughout
an
entire
frame
and
may
change
to
any
other
ModCod
on
the
next
frame.
•
The
near
side
modulator
is
required
to
send
the
value
of
ModCod
at
the
start
of
each
frame
to
inform
the
far
side
demodulator/decoder
how
to
configure
for
the
correct
ModCod.
•
A
far
side
demodulator/decoder
must
be
capable
of
demodulating
and
decoding
the
signal
transmitted
by
the
near
side
modulator
without
any
prior
knowledge
of
when
a
change
has
taken
place,
based
purely
on
the
value
of
ModCod
seen
at
the
start
of
each
Frame.
Again,
this
needs
to
be
accomplished
without
the
corruption
of
data
anywhere
in
the
path.
•
The
far
side
receiver
needs
to
derive
an
estimate
of
the
link
quality,
the
received
Es/No,
and
then
communicate
this
estimate,
via
a
return
channel,
back
to
the
near
side
modulator.
•
The
near
side
modulator
needs
to
process
the
link
quality
metric
from
the
far
side
demodulator
and,
based
upon
a
pre
‐
determined
algorithm,
adapt
the
data
rate
and
change
the
ModCod
sent
to
the
far
side
receiver.
This
closes
the
loop
and
maximizes
the
data
rate
for
the
current
link
conditions.
Содержание CDM-750
Страница 64: ...CDM 750 Advanced High Speed Trunking Modem Revision 2 Rear Panel Connections MN CDM750 3 20 Notes...
Страница 76: ...CDM 750 Advanced High Speed Trunking Modem Revision 2 Updating Firmware MN CDM750 4 12 Notes...
Страница 142: ...CDM 750 Advanced High Speed Trunking Modem Revision 2 Front Panel Operation MN CDM750 5 66 Notes...
Страница 178: ...CDM 750 Advanced High Speed Trunking Modem Revision 2 Ethernet based Remote Product Management MN CDM750 6 36 Notes...
Страница 224: ...CDM 750 Advanced High Speed Trunking Modem Revision 2 Appendix A MN CDM750 A 4 Notes...
Страница 227: ...CDM 750 Advanced High Speed Trunking Modem Revision 2 Appendix B MN CDM750 B 3 This page is intentionally blank...
Страница 234: ...CDM 750 Advanced High Speed Trunking Modem Revision 2 Appendix B MN CDM750 B 10 Notes...
Страница 256: ...CDM 750 Advanced High Speed Trunking Modem Revision 2 Appendix C MN CDM750 C 22 Notes...
Страница 280: ...CDM 750 Advanced High Speed Trunking Modem Revision 2 Appendix D MN CDM750 D 24 Notes...
Страница 300: ...2114 WEST 7TH STREET TEMPE ARIZONA 85281 USA 480 333 2200 PHONE 480 333 2161 FAX...
