US 27428202 A description to aid an understanding of this invention we give a brief description of a c quam transmitted wave a wave transmitted after modulation according to the c quam scheme can be written as s t 1 l r cos u03c9 c t u03c6 t 1 and u03c9 c is the angular frequency of the carrier l r is the sum signal l u2212 r is the difference signal and p is a pilot signal superimposed on the difference signal to ensure that the amplitude modulated component is not overmodulated it is essential that the following embodiments are described in terms of the use of a transmitted wave that can be expressed by equation 1 a first specific embodiment of the present invention will now be described fig1 is a block diagram showing the configuration of this first embodiment which comprises c quam transmitter 100 transmitting antenna 101 receiving antenna 102 of a c quam receiver front end amplifier 103 frequency converter 104 local oscillator 105 intermediate frequency if filter 106 frequency converter 107 local oscillator 108 amplitude limiter hard limiter 109 if filter 110 frequency converter 111 if filter 112 rz ssb demodulation processor 113 delay circuit 114.