A signal processing apparatus is arranged to convert a multi-bit audio signal having the conventional sampling frequency fs KHz and m quantizing bits (m is an integer) into a one-bit audio signal having the sampling frequency 64.times.fs KHz and one quantizing bit. Hence, the apparatus can offer...http://www.google.com.hk/patents/US5831565?utm_source=gb-gplus-share專利 US5831565 - Signal processing apparatus for converting multi-bit signal having sub-data added thereto into one-bit signal 
