Amateur radio system consisting of packets of synchronous data at either 100 or 200 Baud. Data blocks are 960mS long and the acknowledgement 120mS long. Alternates in a 1.25 second cycle. The acknowledgement is always 12 bits long at 100 baud regardless of whether the system data speed is 100 or 200 baud. Each transmitted packet consists of 96 bits at 100 baud and 192 bits at 200 baud.

Each data block, as with AX25 packet, contains an address block, status information and a CRC Checksum for error detection. There are various sub-modes to this system including the use of data compression using Huffman coding.

Click here for a typical PACTOR sound