RECEIVING CIRCUIT FOR A WAVE MODULATED AT ONE TIME IN FREQUENCY BY AN ANALOGUE SIGNAL, AT ANOTHER TIME IN PHASE BY A DIGITAL SIGNAL

摘要

The circuit comprises a surface acoustic wave device. On the substrate (32) of the surface acoustic wave device, are provided two pairs of input transducers (33, 34, 35, 36) connected, in parallel, to the input of the circuit. The transducers (33, 34, 35, 36) initiate surface acoustic waves corresponding to the signals applied on two pairs of paths (41, 42, 43, 44) ending at two pairs of reception transducers (37, 38, 39, 40). The outputs of the output transducers of the first pair (37, 38) are connected to the two inputs of a mixer (28) whose output yields the received digital signal. The outputs of the second pair of transducers (39, 40) are connected to the inputs of two limiters (26, 27) whose outputs are connected to the two inputs of a mixer (29) whose output yields the analog signal. The difference in path lengths of the first pair (41, 42) introduces a delay of the order of one bit and the difference in path lengths of the second pair (43, 44) introduces a delay equal to the inverse of twice the bandwidth between the peaks of the discriminator thus constituted.