 2 main user advantages with ECM: with the data going to memory until corrected data is available. In most practical cases this procedure, and the availability in the 1. The sender is 100% confident that acknowledged pages are receiver of sufficient memory for the next page/partial page, avoids complete and received free of error. waiting between pages due to printer unavailability. 2. That as errors are efficiently corrected transmission time (and With the page/partial page correctly received the receiver replies cost) can be reduced by using higher transmission rates together with MCF and the transmitter continues with the next data. with MMR coding. Figure 60.5 shows ECM operation with errors. If errors are de- tected the receiver sends PPR which has an information field of 256 The transmitter has the opportunity from studying the pattern of bits, one for each frame of the transmitted block. The receiver sets errors in PPR to reduce the frame size to 64 octets or to change the each bit of PPR to 'O' for a correctly received frame and waits for data rate to maximise throughput. The selective retransmission and the transmitter to selectively repeat the unacceptable frames. large window with minimum turnarounds providing efficient long Pages/partial pages are often corrected with a single retransmission haul communication even including 3 satellite links. Receive Frame 0 Frame 1 Error frame Frame 2 information field Frame 3 Address Control (PPR) Frame 255 FIF(PPR) PPS-EOP Frame 1 Error frame Frame 3 PPS-EOP Frame 1 PPS-EOP Corrected by retransmission Figure 60.5 ECM operation with errors G3 facsimile equipment 60/11 60.4.5 Printer rapidly. This technique is being used in facsimile equipment with a replaceable bubble jet ink cartridge. The cartridge is moved across There are several methods of printing the facsimile image including the paper to print several facsimile lines (typically 16 fine mode electrophotographic (laser or LED), ink jet, thermal transfer and, the lines) at once and the ink bubbled appropriatel