A shortcut to save days costs weeks instead

 When it comes to engineering, shortcuts are often tempting but can come with severe consequences. This was something that I learned the hard way early in my career. I was working in the telecommunications industry, designing equipment for last-mile applications. My company manufactured customer premise and pole mount equipment and I was responsible for performing pre-qualification testing on one of our line card systems that acted as a digital multiplexer.

At the time, telecommunication companies had a performance specification for digital subscriber line (DSL) systems. The standard specified that for a certain distance, the data rate had to be maintained at a certain level on the cable which carried both power and data. The issue is that along the length of the cable, different impedances and parasitics like capacitance and inductance can introduce errors into the communication line, degrading the signal.

The test procedure called for verifying link speed and signal strength at line-length intervals from 1,000 to 20,000 feet, looking for any interference on the line that would impact the system's ability to perform as expected. We were supposed to record the data rate and the bit errors that occurred at increments of 1,000 feet, looking for any drop-offs or dead spots. We also tracked the margin, which is the difference between signal and background noise.

We had fallen behind schedule, and our boss was getting pretty worked up. The only way it seemed possible to meet the timetable was to speed up the testing, which was an overnight process for each data point. But then I started thinking: I had done the testing at 1,000 feet, 2,000 feet, 3,000 feet - everything had checked out. Logically, I thought that if the link works at the limit, surely it would work at every length short of that limit. So, we took measurements at 10,000, 15,000, and 20,000 feet.

Everything looked fine, but when we submitted the design to a test lab for full product qualification, the lab came back after a few days and informed us that the product was failing at 8,000 feet. The signal was dropping out. I thought that sounded like crazy talk. Even though I had skipped that interval, I knew the unit had passed at 10,000 feet and beyond. Unfortunately, what I did not know was that the impedance at 8,000 feet just happened to be low enough that it started squashing the signal and dropping the link.

Any hope of staying on schedule quickly faded. We had already lost time because the failure had taken several days to discover. Turns out we had to completely redesign the line communication transformer. Then we had to do our testing over again, making sure we did not skip any intervals, and resubmit the redesign to the lab.

In the end, a shortcut that I thought would save us days ended up costing us weeks. It was a humbling experience and one that I will never forget. I learned that in engineering, shortcuts can be tempting but they can also be detrimental to the final product and the overall success of the project.

This experience also taught me the importance of thorough testing and not making assumptions about the performance of a product based on limited data. Every aspect of the product, including potential problem areas, needs to be thoroughly tested and evaluated. Skipping steps in the testing process can lead to costly mistakes and delays in the final product.

As engineers, it is important to remember that shortcuts may seem like a good idea at the moment, but they can lead to bigger problems down the road. Taking the time to do things correctly and thoroughly is always worth it in the end. It may take more time and effort, but it will ultimately lead to a better and more successful product.