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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.


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.

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.


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.