| 摘要 |
PURPOSE:To eliminate the need for a special processing by utilizing an AGC output of a reception signal processing circuit to extract a repetitive signal such as an SI signal with simple constitution thereby giving an SI signal supervisory time suitable for a MODEM corresponding to the CCITT recommendations V.22bis. CONSTITUTION:The 1st and 2nd data having a coordinate (-rcostheta, jrsintheta ) and a coordinate (-rsintheta, jrcostheta ) respectively are extracted as repetitive patterns with a predetermined Baud rate, where (r) is a radius and theta is a phase angle on a vector plane. The AGC output of a signal processing circuit is intro duced through the extraction, a means value extraction section 1 obtains a means value between the AGC output and an output before 1 Baud rate and a multiplication processing section 3 obtains the product between the means value and a complex conjugated value of the preceding Baud rate. The output is processed by a DC component r subtraction circuit 5, a square circuit section 6, an addition processing section 7 and a comparison processing section 8 via an LPF4 to discriminate and process 9 a value within a prescribed range from a point of a real coordinate. |
