9 CLAIMS

• 1. A hybrid noise cancellation system for canceling unwanted noise, said system comprising
• a first noise canceling electronic means for canceling low frequency noise, and
• a second noise canceling electronic means for canceling periodic noise,
said first and second noise canceling means being connected and implemented in such a way that the second noise canceling means optimizes variable parameters employed in the first noise canceling means.
• 2. A system as in claim 1 wherein the first noise canceling means is an analog system means.
• 3. A system as in claim 2 wherein the analog system means contains a digitally controlled analog filter building block comprising a means to acquire a digital input value, a means to latch such acquired digital input value, and a means to adjust the parameters of said analog filter building block.
• 4. A system as in claim 3 wherein said analog system means is a feedback control system.
• 5. A system as in claim 3 wherein said analog system means is a feed-forward system.
• 6. A system as in claim 2 wherein said second noise canceling electronic means comprises a digital virtual earth system.
• 7. A system as in claim 3 wherein said second noise canceling electronic means comprises a digital virtual earth system.
• 8. A system as in claim 4 wherein said second noise canceling electronic means comprises a digital virtual earth system.
• 9. A system as in claim 5 wherein said second noise canceling electronic means comprises a digital virtual earth system.