| 摘要 |
PURPOSE:To obtain an FSK signal of a frequency with no phase jump by storing ROM with different-frequency data that correspond to two kinds of logical values and change data between frequencies in the form of PCM data and then by A/D- converting them. CONSTITUTION:In ROM303, PCM data of the state of low frequency fL of an FSK signal, state changing from fL to high frequency fH, state of fH, and state changing of FH to FL are stored previously. Clock CL signal from terminal 1, transmitted data D from terminal 2 and delay transmitted data D' obtained by delaying 301 data D by one data period are received by address counter 302 and according to the address of counter 302, one of four states from ROM303 is selected and inputted to D/A converter 304. With signal CL, converter 304 converts the signal from ROM into a PAM signal, which is outputted via LPF305. The beginning and ending of foor PCM data stored in ROM are put in phase, so that an FSK signal having not any phase jump at a frequency change point can be obtained. |
