US 4,048,449 AGranted

Method for forming a conference connection in a telecommunication switching system

AssigneeSiemens Aktiengesellschaft

InventorRoderich Natebusch

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Abstract

A method is described for connecting at least three subscribers in, e.g., a conference call in time division multiplex (TDM) pulse code modulation (PCM) telecommunication switching systems. In each participating subscriber station a TDM signal having the instantaneous value of the speech signal amplitude is stored for one ring circuit signal period in that subscriber station. The stored TDM signal is subtracted from the TDM signal transferred over the section of the ring circuit connected to the foregoing subscriber station in the TDM time segment assigned to the conference call. Added to the difference signal, so obtained, is a TDM signal displaying the instantaneous value of the speech signal amplitude and, the composite TDM signal obtained in this way is transmitted from the aforementioned subscriber station. The latter subscriber station receives either the difference signal or the composite signal as a TDM signal having the instantaneous values of the speech signals of the conferees.

Claims2

Dependent claims

A method for connecting at least three subscribers participating in a conference call in a pulse code modulation (PCM), time division mulitplex(TDM) telecommunication system having subscriber stations connected in a ring-like TDM circuit, comprising the steps of:

generating in each said participating subscriber station a first TDM signal corresponding to the instantaneous value of a speech signal issuing from that subscriber station,
storing said first TDM signal in the subscriber station where it is generated for a period of a signal cycle through said ring-like circuit,
subtracting a second signal from an incoming signal from other subscriber stations in the time position assigned to the conference call to produce a difference signal, said second signal being a previously stored first signal,
adding said first signal and said difference signal to produce a composite signal, and
transmitting said composite signal over said ring-like circuit from the subscriber station where it was produced,
whereby at least said difference signal is received by a said participating subscriber station as a TDM signal corresponding to instantaneous speech values in others of said participating subscriber stations.

3 more elements

Dependencies are inferred from the claim text.