Browse Prior Art Database

Binary FSK Demodulation

IP.com Disclosure Number: IPCOM000099538D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 1 page(s) / 33K

Publishing Venue

IBM

Related People

Edge, BJ: AUTHOR [+2]

Abstract

A technique is disclosed for demodulating binary FSK data using a simple pattern matching process. This novel approach to the demodulation process has several advantages over conventional techniques.

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Binary FSK Demodulation

       A technique is disclosed for demodulating binary FSK data
using a simple pattern matching process.  This novel approach to the
demodulation process has several advantages over conventional
techniques.

      The process consists of forming a fingerprint from each
received symbol (data bit) and using this print to classify the
received symbol as wither the high carrier or low carrier tone.

      In FSK each symbol (data bit) is transmitted as a short burst
of carrier tones and is sampled by the demodulator to produce a
sequence of data samples.  The sequence of samples is reduced to a
fingerpint by setting to zero any small samples, then discarding the
magnitude information for the remaining samples and retaining only
the signs.  The resulting pattern of signs and zeros is processed by
a rule set which has the ability to determine from a series of
logical decisions which symbol generated the fingerprint. The
sequence of symbols (bits) is, therefore, derived from the received
signal.

      The advantages of this technique are as follows:
      1.   It is very efficient.  No multiplications are required,
and it could be implemented on very simple hardware.
   2.   It requires only simple gain control of the incoming data or
adjustment of the low threshold.
      3.   It does not require any filter design or tuning.

      However, the rule set is specific to a particular pair of tones
which are to be d...