<s>
Pulse-amplitude	B-Device
modulation	I-Device
(	O
PAM	O
)	O
is	O
a	O
form	O
of	O
signal	O
modulation	B-Application
where	O
the	O
message	O
information	O
is	O
encoded	O
in	O
the	O
amplitude	B-Application
of	O
a	O
series	O
of	O
signal	O
pulses	O
.	O
</s>
<s>
It	O
is	O
an	O
analog	O
pulse	O
modulation	B-Application
scheme	O
in	O
which	O
the	O
amplitudes	B-Application
of	O
a	O
train	O
of	O
carrier	O
pulses	O
are	O
varied	O
according	O
to	O
the	O
sample	O
value	O
of	O
the	O
message	O
signal	O
.	O
</s>
<s>
Demodulation	O
is	O
performed	O
by	O
detecting	O
the	O
amplitude	B-Application
level	O
of	O
the	O
carrier	O
at	O
every	O
single	O
period	O
.	O
</s>
<s>
There	O
are	O
two	O
types	O
of	O
pulse	B-Device
amplitude	I-Device
modulation	I-Device
:	O
</s>
<s>
Pulse-amplitude	B-Device
modulation	I-Device
is	O
widely	O
used	O
in	O
modulating	B-Application
signal	I-Application
transmission	O
of	O
digital	O
data	O
,	O
with	O
non-baseband	O
applications	O
having	O
been	O
largely	O
replaced	O
by	O
pulse-code	B-Algorithm
modulation	I-Algorithm
,	O
and	O
,	O
more	O
recently	O
,	O
by	O
pulse-position	B-Device
modulation	I-Device
.	O
</s>
<s>
The	O
number	O
of	O
possible	O
pulse	O
amplitudes	B-Application
in	O
analog	O
PAM	O
is	O
theoretically	O
infinite	O
.	O
</s>
<s>
Digital	O
PAM	O
reduces	O
the	O
number	O
of	O
pulse	O
amplitudes	B-Application
to	O
some	O
power	O
of	O
two	O
.	O
</s>
<s>
For	O
example	O
,	O
in	O
4-level	O
PAM	O
there	O
are	O
possible	O
discrete	O
pulse	O
amplitudes	B-Application
;	O
in	O
8-level	O
PAM	O
there	O
are	O
possible	O
discrete	O
pulse	O
amplitudes	B-Application
;	O
and	O
in	O
16-level	O
PAM	O
there	O
are	O
possible	O
discrete	O
pulse	O
amplitudes	B-Application
.	O
</s>
<s>
In	O
particular	O
,	O
100BASE-T4	O
and	O
BroadR-Reach	O
Ethernet	O
standard	O
use	O
three-level	O
PAM	O
modulation	B-Application
(	O
PAM-3	O
)	O
,	O
while	O
1000BASE-T	O
Gigabit	O
Ethernet	O
uses	O
five-level	O
PAM-5	B-Device
modulation	B-Application
and	O
10GBASE-T	O
10	O
Gigabit	O
Ethernet	O
uses	O
a	O
Tomlinson-Harashima	O
Precoded	O
(	O
THP	O
)	O
version	O
of	O
pulse-amplitude	B-Device
modulation	I-Device
with	O
16	O
discrete	O
levels	O
(	O
PAM-16	O
)	O
,	O
encoded	O
in	O
a	O
two-dimensional	O
checkerboard	O
pattern	O
known	O
as	O
DSQ128	O
.	O
</s>
<s>
25	B-Protocol
Gigabit	I-Protocol
Ethernet	I-Protocol
and	O
some	O
copper	O
variants	O
of	O
100	B-Protocol
Gigabit	I-Protocol
Ethernet	I-Protocol
and	O
200	B-Protocol
Gigabit	I-Protocol
Ethernet	I-Protocol
use	O
PAM-4	O
modulation	B-Application
.	O
</s>
<s>
GDDR6X	O
,	O
developed	O
by	O
Micron	O
and	O
Nvidia	O
and	O
first	O
used	O
in	O
the	O
Nvidia	B-Device
RTX	I-Device
3080	I-Device
and	I-Device
3090	I-Device
graphics	O
cards	O
,	O
uses	O
PAM4	O
signaling	O
to	O
transmit	O
2	O
bits	O
per	O
clock	O
cycle	O
without	O
having	O
to	O
resort	O
to	O
higher	O
frequencies	O
or	O
two	O
channels	O
