Signal Quality Error - Also know as heartbeat, a test between the transceiver/MAU and the DTE to ensure that the collision detection circuit in the transceiver/MAU is working. The heartbeat function must be disabled when a transceiver/MAU is attached to a repeater. If a transceiver/MAU, while transmitting, detects a collision, the transceiver/MAU sends the SQE signal to the repeater, or node, to which it is connected. Also see Heartbeat