Method and circuit for triggering an electronic instrument only once during a period of a signal
First Claim
1. A trigger circuit for triggering an electronic instrument only once during a period of an input signal having multiple triggering events during said period, comprising:
- qualifier means for qualifying multiple events occurring during said period of said input signal as being triggering events by producing a preliminary trigger signal in response to each of said events;
timing means for producing and maintaining a held trigger signal for a predetermined interval in response to a preliminary trigger signal, the predetermined interval restarting in response to additional preliminary trigger signals received before the predetermined interval has expired; and
trigger generation means for producing the output trigger signal in response to the held trigger signal.
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Abstract
A method and circuit for triggering an electronic instrument only once during a period of an input signal having multiple triggering events during that period. A signal applied to an electronic instrument, such as an oscilloscope, is acquired. Qualified triggering events occurring on the acquired signal are identified. A selected one of the qualified triggering events during the period of the applied signal causes a trigger signal output to occur, while other qualified triggering events are ignored. In the preferred embodiment a triggering event is qualified by a first comparator that compares the input signal to a first reference level and produces a predetermined logic level output if the input signal bears a predetermined relationship to the reference level. When a qualified triggering event occurs, a buffer amplifier applies the predetermined logic level to charge a capacitor, which thereafter stores some energy from the input signal and applies it to a comparator for a predetermined period of time. The comparator compares the voltage on the capacitor to a second reference level and produces a pulse if the capacitor voltage has a predetermined relationship to the second reference level. The leading edge of the pulse comprises a trigger output signal. Subsequent triggering events which occur before a predetermined period of time are unable to produce another trigger signal. Five alternative embodiments employing the same general principle as the preferred embodiment are disclosed.
26 Citations
14 Claims
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1. A trigger circuit for triggering an electronic instrument only once during a period of an input signal having multiple triggering events during said period, comprising:
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qualifier means for qualifying multiple events occurring during said period of said input signal as being triggering events by producing a preliminary trigger signal in response to each of said events; timing means for producing and maintaining a held trigger signal for a predetermined interval in response to a preliminary trigger signal, the predetermined interval restarting in response to additional preliminary trigger signals received before the predetermined interval has expired; and trigger generation means for producing the output trigger signal in response to the held trigger signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for triggering an electronic instrument only once during a period of an input signal having multiple qualifying triggering events per period, the method comprising the steps of:
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generating preliminary trigger signals upon each occurrence of a qualifying triggering event; starting or restarting a time interval upon each occurrence of the preliminary trigger signal; and producing an output trigger signal when a preliminary trigger signal occurs while the time interval has expired. - View Dependent Claims (11, 12, 13, 14)
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Specification