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Dragon HF Modems



The SCS  P4dragon DR-7800 is a completely new development, and the first PACTOR-4 capable short-wave modem. P4dragon stands for the most ingenious data transfer algorithms and the highest computing power possible in PACTOR controllers of the 4th generation.

Due to its compact construction and focussing on the most important features, the P4dragon DR-7400 offers a lower-priced entry to the P4dragon modem class.

The fast quad-core DSP used in the DR-7X00 modems enables for the very first time, a high data rate, approaching very close to the Shannon limit, as well as an extremely high immunity to interference. PACTOR-4, with its 10 speed levels and adaptive equalizer, adjusts itself ideally to varying channel conditions, and guarantees reliable data transfer even under very poor propagation conditions. Due to this high reliability, P4dragon modems allow transmission of safety relevant data via shortwave, and provide an excellent value for money when compared to many satellite services.

P4dragon modems use a very complex newly developed synchronization algorithm for the link initialization (both ”normal” and ”robust”). This allows that on receipt of a ”connect” request from a calling station, an immediate and loss free automatic frequency compensation of up to ±280 Hz! can be applied to the receiver. The receiver of the ”Connect request” e.g. the Winlink-RMS or similar base station corrects its own receiver frequency AND the transmit frequency of the short radiated acknowledgement directly after the FSK synchronization. The modem of the calling station must then only correct the small remaining error (max ±10 Hz) after the link initialization. Thus PACTOR-2 /-3/-4 connects start immediately with full speed, independent of the initial frequency error. Base stations which operate using DR-7X00 modems thus also allow users initiating a link with a frequency error of greater than 30 Hz immediate full speed operation, even when the user only uses a PTC-II. (PTC-II modems in contrast only have a capture range of ±100 Hz for the reception of a link request, and automatically reduce the PACTOR-3 throughput when frequency errors of greater than ±30 Hz are measured.)

A high Tolerance to frequency errors is especially useful on the ”higher” shortwave bands. A relatively ”normal” frequency error of only 10 ppm produces a frequency error on the 20 meter band for example of 140 Hz.

P4dragon DR-7800

P4dragon DR-7800

£1,189.00

in stock

More info

P4dragon DR-7400

P4dragon DR-7400

£1,068.00

in stock

More info