PACTOR

PACTOR is a family of radio modulation modes used primarily by amateur radio operators and marine radio users for robust, error-corrected data transfer over HF (high frequency) radio channels. It provides a reliable digital communication method in challenging radio propagation environments, such as those experienced with long-distance or noisy transmissions.

PACTOR combines elements of packet radio, AMTOR, and other earlier digital radio modes with advanced forward error correction, adaptive equalization, and data compression to maximize throughput and reliability. Later versions of PACTOR offer improved performance and features compared to earlier iterations.

Key characteristics of PACTOR include:

• Automatic Repeat Request (ARQ): PACTOR uses ARQ, meaning the receiving station automatically requests retransmission of any data blocks received with errors. This ensures data integrity.
• Adaptive Modulation: The system can automatically adjust its modulation scheme and data rate based on the detected quality of the radio channel. This allows it to maintain communication even under varying conditions.
• Forward Error Correction (FEC): FEC is used to correct some errors at the receiver without requiring retransmission, further increasing efficiency.
• Data Compression: PACTOR protocols often incorporate data compression algorithms to reduce the amount of data that needs to be transmitted, thereby increasing throughput.
• Licensing Requirements: Use of PACTOR typically requires an appropriate amateur radio license or authorization, depending on the frequency and transmit power employed.
• Successive versions: PACTOR comes in successive versions (e.g. PACTOR II, PACTOR III, PACTOR IV) where each newer version incorporates improved technology and potentially higher data rates. The higher versions may also be incompatible with older versions.