Universal Synaptics Law of Intermittent Fault Detection

Universal Synaptics’ Law of Intermittent Fault Detection Effectiveness

 E=SC2

E is the Effectiveness that the IFD - IFDIS - Ncompass technology provides in detecting the most evasive of intermittent malfunctions (those causing NFF) in a given Unit Under Test (UUT) device versus any other comparable piece of test equipment (measured in a ratio:1).

S is the single circuit intermittence detection Speed advantage that the IFD has over the single circuit intermittent detection speed capability of any comparable testing technology… for the IFD, use *50ns, 50 nanoseconds, .00000005 seconds.

 

Simply stated, what is the ratio of the shortest glitch detectable by any two pieces of test equipment on just a single circuit?

 

Example: 100us divided by 50ns = 2000:1 or 100ms divided by 50ns = 2,000,000:1

 

C is the number of circuits in the device that require testing.

 

Note:  The number one question that arises when explaining and using the Intermittent Fault Detection Probability formula is; “why do you square the number of circuits to be tested or (C)?” in the comparison formula.  Since this is the key to the entire solution, let’s take a moment to fully understand it.

 

The reason the number of circuits under test is squared is that while other single point or scanning-type testers are measuring one circuit at a time, the IFD is simultaneously testing all of the other circuits at the same time, for the same duration.  As the conventional tester moves on to test a new circuit, the IFD continues to test all the other connected circuits at the same time, for the same period and so forth and so on.  Intermittence by its very definition is random in time, place, amplitude and duration. Therefore, the detection of intermittence is a condition of probabilities and the ability to detect it is measured in test-coverage.

 

The following is a simple explanation of the squaring effect of simultaneous and continuous testing for intermittence.

 

Using an easy example of a 3 by 3 matrix of circuits (9 total circuits to be tested), like a simple 9-pin cable, let’s compare.  Conventional scanning test equipment, while connected to all the circuits, only measures one circuit at a time. So, while this technology might measure test-point-1 for one second, the IFD’s all-lines, all-the-time technology, simultaneously and continuously tests all 9 of the circuits for that same one-second, for 9 total seconds of intermittence test coverage. When conventional equipment then moves (scans) to measure test-point-2, also for one second, the IFD tests all 9 circuits for another second giving you 9 more seconds of intermittence test coverage. Conventional equipment then moves on to test-point-3 for one-second, and the IFD, again tests all 9 circuits for that same one-second.  When conventional testers have finally completed testing each of the 9 circuits for just one second each (9 seconds total), the IFD has simultaneously tested all 9 circuits for 9 seconds each, (9 x 9) or 81 total seconds.

 

It doesn’t matter if you have a 9-pin cable or a 10,000 test point avionics box, with the IFD’s simultaneous and continuous test technology; you square the number of circuits to be tested for the test coverage calculation.

 

Result:

 

Using the E=SC2 formula of test coverage or probability gain of the IFD technology, you can begin to see why the IFD works and other technologies simply don’t.

 

For example, let’s consider a state of the art, scanning continuity tester that claims to test continuity at the rate of 3,500 test points a minute.  The single-circuit intermittent discontinuity detection speed could then be computed to be approximately 17ms (.017 seconds) (60/3500).

 

If you were testing just one wire or circuit, then the IFD at 50ns (nanoseconds) is 340,000 times more sensitive at catching intermittence on a single circuit.

 

S= .017 divided by .00000005 = 340,000 times more likely to detect NFF intermittence on a single circuit.

 

Now, take a 100-circuit chassis or cable.

 

Using the formula E=SC2:

 

E = 340,000 x 100 x 100 = 3,400,000,000

 

In this example, the IFD is 3.4 billion times more sensitive than the scanning continuity tester for detecting intermittent / NFF at 50ns on a 100-circuit chassis or cable.

 

Next, take a 1,000 test point coverage requirement, such as the Modular Low Power Radio Frequency (MLPRF) LRU chassis in the AN/APG-68 radar used on the F-16 Fighting Falcon:

 

Using E=SC2:

 

E = 340,000 x 1,000 x 1,000 = 340,000,000,000

 

In this example, the IFD is 340 billion times more sensitive than the scanning continuity tester for detecting intermittent / NFF at 50ns on a 1,000-circuit chassis or cable.

 

Similarly, take a 3,000 test point coverage requirement, such as the Radar Receiver (RR) WRA chassis in the AN/APG-73 Radar used on the F/A-18 Hornet:

 

Using E=SC2:

 

E = 340,000 x 3,000 x 3,000 = 3,060,000,000,000

 

In this example, the IFD is 3 trillion, 60 billion times more sensitive than the scanning continuity tester for detecting intermittent / NFF at 50ns on a 3,000-circuit chassis.

 

In a final example, consider the 10,000 test point coverage requirement for the Programmable Signal Processor (PSP) LRU chassis in the AN/APG-68 Radar used on the F-16 Fighting Falcon:

 

Using E=SC2:

 

E = 340,000 x 10,000 x 10,000 = 34,000,000,000,000

 

In this example, the IFD is 34 trillion times more sensitive for detecting intermittent / NFF at 50ns on a 10,000- circuit chassis.

 

These demonstrated advantages in detection probability are why IFD technology is actively reducing the intermittent / NFF problem down to a 5 minute test in a typical avionics system as outlined above.  These rather simple to compute metrics also show conclusively why IFD technology works so well for resolving the intermittent / NFF problem.  This technology sees real intermittent circuit occurrences that conventional test equipment cannot see and was not designed to detect. Given this “explosion” in test coverage, it becomes crystal clear why the IFD is the only applicable technology designed specifically for, and capable of, detecting, resolving, and gauging the overall problem and levels of intermittent / NFF.

 

* Intermittent fault detection specifications measured using Hewlett-Packard 8111A Pulse/Function Generator

 

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