An amplitude modulated (AM) radio receiver uses a digital signal processor, responsive to in-phase (I) and quadrature-phase (Q) component signals, to compensate for carrier energy removed by a capacitive coupling circuit. A quadrature mixer converts the received AM signal to the I and Q component signals...http://www.google.com/patents/US5339040?utm_source=gb-gplus-sharePatent US5339040 - AM demodulation receiver using digital signal processor
