Multi-channel electric wave signalling apparatus

Claim 1

MULTI-CHANNEL ELECTRIC WAVE SIGNALLING APPARATUS HAVING SEPARATE SIGNAL-CHANNELS FOR A PLURALITY OF SIGNALS EACH OCCUPYING A BAND OF FREQUENCIES COMPRISING SEPARATE FREQUENCY CHANGING MEANS FOR EACH SIGNAL, THE FREQUENCY CHANGING MEANS TOGETHER TRANSPORTING THE FREQUENCY OF THE PLURALITY OF SIGNALS TO A PLURALITY OF ADJACENT OR CLOSELY SPACED FREQUENCY BANDS; EACH FREQUENCY CHANGING MEANS COMPRISING A FIRST PAIR OF BALANCED MODULATORS HAVING FIRST INPUTS CONNECTED IN PARALLEL AND SUPPLIED WITH THE SIGNAL CONCERNED AND HAVING SECOND INPUTS SUPPLIED FROM A FIRST OSCILLATOR THROUGH FIRST AND SECOND PHASE-SHIFT ING NETWORKS RESPECTIVELY ADVANCING AND RETARDING THE PHASE OF THE FIRST OSCILLATOR SIGNAL, A SECOND PAIR OF BALANCED MODULATORS HAVING FIRST INPUTS SEPARATELY FED FROM THE OUTPUTS OF THE FIRST PAIR OF BALANCED MODULATORS AND HAVING SECOND INPUTS SUPPLIED FROM A SECOND OSCILLATOR THROUGH THIRD AND FOURTH PHASE-SHIFTING NETWORKS RESPECTIVELY ADVANCING AND RETARDING THE PHASE OF THE SECOND OSCILLATOR SIGNAL, AND AN OUTPUT LOAD COMMON TO THE OUTPUTS OF BOTH OF THE SECOND PAIR OF BALANCED MODULATORS, SO THAT EACH SIGNAL IS TRANSPOSED IN FREQUENCY BY SEPARATELY MODULATING THE SIGNAL TWICE USING DIFFERENT CARRIERS IN EACH MODULATION; OUTPUT MEANS BEING PROVIDED IN SAID APPARATUS TO COMBINE THE OUTPUT SIGNALS FROM THE SEPARATE FREQUENCY CHANGING MEANS INTO A SINGLE MULTI-CHANNEL SIGNAL.