1. What is an analog-digital converter?

An Analog-Digital Converter (ADC) is a widely used electronic component that converts an analog electric signal (usually a voltage) into a digital representation. The ADCs are at the front-end of any digital circuit that needs to process signals coming from the exterior world. Its schematic symbol is:

The output of a microphone, the voltage at a photodiode or the signal of an accelerometer are examples of analog values that need to be converted so that a microprocessor can work with them.

2. How does the ADC convert a signal?

Many ways have been developed to convert an analog signal, each with its strengths and weaknesses. The choice of the ADC for a given application is usually defined by the requirements you have: if you need speed, use a fast ADC; if you need precision, use an accurate ADC; if you are constrained in space, use a compact ADC.

All ADCs work under the same principle: they need to convert a signal to a certain number of bits N. The sequence of bits represents the number and each bit has the double of the weight of the next, starting from the Most Significant Bit (MSB) up to the Least Significant Bit (LSB). In a nutshell, we want to find the sequence of bits bN−1, bN−2, ..., b0 that represents the analog value Vin as Vin=∑n=0N−1bn2nVref2N.

                                (www.onmyphd.com/?p=analog.digital.converter. Adaptado)

                                      A Free Press Needs You

By The Editorial Board

August 15, 2018

      In 1787, the year the Constitution was adopted in the USA, Thomas Jefferson famously wrote to a friend, “Were it left to me to decide whether we should have a government without newspapers, or newspapers without a government, I should not hesitate a moment to prefer the latter.”

      That’s how he felt before he became president, anyway. Twenty years later, after enduring the oversight of the press from inside the White House, he was less sure of its value. “Nothing can now be believed which is seen in a newspaper,” he wrote. “Truth itself becomes suspicious by being put into that polluted vehicle.”

      Jefferson’s discomfort was, and remains, understandable. Reporting the news in an open society is an enterprise laced with conflict. His discomfort also illustrates the need for the right of free press he helped to preserve. As the founders believed from their own experience, a well-informed public is best equipped to root out corruption and, over the long haul, promotes liberty and justice. “Public discussion is a political duty,” the Supreme Court said in 1964. That discussion must be “uninhibited, robust, and wide-open” and “may well include vehement, caustic and sometimes unpleasantly sharp attacks on government and public officials.”

(www.nytimes.com/interactive/2018/08/15/opinion/editorials/free-press-local-journalism-news-donald-trump.html?action=click&module=Trending&pgtype=Article®ion=Footer&contentCollection=Trending. Adaptado.)

                                   A Free Press Needs You

By The Editorial Board

August 15, 2018

      In 1787, the year the Constitution was adopted in the USA, Thomas Jefferson famously wrote to a friend, “Were it left to me to decide whether we should have a government without newspapers, or newspapers without a government, I should not hesitate a moment to prefer the latter.”

      That’s how he felt before he became president, anyway. Twenty years later, after enduring the oversight of the press from inside the White House, he was less sure of its value. “Nothing can now be believed which is seen in a newspaper,” he wrote. “Truth itself becomes suspicious by being put into that polluted vehicle.”

      Jefferson’s discomfort was, and remains, understandable. Reporting the news in an open society is an enterprise laced with conflict. His discomfort also illustrates the need for the right of free press he helped to preserve. As the founders believed from their own experience, a well-informed public is best equipped to root out corruption and, over the long haul, promotes liberty and justice. “Public discussion is a political duty,” the Supreme Court said in 1964. That discussion must be “uninhibited, robust, and wide-open” and “may well include vehement, caustic and sometimes unpleasantly sharp attacks on government and public officials.”

(www.nytimes.com/interactive/2018/08/15/opinion/editorials/free-press-local -journalism-news-donald-trump.html?action=click&module=Trending& pgtype=Article®ion=Footer&contentCollection=Trending. Adaptado.)

                                         Knowledge and the library

      It was not until the development of monastic libraries in Europe around 1200 that humanity amassed in a single place what approached the collective wisdom and knowledge of the age. Libraries may be exchanges of information and market places for ideas but they are also the buildings which contain the bulk of human knowledge. Or, at least they were until the electronic digitally stored information revolution of the 1980s.

      Now knowledge is virtually everywhere; it has broken free of the constraint of buildings. Today if you were today to destroy all the world’s libraries, it is unlikely that more than 20% of human knowledge would be lost. Certainly, a large amount of archival material would disappear forever, but a substantial volume of knowledge would survive. If a library is a repository of knowledge, this is now just one of its functions. The library’s prime function is now making that knowledge available and encouraging exchange and reflection upon it.

      Electronic knowledge is nowadays available to everybody – in the home, workplace, airport terminal, school, and so on. The Internet has liberated the library; nevertheless, it has not removed the justification for library facilities.

                 (www.sciencedirect.com/science/article/pii/B978185617619410017X. Adaptado)