Part 2 of this article looked at the amazing engineering and construction of dual under-river tunnels that were constructed to connect NY’s Manhattan Island to New Jersey and the rest of the mainland US and the electric locomotives that made the project possible. This final part looks at the design, short life, and sad fate […]
Electrified Locomotives, Tunnels, and the Pennsylvania Railroad, Part 2: The tunnels
Part 1 of this article established the context of the problem and why it had defied solution for so long. Once electric locomotives became a viable source of motive power, the tunnel project moved ahead with astonishing speed. The tunnel defies the critics Critics said it couldn’t be done, and they had reason to say […]
Electrified Locomotives, Tunnels, and the Pennsylvania Railroad: Astonishing engineering but a partially sad ending, Part 1: The challenge
The development of powerful electric traction motors and locomotives was key to enabling visionaries to realize their dream of a mile-long tunnel under the Hudson River, linking New York to New Jersey and the rest of the mainland USA. Over the past few years, there’s been semi-serious talk about digging new tunnels under the Hudson […]
What are the applications and measurements of S-parameters? (Part 2)
Part 1 of this FAQ was a basic introduction to the context and concept of s-parameters. Part 2 looks at their measurement and application and relationship to the time domain. Q: How do you actually measure s-parameters? A: In general, except for approximate measurements, you cannot use a spectrum analyzer alone for this frequency-domain test. […]
What are the functions and principles of S-parameters (Part 1)?
As design frequencies now routinely go into the hundreds of MHz and tens of GHz range, conventional voltage and current measurements are not useful, but scattering (s) parameters can fully characterize the RF component or path performance. For engineers with experience focused from DC to several hundred megahertz, it is usually sufficient to characterize components […]
Fluxgate compasses, Part 2 – Issues and enhancements
Part 1 of this FAQ examined the underlying context of fluxgate compasses and navigation, as well as the basic principles of the fluxgate design. This part looks at additional fluxgate-compass issues and advances in their implementation. The fluxgate compass is fairly simple in principle. However, as with all things related to magnetism in general and […]
Fluxgate Compasses, Part 1 – Context and principles
Despite the availability of GPS and inertial measurement units, the compass in an electronic fluxgate implementation is still a viable and needed navigational tool. The classic magnetic-needle compass is not getting much respect or attention these days. Between the Global Positioning System (GPS) and the Inertial Measurement Unit (IMU) system, the compass – whether it […]
The Hubble Space Telescope: Part 4
Part 1 looked at the difficult, costly, and lengthy journey from concept to a successful launch. Part 2 looked at the severe problems of the HST discovered after launch, and Part 3 looked at what has been learned from the Hubble “experience.” The final installment of this story looks at the plans for a post-Hubble […]
The Hubble Space Telescope: Part 3
Part 1 looked at the difficult, costly, and lengthy journey from concept to a successful launch. Part 2 looked at the severe problems of the HST discovered after launch. Part 3 of this story looks at what has been learned from the Hubble “experience.” There are many lessons from this expensive disaster turned into spectacular […]
The Hubble Space Telescope: concept, delay, embarrassment, despair, and finally – jubilation, Part 2
Part 1 looked at the difficult, costly, and lengthy journey from concept to a successful launch. Part 2 looks at the severe problems of the HST discovered after launch. Out of Focus: only the most-obvious problem When Hubble’s lens cover was first pulled back, and the imager saw its “first light,” no one expected picture-perfect […]