MDIA 308 Television

Television Like film – television is actually a series of still images presented to the eye in rapid successionLike film – television is actually a series of still images presented to the eye in rapid succession Earliest experiments in 1890sEarliest experiments in 1890s –Italian monk – Casselli –Pictures by wire

Television Mechanical TelevisionMechanical Television Paul Nipkow – scanning diskPaul Nipkow – scanning disk –Nipkow disk John Loge BairdJohn Loge Baird –Scottish inventor working with BBC –Launched the first system based on mechanical scanning

Nipkow disk

Television Electronic television – cathode ray tubeElectronic television – cathode ray tube Vladimir ZworykinVladimir Zworykin –Iconoscope Philo T. FarnsworthPhilo T. Farnsworth –Image Dissector

Television

Electronic scanning

White light Beam splitter

Cathode ray tube White light Beam splitter

Color TV screens

Television standards National Television Standard Commission (NTSC) Standard Definition (SDTV) 4:3 aspect ratio 525 lines of horizontal resolution 30 frames per second 60 fields per second 2 fields per frame Interlace scanning

Television standards High definition (HDTV) 16:9 aspect ratio 1080 lines of horizontal resolution 30 frames per second Progressive scanning

Magnetic tape recording Magnetic recording heads are transducers that convert electrical energy into magnetic Recording heads are electromagnets Audio current creates an alternating magnetic field The magnetic field is focused at the “gap” in the record head

Magnetic tape recording

The fluctuations in the magnetic field are stored on tape by re-arranging the magnetic polarity of the “metal” surface of the tape The tape surface is made from powdered metals, like FeO 2, or iron oxide (rust) The metals are attached to a plastic backing with binder (glue)

Magnetic tape recording Playback heads are constructed in a nearly identical manner During playback, a current is induced to flow in the coil of the head by the magnetic charges of the tape surface

Fundamentals of Audio Production. Chapter Analog tape recording Reel to reel

Videotape Ampex corporation invented the videotape recorder Allowed television programs to be recorded and “mistakes” could be corrected

Quadruplex Videotape

Quadruplex

Helical scan