Multiplexing speech signals
AssigneeThe Post Office
InventorPeter Cochrane
Life of this patent
Estimating the term…
Abstract
To transmit a number of individual speech channels over a smaller number of transmission channels, the frequency range of each speech channel is broken into sub-channels and each of these is considered separately for operational activity. Composite speech signals are then formed from the active frequency sub-channels of the individual speech channels and these are transmitted with coding signals indicative of their composition.
Claims8
Speech signal multiplexing apparatus comprising, for each input channel, a multiplicity of frequency subchannel filter circuits;
- a sensor for determining the level of speech activity in each of the selected frequency subchannels for each of the speech channels and means for forming a composite output signal having frequency sub-channels each of which contains speech subchannel signals from two or more of the individual input speech channels, by allocating each frequency subchannel of a speech channel, while that subchannel is active, to an empty subchannel of the composite signal, the subchannels of any given input signal being at least sometimes assigned to output signal subchannels which are noncontiguous and separated by output signal subchannels corresponding to subchannels of another input signal whereby the frequency subchannels of the composite speech signal are more fully occupied than those of the individual speech signals, and means for including in the composite signal a coding signal indicative of the contents of the said subchannels of the composite output signal.
A method of transmitting a number of individual speech channels over a smaller number of transmission channels, comprising:
- sensing for each speech channel the operational activity of each of a multiplicity of frequency subchannels within the frequency range of that speech channel and allocating those frequency subchannels of a speech channel which are active to empty cubchannels of an output signal to form at least one composite output signal having frequency subchannels some or all of which contain subchannel signals from two or more of the individual speech channels, the active subchannels of any given input signal being at least sometimes assigned to subchannels of the output signal which are non-contiguous and which are separated in frequency by output signal sub-channels to which are assigned subchannels of another input signal whereby the frequency subchannels of the composite speech signal are more fully occupied than those of the individual signals;
- and transmitting the composite speech signal with a coding signal representing the manner in which the individual speech channel signals have been combined to form the composite speech signal.
Dependencies are inferred from the claim text.