HamRadio Tech

DIGITAL MODES: the new generation of HF HAM Radio !


What is PACTOR III??

PACTOR III is the next generation HF data transmission mode developed by SCS of Hanau Germany. SCS invented PACTOR and in 1995 followed with the PACTOR II mode. PACTOR I and II modes are supported by PTC-II, PTC-IIe and PTC-IIpro modems manufactured by SCS. All current PTC modems are upgradable to use PACTOR III via a software update. This update will be available for a fee from SCS and SCS agents worldwide for $150 USD. PACTOR III is not a new modem or hardware. Current PTC modems are upgradable to use PACTOR III via a software update. 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 the mobile and land stations must be in PACTOR III mode in order to benefit from the higher data rates III mode offers. PACTOR III Technical Overview, Link Layer Specification: (C) 2002 SCS GmbH & Co. KG, Hanau, Germany PACTOR III uses a voice channel of 2.4khz and with an optimal link, is 4 to 5 times faster than PACTOR II mode. Current SCS hardware (PTC-IIe and PTC-IIpro) is upgradable to III mode via a firmware update (note that some older models of PTC-IIe and all PTC-II will require a factory bios update). PACTOR III applies 6 different "speedlevels", depending on the actual signal conditions. Switching between the submodes is fully automatic.

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 *


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. * Depends on channel model. Measurements on the 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 on the low SNR edge compared to PACTOR-II.
Maximum occupied bandwidth: 2.4 kHz @ -40 dB, audio passband: 300-2700 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 standard firmware and with PACTOR III firmware it will be set to "3". If a user is only allowed to occupy a 500Hz channel, MYL can be set to "2" and the modem will behave like standard PACTOR II firmware.

For further information: Individual and recreational users, contact Gary Wood at 415-331-1924, press 1 or email garywood@farallon.us Commercial users, multi point and point to point, contact Eric Steinberg at 415-505-6000 or email ericsteinberg@farallon.us

2346 Marinship Way, Suite 101, Sausalito, CA 94965 USA


415-331-2063 / fax


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