Broadcasting Standards

-

Broadcast Standards

Another group of standards combine technical and legal definitions. These are called ATSC, NTSC, PAL, and SECAM. ATSC
ATSC stands for Advanced Television Systems Committee, but the acronym is synonymous with the group's standard for digital television broadcast. ATSC is used for over-the-air transmission of HDTV signals, replacing the former analog standard NTSC. It can support video resolutions up to 1080p and 5.1 surround audio, and can be picked up on the same frequency UHF/VHF antennas as NTSC.
NTSC
NTSC stands for National Television Standards Committee, and is synonymous with the video transmission standard for North and Central America, including Mexico and Canada, and Japan. Its technical format is 525 lines per frame at roughly 30 frames per second refresh rate. The video is interlaced over the even and odd scanlines, for an apparent refresh rate of ~60fps. In quality, NTSC is equivalent to a composite signal. but is not necessarily equivalent to the output from a video capture card that may claim to be NTSC-legal.
NTSC is no longer utilized in the United States, having been replaced with the digital ATSC standard in 2009.
PAL
PAL (Phase Alteration Line) is the European counterpart to the NTSC standard. It has a higher vertical resolution (625 lines per frame) but a lower refresh rate (25 frames per second) that can cause flickering. It is the standard for the UK, Western Europe, the Middle East, and parts of Africa and South America.

Comments

Post a Comment

Popular posts from this blog

Symbol rate, Bandwidth and Bit rate Calculation

-
In satellite communication bandwidth (BW), symbol rate and bit rate are the most vital fact for proper signal transmission. There are many commercial software for BW, Symbol rate and bit rate calculation for TV signal transmission. But the equations of these parameter calculation are as follows. BW= (1+Roll of factor)* Symbol rate In general Roll of factor is 35% Symbol Rate =BW / (1+Roll of factor) and Bit Rate = Symbol rate * Modulation* FEC* (188/204)                                     [when 188 is encoder packet length] or Bit Rate = Symbol rate * Modulation* FEC* (204/188)                                     [when 204 is encoder packet length] Here, FEC = Forward Error Correction. In general FEC is in the range from 1/2 to 7/8. 188/204 = constant Unit ** BW= Hz, KHz, MHz, GHZ ** Symbol Rate= sps or baud, Ksps or Kbaud, Msps or Mbaud, Gsps or Gbaud ** Bit Rate= bps, Kbps, Mbps, Gbps Baud: U nit of signalling speed Baud rate: N umber of symbols transm
Read more

Terminology: EIRP, G/T, Input Back-Off, Output Back-Off

-
  EIRP:   Used to indicate the power transmitted from an antenna. EIRP=Power +Antenna Gain, Both EIRP and Power is expressed in dBW and Gain in dBi. G/T:   It is the figure of merit for an earth station and is expressed as dB/K (dB per K). G/T= Antenna Gain-10*Log (System Noise Temperature) The higher the better-G/T can be raised by using a higher gain antenna or a lower temperature LNA. The earth station G/T determines the received carrier to noise ration. Increasing station G/T will increase the C/N of the received carrier. Input Back-Off (IPBO):   The level of a signal at the input of an amplifier relative to that level at the input that would result in the maximum possible output level. For example, if an input level of -20dBm causes max output and the actual input level is -25dBm, the IPBO is 5dB. Both IPBO and OPBO are commonly used to determine the operating levels in a satellite transponder TWTA. Output Back-Off (OPBO)   The level of a signal at the output
Read more

Bit Error Rate (BER) and Roll Off Factor

-
Image
Roll Off  Factor W hen a digital signal is modulated the output would be a waveform with the shape of sin(x)/x. Now this has an infinite bandwidth. So in order to be able to transmit this signal over satellite we need to filter it to reduce the occupied bandwidth. This is done by applying a "raised cosine roll-off filter". This filter is present both at the modulator output stage and at the input of the demodulator (I believe one says these filters are then matched). The steepness and the resulting occupied bandwidth can be set by the parameter roll-off factor. In DVB-S2 it can be 0.20 (20%); 0.25 (25%) or 0.35 (35%) where the  Occupied bandwidth = symbol rate x (1 + roll-off factor). Figure: Occupied bandwidth, Roll off factor and symbol rate 
Read more

Followers