Method and apparatus for generating error corrected signals

• US 3,936,739 A
• Filed: 02/12/1974
• Issued: 02/03/1976
• Est. Priority Date: 02/12/1974
• Status: Expired due to Term

• Current Assignee: Coulter Electronics, Inc.
• Original Assignee: Coulter Electronics, Inc.
• Inventors: Hogg, Walter R.
• Primary Examiner(s): Segal, Robert
• Application Number:
  US05/441,752
• Time in Patent Office: 721 Days
• Field of Search: 324/71 CP, 328/142
• US Class Current: 377/50
• CPC Class Codes: H03K 21/02 Input circuits
• CPC Class Codes: H03K 3/013 Modifications of generator to prevent operation by noise or interference

Abstract

A method and apparatus for automatically generating error corrected pulses in response to particle pulses which are subject to error due to coincidence. The subject apparatus includes a generator for generating error corrected pulses which has a variable pulse repetition rate controlled via an applied variable control signal. A pulse duration modifying circuit receives the particle pulses and develops first pulses each having a duration equal to a predetermined function of the duration of a particle pulse. A control circuit receives the error corrected pulses and develops a second signal in response thereto. The development of the second signal via the control circuit is inhibited in response to the presence of first pulses coupled thereto from the pulse duration modifying circuit. A comparison circuit develops the control signal which varies in accordance with the difference between the repetition rate of the particle pulses and the third signal.

Claims

1. A method for generating error corrected signals in response to detected signals which are subject to error due to coincidence including the steps of:

generating the error corrected signals,

varying the repetition rate of the error corrected signals in accordance with variations in an applied control signal,

developing first signals in response to the detected signals each having a duration equal to a predetermined function of the duration of the same one of the detected signals,

developing second signals in response to the error corrected signals and said first signals which vary in accordance with the repetition rate and duration of said second signals and the repetition rate of the error-corrected signals, and

comparing said second signals and the detected signals and developing said control signal, said control signal varying in accordance with variations between said second signals and the repetition rate of said detected signals.

2. The method of claim 1 wherein said step of developing said second signals includes the steps of:

generating third signals in response to said error corrected signals having a repetition rate which varies in accordance with the repetition rate of the error corrected signals, said third signals having a predetermined duration, and

developing said second signals in response to said third signals.

3. The method of claim 2 wherein said step of comparing the detected signals and said second signals includes the step of:

developing fourth signals in response to said detected signals having a repetition rate which varies in accordance with said detected signals, said fourth signals having a fixed duration, and

comparing said fourth signals with said second signals.

4. The method of claim 3 wherein said step of developing said second signals includes the step of:

inhibiting the development of said second signals in response to said third signals when said first signals are present.

5. The method of claim 4 wherein said step of developing said first signals includes the step of:

extending the duration of each one of the detected signals by a predetermined function of the duration of the same one of the detected signals.

6. An error correction circuit for correcting first signals which are subject to error including in combination,

generating means for generating error corrected signals, said error corrected signals being variable in accordance with a control signal coupled to said generating means,

receiving means for receiving said first signals,

signal modifying means coupled to said receiving means and operative in response to said first signals to develop second signals, which vary in accordance with said first signals,

first circuit means coupled to said generating means and said signal modifying means and operative to develop third signals in response to said second signals and error corrected signals, and

second circuit means coupled to said receiving means, said first circuit means and said generating means and operative in response to said first signals and said third signals to develop said control signal,

7. The circuit of claim 6 wherein said generating means is a variable frequency oscillator for generating said error corrected signals, said error corrected signals varying in frequency in accordance with said control signal coupled thereto.

8. The circuit of claim 6 wherein the first signals have first signal durations and said signal modifying means includes signal duration modifying means responsive to the first signals to develop said second signals having signal durations which are functions of the durations of the first signals.

9. The circuit of claim 6 wherein said second circuit means includes comparison means operative in response to the first signals and said third signals to develop said control signal.

10. The circuit of claim 8 wherein said first circuit means includes control circuit means operative in response to the error corrected signals to develop said third signals and operative in response to said second signals to control development of said third signals.

11. The circuit of claim 10 wherein the first signals are first pulses having pulse durations and said signal duration modifying means is a pulse duration modifying circuit for developing second pulses having durations which are functions of the durations of the first pulses.

12. The circuit of claim 11 wherein the first signals have varying amplitudes, said receiving means including detecting means for detecting the first signals having particular amplitudes.

13. The circuit of claim 12 wherein said pulse duration modifying circuit includes a pulse stretching circuit for developing second pulses having a pulse duration greater than the first pulses by a predetermined percentage of the duration of the first pulses.

14. The circuit of claim 12 wherein said control circuit means is a chopper circuit operative in response to the error corrected signals to develop said third signals, said chopper circuit being operative in response to said second pulses to chop said third signals for said duration of said second pulses.

