| 摘要 |
PURPOSE:To attain synchronism supervision with improved S/N by detecting the difference between the maximum value and the 2nd larger value in the outputs of a multi-value error correction decoder and deciding it as the deterioration of S/N when the difference is smaller than the preset threshold value. CONSTITUTION:An antenna 21 receives a signal subject to frequency hopping FH, a mixer 22 is applied with inverse-spread by using a local signal fL generated from an FH synthesizer 23 driven by a spread core generator 24 so as to generate a multi-value FSK signal based on an error correction code. Frequency components f1, f2... are extracted by a filter bank 25, detected (24) and inputted to an analog register 27. Then the signal is added (28), the maximum value Vmax is detected (29), and further the 2nd maximum value Vmax2 is detected (41). The difference between the Vmax and the Vmax2 is obtained by a synchronism supervising device 42, the result is compared with a prescribed threshold value, and when the difference is small, it is decided as the deterioration of S/N. Thus, the synchronism supervision is attained by using a signal with improved S/N. |
