Input circuit for electricity meter or power line carrier receiver - has sigma-delta modulator producing bit sequence having clock frequency higher than Nyquist frequency of sinusoidal information signal

摘要

The input circuit includes a sigma-delta modulator (1) for converting an sinusoidal information signal (u(t)) into a one-bit sequence. The bit sequence has a clock frequency which is larger than the Nyquist frequency. For each modulated sinusoidal signal to be evaluated, a quadrature demodulator is provided (4a, 4b). The one-bit output (2) of the sigma-delta modulator is connected to one respective input of a quadrature demodulator. The one-bit output of the sigma-delta modulator is connected to a low-pass filter (3) which has a bandwidth at least as large as the highest frequency of the unmodulated sinusoidal signal to be evaluated. USE/ADVANTAGE - E.g. for centralised ripple control receivers or high voltage line telephony. Has sufficiently high resolution and high threshold frequency, while being constructed from components mfd. in same technology, e.g. in one-chip receiver.