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The ultimate speed experience!
We are proud to announce our new PACTOR-III mode.
PACTOR-III is our new data transmission mode which is superior to PACTOR-II
in both speed and robustness.
PACTOR-III is not a new modem or hardware.
Current PTC modems will be upgradable to use PACTOR-III via a software
update.
PACTOR-III is available as part of the professional firmware!
To use PACTOR-III both transmitting and receiving stations must support
PACTOR-III. If you are a mobile station transmitting to a land based station
both mobile and land stations must be in PACTOR-III mode in order to benefit
from the higher data rates PACTOR-III mode offers.
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PACTOR-III Protocol Specification:
SLV = "Speedlevel", sub protocol level - adaptation fully automatic.
NTO = Number of tones (sub carriers) used on actual "Speedlevel".
PDR = Physical data rate, raw bit rate (Bit/sec) transferred on the physical
protocol layer.
NDR = Net user data rate (without data compression) (Bit/sec). If PMC (automatic
online data compression) is activated, multiply with factor 1.9 in case of
text files.
CFR = Crestfactor, envelope power ratio, peak / average power (dB). If CFR
is 3 dB, a 100 W SSB transmitter generates 50 W mean output power without
signal clipping or limitting.
SNR = Required signal to noise ratio.
SLV NTO PDR NDR CFR SNR
1 2 200 76.8 1.9 *)
2 6 600 247.5 2.6 *)
3 14 1400 588.8 3.1 *)
4 14 2800 1186.1 3.8 *)
5 16 3200 2039.5 5.2 *)
6 18 3600 2722.1 5.7 *)
*) Depends on channel model. Measurements on an Ionospheric Simulator will
follow. On an average channel, PACTOR-III is around 3.5 times faster than
PACTOR-II. On good channels, the effective throughput ratio between PACTOR-III
and PACTOR-II can exceed 5. PACTOR-III achieves slightly higher robustness
at the low SNR edge compared to PACTOR-II.
Maximum occupied bandwidth: 2.4 kHz @ -40 dB, audio passband: 400-2600 Hz.
Maximum net throughput with online data compression: ca. 5200 Bit/sec.
Notice that the online data compression provided by the PTC modems is
especially useful for applications which do not allow offline (file)
compression, e.g. email via TCP/IP, etc. The PTC-II is the only HF modem on
the market which offers efficient online data compression.
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Link establishment:
The calling modems uses the PACTOR-I FSK connect frame to be compatible with
the lowest (PT-I) level. The called modem then answers and the modems
negotiate to the highest possible level both modems are capable of. If one
modem is only capable of PACTOR-II, then the 500Hz PACTOR-II mode is used
for the session. With the MYLevel command a user may limit a modems highest
mode. An example: a user may set MYL to "1" and a PTC will only make a
PACTOR-I connection, set to "2" and PACTOR-I and II connections are
available, set to "3" and PACTOR-I through III connections are enabled. The
default MYL is set to "2" with the current firmware and with PACTOR III
firmware it will be set to "3". When PACTOR-III is released, if a user is
only allowed to occupy a 500Hz channel MYL can be set to "2" and the modem
will behave like the current PACTOR-II firmware.
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