| 摘要 |
PURPOSE:To eliminat a malfunction against an hourly variation of a system by making a tone burst of an (n) wave having a different frequency correspond to a data of an (n) value, discriminating the data of an (n) value by a difference of frequency of the tone burst, and executing a reproducing. CONSTITUTION:Low band and high band tone oscillating parts 11, 12 always output a sine wave, and an output waveform is controlled by a data control part 14. The data control part 14 controls a changeover switch 13 so that a low band frequency fL and a high band frequency fH are obtained when a data is ''1'', and when the data is ''0'', respectively, and so that there is no tone when the data is ended. In a magnetic tape sound recording device 15, a data is sound-recorded by a signal format. A signal outputted from a magnetic tape reproducing device 21 is discriminated as to frequency by low band and high band passing filters 22, 23. A signal system of a mark signal 1 rectifies a level of a tone passing through the low band passing filter 22 by a level detector 24, outputs it from a level comparator 26, and a decoding system of a space signal ''0'' outputs the tone at an H level from a level comparator 27. A stop part becomes necessary for every 1-bit of the data, and sound recording and reproducing are executed without causing a malfunction. |
