Digital Coding and Transmission

Course Syllabus

Digital Coding and Transmission (DCT)
A 5 day course

This course can be provided 'in-house' on request

Course Outline
This course aims to update the broadcast engineer who is well versed in digital audio technology, but now needs to consolidate their knowledge and understanding of some of the latest techniques being offered for video and audio recording and broadcasting.

The course aims to answer the question "Just how do you achieve considerably more broadcast quality digital channels where there was previously only one analogue channel?". Compression techniques are generally described and the various algorithms available such as MPEG 2 are discussed.

An overview of digital signal traffic schemes is given including those proposed for the imminent terrestrial and satellite broadcasting standards. A brief introduction is given to network technology.

Course Syllabus

DAY 1
AM

Session 1 and 2 - Lecture NT1 Revision of current digital signal technology

Sampling and quantising considerations. Over sampling and dither. Multidimensional sampling. Consideration of channel codes, bi phase mark, bit mapping and block codes. Error code, CRCC, Hamming, Reed Solomon Tactics etc.

Session 3 and 4 - Lecture NT2 Review of 601 Parameter and Specification

ITU-R 601 and 656 extensible family of digital video coding standards. 4:4;4, 4:2:2 etc. The composite video serial digital interface and its parameters. The Sony SDI system for 10 bit encoding. Specification and parameters of the Serial Digital Interface. Ancillary data and embedded audio Scrambled NRZI channel code. 16 x 9 wide screen serial interface specification.

DAY 2
AM

Session 1 - Lecture NT2 Continued
Session 2 - Lecture NT3 Digital Audio Interfacts

Sample rates and word size, Frame structure, preamble, CUV and R bits, channel status word, AES timecode, AES channel code, balanced and unbalanced interfaces, working impedance. MADI, SDIF digital audio word clocking and timing.

Session 3 - Lecture NT3 Digital Audio Interfaces (cont.)
Session 4 - Lecture NT4 Data Compression Techniques, an overview

Why compress? Entropy, information and statistical redundancy.? Lossless coding. Adaptive and non adaptive methods.Difference coding and prediction (DPCM). Sub-Nyquist sampling. Variable length coding, run length coding. Entropy encoding interpolation and concealment. Perceptive coding.

DAY 3
AM

Session 1 and 2 - Lecture NT5 Compression Processes

Transforms the two dimensional DCT, thresholding and quantisation, block scanning, the motion compensated inter frame DCT, block matching, adaptive interframe and intra field coding, motion prediction, I, P and B frames variable length coding and the Huffman code, error protection. Sub band coding.

Session 3 - Lecture NT6 Video Compresion Systems

An overview of JPEG, MPEG 1 and 2, data rates, temporal and spatial entropy, the spatial DCT, motion compensated inter frame prediction, compression profiles, scaleable family concept, tools for scalability. Summary of the main tools available for MPEG 2 Compression. 422P @ML for studio applications.

Session 4 - Lecture NT7 Audio Compression Systems

Psycho aural aspects of the hearing mechanism. Noise masking profiles, Sub band coding, transform coding, a sub-band codec. Audio compression methods, Nicam MPEG 2 audio compression ISO layers., ISO layers, aptx100, Atrac Dolby AC3.

DAY 4
AM

Session 1 - Lecture NT8 MPEG 2 Bitstream Syntax

Structure of the MPEG 2 video, audio and data elementary streams. Access units, video, audio and data elementary streams, PES packets, transport packets, MPEG 2 transport stream multiplex. PSI tables, time stamps, PTS access units, overview of the MPEG 2 mux and demux processes. Range of compression ratios and impairments anticipated. Audio and MPEG, frame delays. FEC tactics and stuffing.

Session 2 - Lecture NT9 Digital Transmission Processes

Review of analogue modulation methods. Phase shift keying, QSPK, QAM, FDM, OFDM. Comparison of digital modulation methods and their application to terrestrial, cable and satellite transmission. Bitstream switching and the MOLE. Seamless concatenation and the Atlantic Project.

Session 3 - Demonstration Analysing the MPEG 2 Mux Data

Demonstration of the Snell and Wilcox range of MPEG 2 MUX data stream test equipment.
It is hoped to demonstrate the Snell and Wilcox MSA 100 Data Integrity Analyser, the MVA data content analyser, and the MSP 100 data stream generator dependent upon equipment availability.

Session 4 -Demonstration Compression Artifacts

Discussion and demonstration of compression artefacts, blocking, motion noise, banding, posterising, mosquito wings etc.

DAY 5
AM

Session 1 - Lecture NT10 MPEG2 Terrestrial and Satellite Transmission Paths

Overview of the complete MPEG mux/demux path. Examining signal processing, from MPEG encoding, through the IRD, to the consumer receiver, via terrestrial and satellite paths. Reference will be made to relevant aspects of DVB and Digital TV Group documents.

Session 2 - Lecture NT11 Digital Networking and Distribution Methods

Topics will be selected from the following:- Networking/communication systems and methods PDH, SDH, ISDN, ADSL, ATM, frame relay, ADSL and HDSL, FDDI, fibre channel, cable networking, statistical multiplexing.

Session 3 - Revision and Buffer Session

Session 4 - Revision, Assessment and Course Review