In the absence of communication signals, monitoring signals are applied at the beginning of at least one monitoring line (7, 8) of said communication system and then extracted at the end of said monitoring line (7, 8).

Depending on the result of comparison, monitoring signals (S1, S2, S3, S4) are derived therefrom which are imitated in the monitoring signals provided by mechanical transmitters in travel and torque detection.

A IQ modulator output signal (MOS) converted into electrical monitoring signals (MOS) and monitored.

A signal net (SN) is transferring traffic control signals, including connection control signals, to the subordinated units (BSC, LE) in which said connections are made, using said trunks.

A monitoring signal routing device within the branch terminal routes a monitoring signal from a branch-drop path to a branch-add path.

The BRE (30) comprises a monitor signal interface for notifying the MDE (200) of monitor signals that denote the status of a wireless unit (50).

Said extraction unit is designed for detecting and extracting monitoring signals applied by the power supply (2).

The user device broadcasts surveillance signals which the processing apparatus uses to derive the position of the user device.

The fault signals can be used for training operators, as well as providing monitoring signals, and can be stored with weld data in a database for later analysis.

During operation, the system receives instrumentation signals from the computer system while the computer system is operating.

The parameter selection unit selects parameters for approximate Cholesky decomposition based on the first and second channel monitor signals.