Abstract: A signal generator digitally synthesizes a complex analog signal which has a frequency domain representation including a precise low-frequency offset for each spectral component. The complex analog signal is particularly adapted to increase the accuracy and reliability of a conventional ratio measurement technique. This ratio measurement technique provides a single number rating which is the comprehensive measure of the fidelity of a transmission channel. The complex analog signal is thoroughly compensated for a number of effects. The transfer response of filters and fundamental sources of spectral distortion inherent to digital synthesis, such as aperture effect and quantizing distortion, are items for which compensation is provided. The signal generator has complementary circuitry which conveniently assists to provide desirable odd half-wave symmetry in the analog signal and reduces by one-half the number of stored code words from which the signal is derived.

Abstract: A digital timing circuit comprising integrated circuits is presented for multifrequency signal receivers in which a first counter is pulsed by a clock to generate predetermined timing intervals under the control of a second counter. The second counter sequentially recycles the first counter to make multiple use of the stages therein to provide various timing intervals, each associated with a timing function, e.g., initial state and signal persistence timing, fixed duration output pulse, signal check and delayed steering release. Multiple use of the first counter by the second counter provides efficient use of the first counter and reduces size and cost of the circuit.