or	O
lanes	O
with	O
associated	O
transmitters	O
and	O
receivers	O
,	O
which	O
may	O
increase	O
power	O
or	O
space	O
consumption	O
and	O
cost	O
.	O
</s>
<s>
Higher	O
frequencies	O
require	O
higher	O
bandwidth	B-Algorithm
,	O
which	O
is	O
a	O
significant	O
problem	O
beyond	O
28GHz	O
when	O
trying	O
to	O
transmit	O
through	O
copper	O
.	O
</s>
<s>
PAM4	O
costs	O
more	O
to	O
implement	O
than	O
earlier	O
NRZ	O
(	O
non	B-Protocol
return	I-Protocol
to	I-Protocol
zero	I-Protocol
,	O
PAM2	O
)	O
coding	O
partly	O
because	O
it	O
requires	O
more	O
space	O
in	O
integrated	O
circuits	O
,	O
and	O
is	O
more	O
susceptible	O
to	O
SNR	O
(	O
signal	O
to	O
noise	O
ratio	O
)	O
problems	O
.	O
</s>
<s>
The	O
higher	O
data	O
transmission	O
rate	O
per	O
cycle	O
compared	O
to	O
NRZ/PAM2	B-Protocol
-signaling	O
used	O
by	O
GDDR6	O
and	O
prior	O
generations	O
improves	O
power	O
efficiency	O
and	O
signal	O
integrity	O
.	O
</s>
<s>
Unlike	O
the	O
traditional	O
dark-adapted	O
chlorophyll	O
fluorescence	O
measurements	O
,	O
pulse	O
amplitude	B-Application
fluorescence	O
devices	O
allow	O
measuring	O
under	O
ambient	O
light	O
conditions	O
,	O
which	O
made	O
measurements	O
significantly	O
more	O
versatile	O
.	O
</s>
<s>
Pulse-amplitude	B-Device
modulation	I-Device
has	O
also	O
been	O
developed	O
for	O
the	O
control	O
of	O
light-emitting	O
diodes	O
(	O
LEDs	O
)	O
,	O
especially	O
for	O
lighting	O
applications	O
.	O
</s>
<s>
LED	O
drivers	O
based	O
on	O
the	O
PAM	O
technique	O
offer	O
improved	O
energy	O
efficiency	O
over	O
systems	O
based	O
upon	O
other	O
common	O
driver	O
modulation	B-Application
techniques	O
such	O
as	O
pulse-width	B-Algorithm
modulation	I-Algorithm
(	O
PWM	O
)	O
as	O
the	O
forward	O
current	O
passing	O
through	O
an	O
LED	O
is	O
relative	O
to	O
the	O
intensity	O
of	O
the	O
light	O
output	O
and	O
the	O
LED	O
efficiency	O
increases	O
as	O
the	O
forward	O
current	O
is	O
reduced	O
.	O
</s>
<s>
Pulse-amplitude	B-Device
modulation	I-Device
LED	O
drivers	O
are	O
able	O
to	O
synchronize	O
pulses	O
across	O
multiple	O
LED	O
channels	O
to	O
enable	O
perfect	O
color	O
matching	O
.	O
</s>
<s>
The	O
North	O
American	O
Advanced	B-Device
Television	I-Device
Systems	I-Device
Committee	I-Device
standards	I-Device
for	O
digital	B-Application
television	I-Application
uses	O
a	O
form	O
of	O
PAM	O
to	O
broadcast	O
the	O
data	O
that	O
makes	O
up	O
the	O
television	O
signal	O
.	O
</s>
<s>
This	O
system	O
,	O
known	O
as	O
8VSB	B-Device
,	O
is	O
based	O
on	O
an	O
eight-level	O
PAM	O
.	O
</s>
<s>
It	O
uses	O
additional	O
processing	O
to	O
suppress	O
one	O
sideband	B-Device
and	O
thus	O
make	O
more	O
efficient	O
use	O
of	O
limited	O
bandwidth	B-Algorithm
.	O
</s>
<s>
Using	O
a	O
single	O
6MHz	O
channel	O
allocation	O
,	O
as	O
defined	O
in	O
the	O
previous	O
NTSC	O
analog	O
standard	O
,	O
8VSB	B-Device
is	O
capable	O
of	O
transmitting	O
32Mbit/s	O
.	O
</s>
