Network equalisation

In a quasi-synchronous radio system, e.g. for use with mobile subscribers, transmitters are coupled by links (land-line or radio) to a control station, and each such link has a programmable equaliser (PEQR) to ensure that the modulation applied to all transmitters is in phase; etc. To adjust these equalisers, the control station has a reference equaliser (RP) and a modulation, varying over the modulation band-width, which is applied to the reference equaliser (RP) and the link equaliser (PEQR) to be adjusted. The output of the reference equaliser and a monitor of the signal from the transmitter are both applied to a comparator (COMP) whose output is used to suitably adjust the coefficients of the link equaliser. This can be done singly for the transmitters, as required, or to all transmitters.