Direct microwave demodulator of PSK signals with automatic gain control

DETAILED DESCRIPTION The problem resolved by the present invention consists in the provision of a direct demodulation microwave reception, chain which, in association with other functions, comprises the automatic gain control function, the elements needed to establish this function being conventional commercial circuits which enable a reduction in the cost of the reception chain as a whole whilst retaining its performance.
Accordingly, the present invention provides a microwave reception chain comprising a circuit for direct demodulation of a modulated signal resulting from mixing two carriers in quadrature modulated by digital signals scrambled so as not to comprise long series of one or zeros, of which the input is coupled with the received signal input, associated with an oscillator operated at the carrier frequency of the received signal, controllable so that the phase of the carrier coming from the oscillator coincides with the phase of the signal received and supplying demodulated digital signals, and furthermore comprising a phase calculator having two inputs coupled to the output for demodulated digital signals, of which the output provides a signal as a function of the phase difference between the received carrier and the local carrier, this output being connected to the control input of the oscillator via a loop integrator filter, wherein the arrangement also comprises means for automatically controlling the level of the demodulated signals X(t) and Y(t), comprising wide-band amplifiers whose signal inputs are coupled to the outputs of the demodulation circuit, and which comprise an automatic gain control input, the outputs of these amplifiers being connected to the inputs of a control circuit comprising integrating means, and of which the outputs are connected to the control inputs of the amplifiers.