首页>
外国专利>
Digital demodulator reference signal generator having DC blocker and first Hilbert transformation with quadrature output followed by gain staging and combination for second Hilbert transformation quadrature output
Digital demodulator reference signal generator having DC blocker and first Hilbert transformation with quadrature output followed by gain staging and combination for second Hilbert transformation quadrature output
Information often modulates an underlying carrier signal, thereby producing a modulated information signal 70. This same carrier signal is required, with a few modifications, to demodulate the modulated information signal. This required signal is called the demodulator reference signal. It must be complex, that is, it must contain separate in-phase and quadrature outputs. A degraded version 10 of this signal is often available with the correct frequency, but with the wrong phase and amplitude, and with a direct current (dc) offset. The present invention 68 produces a digital demodulator reference signal 38, 46 from the degraded signal 10. It eliminates dc offset with a dc blocker 18, adjusts amplitude with a scaler 14, adjusts phase with a first Hilbert transformer 20, multipliers 26 and 28 and summer 34, and produces in- phase and quadrature outputs with a second Hilbert transformer 36 cascaded with the first.
展开▼
