DIGITAL CORRELATOR AND INTEGRATOR

• US 3,646,333 A
• Filed: 12/12/1969
• Issued: 02/29/1972
• Est. Priority Date: 12/12/1969
• Status: Expired due to Term

• Current Assignee: Cabell N. Pryor Jr
• Original Assignee: Cabell N. Pryor Jr
• Inventors: Pryor, Cabell N. Jr.
• Primary Examiner(s): Botz, Eugene G.
• Assistant Examiner(s): Gruber, Felix D.
• Application Number:
  US04/884,392
• Time in Patent Office: 809 Days
• Field of Search: 235/181,183,194,150.5-150.53,156 324/77G
• US Class Current: 708/422
• CPC Class Codes: G06F 17/15 Correlation function computation including computation of convolution operations arithmetic circuits for sum of products per se, e.g. multiply-accumulators G06F7/5443; digital filters, e.g. FIR, IIR, adaptive filters H03H17/00

Abstract

A digital correlator and integrator which uses a core memory to implement the cross-correlation and post-integration operations simultaneously. The system is a hybrid correlator that treats one of two sample channels linearly while it delays and stores the information in the other channel. The samples from both channels are multiplied together then averaged repetitively into stored data to generate a time-compressed correlation function which is retained in digital form within the memory.

Claims

1. A digital correlator and integrator comprising:

first sampling means for sampling a first input analog signal;

second sampling means for sampling a second input analog signal;

an analog-to-digital converter coupled to the output of said first sampling means for converting the sampled first input analog signal into a first digital signal;

means for polarity quantizing the sampled second input analog signal to thereby produce a second digital signal;

temporary storage means for temporarily storing said second digital signal and for thereafter temporarily storing previously generated second digital signals;

multiplying means for digitally multiplying said first digital signal with said second digital signal to form a digital product signal representative of the instantaneous estimate of a point of a correlation function;

memory means having a first storage section for storing a plurality of previously calculated estimates of points of said correlation function, and a second storage section coupled to the output of said temporary storage means for storing said second digital signal and said previously generated second digital signals;

subtraction means coupled to the output of said multiplying means and coupled to the output of said first storage section for digitally subtracting a selected one of said previously calculated estimates of said points of said correlation function from said digital product signal;

division means coupled to the output of said subtraction means for dividing the output of said subtraction means by a predetermined scale factor; and

addition means coupled to the output of said division means and coupled to the input of said first storage section for adding said selected one of said previously calculated estimates of said points of said correlation function to the output of said division means to produce an updated estimate of said point of said correlation function.

2. The digital correlator and integrator of claim 1, wherein said first sampling means comprises a sample gate and said second sampling means comprises a sample gate.

3. The digital correlator and integrator of claim 1, wherein said means for polarity quantizing said second input analog signal comprises a hard clipper.

4. The digital correlator and integrator of claim 1, further including a buffer coupled between the output of said second storage section and the input to said temporary storage means for temporarily storing said previously generated second digital signals.