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Comment: Re:EMC compliance (Score 4, Informative) 811

From an electrical point of view, many medical devices are simply to sensitive to be made immune to induced interference. The noise will have to affect them some how. It is just a matter of how big the noise source is (magnitude), the frequency of the noise source (Hz), and what geometry it sits relative to the medical device (coupling.)

Obviously, the TSA has found a big enough noise source.

In particular, the difficulty with mm-wave interference is that it can induce noise directly onto the geometries of integrated circuits and thin-film devices. The only way to guard against the problem would be to heavily shield the chips in question. Maybe it is time for medical devices to start using radiation-hardened integrated circuits. Radiation hardened circuits are designed to withstand short and intense blasts of EMI, including high-frequency EMI sources.

Comment: They are called: Submarine Patents (Score 2) 285

by Cassini2 (#39844231) Attached to: Congress Asks Patent Office To Consider Secret Patents

Submarines patents are when a patent is deliberately kept hidden until the competitors develop competing products. They are particularly effective when they allow a company to patent an industry standard, as in the Rambus lawsuit against DDR-RAM.

This proposal would allow lawyers to easily create submarine patents. Because of the secrecy, it could even happen that more than one company has submarine patents on the same industry standard technology.

Submarine patents block industry standards and free software.

Comment: Sad state of modern technology ... (Score 4, Interesting) 143

by Cassini2 (#39759431) Attached to: 30 Years of the TRS-80 Model 100

The Model 100 had a number of features that modern computers lack. If you need a simple computer to make notes, its battery life was in the 20 hours region. It was many many long years before the modern PC laptop was "portable" and had a battery life greater than 3 hours. (I'm thinking of some of the old transportables, which weighed 35 lbs and had no batteries.)

At long last, with the advent of the OLPC, the Eee PC, the smartphone, and a few of the smaller laptops, battery life has reached the 6 to 12 hours. However, for taking a piece of equipment to strange places with no power, being able to use AA batteries to power your computer is a really helpful feature.

Really wish the modern laptop could run from batteries longer. It's sad that a 30 year old PC is still competitive with regards to battery life.

Comment: Re:Personal Experience: Brakes do not stop the eng (Score 1) 911

by Cassini2 (#39682325) Attached to: Mandatory Brake-Override Proposed For All Cars

I was on ice. Ice also jammed the accelerator cable (which is what locked the engine at full throttle.)

Personally, I suspect three problems:
1. On ice, the ABS system may actually prevent applying full power to the brakes.
2. It was a pickup truck, and it had a ton of torque. As an engineer, I have my doubts that brakes could stop the engine. However, at least historically, brakes on most cars are not rated to full engine output. As a GM mechanic explained it to me: brakes on GM vehicles were rated to 70 mph, because that is (was) the legal requirement. Never mind the fact that most vehicles can go much faster than 70 mph.
3. If I had ice on the road, and ice on my accelerator cable, then it is possible that ice was present on the brakes themselves. However, I would think the pads would heat, and boil off the ice. Alternatively, the pads may possibly have heated and glazed, in which case there stopping power would be limited.

I religiously maintain my brakes. Lack of maintenance was not a factor in the failure.

Comment: Personal Experience: Brakes do not stop the engine (Score 1) 911

by Cassini2 (#39676353) Attached to: Mandatory Brake-Override Proposed For All Cars

The brakes are not more powerful than the engine. Firstly, I work in automotive. The design specification on most modern braking systems is below what is required for a worst case stop. Secondly, in an emergency situation, full power assist may not be present. You would have to be superman to apply full brakes without power assist. Parking brakes do not help either. On most cars, it is trivial to demonstrate driving out of the driveway with the parking brake on.

Lastly, I have been in a car with a runaway engine. THE BRAKES WERE NOT CAPABLE OF STOPPING THE ENGINE. Putting the car in neutral, and turning off the engine both worked. Getting caught in a snow bank helps too. :-)

Comment: Officials not allowed to use their own judgement (Score 2) 537

It used to be that police would investigate intelligently, and lay charges appropriately. Now, it appears that everything must reach a judge before common sense is applied. We are living in the days where losing a cell phone will cause a plane to be grounded. We need to get people to use their brains again, and not make major incidents out of false alarms.

Comment: Re:The bit depth does matter (Score 1) 841

The GP post is essentially correct. I did a bunch of the math behind it in my undergraduate thesis / research project in the context of high-speed PWMs for motor drives.

Essentially, if you reconstruct the sampled information with a non-ideal DAC converter, it phase shifts the output based on the time varying magnitudes of the input signals. When analyzed mathematically, the effect is very similar to phase modulation (PM) or frequency modulation (FM). Normally, phase and frequency modulation is used in the context of radio receivers, which use complex filters prevent distortion. The audio amplifier has none of these filters, and the result is that the phase modulation shows up as audible distortion inside the normal frequency band. The effects of this distortion are significant. I noted them in the context of a motor drive.

Modern DAC manufacturers are well aware of the fact that their products are non-ideal. As such, almost all of the new audo DACs feature circuits to reduce the distortion. However, this distortion ellimination isn't perfect, especially for a 16-bit/44.1 kHz signal. Nevertheless, numerous papers have been published on how to create a DAC converter that behaves more closely to the ideal DAC converter modelled in Nyquist sampling theory.

Realistically, the bigger problem with the 16 bit/44.1 kHz format is the loudness wars. The loudness wars cause clipping. No amount DAC converter trickery can fix clipping. The result is that people say old LPs now sound better than new CDs. They are correct. The old LPs were mastered with more dynamic range and less clipping than modern recordings.

Comment: Re:Could make sense (Score 3, Interesting) 217

Power failures can last several days. Parts of the north eastern U.S. and Ontario have been blacked out for several days at a time. Montreal was hit by an ice-storm that caused them to lose power for several days too.

It doesn't happen often, but the problem with big disasters is that they are big. Emergency equipment still has to run.

Copper phone line work well as a backup.

We will have solar energy as soon as the utility companies solve one technical problem -- how to run a sunbeam through a meter.

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