PHYSICAL SCIENCEFORCES and INTERACTIONS

Bell RingerWhy are MP3’s better than cassette tapes? List as many reasons as you can for class discussion (at

least 2)

Objectives For Today:

•By the end of the day you should:

Be able to… Make an argument that digitized signals are a more reliable way to encode and transmit information than analog signals

Agenda/Announcements!

Bell RingerDigital Vs. Analog NotesDigital Vs. Analog reading/writing

Homework: If not finished, statement defense needs to be finished before tomorrow in order to obtain ipad for Friday time.

Digital Vs. Analog – Defining termsDigital signals - A direct pulse, either on or off, that conveys information in a binary form (1's and 0's)

Analog signals - are continuous waves that vary in strength and quality

Helpful visual:

The Journey from Analog to Digital (Audio)In 1857, a French inventor created the phonautograph, a device that could record sound waves as it passed through the air. It consisted of a soot covered paper wrapped around a cylinder that had a rod that would scratch out a waveform.

In 1877, Thomas Edison (creator of the lightbulband many other inventions) created the first machine that could record and replay sounds. His machine was called the phonograph. Edison used a rotating cylinder coated in wax that would etch grooves and when a needle hit the vibrations, it would re-play the recorded sound

The Journey from Analog to Digital (Audio)

The phonograph eventually led to the vinyl record player, which was a more reliable and easily manufactured way to reproduce sound.

The record player had limitations in that to make copies, only a limited number could be made, and the original recording was destroyed in the process.

Magnetic tapes were developed by the Germans in WWII and perfected by an American audio engineer John T. Mullin in 1947. This allowed for unlimited copies and higher audio quality

The Journey from Analog to Digital (Audio)Throughout the 1970’s digital audio recorders were created and developed. Digital audio took samples of a sound at 44.1 kHz, or 44,100 times per second

Magnetic tapes had serious drawbacks. They were susceptible to magnetic interference and had to be rewound.

The fully digital Compact Disc (CD) was created in 1982. Sales peaked in the year 2000.

Currently, audio tracks are stored in .mp3 format which is a completely digital medium.

So What IS Digital?

The main difference between digital and analog is HOW the information is stored.

In an analog device, information is continuously recorded. In a digital device, sound is sampled at thousands of times per second.

The difference is largely unnoticeable.

How much does the internet weigh?

Reading and Writing Prompt

Passing out of Reading – Read and Discuss

Other Examples of Digital Development:Cameras (Visual):

Pinhole cameras invented by ancient chinese and greeks to project an upside down image onto a viewing surface

1839 First conventional camera invented called the Daguerrotype

1889 First film cameras

1988 First fully digital camera

Pros and Cons of Digital SignalsPros•Storage – lots of

information in a small space•Reproducibility – can be

copied indefinitely with zero loss of quality

•Capability –You can layer more information together with digital signals (DTV, Mantis Shrimp eye)

•***Easily created and edited***

Cons•Lacks fidelity – isn’t the

“true” record

•***Easily created and edited*** (Internet hot-heads, mistakes last forever…think before you post)

•Easily forgotten – Think about letters, newspapers, Rosetta stone etc

Pros and Cons of Analog SignalsPros•Fidelity – The first copy is the closest to the original performance

•Accessibility – Easily created with low-tech, lost cost means.

Cons•Storage – requires large amounts of space

•Reproducibility –reproducing difficult, often loses quality

•Fragility – Analog recordings are subject to data loss

Other Examples of Digital Development:Movies:

The first motion picture was the famous “Horse in motion” it was literally a series of pictures that moved.

1890’s The first film movies. Movies recorded on a film medium, but were silent.

1976 First VHS film

1995 First DVD

1998 Fully digital online HD movie file types

2007 Netflix streaming internet video

Reading and Writing PromptIn your notebook, write three short paragraphs summarizing why you think digitized signals are a more reliable way to encode and transmit information.

Use your notes, feel free to use examples from your personal life and interaction with technology

This will be checked tomorrow before you check out ipads