<s>
PACTOR	B-Device
is	O
a	O
radio	O
modulation	O
mode	O
used	O
by	O
amateur	O
radio	O
operators	O
,	O
marine	O
radio	O
stations	O
,	O
military	O
or	O
government	O
users	O
such	O
as	O
the	O
US	O
Department	O
of	O
Homeland	O
Security	O
,	O
and	O
radio	O
stations	O
in	O
isolated	O
areas	O
to	O
send	O
and	O
receive	O
digital	O
information	O
via	O
radio	O
.	O
</s>
<s>
PACTOR	B-Device
is	O
an	O
evolution	O
of	O
both	O
AMTOR	B-Device
and	O
packet	B-Application
radio	I-Application
;	O
its	O
name	O
is	O
a	O
portmanteau	O
of	O
these	O
two	O
technologies	O
 '	O
names	O
.	O
</s>
<s>
PACTOR	B-Device
uses	O
a	O
combination	O
of	O
simple	O
FSK	O
modulation	O
,	O
and	O
the	O
ARQ	B-Error_Name
protocol	I-Error_Name
for	O
robust	O
error	B-Error_Name
detection	I-Error_Name
and	O
data	O
throughput	O
.	O
</s>
<s>
Generational	O
improvements	O
to	O
PACTOR	B-Device
include	O
PACTORII	O
,	O
PACTORIII	O
,	O
and	O
PACTORIV	O
which	O
are	O
capable	O
of	O
higher	O
speed	O
transmission	O
.	O
</s>
<s>
PACTOR	B-Device
is	O
most	O
commonly	O
used	O
on	O
frequencies	O
between	O
1MHz	O
and	O
30MHz	O
.	O
</s>
<s>
PACTOR	B-Device
(	O
Latin	O
:	O
The	O
mediator	O
)	O
was	O
developed	O
by	O
Special	O
Communications	O
Systems	O
GmbH	O
(	O
SCS	O
)	O
and	O
released	O
to	O
the	O
public	O
in	O
1991	O
.	O
</s>
<s>
PACTOR	B-Device
was	O
developed	O
in	O
order	O
to	O
improve	O
the	O
reception	O
of	O
digital	O
data	O
when	O
the	O
received	O
signal	O
was	O
weak	O
or	O
noisy	O
.	O
</s>
<s>
It	O
combines	O
the	O
bandwidth	B-Algorithm
efficiency	O
of	O
packet	B-Application
radio	I-Application
with	O
the	O
error-correction	B-Error_Name
(	O
CRC	O
)	O
and	O
automatic	B-Error_Name
repeat	I-Error_Name
request	I-Error_Name
(	O
ARQ	B-Error_Name
)	O
of	O
AMTOR	B-Device
.	O
</s>
<s>
PACTOR	B-Device
radio	O
equipment	O
consists	O
of	O
an	O
HF	O
transceiver	O
,	O
a	O
computer	O
and	O
a	O
terminal	B-Protocol
node	I-Protocol
controller	I-Protocol
.	O
</s>
<s>
Software	O
running	O
on	O
the	O
computer	O
drives	O
the	O
terminal	B-Protocol
node	I-Protocol
controller	I-Protocol
.	O
</s>
<s>
PACTOR	B-Device
is	O
used	O
by	O
Amateur	O
Bulletin	B-Application
board	I-Application
system	I-Application
operators	O
to	O
exchange	O
public	O
messages	O
,	O
and	O
open	O
conversations	O
across	O
the	O
world	O
.	O
</s>
<s>
Newer	O
PACTOR	B-Device
modes	O
are	O
used	O
to	O
transfer	O
large	O
binary	O
data	O
files	O
and	O
Internet	O
e-mail	O
,	O
particularly	O
via	O
the	O
Winlink	B-Protocol
global	O
e-mail	O
system	O
.	O
</s>
<s>
PACTOR	B-Device
is	O
a	O
set	O
of	O
standardized	O
modes	O
used	O
by	O
radio	O
operators	O
