Table of Contents
Advertisement
1.1.06 Error Correction Mode (ECM)
Error Correction Mode (ECM) provides error-free transmission when communicating with a remote unit
that also has ECM.
Here is an explanation of the ECM process.
· The transmit machine groups image data into blocks and transmits one block of data at a time to the
receive machine. At the end of each block, a Partial Page Signal (PPS) is transmitted.
· The receive machine stores the data block in memory and checks each frame within that block for
errors.
Modified Huffman assigns a binary code to consecutive recurring bits of white or black. The codes must
add up to a total of 1728 bits, which is the Main Scan Rate established by CCITT.
Modified Read uses a comparison technique. The line being coded is compared to the previous line and
differences are noted. Codes are then assigned to reflect the differences between the two lines.
· If no errors are detected, the receiver sends Message Confirmation (MCF). MCF requests the transmit
machine to transmit the next data block.
· If an error is detected by the receive machine, the receive machine will transmit the frame number of
the defective frame back to the transmit machine in a signal called Partial Page Request (PPR).
· The transmit machine will then re-transmit the frame to the receive machine as a Partial Page.
· The receive machine rechecks the Partial Page, and (if all frames are correct) the receive machine
transmits MCF.
· The next data block is transmitted.
Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business
Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)
Service Guide OF2200/2400/2600
Chapter 1 Principles of Operation
Page: 9
Advertisement
Chapters
Table of Contents
