Procedure for recording a newly encoded message instead of an older message encoded on a magnetic track of a carrier document by a manual replacement of that document and a system to perform this procedure

摘要

The method consists in that the message is broken down into a first part M1 and into a second part M2 which are separated by a gap I and in that, for writing the first part M1 of the new message, the clock signal extracted from the reading of the second part M2 of the previous message is used as clock signal, and, for writing the second part M2 of the new message, the clock signal extracted from reading the first part M1, newly written, of the new message is used as clock signal. The system includes a write head (9) framed by two synchronisation heads (8, 10) and an electronic circuit (15) which derives, from the signals from the two synchronisation heads (8 and 10), a clock signal (14) slowed to the speed of movement of the support document (1). This clock signal (14) is sent to a write generator (12) linked to the write head (9). The write generator furthermore receives the data (13) to be recorded. …IMAGE…