for	O
FSK	O
radioteletype	O
transfer	O
of	O
digital	O
information	O
over	O
shortwave	O
bands	O
.	O
</s>
<s>
Effective	O
radio-frequency	O
communications	O
over	O
long	O
distances	O
over	O
hostile	O
radio	O
paths	O
require	O
that	O
special	O
attention	O
be	O
paid	O
to	O
the	O
rate	O
at	O
which	O
data	O
is	O
repeated	O
and	O
error	B-Error_Name
correction	I-Error_Name
.	O
</s>
<s>
To	O
reduce	O
the	O
amount	O
of	O
data	O
sent	O
,	O
on-line	O
data	O
compression	O
is	O
utilized	O
,	O
along	O
with	O
memory	O
ARQ	B-Error_Name
error	B-Error_Name
correction	I-Error_Name
.	O
</s>
<s>
PACTOR	B-Device
utilizes	O
very	O
rapid	O
time-division	O
duplexing	O
,	O
giving	O
PACTOR	B-Device
communications	O
its	O
characteristic	O
cricket-like	O
chirping	O
sound	O
when	O
listened	O
through	O
a	O
single-sideband	B-Device
(	O
SSB	O
)	O
receiver	O
.	O
</s>
<s>
Depending	O
on	O
the	O
version	O
of	O
PACTOR	B-Device
protocol	O
used	O
and	O
the	O
radio-frequency	O
conditions	O
,	O
PACTOR	B-Device
transmission	O
speeds	O
range	O
from	O
20	O
to	O
5200bits	O
per	O
second	O
(	O
bit/s	O
;	O
net	O
rate	O
)	O
or	O
9000bit/s	O
gross	O
rate	O
utilizing	O
speed10	O
(	O
32-QAM	O
)	O
.	O
</s>
<s>
The	O
International	O
Telecommunication	O
Union	O
(	O
ITU	O
)	O
emission	O
designators	B-Device
:	O
</s>
<s>
Pactor	B-Device
I	O
is	O
340HJ2D	O
or	O
440HJ2D	O
(	O
at	O
a	O
symbol	O
rate	O
up	O
to	O
200symbols	O
per	O
second	O
)	O
.	O
</s>
<s>
Pactor	B-Device
II	O
is	O
450HJ2D	O
(	O
at	O
a	O
symbol	O
rate	O
of	O
100symbols	O
per	O
second	O
)	O
.	O
</s>
<s>
Pactor	B-Device
III	O
is	O
2K20J2D	O
(	O
at	O
a	O
symbol	O
rate	O
of	O
100symbols	O
per	O
second	O
)	O
.	O
</s>
<s>
Pactor	B-Device
IV	O
is	O
2K20J2D	O
or	O
2K40J2D	O
(	O
at	O
a	O
symbol	O
rate	O
up	O
to	O
1800symbols	O
per	O
second	O
)	O
.	O
</s>
<s>
A	O
robust	O
network	O
of	O
PACTOR	B-Device
stations	O
has	O
been	O
established	O
to	O
transfer	O
data	O
between	O
radio	O
stations	O
and	O
the	O
Internet	O
,	O
extending	O
Internet	O
access	O
to	O
sea-based	O
and	O
other	O
isolated	O
users	O
,	O
led	O
by	O
volunteers	O
involved	O
with	O
Winlink	B-Protocol
,	O
under	O
the	O
auspicies	O
of	O
ARSFI	O
(	O
a	O
Florida-based	O
non-profit	O
organization	O
)	O
.	O
</s>
<s>
Pactor	B-Device
modes	O
other	O
than	O
level1	O
(	O
P1	O
)	O
are	O
not	O
open	O
source	O
,	O
but	O
are	O
publicly	O
documented	O
and	O
can	O
be	O
monitored	O
and	O
decoded	O
easily	O
over	O
the	O
air	O
by	O
third	O
parties	O
using	O
free	O
Raspberry	O
Pi	O
software	O
(	O
"	O
PMON	O
for	O
Raspberry	O
Pi	O
"	O
)	O
or	O
PMON	O
utility	O
on	O
the	O
modem	O
itself	O
.	O
</s>
