Digital television systems - (DTS) Lectures Digitization Technical Univ. of Kosice Faculty of Electrical Engineering and Informatics Lˇ. Maceková, 2017

Why Digitization? ---- Digitizing information makes it easier to preserve, access, and share. For example, an original historical document may only be accessible to people who visit its physical location, but if the document content is digitized, it can be made available to people worldwide. There is a growing trend towards digitization of historically and culturally significant data. Digital data (binary computer language) are well processed by special processors and computers (that are digital devices) Digitization is the process of converting information into a digital format . In this format, information is organized into discrete units of data (called bit s) that can be separately addressed (usually in multiple-bit groups called byte s). This is the binary data that computers and many devices with computing capacity (such as digital camera s and digital hearing aid s) can process. Text and images can be digitized similarly: a scanner captures an image (which may be an image of text) and converts it to an image file, such as a bitmap . An optical character recognition ( OCR ) program analyzes a text image for light and dark areas in order to identify each alphabetic letter or numeric digit, and converts each character into an ASCIIcode. Analog-to-digital conversion processes: continuously variable ( analog ) signal is changed, without altering its essential content, into a multi-level (digital) signal. The process of sampling measures the amplitude (signal strength) of an analog waveform at evenly spaced time markers and represents the samples as numerical values for input as digital data.

Color signal - PAL norm Image color signal PAL The sequence of color hues (in the measurement color bars with decremented level of brightness) [1]

The source od digital color signal Sampling (after this, quantization) and codding of analogue signal – by standard ITU-T BT.601

2. Raster (matrix) model of digital color image and image sequence 5 2. Raster (matrix) model of digital color image and image sequence matrices M x N picture elements (pixels) brightness level: 8 bit/pixel (BW picture) 3 x 8 bit /pixel - dig. expression of the colour (e.g.. RGB) image sequence = (n frames / sec.)  time,  there is a huge amount of data N M the sum of data volume: M x N x 8 x n x number of seconds (enough... )

Encoding parameter values for the 4:2:2 member of the family The specification (see Table 3) applies to the 4:2:2 member of the family, to be used for the standard digital interface between main digital studio equipment and for international programme exchange of 4:3 aspect ratio digital television or wide-screen 16:9 aspect ratio digital television when it is necessary to keep the same analogue signal bandwidth and digital rates Fig.: Table 3 from the ITU-T B.601 standard

Example: Calculate the bit rate at 4:2:2 sampling scheme [ITU-T B.601], at: a)8 bit per sample for each, Y, CR, CB sample, b) 10 bit per sample for each, Y, CR, CB sample, Solution: a) luminance: 13,5 MHz x 8 bits = 108 Mbps each color difference signals: 6,5 MHz x 8 bits x 2 = 108 Mbps ------ Together: 108 + 108 = 216 Mbps b) luminance: 13,5 MHz x 10 bits = 135 Mbps each color difference signals: 6,5 MHz x 10 bits x 2 = 135 Mbps Together: 135 + 135 = 270 Mbps This is the basic data rate for SDI (Serial Digital Interface) for digital component signal transmission.

Channel Spacing Existing analog TV channels are spaced so they do not interfere with each other. Gap between PAL TV services VHF 1 channel UHF 2 channels Digital TV can make use of these gaps I talked earlier about there being problems with channel spacing and taboo channels. Analog TV cannot cope with another analog service in the adjacent channel without some interference occuring. An analog service in channel 8 above would interfere with channel 7 & 9 in the same area. Digital has been designed to use these inbetween channels without interfering with the Analog service. Ch 6 Ch 7 Ch 8 Ch 9 Ch 9A Taboo Taboo Taboo VHF Television Spectrum

Digital Challenges Digital TV must co-exist with existing PAL services DTV operates at lower power DTV copes higher interference levels Share transmission infra-structure DTV needs different planning methods The digram here shows the spectrums of both 8-VSB and COFDM in the adjacent channels 6 & 8. Note that the 8-VSB has a lot more room at the edge of the channel. This is because it is a 6 MHz system operating in a 7MHz channel. The COFDM signal gets very close to the sound subcarriers of channel 7. Because it is in the same area as current transmissions the antennas & towers can be shared by combining the signals. This avoids constructing new towers but does need some complex combiners to be built. Ch 6 Ch 7 Ch 8 Ch 9 Ch 9A 8-VSB COFDM VHF Television Spectrum

DTTB & PAL

Channel Combining VISION CARRIER VISION CARRIER 7 MHz 7 MHz 7 MHz PAL DIGITAL CHANNEL N WANTED Colour Sub Carrier Colour Sub Carrier AUDIO CARRIERS CHANNEL [N - 1] LOWER ADJACENT CHANNEL [N + 1] UPPER ADJACENT

UHF Channels: London Photograph by courtesy and © BBC R&D As we have discussed, each IRD contains components which are responsible for the decoding, demultiplexing and demodulation of signals and components which are responsible for decrypting of signals. NDS licenses its technologies to a number of hardware manufacturers. These include Thomson, Sony, Hughes, Sanyo, Samsung and Panasonic for conditional access, and Pace and Mitsubishi for digital IRD technology NDS receives upfront integration fees and ongoing royalties under these license arrangements Core operating software and electronic program guide software are new offerings first being shipped this quarter to StarTV, NetSat and Innova initial licensee - Pace 38