of existing apparatus application_number US 201113246893 A description fig1 illustrates how the invention in a repeater system 1 or a repeater cascade 1 makes use of frequency transposing repeaters where isolation against echo between repeaters is made redundant by the use of three frequency bands f 1 f 2 f 2 for each information channel possibly each signal direction in use the figure shows in more detail how the invention makes use of a repeater cascade 1 with the help of frequency transposing repeaters 6 8 in combination with repeaters that amplifies within the same channel 7 9 by applying only two frequency bands f 1 and f 2 for on and the same information channel this is achieved in a symmetrical system by repeater 6 frequency shifting from frequency f 1 to f 2 the nest repeater 7 repeats the signal within the same frequency band f 2 the next repeater 8 repeats by frequency shifting to f 1 further on the sequence is repeated starting with the subsequent attenuation 5 and repeater 9 in this way echo for example into one repeater 6 from a different repeater 8 is avoided because the gain in each individual repeater 6 7 8 is substantially lower than the attenuation 3 4 between three.