Triggering for waveform recording

• US 4,755,887 A
• Filed: 10/31/1986
• Issued: 07/05/1988
• Est. Priority Date: 10/31/1986
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Company (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Allen, Mark S., Bird, Steven C., Deaver, Phillip E., Will, Stephen K.
• Primary Examiner(s): Canney, Vincent P.
• Application Number:
  US06/925,346
• Time in Patent Office: 613 Days
• Field of Search: 360/5, 360/6, 360/7, 360/69, 360/61, 369/19
• US Class Current: 360/5
• CPC Class Codes: G01R 13/32 Circuits for displaying non-recurrent functions such as transients; Circuits for triggering; Circuits for synchronisation; Circuits for time-base expansion
• CPC Class Codes: G11B 20/025 Error detection or correction
• CPC Class Codes: G11B 20/18 Error detection or correction; Testing , e.g. of drop-outs

Abstract

A drop out trigger captures waveform data when a normally continuous input signal is disrupted or interrupted. In the preferred embodiment, a conventional trigger detects a parameter periodically satisfied by the continuous signal and resets a timer whenever a trigger event occurs. The alarm count of the timer is set for an interval slightly larger than the periodic interval. If the timer reaches the alarm count, a measurement signal is generated.

Claims

1. A triggering circuit responsive to the disruption of a normally continuous input signal to produce a measurement signal output, comprising:

timer means having an adjustable alarm count and a reset input, producing a measurement signal output if the alarm count is reached;

control means for programming the alarm count of the timer means at a value larger than the periodic interval at which the continuous input signal satisfies a predetermined condition;

means responsive to the input signal, connected to the reset input of the timer, for producing a reset signal when the input signal satisfies the predetermined condition.

2. A method for detecting and recording the disruption of a normally continuous input signal, comprising the steps of:

monitoring the input signal to determine when the input signal satisfies a predetermined condition characteristic of the periodic cycle of the continuous signal;

producing a trigger signal, indicating the normal behavior of the input signal, whenever the input signal satisfies the predetermined condition;

timing the interval from the occurrence of each trigger signal;

producing a measurement signal, indicating the disruption of the input signal, if the timed interval exceeds the periodic interval at which the continuous signal satisfies the predetermined condition;

storing the input signal in a memory when a measurement signal occurs.