19-06-2013, 12:29 PM
Summer Training Report On Production and Broadcasting of Television Programs In Doordarshan Kendra, Lucknow
Broadcasting of Television.docx (Size: 1.58 MB / Downloads: 59)
Introduction to Doordarshan Kendra, Lucknow
Lucknow Doordarshan started functioning on 27th Nov. 1975 with an interim setup at 22, Ashok Marg, Lucknow. The colour transmission service of National Channel (only with Transmitter) started from 15-8-82. While the regular colour transmission service from studio was started in 1984 with ENG gadgets.
During Reliance Cup, OB Van came to Kendra for outdoor telecast having 4 colour camera chain, recording equipments, portable microwave link. In March 1989 new studio complex started functioning. EFP Van came to Doordarshan Kendra, Lucknow in 1989 with compliment of 3 colour camera chain and recording setup for outdoor telecast. The entire recording of studio/van have been replaced to Beta format High Band edit VCR and still in use as the old recording are on H.B.
SYNC Pulse Generator
Television signals for broadcasting are originated by cameras and telescenes, recorded and replayed by video tape recorders, mixed in studio vision mixers and finally distributed for transmission. Fig. 1 shows the use of sync pulse generator for generating colour composite video signal (CCVS).
Colour Composite Video Signal
CCVS or Colour Composite Video Signal consists of
1) Video signal along with synchronizing signal, composed of line and field synchronising pulses to ensures the locking of scanning systems of a source and destination.
2) Blanking pulses to blank retrace period around the horizontal and vertical synchronising period.
3) Sub carrier and its modulated components to carry the colour information.
4) Burst gate signal (responsible for the correct positioning of the colour burst within the blanking interval) and swinging burst.
The generation of synchronising pulses has been shown in figure 2.
All the pulses required for the generation of CCVS signal are produced by sync pulse generator (SPG). These pulses are produced from a common reference of 4.43 MHz and then by dividing it digitally.
Pulse Distribution
With only one SPG centrally located a mechanism of pulse distribution is required. With each and every 75 ohm destination requires a dedicated 75 ohm source. If this is not done then cables will be incorrectly terminated, signals will have the wrong amplitude and will suffer from reflections. Use of PDA provides multiple feed to various destinations.
SERIAL DIGITAL INTERFACE
Transmission of digital video as serial data has proved more popular than bit-parallel implementations. Serial transmission offers the advantage of smaller, simpler connectors and the freedom from data skew problems means that transmission over longer cable lengths (or increased bit rate) is possible. The multiplex structure shown in Figure 2.8.5 is serialised transmitting the LSB of each 10-bit word first. Assuming13.5MHz luminance sampling, the resulting 27MHz multiplex is serialised to a bit rate of 270 Mb/s.
AUDIO BASE BAND SIGNALS
Audio signal processing, sometimes referred to as audio processing, is the intentional alteration of auditory signal, or sound, often through an audio effect or effects unit. As audio signals may be electronically represented in either digital or analog format, signal processing may occur in either domain. Analog processors operate directly on the electrical signal, while digital processors operate mathematically on the digital representation of that signal.
"Analog" indicates something that is mathematically represented by a set of continuous values; for example, the analog clock uses constantly-moving hands on a physical clock face, where moving the hands directly alters the information that clock is providing. Thus, an analog signal is one represented by a continuous stream of data, in this case along an electrical circuit in the form of voltage, current or charge changes (compare with digital signals below). Analog signal processing (ASP) then involves physically altering the continuous signal by changing the voltage or current or charge via various electrical means.
AUDIO ENGINEERING SOCIETY (AES)
The Audio Engineering Society is the only professional society devoted exclusively to audio technology. Founded in the United States in 1948, the AES has grown to become an international organization that unites audio engineers, creative artists, scientists and students worldwide by promoting advances in audio and disseminating new knowledge and research.
Currently, over 14,000 members are affiliated with more than 75 AES professional sections and more than 95 AES student sections around the world. Section activities may include guest speakers, technical tours, demonstrations and social functions. Through local AES section events, members experience valuable opportunities for professional networking and personal growth.
The AES also serves the educational needs of its members and the audio industry at large through international technical meetings, equipment exhibitions, and a wide range of publications.
Conventions, which include scientific presentations, student activities, workshops, and exhibitions, are held annually both in the US and Europe. Additional conferences and regional summits are held periodically throughout Latin America, Asia, Europe, and North America.