FSK data receiving system

摘要

The present invention has a purpose to obtain an FSK data receiving system which is capable of constituting a direct-conversion receiver suitable for realizing an integrated circuit, is capable of decoding in a wide receiving band width, and is capable of realizing a small-sized and less-electric power consumption data receiving. The FSK-modulated local oscillator signal 3 is applied to the local oscillator 2, and there is provided the decode circuit 15 which obtains the decode signal 14 by judging whether the FSK-modulated frequency deviation of the carrier wave signal 1 is a positive deviation or a negative deviation on the basis of the comparison result of the voltage change in the frequency-voltage conversion circuit 16 for the base-band signal 8; i.e. the output signal of the frequency mixer 6. The offset amount of the local oscillator frequency is judged by the voltage judging means 17 to produce the control signal 18, And further, there is provided the another decode circuit 22 which makes the judgement of frequency change of the base-band signal 8 and the judgement of in-phase/opposite-phase relationship from the decode signal 14 and the output of the voltage judging means 17 so as to obtain the decode signal 23. Moreover, there is provided the decode signal processing circuit 25 which obtains the decode signal 24 from the decode signals 14, 23 in response to the control signal 18. <IMAGE>