| 摘要 |
PURPOSE:To eliminate external noise and to gather switching information of many switches with one coaxial line by obtaining correlations between a false noise signal transmitted to the coaxial line and its reflected waves. CONSTITUTION:When a switch S2 is closed, an impedance rightward from a connection point P2 is lowered because a series resistance (r) is connected in parallel to a terminal resistance R. Consequently, a part of a PN code P(t) transmitted from a transmitting circuit 4 to a coaxial line 1 is reflected at the connection point P2, and a reflected wave PN code r(t) which reaches a reference point P0 has the opposite polarity and is delayed by a time corresponding to a length L2+L1 (two bits in this example). These original and reflected wave signals are superposed and are led to a correlating circuit 6, and correlations between both signals are obtained by this circuit 6. The switch (S2 in this example) whose contact is closed is discriminated on a basis of the value of a correlation output C. |
