4380088 Tester For Collision Detect Circuitry Aug81

This patent describes a tester for the collision detection circuitry within a transceiver operating in a Carrier Sense Multiple Access/Collision Detection (CSMA/CD) network. The primary purpose of this tester is to ensure the transceiver's ability to detect collisions is functioning correctly, thereby preventing network disruption from faulty equipment.

The testing mechanism operates automatically at the conclusion of every data transmission. It involves an end-of-transmission detector that monitors the transceiver's transmitter squelch signal (which controls transmitter output). Upon detecting the end of a transmission, this detector triggers a collision simulator circuit.

The simulator then injects a signal of specific, predetermined amplitude and duration into the transceiver's receiver, mimicking a genuine data collision. If the receiver's collision detection circuitry is operational, it will register this simulated collision and report it to the connected host device (e.g., computer, terminal).

The host is programmed to recognize this collision, appearing at a specific time after transmission, as a successful validation of the test. Conversely, the absence of this expected collision signal alerts the host to a failure in either the transceiver's collision detection system or the tester itself, allowing for intervention before network integrity is compromised.