Videorecorder for adding data signals on previously recorded signals,

Abstract

A video recorder having recording/reproducing apparatus for subsequent recording of data signals in defined video lines of a previously recorded signal existing on a magnetic tape. The recording/reproducing apparatus (10, 11, 12, 19, 20) records FM signals onto the magnetic tape and reads previously recorded FM signals from the magnetic tape. A voltage controlled oscillator VCO (13) is connected between a data signal input terminal (16) and a recording terminal (11), for converting data signals routed to the data input terminal (16) into FM data signals. A switch (14) is connected between the recording terminal (11) and a VCO (13) output, for switching the recording terminal (11) to the VCO (13) output for the duration of the recording mode of the data recording apparatus. A circuit (17) detects a line sync signal (22) of the video lines passing through the data recording apparatus, for switching the recording/reproducing apparatus from recording mode to reproducing mode immediately before the end of a video line, and for switching from the reproducing mode to the recording mode immediately after detection of the line sync signal (22). A phase comparator circuit (23) has phase comparator inputs, one connected to the VCO (13) output and another to the reproducing output (12), for generating a phase deviation signal for the VCO (13) input and for setting an in-phase oscillation of the VCO (13) with the oscillation picked up by the phase comparator circuit (23). A data signal switch (18) has the VCO (13) input connected either to the output of the phase comparator circuit (23), or to the data signal recording apparatus input terminal (16) for the duration of the recording mode of the data signal recording apparatus.