Method and apparatus for detecting a peak value of an analog signal

• US 4,165,508 A
• Filed: 02/28/1978
• Issued: 08/21/1979
• Est. Priority Date: 02/28/1978
• Status: Expired due to Term

• Current Assignee: Beckman Instruments, Inc. (Danaher Corporation)
• Original Assignee: Beckman Instruments, Inc. (Danaher Corporation)
• Inventors: Barter, LeRoy D.
• Primary Examiner(s): Morrison, Malcolm A.
• Assistant Examiner(s): Chin, Gary
• Application Number:
  US05/882,286
• Time in Patent Office: 539 Days
• Field of Search: 340/347 M, 324/103 P, 235/92 CA, 235/92 FP, 307/351
• US Class Current: 341/132
• CPC Class Codes: H03M 1/52 Input signal integrated with linear return to datum

Abstract

Apparatus for detecting a peak value of an analog signal includes a first counter for counting pulses from a digital clock for successive samplings of the analog signal to convert each sample of the analog signal into digital form and a counting register into which the pulse count in the first counter is transferred to be recounted at a later sampling. With a prior digital count in the register, the digital clock simultaneously (1) increments the counter to count the current signal sampling and (2) decrements the register to zero to recount the prior signal sampling. The counter is constrained to count up until both counting and recounting steps are complete before the count in the counter is transferred to the register. In this manner the counter will always attain the greater of the current and the prior sampling pulse count values and this maximum value will always be transferred into the register. A peak is signaled when the prior maximum pulse count exceeds current pulse counts for a predetermined number of successive samplings.

Claims

1. In combination with apparatus for measuring an analog signal of the type which includes converter means for sampling said analog signal at successive times having counting means for counting pulses from a source of digital pulses during time intervals following each sampling time to provide a digital pulse count of the amplitude value for each sample of said analog signal and for generating a first timing signal upon the completion of each digital pulse count, said counting means being adapted to continue to count beyond the value of said digital pulse count, apparatus for detecting peak values of said analog signal comprising:

register means for (1) storing a prior digital pulse count corresponding to an amplitude value of said analog signal at a prior sampling time, (2) recounting said prior count, and (3) generating a second timing signal when said recount is completed;

means responsive to a current sampling of said analog signal for enabling said register means to recount said prior digital pulse count simultaneous with said counting means counting toward the current digital pulse count for the current sample of said analog signal; and

means responsive to the later occurring of said first and second timing signals for storing the digital pulse count then attained by said counting means in said register means, whereby the digital pulse count stored in said register means is always the greater of said prior digital pulse count and said current digital pulse count.

2. The apparatus of claim 1 wherein said means responsive includes means for signaling the occurrence of a peak when said first timing signal precedes said second timing signal a predetermined number of successive times.

3. The apparatus of claim 1 further including display means connected to said register means for displaying the digital pulse count contents of said register means.

4. For use with apparatus for measuring an analog signal of the type which includes converter means for sampling said analog signal at successive times having counting means for counting pulses from a source of digital pulses during time intervals following each sampling time to provide a digital pulse count of the amplitude value for each sample of said analog signal and for generating a first timing signal upon the completion of each digital pulse count, said counting means being adapted to continue to count beyond the value of said digital pulse count, a method of detecting peak values of said analog signal comprising the steps of:

storing a prior digital pulse count corresponding to an amplitude value of said analog signal for a prior sampling time;

counting a current sampling of said analog signal while simultaneously recounting the stored prior digital pulse count;

generating a second timing signal when said recounting is completed;

storing the count in said counting means in response to the later of the first and second timing signals;

outputting the latter stored pulse count value as a peak value of the analog signal when said second timing signal is the later of said first and second timing signals for a predetermined number of consecutive sampling times of said analog signal.