15. The circuit of claim 13 wherein said control circuit means is a gating circuit operative in response to the error corrected signals to develop said third signals and operative in response to said second pulses to inhibit said third signals for the duration of said second pulses.

16. The circuit of claim 14 wherein the first pulses have an irregular repetition rate, and wherein said receiving means includes pulse storage means coupled to said detecting means and said second circuit means for developing a pulse storage signal in response to the repetition rate of the first pulses which varies in accordance with the repetition rate of the first pulses, said control circuit means including filter means coupled to said chopper circuit and said second circuit means for developing a filter signal in response to said chopped third signals which varies in accordance with said chopped third signals, said second circuit means operative in response to said filter signal and said pulse storage signal to develop said control signal.

17. The circuit of claim 16 wherein said second circuit means includes comparison means for developing said control signal, said control signal varying in accordance with the difference between said pulse storage signal and said filter signal.

18. The circuit of claim 16 wherein said generating means is a variable frequency oscillator having a frequency which varies in accordance with said control signal.

19. An apparatus for automatically generating error corrected pulses in response to particle pulses which are subject to error due to coincidence including in combination,

generating means for generating the error corrected pulses, said repetition rate of the error corrected pulses being variable in accordance with a control signal coupled to said generating means,

receiving means for receiving the particle pulses,

pulse duration modifying means coupled to said receiving means and operative in response to the particle pulses to develop first pulses having a duration equal to the duration of the particle pulses and at least a predetermined percentage of the duration of the particle pulses,

control circuit means coupled to said pulse duration modifying means and said generating means and operative in response to the error corrected pulses to develop a second signal, said control circuit means being further operative in response to said first pulses to control development of said second signal, and

comparison means coupled to said receiving means, said control circuit means and said generating means for developing said control signal, said control signal varying in accordance with the difference between the repetition rate of the particle pulses and said second signal.

20. The apparatus of claim 19 wherein said receiving means includes detecting means for detecting the particle pulses having particular amplitudes.

21. The apparatus of claim 20 wherein said receiving means includes a first pulse generator coupled to said detecting means for developing first fixed duration pulses in response to said particle pulses.

22. The apparatus of claim 21 further including second pulse generator means coupled between said generating means and said control circuit means for generating second fixed duration pulses in response to said error corrected pulses.

23. The apparatus of claim 22 wherein said generating means is a variable frequency oscillator having a frequency which varies in accordance with said control signal.

24. The apparatus of claim 23 wherein said receiving means further includes first pulse storage means coupled to said first pulse generator means and said comparison means for developing a pulse storage signal which varies in accordance with the repetition rate of said first fixed duration pulses.

25. The apparatus of claim 24 wherein said control circuit is a chopper circuit operative in response to said error corrected pulses to develop said second signal and further operative in response to said first pulses to chop said second signal for said duration of said first pulses, and filter means coupled to said chopper circuit and said comparison means for developing a filter signal in response to said chopped second signal.

26. The apparatus of claim 25 wherein said comparison means is a comparator for comparing said pulse storage signal and said filter signal to develop said control signal, said control signal varying in accordance with the difference between said pulse storage signal and said filter signal.

27. The apparatus of claim 23 wherein said control means is a gate circuit operative in response to said error corrected pulses to develop said second signal, said second signal being gate pulses, said gate circuit being further operative in response to said first pulses to inhibit said gate pulses for said duration of said first pulses.

28. The apparatus of claim 27 wherein said control means further includes a third pulse generator means coupled to said gate circuit, said third pulse generator means operative in response to said gate pulses to develop third fixed duration pulses and second pulse storage means coupled to said third pulse generator means and said comparison means for developing a second pulse storage signal in response to the repetition rate of said third fixed duration pulses.

29. The apparatus of claim 28 wherein said comparison means is a comparator for comparing said first fixed duration pulses and said second pulse storage signal and developing said control signal, said control signal varying in accordance with the difference between said first fixed duration pulses and said second pulse storage signal.

30. The apparatus of claim 27 wherein said comparison means is a counter means, said counter being operative to add said first fixed duration pulses coupled thereto and substract said gate pulses coupled thereto and develop a count signal in accordance with a count of said added and subtracted pulses, and converter means coupled to said counter means and operative in response to said count signal to develop said control signal, said control signal varying in accordance with said count.

31. The apparatus of claim 27 wherein said comparison means includes a bistable multivibrator operative in response to said first fixed duration pulses to develop a first output signal and operative in response to said gate pulses to develop a second output signal and converter means coupled to said bistable multivibrator means and operative in response to said first and second output signals to develop said control signal, said control signal varying in accordance with the difference in repetition rate between said first and second output signals.

32. The apparatus of claim 23 wherein said pulse duration modifying means is a pulse stretcher for stretching said detected pulses to develop said first pulses.