Data detection by statistical analysis

• US 4,710,957 A
• Filed: 04/30/1986
• Issued: 12/01/1987
• Est. Priority Date: 04/30/1986
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Bocci, Paul M., Wilson, Alan L., Pietrzak, Carl M. Jr.
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Busch, James E.
• Application Number:
  US06/858,461
• Time in Patent Office: 580 Days
• Field of Search: 375/76, 375/94, 329/104, 455/135, 364/554, 371/6, 380/37, 380/42, 380/46
• US Class Current: 380/42
• CPC Class Codes: H04B 14/066 using differential modulation with several bits [NDPCM]

Abstract

A data detector is disclosed wherein a received signal is analyzed to determine its statistical characteristics. These characteristics are compared to a predetermined statistical distribution. If the signal is statistically close to the statistical characteristics of a known signal a detect signal is generated and the received signal is passed for further processing and reception.

Claims

1. A method for detecting a digital signal from a received signal to provide a detect signal, comprising the steps of:

(a) storing the received signal to provide a stored signal;

(b) parsing said stored signal to provide a plurality of segments;

(c) parsing each of said segments into a plurality of sub-segments each having a predetermined length;

(d) tallying the number of occurrences of each of a plurality of predetermined bit patterns defined by said predetermined length of said sub-segments;

(e) computing the difference of each of said tallied occurrences to a predetermined expected value of occurrences to provide a plurality of differences;

(f) summing said plurality of differences to provide a quality signal;

(g) comparing said quality signal to a predetermined threshold;

(h) providing the detect signal in response to step (g).

2. A method for detecting a digital signal from a received signal to provide a detect signal, comprising the steps of:

(a) storing the received signal to provide a stored signal;

(b) parsing said stored signal into segments having a predetermined length;

(c) parsing each of said segments into a plurality of sub-segments having a predetermined length;

(d) tallying the number of occurrences of each of a plurality of predetermined bit patterns defined by said predetermined length of said sub-segments;

(e) computing the difference of each of said tallied occurrences to a predetermined expected value of occurrences to provide a plurality of differences;

(f) summing said plurality of differences to provide a quality signal;

(g) averaging said quality signal with previous quality signals to provide an averaged quality signal;

(h) comparing said averaged quality signal to a predetermined threshold to provide the detect signal;

(i) repeating steps (d) through (h) until all of said segments of said stored signal are evaluated.

3. An apparatus for detecting a digital signal from a received signal to provide a detect signal, comprising:

means for storing the received signal to provide a stored signal;

means for parsing said stored signal into segments having a predetermined length;

means for parsing a segment into a plurality of sub-segments having a predetermined length;

means for tallying the number of occurrences of each of a plurality of predetermined bit patterns defined by said predetermined length of said sub-segments;

means for computing the difference of each of said tallied occurrences to a predetermined expected value of occurrences to provide a plurality of differences; and

means for summing said plurality of differences to provide a quality signal;

means for comparing said quality signal to a predetermined threshold to provide a detect signal.

4. An apparatus for detecting a digital signal from a received signal, comprising:

means for storing the received signal to provide a stored signal;

means for parsing said stored signal into segments having a predetermined length;

means for parsing a segment into a plurality of sub-segments having a predetermined length;

means for tallying the number of occurrences of each of a plurality of predetermined bit patterns defined by said predetermined length of said sub-segments;

means for computing the difference of each of said tallied occurrences to a predetermined expected value of occurrences to provide a plurality of differences; and

means for summing said plurality of differences to provide a quality signal;

means for averaging said quality signal with previous quality signals to provide an averaged quality signal;

means for comparing said averaged quality signal to a predetermined threshold to provide a detect signal.

5. In a secure communication system, a method for detecting an encrypted signal from a received signal and for providing a decrypted information signal, comprising the steps of:

(a) storing the received signal to provide a stored signal;

(b) parsing said stored signal into segments having a predetermined length;

(c) parsing each of said segments into a plurality of sub-segments having a predetermined length;

(d) tallying the number of occurrences of each of a plurality of predetermined bit patterns defined by said predetermined length of said sub-segments;

(e) computing the difference of each of said tallied occurrences to a predetermined expected value of occurrences to provide a plurality of differences;

(f) summing said plurality of differences to provide a quality signal;

(g) comparing said quality signal to a predetermined threshold to provide a signal representing the detection of an encrypted signal;

(h) operating, in response to step (g), upon said received signal to provide the decrypted information signal.

6. A receiver for use in a secure communication system, said receiver having means for detecting an encrypted signal from a received signal, and mean for decrypting said encrypted signal to recover an information signal, comprising:

means for storing the received signal to provide a stored signal;

means for parsing said stored signal into segments having a predetermined length;

means for parsing a segment into a plurality of sub-segments having a predetermined length;

means for tallying the number of occurrences of each of a plurality of predetermined bit patterns defined by said predetermined length of said sub-segments;

means for computing the difference of each of said tallied occurrences to a predetermined expected value of occurrences to provide a plurality of differences;

means for summing said plurality of differences to provide a quality signal;

means for comparing said quality signal to a predetermined threshold to provide a signal representing the detection of an encrypted signal; and

means for operating upon said received signal to decrypt said encrypted signal to recover said information signal.