Signals

What are signals? Research it on your phones. What is the definition of a signal? What are they used for? What are some examples? How do you think waves fit into this phenomenon?

Signals Transmit information from a sender to a receiver Communicate information Store information Convey a message They are actions that can be interpreted They can be noise, pictures, gestures, writing, numbers, equations

Types of Signals: Digital Analog Square wave Sine wave Sent as mathematical coded waves and can be sent over long distances Representations of actual images, sounds, or words using sound or light waves EX: human voice embedded in the grooves of a record, light waves captured on plastic film

Is Digital or Analog more accurate and reliable? Quality of signal is maintained with no interference like analog. Can Carry more information per second than analog. Easier to store information. Takes up less room to store information. More secure-encrypted. Easy to edit. Does not deteriorate the original information during transmission and write/read cycle Analog watches can be more accurate than digital or quartz—high precision movement. Atomic clocks are still the most accurate. The “vintage” coolness factor

Film camera Digital Camera

Have you ever used a decoder to interpret a secret message like George Washington did during the American Revolutionary War?

Fireflies talk to each other by blinking the light in their abdomen Fireflies talk to each other by blinking the light in their abdomen. They use light waves to send flashes in patterns that are unique to communicate information.

How do humans communicate over long distances How do humans communicate over long distances? How is that signal get sent and then received?

How have humans communicated over long distances How have humans communicated over long distances? How is that signal get sent and then received? Morse code Telephone Writing a letter Telegraph Recording a message and then sending it to get played Video tape Cassette Tape

Which one is easier to use? Which one has less human error?

Just because digital technology has advantages, that doesn't mean it's always better than analog. An analog watch might be far more accurate than a digital one if it uses a high-precision movement (gears and springs) to measure time passing, and if it has a sweeping second hand it will represent the time more precisely than a digital watch whose display shows only hours and minutes. Surprisingly, analog watches can also keep time better than quartz ones: the day-to-day variations in a mechanical, analog watch tend to cancel one another out, while those in an electronic quartz watch tend to compound one another. Generally, the most expensive watches in the world are analog ones (of course, that's partly because people prefer the way they look), though the world's most accurate atomic clocks show time with digital displays.

One interesting question is whether information stored in digital form will last as long as analog information. Museums still have paper documents (and ones written on clay or stone) that are thousands of years old, but no-one has the first email or cellphone conversation. Open any book on the history of photography and you'll see reproductions of early photos taken by Niepce, Daguerre, and Fox-Talbot. But you won't see any pictures of the first digital photo: even though it was much more recent, probably no-one knows what it was or who took it! Lots of people own and cherish plastic LP records that are decades old, but no-one attaches the same importance to disposable MP3 music files. A lot of information recorded on early computer memory devices is completely impossible to read with newer computers; even floppy disks, commonplace as recently as the mid-1990s, are impossible to read on modern computers that no longer have built-in floppy drives.