scanning correlation general logic and approximate matching functions on the signals received from the storage medium in conjunction with digital or analog representations of query directed key information the functions may be performed by dedicated logic and circuitry programmable logic and circuitry or by use of programmable processors such as digital signal processors dsps the inventors contemplate that many different variations of hardware or programmed software devices may be used to virtually equal advantage in implementing the present invention and therefore do not contemplate any particular implementation as a better mode than another at present except as otherwise expressed herein furthermore the present invention should not be considered as being tied to any specific data structure or application those having been used herein are instead to be viewed as illustrative only using the present disclosure as a template it is contemplated that one of ordinary skill in the art could readily construct a device as would perform the functions and operation necessary to achieve the purposes of the invention as has been explained above the present invention may be used to perform both exact matches and approximate matches when performing an exact match in the analog domain at point a in fig1 a where matching is done using analog comparators and correlation techniques there an exact match corresponds to setting a sufficiently high threshold value for matching the key with analog source data on the storage medium approximate matching in.