Abstract: The present invention relates to a measurement circuit for providing the digital value of an analog electrical signal. The digital measurement circuit for measuring an analog electrical signal produces a measurement signal (M) and includes an amplifier (1) which receives said electrical signal (I), followed by an analog-to-digital converter (2) which delivers digital data (N). The gain of the amplifier (1) is controlled by a control signal (C) and said gain can take up at least two values. The measurement circuit further includes a control unit (3) producing said control signal (C) and storing the digital data corresponding to different gain values, and includes means for producing the measurement signal (M) on the basis of said digital data (N).

Abstract: A 16-quadrature amplitude modulation (QAM) modulator for radio links converts a train of data into signals having a phase selected from sixteen predetermined phase values and an amplitude selected from four values. The modulator divides the data train into two data sub-trains. The two data sub-trains are respectively applied to a pair of four-phase modulators that are fed by a carrier source. The 16-QAM modulator also comprises two phase locked loops each including a voltage controlled microwave oscillator and an associated differential phase detector. The differential phase detector responds to the output of the associated four-phase modulator and the output of the associated voltage controlled microwave oscillator. Predetermined parts of the output signals of the two phase locked loops are added.