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Author Archives: mathscinotes
Pope Gregory XIII and Dual Modulus Counters
I discussed a recent dual-modulus counter design in a previous post. I had not thought much about the history of these counters, but I noticed that our calendar is really a dual-modulus counter. Pope Gregory XIII (Figure 1) established the Gregorian calendar (1582) to resolve issues with the Julian calendar. The reason that calendar development is complicated is because a solar year is 365.24219879 days long, which is not easily expressed in terms of simple integer ratios. Ideally, a calendar system is chosen that is simple and that has a mean year length exactly equal to that of a solar year. While not ideal, the Gregorian calendar provides a simple and fairly accurate approximation to a solar year through the use of a dual-modulus counter design based on years with durations of 365 and 366 days. Continue reading
The Difficulties Posed By Communications
My company currently has engineering work occurring at a number of sites that are widely separated geographically. Trying to coordinate these sites is definitely a challenge. However, this really is nothing new. When I was at HP, my first manager used to say that "Engineering communication reduces by 10 dB per foot." Continue reading
Posted in Management
Tagged communication, management
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The Law of Employee Retention
I was just interviewing a large number of people as part of an acquisition. After the interviews were done, the interviewers all went out to dinner and discussed the day's events. While at dinner, the topic of employee retention came … Continue reading
Posted in Management
Tagged engineers, interviewing, laws, management
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Dual Modulus Counter Design Example
Quote of the Day I have long been of the opinion that if work were such a splendid thing the rich would have kept more of it for themselves. — Bruce Grocott, British politician Introduction One of the more common … Continue reading
Little Stories from the History of Science and Technology
Introduction I have always been interested in the connectedness of people. The theory that each of us is separated by only six degrees from anyone else is a theory I like to test. If you examine things carefully, you may … Continue reading
Posted in Electronics, History of Science and Technology
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Test Time and Estimating Bit Error Rate
Test time is expensive. Since our products need to conform to industry standards for Bit Error Rate (BER), we need to test for BER. It is important that we test long enough to ensure that we meet the requirements, yet not so long as to spend more money than we need to. Continue reading
Calculating the Earth's Age
I have been listening to the audio book The Disappearing Spoon, which is an excellent tale about all of the elements of the periodic table. Of particular interest to me was the discussion of how geologists date the age of the Earth using ratios of uranium and lead. The book also discusses determining the ages of meteorites and the Sun. The discussions were interesting enough that I thought I would look up some additional information. As frequently happens, I was amazed at the amount of information on the web about this subject. This technique has been around since 1956, when it was first used to date meteor fragments from a well-known impact site (Figure 1). Continue reading
Posted in Astronomy, General Science
Tagged Geology, Radioactive Dating
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Power Dissipated in a Maximum Phone Load During Ringing
I am writing a specification this morning and I realized that I have never calculated the maximum power drawn by a phone during ringing. I was surprised by the number – 3 W. This is a lot for unit that … Continue reading
Posted in Electronics
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Thermal Runaway Model of Lead-Acid Battery (Part 2)
Derivation of the Output Power Equation The output power equation (Equation 3) is really a restatement of Newton's law of cooling. Equation 3 states the battery's steady-state power dissipation is a linear function of the battery's temperature and the ambient … Continue reading
Thermal Runaway Model of a Lead-Acid Battery (Part 1)
Introduction Very nearly every product we make ships with one or more lead-acid batteries. Since we have built hundreds of thousands of units, that is a lot of batteries. While most people encounter batteries everyday, few really understand the problems … Continue reading
Posted in Batteries, Electronics
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