1. Field of the Invention
The present invention relates to a method and associated detecting circuits for detecting connection polarity of network transmission lines, and more particularly, to a method and associated detection circuits for detecting and correcting the connection polarity of network transmission lines by counting the number of signal pulses.
2. Description of the Prior Art
In a modern, information based society, computer networks allow people to exchange information. Hence, the manufacture and maintenance of these computer networks is an important issue.
Please refer to FIG. 1A. FIG. 1A is a schematic diagram of a connection between two network clients 12A and 12B via a network transmission line 14. The clients 12A and 12B can be a switch, a router, a terminal of a network system, or other types of network clients. The transmission media between these two clients can be an Ethernet, in which the network transmission line 14 is typical Ethernet transmission cable. The connection port of each client has two ports, a transmitting port and a receiving port, for exchanging information via the network transmission line 14. A transmitting port Tx0 and a receiving port Rx0 are provided in the client 12A, whereas a transmitting port Tx1 and a receiving port Rx1 are provided in the client 12B. Each port transmits or receives, for example, a differential signal by a pair of wires inside the network transmission line 14. Under a correct connection, the transmitting port Tx0 of the client 12A connects to the receiving port Rx1 of the client 12B and the receiving port Rx0 of the client 12A connects to the transmitting port Tx1 of the client 12B via the network transmission line 14, as shown in FIG. 1A, so as to provide a correct connection polarity. If the connection polarity is correct then the two clients 12A and 12B can communicate properly.
In practical situations, it happens that the connection polarity of the network transmission line 14 connected between the clients 12A and 12B is inverted. Please refer to FIG. 1B. FIG. 1B is a schematic diagram of the network system shown in FIG. 1A but with inverted connection polarity. That is, the transmitting port Tx1 of the client 12B connects to the transmitting port Tx0 of the client 12A instead of the receiving port Rx0. Similarly, the receiving port Rx1 of the client 12B does not correctly connect to the corresponding transmitting port Tx0 of the client 12A instead of the receiving port Rx0. Thus, the receiving ports Rx0 and Rx1 of the clients 12A and 12B will not receive any meaningful signals, since the network system malfunctions.