Supervision arrangement for a pulse code-modulation system

Claim 1

Terminal station apparatus for the transmission of information by means of pulse code modulation using n channels, m channels of which are provided for the transmission of analog information signals and (n-m) channels are provided for the transmission of signalling and synchronizing information, which comprises a transmitter including a multiplex apparatus having inputs connected to the information channels to be transmitted and a coder whose input is connected to the output of the multiplex arrangement; a receiver including a decoder having an input for receiving the pulse code modulation signal and having an output connected to a demultiplex apparatus having outputs from which signals associated with the different information channels can be derived; said multiplex apparatus cyclically scanning the channels for the analog information signals; said coder quantizing said analog information signals in accordance with a piecewise linear coding characteristic, said terminal station apparatus Including a test pulse pattern generator having an output connected to the input of said decoder on the receive side during a period defined by at least one of the (n-m) channels for the transmission of signalling and synchronizing information and which generates a test pulse pattern corresponding to a PCM channel code word, said pattern being applied to said decoder for conversion into the corresponding analog value, the output of the decoder and the input of the coder being connected during said period to a connection line passing the analog value corresponding to the decoded test pulse pattern, said analog value being applied, through said connection line to the coder in which said analog value is converted into a second pulse pattern by means of coding, the apparatus further comprising means for storage of said second pulse pattern, and a comparator connected to the output of said means for storage as well as the output of said test pulse pattern generator, said comparator giving an alarm when said test pulse pattern and said second pulse pattern are not equal.